cssi/SciSciGPT-SciSciNet huggingface dataset:
Neural network prediction and control of three-dimensional unsteady separated flowfields

Using artificial neural networks (ANN), one approach to the control of unsteady aerodynamics is to develop real-time models which, given the actuator control signals, anticipate the unsteady flowfield wing interactions. These models of flow-wing interactions can then be used as the foundation upon which to develop adaptive control systems. This article supports this concept using three-dimensional unsteady surface pressure topologies collected from a rectangular wing pitched through the static stall angle at seven nondimensional pitch rates. A neural network model of the unsteady surface pressures was developed by training an ANN on five of these seven data sets. Following training, the only inputs required for the model were instantaneous angle of attack and angular velocity. These network-predicted unsteady surface pressure time histories were compared directly to the experimental pressure data. Then, a neural network controller for the wing motion history was developed using the pressure model. The results indicated that the controller actuator signals reliably yielded motion histories that generated the measured lift to drag ratio (LID) time histories. Further, the results suggest that for any desired LID requirement optimized motion histories can be generated.
N = 1 dual string pairs and their modular superpotentials

Abstract We review the duality between heterotic and F-theory string vacua with N = 1 space-time supersymmetry in eight, six and four dimensions. In particular, we discuss two chains of four-dimensional F-theory/heterotic dual string pairs, where F-theory is compactified on certain elliptic Calabi-Yau fourfolds, and the dual heterotic vacua are given by compactifications on elliptic Calabi-Yau threefolds plus the specification of the E 8 × E 8 gauge bundles. We show that the massless spectra of the dual pairs agree by using, for one chain of models, an index formula to count the heterotic bundle moduli and determine the dual F-theory spectra from the Hodge numbers of the fourfolds and of the type IIB base spaces. Moreover as a further check, we demonstrate that for one particular heterotic/F-theory dual pair the N = 1 superpotentials are the same.
Non-perturbative singularity structure of gluon and quark propagators

Abstract A gauge invariant, non-local observable is constructed in lattice pure gauge theory, which is identical to the gluon propagator in a particular gauge. The transfer matrix formalism is used to show that this correlator decays exponentially with eigenvalues of the Hamiltonian. This implies a gauge invariant singularity structure of the propagator in momentum space, permitting a non-perturbative definition of a parton mass. The relation to gauge fixing and the extension to matter fields are discussed.
Saving, Investment, and the Regional Current Account: An Analysis of Canadian, British, and German Regions

The relationship between regional saving and investment is examined to measure the extent of capital mobility. The relationship between total regional saving and investment is significantly negative in Canada and the United Kingdom, in contrast to the significant positive relationship found across countries. The difference is attributed to government subsidies to poor regions. The relationship between personal saving and private investment is insignificant in the U.K. and Germany and is negative in Canada which suggests that capital is mobile for individuals. The relationship between retained earnings and private investment is significantly positive in the U.K. and Canada suggesting capital immobility for firms but a test for the presence of regional corporate liquidity constraints yields no effects.
Different types of social entrepreneurship: The role of geography and embeddedness on the measurement and scaling of social value

With its continued emergence in both academic and practitioner communities, the diversity of organizations categorized as social entrepreneurship continues to expand. The increasing diversity represents a challenge to the field as it attempts to build a scientific base of knowledge. To address this issue, we build upon a typology of different forms of social entrepreneurship to theorize about how the role of ‘sites and spaces’ may affect the social entrepreneurial process. Specifically, we explain how variance in the geographic focus of different types of social entrepreneurship influences the types of social networks in which social entrepreneurship is embedded. Drawing upon this logic of embeddedness, we develop propositions about how the structural embeddedness of social entrepreneurship may affect the measurement and scaling of social value. The purpose of this article is to add to the relatively sparse but growing theoretical foundation of the field of social entrepreneurship.
Knowledge-based robotics

A major hurdle in the development of intelligent robots is that we still do not possess efficient computational and representational methodologies for emulating knowledge and expectation driven behaviour so basic to human cognition and problem solving. Even if we use techniques such as geometric modelling for representing objects in the robot world, we are still lacking in methods for linking such representations with sensory feedback. In this paper, we have proposed the use of intermediate representations—we call them sensor-tuned representations—for linking CSG based solid modelling with sensory information. We also discuss how sensor-tuned representations are constructed from range data and how object recognition can be done with sensor-tuned representations. Finally, we show results of manipulation experiments produced by the current implementation of the system.
Polyaromatic Ribbon/Benzofuran Fusion via Consecutive Endo Cyclizations of Enediynes

The Sonogashira/5-endo-dig/6-endo-dig cascade fuses a polycyclic aromatic backbone to the electron-rich furan subunit. The transformation proceeds in modest yields as a one-pot reaction. Efficiency of the full cascade is increased by removal of base prior to the addition of gold catalyst. Under these conditions, conversion to the full cascade products is achieved in nearly quantitative yields without purification of the intermediate products. Extension of the cascade toward triynes opens access to benzofuran-fused chrysene derivatives.
Thermal conversion of phorone into isophorone via (trimethylsilyl)oxyhexatriene (soh) cyclization

Abstract Heating of 3-Z-4-(trimethylsilyl)oxy-2,6-dimethylhepta-1,3,5-triene, readily available from phorone (LDA; TMSCl), at 220°C caused isomerization and cyclization to afford isophorone after deprotection.
Bifunctional reactions of alkanes on tungsten carbides modified by chemisorbed oxygen

Abstract Tungsten carbides modified by chemisorbed oxygen catalyze n-heptane isomerization with high selectivity. Kinetic, isotopic tracer, and deuterium-exchange measurements show that the reaction proceeds via sequential n-heptane dehydrogenation and heptene isomerization steps. At low temperatures, isomerization rates are limited by heptene rearrangements but dehydrogenation steps become increasingly rate-limiting as temperature increases. The isomer distribution in n-heptane and 3,3-dimethylpentane reaction products and the 13C distribution in isoheptanes formed from n-heptane-1-13C show that isomerization occurs predominantly by methyl migration steps typical of carbenium-ion rearrangements on acid sites. WOx species on carbide surfaces appear to introduce acid sites similar to those present in supported tungsten oxides. n-Heptane dehydrocyclization and hydrogenolysis reactions also require heptene intermediates. Dehydrocyclization occurs predominantly by (1, 6) ring closure while hydrogenolysis leads to random cleavage of carbon-carbon bonds in n-heptane.
On two color QCD with baryon chemical potential

Abstract We study SU(2) color QCD with even number of quark flavors. First, using QCD inequalities we show that at finite baryon chemical potential μ, condensation must occur in the channel with scalar diquark quantum numbers. This breaks the U(1) symmetry generated by baryon charge (baryon superconductivity). Then we derive the effective Lagrangian describing low lying meson and baryon excitations using extended local chiral symmetry of the theory. This enables us to determine the leading term in the dependence of the masses on μ exactly.
The Diffusion of Imprisoned Resonance Radiation in Mercury Vapor

The rate of diffusion of imprisoned resonance radiation in mercury vapor.---The imprisonment of resonance radiation in mercury vapor was studied by measuring the rate at which resonance radiation emerged from one face of a slab of vapor after the exciting light, incident upon the other face, was cut off. The radiation was found to fall off exponentially, and the exponential constant of decay was measured for vapor densities ranging from 0.77\ifmmode\times\else\texttimes\fi{}${10}^{15}$ atoms per cc to 29\ifmmode\times\else\texttimes\fi{}${10}^{15}$ atoms per cc, corresponding to temperatures ranging from 60\ifmmode^\circ\else\textdegree\fi{}C to 130\ifmmode^\circ\else\textdegree\fi{}C. Slabs of two different thicknesses were studied, one 1.95 cm, and the other 1.30 cm. It was found that for vapor densities lower than about 4\ifmmode\times\else\texttimes\fi{}${10}^{15}$ atoms per cc, the exponential constant varied approximately inversely as the square of the thickness of the slab, in qualitative agreement with the theory of the diffusion of imprisoned radiation as worked out by Milne.Extension of Milne's theory: broad exciting line; collisions of second kind.---In this region of vapor densities it was found also that the exponential constant decreased with the vapor density. The failure of Milne's results to give quantitative agreement with this result is discussed and it is suggested that this discrepancy is due to the fact that the exciting light in this experiment was a very broad spectral line, and that postulated by Milne of very narrow width. A rough method of extending Milne's theory to include the absorption and imprisonment of frequencies larger and smaller than the heart of the 2536.7 line is discussed, and it is shown that the experimental results can be explained on this basis. At higher vapor densities, the decay constant increased almost linearly with the number of absorbing atoms per cc. It is shown that this result is in accordance with the theory of imprisonment when extended to include impacts of the second kind. The probability of an impact of the second kind between a normal and an excited mercury atom is calculated from the experimental data and found to be approximately 9\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$.
Redox State-Dependent Interaction of HMGB1 and Cisplatin-Modified DNA

HMGB1, one of the most abundant nuclear proteins, has a strong binding affinity for cisplatin-modified DNA. It has been proposed that HMGB1 enhances the anticancer efficacy of cisplatin by shielding platinated DNA lesions from repair. Two cysteine residues in HMGB1 domain A form a reversible disulfide bond under mildly oxidizing conditions. The reduced domain A protein binds to a 25-bp DNA probe containing a central 1,2-d(GpG) intrastrand cross-link, the major platinum-DNA adduct, with a 10-fold greater binding affinity than the oxidized domain A. The binding affinities of singly and doubly mutated HMGB1 domain A, respectively deficient in one or both cysteine residues that form the disulfide bond, are unaffected by changes in external redox conditions. The redox-dependent nature of the binding of HMGB1 domain A to cisplatin-modified DNA suggests that formation of the intradomain disulfide bond induces a conformational change that disfavors binding to cisplatin-modified DNA. Hydroxyl radical footprinting analyses of wild-type domain A bound to platinated DNA under different redox conditions revealed identical cleavage patterns, implying that the asymmetric binding mode of the protein across from the platinated lesion is conserved irrespective of the redox state. The results of this study reveal that the cellular redox environment can influence the interaction of HMGB1 with the platinated DNA and suggest that the redox state of the A domain is a potential factor in regulating the role of the protein in modulating the activity of cisplatin as an anticancer drug.
Rhodium-catalyzed 1,4-addition reactions of diboron reagents to electron deficient olefins

Abstract The 1,4-addition of bis(pinacolato)diboron and bis(neopentyl glycolato)diboron to α,β-unsaturated ketones, esters, nitriles, and aldehydes was developed using a rhodium catalyst.
Responses of roadside soil cation pools to vehicular emission deposition in southern California

Roadside soils are heavily loaded with reactive nitrogen due to vehicular emissions, and these loadings likely acidify near-road soils. Cationic metals are mobilized from acidified soils during exchange reactions. Depletion of soil cation pools is well documented in forest soils, but poorly understood in roadside soils despite heavy nitrogen loadings to roadside environments and the continued growth of road networks. This study considers soil acidification impacts across gradients of soil chemistry, road network density, climate, and geology in southern California, clarifying acidification processes in near-road environments. Although there is no direct relationship between soil pH and road proximity, several elements (Al, Be, K) are depleted in near-road environments. The depletion of these elements occurs despite more sediment surface area and organic matter in near-road soils. In contrast, the weathering of road construction materials (i.e., concrete) replenishes soil Ca and Mg pools and likely buffers soil pH. These observed near-road patterns in soil chemistry point to the potential for mobilization of metal contamination from roadside environments. Improved understanding of metal dynamics in roadside soils is essential to the effective management of road-sourced nutrients and storm water, particularly as expanding road networks continue to affect wider areas.
C‐2 Arylamino substituted purine ara‐carbocyclic nucleosides as potential anti‐cytomegalovirus agents

There are reports in the literature that placement of an arylamino side chain at the C-2 position of purine nucleosides produces compounds capable of inhibiting DNA polymerase. To evaluate the potential of this class of compounds as antiviral agents that act by inhibiting viral DNA polymerase, ara-carbocyclic purine nucleosides possessing a 4-(l-butyl)phenylamino and a 3,5-dichlorophenylamino substituent at C-2 were chosen as the prototype structures and have been prepared from 2,4,6-trichloropyrimidine in 6 steps. For the antiviral analysis, human cytomegalovirus served as the principal virus since it expresses a virally specific DNA polymerase. None of the compounds showed activity towards this virus, but they were found to display some toxicity towards one or more cell lines.
The effect of military participation on women's wages with double correction for selectivity bias

Abstract This study examines the impact of military experience on civilian wages for a sample of NLSY women. There is a negative return to additional years spent in the military suggesting women should not sign up for a second enlistment, but would have higher wages spending those years working in the civilian labor force. The empirical result of positive returns to military participation, yet negative returns to additional years of military experience is consistent with the screening hypothesis. Military participants have a lower rate of return to schooling but a higher return to civilian work experience than their civilian counterparts.
A predator–prey model for moon-triggered clumping in Saturn’s rings

Abstract UVIS occultation data show clumping in Saturn’s F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations that are perturbed by Prometheus and by Mimas. The inferred timescales range from hours to months. Occultation profiles of the edge show wide variability, indicating perturbations by local mass aggregations. Structure near the B ring edge is seen in power spectral analysis at scales 200–2000 m. Similar structure is also seen at the strongest density waves, with significance increasing with resonance strength. For the B ring outer edge, the strongest structure is seen at longitudes 90° and 270° relative to Mimas. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator–prey system: the mean aggregate size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. Moons may trigger clumping by streamline crowding, which reduces the relative velocity, leading to more aggregation and more clumping. Disaggregation may follow from disruptive collisions or tidal shedding as the clumps stir the relative velocity. For realistic values of the parameters this yields a limit cycle behavior, as for the ecology of foxes and hares or the “boom-bust” economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag roughly consistent with the UVIS occultation measurements. We conclude that the agitation by the moons in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material may also allow fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. Any of these more persistent objects would then orbit at the Kepler rate. We would also expect the formation of clumps and some more permanent objects at the other perturbed regions in the rings… including satellite resonances, shepherded ring edges, and near embedded objects like Pan and Daphnis (where the aggregation/disaggregation cycles are forced similar to Prometheus forcing of the F ring).
Periodic Heat Transfer in Radiating and Convecting Fins or Fin Arrays

A finite-element solution is presented for the heat transfer from radiating and converting fins or fin arrays. Consideration is given to thin, straight fins attached to a base surface for which the temperature varies periodically. Fin-to-fin, fin-to-base, and fin-to-environment radiative interactions are considered. It is assumed that the radiating surfaces are gray, the environment is black, and the surrounding fluid is transparent. An absorption factor technique is employed for the computation of energy exchange within the nonisothermal enclosure of the fin array.
Chamber, target and final focus integrated design

Abstract Liquid wall protection, which challenges chamber clearing, has advantages in Heavy Ion Fusion's (HIF) main line chamber design. Thin liquid protection from X-rays is necessary to avoid erosion of structural surfaces and thick liquid makes structures behind 0.5 m of flibe (7 mean free paths for 14 MeV neutrons), last the life of the plant. Liquid wall protection holds the promise of greatly increased economic competitiveness. The illumination must be compatible with liquid wall protection. The “best” values for driver energy, gain, yield and pulse rate comes out of well-known trade-off studies to arrive at the minimum cost of electricity. In order to reduce the driver cost and therefore reduce the cost of electricity, driver designers are attempting to reduce driver energy from the old 10 GeV value and increase the number of beams to about 200 to illuminate recent target designs from two sides. We have not yet succeeded in coming up with an integrated chamber design compatible with 200 beams. The present design iteration and future ones will depend on several key assumptions, such as jet surface smoothness and rapid chamber clearing. Before HIF can be considered feasible and economical, we need an integrated chamber, target, and final focus design and successful resolution of key technical issues by the chamber R&D efforts.
Turbulence Model Predictions of Strongly Curved Flow in a U-Duct

The ability of three types of turbulence models to accurately predict the effects of curvature on the flow in a U-duct is studied. An explicit algebraic stress model performs slightly better than one- or two-equation linear eddy viscosity models, although it is necessary to fully account for the variation of the production-to-dissipation-rate ratio in the algebraic stress model formulation. In their original formulations, none of these turbulence models fully captures the suppressed turbulence near the convex wall, whereas a full Reynolds stress model does. Some of the underlying assumptions used in the development of algebraic stress models are investigated and compared with the computed flowfield from the full Reynolds stress model. Through this analysis, the assumption of Reynolds stress anisotropy equilibrium used in the algebraic stress model formulation is found to be incorrect in regions of strong curvature. By the accounting for the local variation of the principal axes of the strain rate tensor, the explicit algebraic stress model correctly predicts the suppressed turbulence in the outer part of the boundary layer near the convex wall.
Compatible triangulations and point partitions by series-triangular graphs

We introduce series-triangular graph embeddings and show how to partition point sets with them. This result is then used to prove an upper bound on the number of Steiner points needed to obtain compatible triangulations of point sets. The problem is generalized to finding compatible triangulations for more than two point sets and we show that such triangulations can be constructed with only a linear number of Steiner points added to each point set. Moreover, the compatible triangulations constructed by these methods are regular triangulations.
Theory of laser-induced phenomena on conventional and phase-conjugated surfaces

Laser-induced processes on conventional and phase-conjugated surfaces are investigated theoretically. Resonance fluorescence of two-level atoms on smooth and rough surfaces are reviewed. The new phenomenon of a radiative dipole at a phase-conjugated surface (PCS), in which the lifetime of the dipole can be virtually infinite under certain conditions, is examined. A PCS originates from the interference of two laser beams incident upon an absorbing layer, and this effect is discussed in terms of a phenomenological model and a hydrodynamic theory in which laser-induced periodic structure and the PCS reflectivity are analyzed. Finally, practical applications of these new phenomena occurring on PCS are discussed.
Landau theory for shape memory polycrystals

Abstract We propose a Ginzburg–Landau theory for the elastic properties of shape memory polycrystals. A single crystal elastic free energy for a system that undergoes a square-to-rectangle transformation is generalized to a polycrystal by introducing a crystal orientational field that is determined from a continuum phase-field model. The coupled system is used to study domain morphology and mechanical properties of shape memory alloys in different temperature regimes.
Impact Performance of Magnetorheological Fluids

As part of an emerging effort in what is now termed the area of mechamatronics (Browne et al., 2004), an effort was begun to assess the suitability of magnetorheological (MR) material-based devices...
An Attempted Integration of the Literature on the Export Behavior of Firms

Forty-three studies on the export behavior of firms involving eleven countries were assembled. (The author believes that they constitute nearly all of the available literature on the subject.) An attempt was made to integrate them into a more-or-less meaningful whole that both yields interesting implications and provides a useful background guide for future research on the subject.
Syndrome measurement strategies for the [[7,1,3]] code

Quantum error correction (QEC) entails the encoding of quantum information into a QEC code space, measuring error syndromes to properly locate and identify errors, and, if necessary, applying a proper recovery operation. Here we compare three syndrome measurement protocols for the [[7,1,3]] QEC code: Shor states, Steane states, and one ancilla qubit by simulating the implementation of 50 logical gates with the syndrome measurements interspersed between the gates at different intervals. We then compare the fidelities for the different syndrome measurement types. Our simulations show that the optimal syndrome measurement strategy is generally not to apply syndrome measurements after every gate but depends on the details of the error environment. Our simulations also allow a quantum computer programmer to weigh computational accuracy versus resource consumption (time and number of qubits) for a particular error environment. In addition, we show that applying syndrome measurements that are unnecessary from the standpoint of quantum fault tolerance may be helpful in achieving better accuracy or in lowering resource consumption. Finally, our simulations demonstrate that the single-qubit non-fault-tolerant syndrome measurement strategy achieves comparable fidelity to those that are fault tolerant.
Bromination of bicyclo[7.3.1]enediynes: Unusual rearrangement of the azabicyclo[7.3.1]enediyne dynemicin core structure

Abstract Enediyne model compounds containing the calicheamicin and dynemicin core skeleton can be brominated to give stable adducts, but in one case a deep-seated rearrangement takes place.
Particle acceleration mechanisms

High-energy particle acceleration is observed to proceed in a diverse variety of astrophysical sites ranging from the terrestrial aurorae to the most distant quasars. Particle acceleration is a fairly common channel for the release of large-scale kinetic, rotational, and magnetic energy. Physical mechanisms include electrostatic acceleration, stochastic processes, and diffusive shock energization. Cosmic-ray energy spectra have shapes which reflect escape, collisional, and radiative losses. The overall acceleration efficiency is controlled by the low-energy particle injection which may, in turn, feed back into the energization. Recent observational developments, which illustrate these general principles and raise fresh questions, are briefly summarized.
Fragmentation of headquarter services and FDI

Abstract This paper develops a model of foreign direct investment (FDI), in which the skilled labors of different countries are imperfect substitutes for one another. As a result, multinational firms combine them and FDI occurs without trade costs or factor-price differences. Additionally, FDI increases in the skilled-labor stock of either country. Data on U.S. FDI reveal patterns consistent with the model. The introduction of imperfectly substitutable skilled labors also yields domestic wage effects that can help to offset those previously recognized.
Battery Cycle Life Prediction with Coupled Chemical Degradation and Fatigue Mechanics

Coupled mechanical-chemical degradation of electrodes upon charging and discharging has been recognized as a major failure mechanism in lithium ion batteries. The instability of commonly employed electrolytes results in solid electrolyte interphase (SEI) formation. Although the SEI layer is necessary, as it passivates the electrode-electrolyte interface from further solvent decomposition, SEI formation consumes lithium and thus contributes to irreversible capacity loss. In this paper, we study irreversible capacity loss in a graphite-LiFePO 4 cell. Our results support the mechanism of irreversible capacity loss due to the consumption of lithium in forming SEI. We attribute irreversible capacity loss to diffusion induced stresses (DISs) that cause pre-existing cracks on the electrode surfaces to grow gradually upon cycling, leading to the growth of SEI on the newly exposed electrode surfaces. Because lithium is consumed in forming the new SEI, irreversible capacity loss continues with cycling. Along with the SEI formation upon newly exposed (cracked) surfaces, the existing SEI thickness also grows with cycling, resulting in additional loss of lithium. In this study, we provide, a simple mathematical model, based on the Paris' Law formulation of mechanical fatigue, in combination with chemical degradation to explain battery life. We compare the predicted capacity at different temperatures with the experimental data obtained from electrochemical measurements on graphite-LiFePO 4 cells.
Covariant Kinetic Theory with an Application to the Coma Cluster

In this paper, we introduce a novel solution to the covariant Landau equation for a pure electron plasma. The method conserves energy and particle number and reduces smoothly to the Rosenbluth potentials of nonrelativistic theory. We find that the covariant relaxation timescale agrees with past results; however, as a full solution to the covariant Boltzmann equation, our technique allows for anisotropic or degenerate distributions, which makes it unique. To demonstrate the power of our solution in dealing with hot, astrophysical plasmas, we use this technique to show that one of the currently considered models, continuous stochastic acceleration of thermal electrons, for the hard X-ray emission in the Coma Cluster actually cannot work because the energy gained by the particles is distributed to the whole plasma on a timescale much shorter than that of the acceleration process itself.
On the Topology of Invariant Subspaces of a Shift of Higher Multiplicity

Following Beurling’s theorem R. Douglas and C. Pearcy have studied topology of invariant subspace lattice. R.Yang offered a description of path connected components of invariant subspace lattice for shift of multiplicity one. This paper generalizes the result to arbitrary finite multiplicity. We show that there exists a one to one correspondence between the invariant subspace lattice of shift of arbitrary finite multiplicity and the space of inner functions.
Exploring the Final Frontier: An Empirical Analysis of Global Civil Space Proliferation

While space capabilities were once concentrated among a handful of leading powers, an increasingly large number of states have gained access to them. As of 2007, 58 countries possessed dedicated civil space programs, 44 countries had placed nationally owned satellites into orbit, and 9 countries had achieved domestic space launch capabilities. To date, however, no systematic inquiries have ever been conducted into which countries acquire space capabilities and why. Within this paper, I develop an explanatory account that explores the capacity-based factors and political motivations that influence countries' acquisition of space capabilities. I test my hypotheses via a quantitative analysis of the factors affecting 143 countries' acquisition of civil space programs, satellite capabilities, and space launch capabilities from 1950 to 2002. My findings shed new light on the primary causes of the proliferation of civil space capabilities and yield a number of important policy implications.
Optical pulse squaring effects in a dispersive delay line

Abstract Using a pair of diffraction gratings, we have produced temporal squaring effects on 30 ps duration 1.06 μm pulses that were negatively self phase modulated in cesium vapor. The results are in good agreement with the theory, which is discussed in detail. Further enhancement of the squaring by a saturable absorber is also discussed.
Convective Cooling of Protoplanetary Disks and Rapid Giant Planet Formation

The rapid formation of self-gravitating clumps of gas and dust in a marginally gravitationally unstable disk requires a reasonably efficient means of cooling the disk gas. Clumps form on the dynamical timescale of a few orbital periods in the disk instability scenario. Radiative transfer is not able to cool the midplanes of optically thick protoplanetary disks fast enough to permit the disk instability mechanism to form dense clumps. However, vertically oriented convective cells, driven by the temperature gradient between the disk's midplane and surface, appear to be capable of cooling the disk midplanes on the desired timescale. We demonstrate this possibility by analyzing in detail the vertical convective energy fluxes in the first three-dimensional radiative hydrodynamics model of clump formation by disk instability, which we presented in 2001. Similarly robust convective fluxes occur in the models we presented in 2002. Transient convective cells can be seen in all of these simulations, with vertical velocities (~0.1 km s-1) and energy fluxes large enough to cool the outer disk at the desired rate.
Viscous cross‐waves: An analytical treatment

Viscous effects on the excitation of cross‐waves in a semi‐infinite box of finite depth and width are considered. A formalism using matched asymptotic expansions and an improved method of computing the solvability condition is used to derive the relative contributions of the free‐surface, sidewall, bottom, and wavemaker viscous boundary layers. This analysis yields an expression for the damping coefficient previously incorporated on heuristic grounds. In addition, three new contributions are found: a viscous detuning of the resonant frequency, a slow spatial variation in the coupling to the progressive wave, and a viscous correction to the wavemaker boundary condition. The wavemaker boundary condition breaks the symmetry of the linear neutral stability curve at leading order for many geometries of experimental interest.
Artificial agency, consciousness, and the criteria for moral agency: what properties must an artificial agent have to be a moral agent?

In this essay, I describe and explain the standard accounts of agency, natural agency, artificial agency, and moral agency, as well as articulate what are widely taken to be the criteria for moral agency, supporting the contention that this is the standard account with citations from such widely used and respected professional resources as the Stanford Encyclopedia of Philosophy, Routledge Encyclopedia of Philosophy, and the Internet Encyclopedia of Philosophy. I then flesh out the implications of some of these well-settled theories with respect to the prerequisites that an ICT must satisfy in order to count as a moral agent accountable for its behavior. I argue that each of the various elements of the necessary conditions for moral agency presupposes consciousness, i.e., the capacity for inner subjective experience like that of pain or, as Nagel puts it, the possession of an internal something-of-which-it is-is-to-be-like. I ultimately conclude that the issue of whether artificial moral agency is possible depends on the issue of whether it is possible for ICTs to be conscious.
The Decay of Debris Disks around Solar-type Stars

We present a Spitzer MIPS study of the decay of debris disk excesses at 24 and 70 ?m for 255 stars of types F4-K2. We have used multiple tests, including consistency between chromospheric and X-ray activity and placement on the H-R diagram, to assign accurate stellar ages. Within this spectral type range, at 24 ?m, 13.6% ? 2.8% of the stars younger than 1?Gyr have excesses at the 3? level or more, whereas none of the older stars do, confirming previous work. At 70 ?m, 22.5% ? 3.6% of the younger stars have excesses at ?3? significance, whereas only % of the older stars do. To characterize the far-infrared behavior of debris disks more robustly, we doubled the sample by including stars from the DEBRIS and DUNES surveys. For the F4-K4 stars in this combined sample, there is only a weak (statistically not significant) trend in the incidence of far-infrared excess with spectral type (detected fractions of 21.9, late F; 16.5, G; and 16.9, early K). Taking this spectral type range together, there is a significant decline between 3 and 4.5?Gyr in the incidence of excesses, with fractional luminosities just under 10?5. There is an indication that the timescale for decay of infrared excesses varies roughly inversely with the fractional luminosity. This behavior is consistent with theoretical expectations for passive evolution. However, more excesses are detected around the oldest stars than are expected from passive evolution, suggesting that there is late-phase dynamical activity around these stars.
The Value of Adoption

Recent work shows that the governmental cost of adoption is about half the cost of long-term foster care for children whose birth parents' rights have been terminated. Because adoption is also asso...
An Application of the Seasonal Fractionally Differenced Model to the Monetary Aggregates

Abstract In this article, three significant variables used by the U.S. Federal Reserve as targets to shape monetary policy, the monetary aggregates M1, M2, and M3, are examined using a seasonal fractionally differenced model. The sample autocorrelation functions of these monetary variables exhibit a decay pattern at the seasonal lags that is typical of a fractional model. The seasonal fractionally differenced model is found to remove a great deal of the autocorrelation at the seasonal lags, especially when a series is extended by splicing together earlier monetary data. Some Monte Carlo evidence as to the efficacy of this technique is presented. Finally, one-year-ahead out-of-sample forecasts of M1 are made using both the Box—Jenkins airline model and the seasonal fractionally differenced model.
An efficient synthesis of N,N′-linked oligoureas

Abstract This paper reports an efficient synthesis of N -alkyl- N,N′ -linked oligoureas [NRCONHCH 2 CH 2 ] n , which involves the repetition of three steps: (1) main-chain extension by ring-opening of N -(2-nitrobenzenesulfonyl)-2-imidazolidone ( 1 ) by a secondary amine RR′NH to afford sulfonamide RR′NCONHCH 2 CH 2 NHSO 2 Ar (2) side-chain attachment by N -alkylation of the sulfonamide with alkyl halide R″X, and (3) removal of the sulfonyl group to give a new secondary amine RR′NCONHCH 2 CH 2 NHR″). A tetraurea was prepared in 10 steps and 58% overall yield by this method.
Near-term SEI science missions utilizing an evolutionary lunar transportation system

An evolutionary program of space science missions for the lunar surface and the transportation system concept developed to deploy them are described. Lunar-based science systems will evolve from simple, robotic instruments such as a lunar transit telescope (LTT) to large, observatory-class instruments like a 16-meter optical telescope assembled by astronauts at a lunar base. A transportation system concept to support the Space Exploration Initiative (SEI) and the deployment of these science payloads is described. Beginning with a post-Artemis lander capability, a modular approach to lunar landers is proposed as a way to maximize commonality and to support evolving SEI transportation requirements.
Membrane scattering in curved space with M-momentum transfer

We study membrane scattering in a curved space with non-zero M-momentum p11 transfer. In the low-energy short-distance region, the membrane dynamics is described by a three-dimensional N = 4 supersymmetric gauge theory. We study an n-instanton process of the gauge theory, corresponding to the exchange of n units of p11, and compare the result with the scattering amplitude computed in the low-energy long-distance region using supergravity. We find that they behave differently. We show that this result is not in contradiction with the large-N Matrix Theory conjecture, by pointing out that cutoff scales of the supergravity and the gauge theory are complementary to each other.
Equilibrium, stability, and orbital evolution of close binary systems

We present a new analytic study of the equilibrium and stability properties of close binary systems containing polytropic components. Our method is based on the use of ellipsoidal trial functions in an energy variational principle. We consider both synchronized and nonsynchronized systems, constructing the compressible generalizations of the classical Darwin and Darwin-Riemann configurations. Our method can be applied to a wide variety of binary models where the stellar masses, radii, spins, entropies, and polytropic indices are all allowed to vary over wide ranges and independently for each component. We find that both secular and dynamical instabilities can develop before a Roche limit or contact is reached along a sequence of models with decreasing binary separation. High incompressibility always makes a given binary system more susceptible to these instabilities, but the dependence on the mass ratio is more complicated. As simple applications, we construct models of double degenerate systems and of low-mass main-sequence star binaries. We also discuss the orbital evoltuion of close binary systems under the combined influence of fluid viscosity and secular angular momentum losses from processes like gravitational radiation. We show that the existence of global fluid instabilities can have a profound effect on the terminal evolution of coalescing binaries. The validity of our analytic solutions is examined by means of detailed comparisons with the results of recent numerical fluid calculations in three dimensions.
Vector bundles over Grassmannians and the skew-symmetric curvature operator

Abstract A pseudo-Riemannian manifold is said to be spacelike Jordan IP if the Jordan normal form of the skew-symmetric curvature operator depends upon the point of the manifold, but not upon the particular spacelike 2-plane in the tangent bundle at that point. We use methods of algebraic topology to classify connected spacelike Jordan IP pseudo-Riemannian manifolds of signature ( p , q ) , where q ⩾ 11 , p ⩽ q − 6 4 and where the set { q , … , q + p } does not contain a power of 2.
α-Amination of keto-nitrones via Multihetero-Cope rearrangement employing an imidoyl chloride reagent

α-Aminations of ketone-derived nitrones have been developed via [3,3]-rearrangement of the intermediates generated upon condensation with imidoyl chlorides. Careful reagent selection provides synthetically attractive amino protecting groups. The enediamide or α′-carbamoyl enamide products can be hydrolyzed to the desired carbonyl, or exposed to electrophiles for further α-functionalization.
MASSIVE STAR MULTIPLICITY: THE CEPHEID W Sgr*

We have obtained spectra of the W Sgr system with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST). The spectra resolve the system into a distant companion B which is the hottest star in the system and the spectroscopic binary (A = Aa + Ab). A and B are separated by 016. We have extracted the spectra of both of these. We see no flux in the Aa + Ab spectrum which cannot be accounted for by the Cepheid, and put an upper limit on the spectral type and mass of the companion Ab of F5 V and ≤1.4 M ☉. Using the orbit from HST fine guidance sensor measurements from Benedict et al., this results in an upper limit to the mass of the Cepheid of ≤5.4 M ☉. We also discuss two possible distant companions. Based on the photometry from the Two Micron All Sky Survey Point Source Catalog, they are not physical companions of the W Sgr system.
Alkyl nitrate nitration of active methylene compounds. Nitration of 2‐substituted 2‐oxazolines

2-Alkyl- and 2-aralkyl-2-oxazolines are readily converted to the corresponding α-nitroalkyl- and α-nitroaralkyl-2-oxazolines on treatment with an alkali metal amide such as potassium or sodium amide in liquid ammonia or with lithium diisopropylamide (LDA) in THF and an alkyl nitrate. Tertiary nitro compounds, such as 2-(2-nitro-2-propyl)-4,4-dimethyl-2-oxazoline (16) and 2-(diphenylnitromethyl)-4,4-dimethyl-2-oxazoline (17) are obtained in good yield when the anions of 2-(2-propyl)-4,4-dimethyl-2-oxazoline (14) and of 2-(diphenylmethyl)-4,4-dimethyl-2-oxazoline (23), generated by LDA are added to the nitrate in THF (inverse addition). The spectral data of the primary and secondary α-nitroalkyl- and α-nitroaralkyl-2-oxazolines reveal that they exist mostly in their dipolar structure. These compounds are readily converted to the corresponding α-halonitro-2-oxazolines on treatment with potassium hypobromite or hypochlorite.
Bispectral Darboux transformations: the generalized Airy case

Abstract This paper considers Darboux transformations of a bispectral operator which preserve its bispectrality. A sufficient condition for this to occur is given, and applied to the case of generalized Airy operators of arbitrary order r > 1. As a result, the bispectrality of a large family of algebras of rank r is demonstrated. An involution on these algebras is exhibited which exchanges the role of spatial and spectral parameters, generalizing Wilson's rank one bispectral involution. Spectral geometry and the relationship to the Sato grassmannian are discussed.
Exclusive Contracts in Health Insurance

Competition between insurance companies often increases the prices and reduces the availability of high qualityhealth plans offered to employees. An insurance company can reduce competition by signing an exclusive contract,which guarantees that the company is the only insurance provider. This artcile shows whether exclusive contracts canalleviate the negative consequences of competition. Using the nation-wide survey of employers, I find that exclusiveinsurers charged less for a unit of insurance quality than non-exclusive insurers. Furthermore, I find that the patternof insurance quality dispersion is consistent with the exclusive insurers offering more high quality plans.
Evaluation of head CT exams - resident and attending diagnoses

The goal of this study was to evaluate performance of radiology resident in interpretation of head CT exams ordered by emergency room physicians, and to compare their accuracy with the attending radiologists. 1324 consecutive CT head exams ordered by the ER were interpreted by radiology residents. They reported whether the case was normal or abnormal, noted the relevant findings, and reported their decision confidence using a 6-point scale. Attending neuroradiologists subsequently interpreted the exams. The exams were grouped into 3 categories based on correlation of readings: agree, disagree-insignificant, disagree-significant. There was 91% agreement between resident and attending diagnoses, 7% disagree-insignificant and 2% disagree- significant. Disagreements occurred more often on abnormal than normal cases. Disagreements occurred more often with 1st and 2nd year residents than with 3rd and 4th. Resident confidence was highest for 3rd years, followed by 4th, 2nd and 1st. The less confident a resident was in their diagnosis, the more likely a disagreement occurred. Cases in which a resident expresses a low level of confidence should be carefully checked by the attending since these cases were more often associated with a disagreement than those with high confidence.
Efficient crawling through URL ordering

In this paper we study in what order a crawler should visit the URLs it has seen, in order to obtain more "important" pages first. Obtaining important pages rapidly can be very useful when a crawler cannot visit the entire Web in a reasonable amount of time. We define several importance metrics, ordering schemes, and performance evaluation measures for this problem. We also experimentally evaluate the ordering schemes on the Stanford University Web. Our results show that a crawler with a good ordering scheme can obtain important pages significantly faster than one without.