cssi/SciSciGPT-SciSciNet huggingface dataset:
A Moderate Communitarian Proposal

O N SOME OF THE long-debated issues between libertarians and communitarians, the two sides are narrowing-if not "settling"-their differences.' Recognizing this progress makes it possible to focus on the "remaining" issues that contain some rather challenging and less often discussed topics. Among the issues in which convergence is already progressing are the social nature of the person (an ontological issue), the relations between a community-based definition of virtue and ones provided by individuals (a normative issue), the need to balance individual rights with social and personal responsibilities, and the ways to defend against community majoritarianism. This essay focuses on two of the "remaining" issues: the source of values that contextuate communities and the implications of one's characterization of human nature for the issues at hand. In this essay, I circumvent the customary review of the relevant literature on the grounds that such reviews have been carried out often and very well.2 Instead, I proceed directly to a modest suggestion for a moderate communitarian position.
Probes of the inner jets of blazars.

I review models for the 'inner jet' in blazars, the section that connects the central engine with the radio jet. I discuss how the structure and physics of the inner jet can be explored using millimeter-wave Very-Long-Baseline Radio Interferometry (VLBI) as well as multiwaveband observations of blazars. Flares at radio to gamma-ray frequencies should exhibit time delays at different wavebands that can test models for both the high-energy, emission mechanisms and the nature of the inner,jet in blazars.
Detection of Structure in Infrared-Dark Clouds with Spitzer: Characterizing Star Formation in the Molecular Ring

We have conducted a survey of a sample of infrared-dark clouds (IRDCs) with the Spitzer Space Telescope in order to explore their mass distribution. We present a method for tracing mass using dust absorption against the bright Galactic background at 8 μm. The IRDCs in this sample are comprised of tens of clumps, ranging in sizes from 0.02 to 0.3 pc in diameter and masses from 0.5 to a few 103 M sun, the broadest dynamic range in any clump mass spectrum study to date. Structure with this range in scales confirms that IRDCs are the precursors to stellar clusters in an early phase of fragmentation. Young stars are distributed in the vicinity of the IRDCs, but the clumps are typically not associated with stars and appear prestellar in nature. We find an IRDC clump mass spectrum with a slope of α = 1.76 ± 0.05 for masses from 30 M sun to 3000 M sun. This slope is consistent with numerous studies, culled from a variety of observational techniques, of massive star formation regions and is close to the mass function of Galactic stellar clusters and star clusters in other galaxies. We assert that the shape of the mass function is an intrinsic and universal feature of massive star formation regions that are the birth sites of stellar clusters. As these clouds evolve and their constituent clumps fragment, the mass spectrum will steepen and eventually assume the form of the core mass function that is observed locally.
A Note on the Asymptotic Properties of Correlated Random Walks

We describe a simple relation between the asymptotic behavior of the variance and of the expected number of distinct sites visited during a correlated random walk. The relation is valid for multistate random walks with finite variance in dimensions 1 and 2. A similar relation, valid in all dimensions, exists between the asymptotic behavior of the variance and of the probability of return to the origin.
Evaluation of VIIRS cloud and aerosol products for the NPOESS Preparatory Project

The activities of the Atmosphere PEATE are discussed with respect to the evaluation of MODIS and VIIRS cloud and aerosol products within the LEOCAT development framework. The relevant properties of the MODIS and VIIRS sensors are compared.
Computing prior to FORTRAN

The life of the programmer in pre-FORTRAN days is characterized in modern terminology, indicating how strongly FORTRAN has changed the programmer's condition and working habits.
Rigid, Conjugated, Fluoresceinated Thymidine Triphosphates: Syntheses and Polymerase Mediated Incorporation into DNA Analogues

Syntheses of a unique set of energy transfer dye labeled nucleoside triphosphates, compounds 1-3, are described. Attempts to prepare these compounds were only successful if the triphosphorylation reaction was performed before coupling the dye to the nucleobase, and not the other way around. Compounds were prepared as both the 2'-deoxy (a) and 2',3'-dideoxy- (b) forms. They feature progressively longer rigid conjugated linkers connecting the nucleobase and the hydroxyxanthone moiety. UV spectra of the parent nucleosides 12-14 show that as the length of the linker increases so does the absorption of the donor in the 320-330 nm region, but with relatively little red-shift of the maxima. Fluorescence spectra of the same compounds show that radiation in the 320-330 nm region results in predominant emission from the fluorescein. When the linker is irradiated at 320 nm, the only significant emission observed corresponds to the hydroxyxanthone part of the molecules at 520 nm; this corresponds to an effective Stokes' shift of 200 nm. As the absorption at 320-330 nm by the linker increases with length, so does the intensity of the fluorescein emission. A gel assay was used to gauge relative incorporation efficiencies of compounds 1-3, dTTP, ddTTP, and 6-TAMRA-ddTTP. Throughout, the thermostable polymerase TaqFS was used, as it is the one most widely applied in high throughput DNA sequencing. This assay showed that only compounds 3 were incorporated efficiently; these have the longest linkers. Of these, the 2'-deoxy nucleoside 3 a was incorporated and did not prevent the polymerase from extending the chain further. The 2',3'-dideoxy nucleoside 3 b was incorporated only about 430 times less efficiently than ddTTP under the same conditions, and caused chain termination. The implications of these studies on modified sequencing protocols are discussed.
The market for certification by external parties: Evidence from underwriting and banking relationships☆

Abstract This paper provides evidence that an underwriter is better able to certify an equity issue if it has a lending relationship with the firm. An announcement of being underwritten by the firm’s lending-relationship bank reduces ex post information asymmetry, thereby improving the announcement return. Further, because this reduction in information asymmetry effectively disseminates what was previously the lending bank’s private information, it decreases its affiliated market maker’s information advantage, thus reducing its contribution to price discovery and liquidity. These results provide evidence on the value of information production and transmission by banks, and more generally on the role of external parties in reducing information asymmetry.
Tree-inspired piezoelectric energy harvesting

Abstract We design and test micro-watt energy-harvesters inspired by tree trunks swaying in the wind. A uniform flow vibrates a linear array of four cylinders affixed to piezoelectric energy transducers. Particular attention is paid to measuring the energy generated as a function of cylinder spacing, flow speed, and relative position of the cylinder within the array. Peak power is generated using cylinder center-to-center spacings of 3.3 diameters and flow speeds in which the vortex shedding frequency is 1.6 times the natural frequency of the cylinders. Using these flow speeds and spacings, the power generated by downstream cylinders can exceed that of leading cylinders by more than an order of magnitude. We visualize the flow in this system by studying the behavior of a dynamically matched flowing soap film with imbedded styrofoam disks. Our qualitative visualizations suggest that peak energy harvesting occurs under conditions in which vortices have fully detached from the leading cylinder.
Chief Justice Roberts, Justice Alito, and New Federalism Jurisprudence

The Rehnquist Court returned power back to the states in rulings that scholars have dubbed “New Federalism.” The appointments of Chief Justice Roberts and Justice Alito invite speculation about the future direction of federalism cases in the Supreme Court. A survey of the Roberts Court's federalism rulings discovers that the ideological pathways of new federalism depend upon Justice Kennedy's swing vote and the effects the new appointments have on shaping voting coalitions in light of the vacancies they have filled. Although there is a reconfigured “States’ Rights Five” voting coalition, neither Roberts nor Alito endorses rigid viewpoints about federalism and it remains uncertain if the Court will return to the type of aggressive new federalism which arguably defined the legacy of the Rehnquist Court.
Swimming Microorganisms in Gels

Many swimming microorganisms must move through viscoelastic fluids and gels. I present work on swimming in gels. First, unlike incompressible fluids, a gel can have compressional modes with relative motion between polymer and solvent fractions. In a continuum model for a gel, we show that compressibility can increase the swimming speed of Taylor's swimming sheet. The zero-frequency shear modulus of a gel requires altered boundary conditions on the swimmer. Second, many biological gels are heterogeneous on the lengthscale of swimming microorganisms, necessitating non-continuum models that treat the gel network and swimmer on equal footing. We show that a random network modeled as dilute, immobile spherical obstacles increases the average swimming speed of a Golestanian three-sphere swimmer.
Equivalent linear two-body equations for many-body systems

Abstract A method has been developed for obtaining equivalent linear two-body (ELTB) equations for the system of many (N) bosons using the variational principle. The method has been applied to the one-dimensional N-body problem with pair-wise contact interactions (McGurie–Yang N-body problem) and to the dilute Bose–Einstein condensation (BEC) of atoms in anisotropic harmonic traps at zero temperature. For both cases, it is shown that the method gives excellent results for large N.
Notable difference in anti-HIV activity of integrase inhibitors as a consequence of geometric and enantiomeric configurations.

Abstract While some examples are known of integrase inhibitors that exhibit potent anti-HIV activity, there are very few cases reported of integrase inhibitors that show significant differences in anti-HIV activity that result from distinctions in cis- and trans-configurations as well as enantiomeric stereostructure. We describe here the design and synthesis of two enantiomeric trans-hydroxycyclopentyl carboxamides which exhibit notable difference in anti-HIV activity. This difference is explained through their binding interactions within the active site of the HIV-1 integrase intasome. The more active enantiomer 3 (EC50 25 nM) was relatively stable in human liver microsomes. Kinetic data revealed that its impact on key cytochrome P450 isozymes, as either an inhibitor or an activator, was minor, suggesting a favorable CYP profile.
A better large N expansion for chiral Yukawa models

Abstract We consider the most general renormalizable chiral Yukawa model with SU(3)color replaced by SU(Nc), SU(2)L replaced by SU(Nw) and U(1)Y replaced by U (1)Nw−1 in the limit Nc → ∞, Nw → ∞ with the ratio ρ= N w N c ≠ 0 , ∞ held fixed. Since for Nw ⩾ 3 only one renormalizable Yukawa coupling per family exists and there is no mixing between families the limit is appropriate for the description of the effects of a heavy top quark when all the other fermions are taken to be massless. The large N= N c N w expansion is expected to be no worse quantitatively in this model that in the purely scalar case and the N = ∞ limit is soluble even when the model is regularized non-perturbatively. A rough estimate of the triviality bound on the Yukawa coupling is equivalent to mt ⩽ 1 itTeV.
An Efficient Technique to Determine the Power Spectrum from Cosmic Microwave Background Sky Maps

There is enormous potential to advance cosmology from statistical characterizations of cosmic microwave background (CMB) sky maps. The angular power spectrum of the microwave anisotropy is a particularly important statistic. Existing algorithms for computing the angular power spectrum of a pixelized map typically require O(N3) operations and O(N2) storage, where N is the number of independent pixels in the map. The MAP and Planck satellites will produce megapixel maps of the CMB temperature at multiple frequencies; thus, existing algorithms are not computationally feasible. In this article, we introduce an algorithm that requires O(N2) operations and O(N3/2) storage that can find the minimum variance power spectrum from sky map data roughly one million times faster than was previously possible. This makes feasible an analysis that was hitherto intractable.
THE MOTION OF WATER MASERS IN THE PRE-PLANETARY NEBULA IRAS 16342-3814

We present high angular resolution observations, using the Very Long Baseline Array of the NRAO4The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc., of the high-velocity water masers toward the water fountain pre-planetary nebula, IRAS 16342-3814. The detailed structure of the water masers appears to be that of bow shocks on either side of a highly collimated jet. The proper motions of the water masers are approximately equal to the radial velocities; the three-dimensional velocities are approximately ± 180 km s–1, which leads to a very short dynamical timescale of ~100 yrs. Although we do not find direct evidence for precession of the fast collimated jet, there may be indirect evidence for such precession.
Thurston maps and asymptotic upper curvature

A Thurston map is a branched covering map from $$\mathbb {S}^2$$ to $$\mathbb {S}^2$$ with a finite postcritical set. We associate a natural Gromov hyperbolic graph $$\mathcal {G}=\mathcal {G}(f,{\mathcal {C}})$$ with an expanding Thurston map $$f$$ and a Jordan curve $${\mathcal {C}}$$ on $$\mathbb {S}^2$$ containing $${{\mathrm{post}}}(f)$$ . The boundary at infinity of $$\mathcal {G}$$ with associated visual metrics can be identified with $$\mathbb {S}^2$$ equipped with the visual metric induced by the expanding Thurston map $$f$$ . We define asymptotic upper curvature of an expanding Thurston map $$f$$ to be the asymptotic upper curvature of the associated Gromov hyperbolic graph, and establish a connection between the asymptotic upper curvature of $$f$$ and the entropy of $$f$$ .
High Precision Superconducting Magnets

Window-frame type superconducting dipole magnets have demonstrated accuracy and predictability of fields which compare well with the best conventional accelerator-type magnets. Precision measurements were made on the two series powered 2 m long 4 T modules comprising the 80 bending magnet at BNL after two years of beam operation including several dozen beam induced quenches. The integral field of the two units is identical to measurement accuracy, ? 1 × 10-4 parts at ~ full aperture, for all multipoles except quadrupole. Random quadrupole terms of G/B = 6 × 10-5 cm-1 or 2 × 10-4 parts are present. A 1 m long 6 T model of more advanced design shows pure dipole field, at all field levels, to 1 × 10-4 parts, using a single correction coil with predetermined excitation. The field shape at ~ 0.5 T/sec rise rate is identical to dc. The advantages of the extended current sheet coil construction are discussed. Results will be compared with computer simulations of construction errors. Suitable conceptual designs of compact 6 T dipoles and of quadrupoles applied to a 1 km accelerator lattice will be presented.
Microscopic interface phonon modes in structures of GaAs quantum dots embedded in AlAs shells

Abstract By means of a microscopic valence force field model, a series of novel microscopic interface phonon modes are identified in shell quantum dots (SQDs) composed of a GaAs quantum dot of nanoscale embedded in an AlAs shell of a few atomic layers in thickness. In SQDs with such thin shells, the basic principle of the continuum dielectric model and the macroscopic dielectric function are not valid any more. The frequencies of these microscopic interface modes lie inside the gap between the bulk GaAs band and the bulk AlAs band, contrary to the macroscopic interface phonon modes. The average vibrational energies and amplitudes of each atomic shell show peaks at the interface between GaAs and AlAs. These peaks decay fast as their penetrating depths from the interface increase.
Impacts of Ethanol Policy on Corn Prices: A Review and Meta-Analysis of Recent Evidence

Abstract The literature on the impacts of biofuels on agricultural commodity prices is characterized by contradictory findings. We review studies published between 2007 and 2014 that estimate the effects of U.S. corn ethanol policy on corn prices and find estimates ranging from nil to over 80%. Such divergent results make it difficult to assess the merits of alternative biofuel policies. To bring more clarity to the issue and facilitate comparisons across studies, we assemble a database of over 150 medium-to-long run estimates of the effect of corn ethanol production on corn prices from 29 published studies. We first normalize corn price impacts by the change in corn ethanol volume to control for the large differences in ethanol quantities across scenarios. We then conduct a meta-analysis to identify the factors that drive the remaining variation in corn price impacts across studies. In addition to ethanol volumes, we find that modeling framework, projection year, inclusion of ethanol co-products, and biofuel production from other feedstocks explain much of the differences in price effects. The results indicate that a one billion gallon expansion of the US corn ethanol mandate in the year 2015 would lead to a three to four percent increase in corn prices, with smaller price changes projected in future years.
Integrated GaN photonic circuits on silicon (100) for second harmonic generation

We demonstrate second order optical nonlinearity in a silicon architecture through heterogeneous integration of single-crystalline gallium nitride (GaN) on silicon (100) substrates. By engineering GaN microrings for dual resonance around 1560 nm and 780 nm, we achieve efficient, tunable second harmonic generation at 780 nm. The χ2 nonlinear susceptibility is measured to be as high as 16 ± 7 pm/V. Because GaN has a wideband transparency window covering ultraviolet, visible and infrared wavelengths, our platform provides a viable route for the on-chip generation of optical wavelengths in both the far infrared and near-UV through a combination of χ2 enabled sum-/difference-frequency processes.
Data relation vectors: a new abstraction for data optimizations

We present an abstraction, called data relation vectors, to improve the data access characteristics and memory layouts in regular computations. The key idea is to define a relation between the data elements accessed by close-by iterations and use this relation to guide to a number of optimizations for array-based computations. The specific optimizations studied in this paper include enhancing group-spatial and self-spatial reuses and improving intratile and intertile data reuses. In addition, this abstraction works well with other known abstractions such as data reuse vectors. We also present a unified scheme for optimizing the memory performance of programs using this new abstraction in conjunction with reuse vectors. The data relation vector abstraction has been implemented in the SUIF compilation framework and has been tested using a set of 12 benchmarks from image processing and scientific computation domains. Preliminary results on a superscalar processor show that it is successful in reducing compilation time and outperforms two previously proposed techniques, one that uses only loop transformations and one that uses both loop and data transformations. Our experiments also show that the proposed abstraction helps one to select good data tile shapes which can subsequently be used to determine iteration space tiles.
A Comparison of Linking and Concurrent Calibration Under the Graded Response Model

Developing a common metric is essential to successful applications of item response theory to practical testing problems, such as equating, differential item functioning, and computerized adaptive testing. In this study, the authors compared two methods for developing a common metric for the graded response model under item response theory: (a) linking separate calibration runs using equating coefficients from the characteristic curve method and (b) concurrent calibration using the combined data of the base and target groups. Concurrent calibration yielded consistently albeit only slightly smaller root mean square differences for both item discrimination and location parameters. Similar results were observed for distance measures between item parameter estimates and item parameters. Concurrent calibration also yielded consistently though only slightly smaller root mean square differences for ability than linking.
Faceted Grain Boundaries in Al2O3

Different types of faceted grain boundaries in commercial poly-crystalline Al2O3 were examined. Three distinct cases, namely the basal twin, the rhombohedral twin, and other special high-angle grain boundaries, are discussed, comparing theoretical models and experimental observations. It is shown that the faceting of the boundaries can be associated with their migration. A mechanism for the separation of a σ= 13 grain houndary from a pinning void, small grain, or second-phase particle is illustrated. It is also shown experimentally that faceting of high-angle boundaries can occur on a scale of Σ 5 nm, and that, theoretically, faceting most likely also occurs on an atomistic scale. Throughout the theoretical analysis the basal plane is predicted to be a favored facet plane, which is confirmed by experimental observation.
Total synthesis and structural revision of vannusals A and B: synthesis of the true structures of vannusals A and B.

Having determined through total synthesis that the originally assigned structure of vannusals A and B were incorrect, we set out to uncover the identity of the true structures of these novel marine...
Vertex coalgebras, comodules, cocommutativity and coassociativity

We introduce the notion of vertex coalgebra, a generalization of vertex operator coalgebras. Next we investigate forms of cocommutativity, coassociativity, skew-symmetry, and an endomorphism, D*, which hold on vertex coalgebras. The former two properties require grading. We then discuss comodule structure. We conclude by discussing instances where graded vertex coalgebras appear, particularly as related to Primc�s vertex Lie algebra and (universal) enveloping vertex algebras.
Advances in nucleophilic phosphine catalysis of alkenes, allenes, alkynes, and MBHADs

In nucleophilic phosphine catalysis, tertiary phosphines undergo conjugate additions to activated carbon–carbon multiple bonds to form β-phosphonium enolates, β-phosphonium dienolates, β-phosphonium enoates, and vinyl phosphonium ylides as intermediates. When these reactive zwitterionic species react with nucleophiles and electrophiles, they may generate carbo- and heterocycles with multifarious molecular architectures. This article describes the reactivities of these phosphonium zwitterions, the applications of phosphine catalysis in the syntheses of biologically active compounds and natural products, and recent developments in the enantioselective phosphine catalysis.
Chemical bonding in group III nitrides.

We analyze in this article the evolution of the chemical bonding in group III nitrides (MN, M = Al, Ga, In), from the N−N bond dominated small clusters to the M−N bond dominated crystals, with the aim of explaining how the strong multiple bond of N2 is destabilized with the increase in coordination. The picture that emerges is that of a partially ionic bond in the solid state, which is also present in all the clusters. The covalent N−N bond, however, shows a gradual decrease of its strength due to the charge transfer from the metal atoms. Overall, Al clusters are more ionic than Ga and In clusters, and thus the N−N bond is weakest in them. The nitrogen atom charge is seen to be proportional to the metal coordination, being thus a bond-related property, and dependent on the M−N distance. This explains the behavior observed in previous investigations, and can be used as a guide in predicting the structures and defects on semiconductor quantum dot or thin film devices of these compounds.
Vortex Dynamics in a Spin-Orbit-Coupled Bose-Einstein Condensate

Vortices in a one-component dilute atomic ultracold Bose–Einstein condensate (BEC) usually arise as a response to externally driven rotation. Apart from a few special situations, these vortices are singly quantized with unit circulation (Fetter, Rev Mod Phys 81, 647–691, 2009). Recently, the NIST group has constructed a two-component BEC with a spin-orbit-coupled Hamiltonian involving Pauli matrices (Spielman, Phys Rev A 79, 063613, 2009; Y.-J. Lin et al., Nature 462, 628–632, 2009; Y.-J. Lin et al., Nature 471, 83–87, 2011), and I here study the dynamics of a two-component vortex in such a spin-orbit-coupled condensate. These spin-orbit-coupled BECs use an applied magnetic field to split the hyperfine levels. Hence, they rely on a focused laser beam to trap the atoms. In addition, two Raman laser beams create an effective (or synthetic) gauge potential. The resulting spin-orbit Hamiltonian is discussed in some detail. The various laser beams are fixed in the laboratory, so that it is not feasible to nucleate a vortex by an applied rotation that would need to rotate all the laser beams and the magnetic field. In a one-component BEC, a vortex can also be created by a thermal quench, starting from the normal state and suddenly cooling deep into the condensed state (Freilich et al., Science 329, 1182–1185, 2010). I propose that a similar method would work for a vortex in a spin-orbit-coupled BEC. Such a vortex has two components, and each has its own circulation quantum number (typically \(0,\pm 1\)). If both components have the same circulation, I find that the composite vortex should execute uniform precession, like that observed in a single-component BEC (Freilich et al., Science 329, 1182–1185, 2010). In contrast, if one component has unit circulation and the other has zero circulation, then some fraction of the dynamical vortex trajectories should eventually leave the condensate, providing clear experimental evidence for this unusual vortex structure. In the context of exciton–polariton condensates, such a vortex is known as a “half-quantum vortex” (Rubo, Phys Rev Lett 99, 106401, 2007; Lagoudakis et al., Science 326, 974–976, 2009).
DOES A NORMAL FOETUS REALLY HAVE A FUTURE OF VALUE? A REPLY TO MARQUIS

The traditional approach to the abortion debate revolves around numerous issues, such as whether the foetus is a person, whether the foetus has rights, and more. Don Marquis suggests that this traditional approach leads to a standoff and that the abortion debate 'requires a different strategy.' Hence his 'future of value' strategy, which is summarized as follows: (1) A normal foetus has a future of value. (2) Depriving a normal foetus of a future of value imposes a misfortune on it. (3) Imposing a misfortune on a normal foetus is prima facie wrong. (4) Therefore, depriving a normal foetus of a future of value is prima facie wrong. (5) Killing a normal foetus deprives it of a future value. (6) Therefore, killing a normal foetus is prima facie wrong. In this paper, I argue that Marquis's strategy is not different since it involves the concept of person--a concept deeply rooted in the traditional approach. Specifically, I argue that futures are valuable insofar as they are not only dominated by goods of consciousness, but are experienced by psychologically continuous persons. Moreover, I argue that his strategy is not sound since premise (1) is false. Specifically, I argue that a normal foetus, at least during the first trimester, is not a person. Thus, during that stage of development it is not capable of experiencing its future as a psychologically continuous person and, hence, it does not have a future of value.
Infrared extrapolations for atomic nuclei

Harmonic oscillator model-space truncations introduce systematic errors to the calculation of binding energies and other observables. We identify the relevant infrared (IR) scaling variable and give values for this nucleus-dependent quantity. We consider isotopes of oxygen computed with the coupled-cluster method from chiral nucleon–nucleon interactions at next-to-next-to-leading order and show that the IR component of the error is sufficiently understood to permit controlled extrapolations. By employing oscillator spaces with relatively large frequencies, well above the energy minimum, the ultraviolet corrections can be suppressed while IR extrapolations over tens of MeVs are accurate for ground-state energies. However, robust uncertainty quantification for extrapolated quantities that fully accounts for systematic errors is not yet developed.
Induced Innovation and Social Inequality: Evidence from Infant Medical Care

We develop a model of induced innovation that applies to medical research. Our model yields three empirical predictions. First, initial death rates and subsequent research effort should be positively correlated. Second, research effort should be associated with more rapid mortality declines. Third, as a byproduct of targeting the most common conditions in the population as a whole, induced innovation leads to growth in mortality disparities between minority and majority groups. Using information on infant deaths in the United States between 1983 and 1998, we find support for all three empirical predictions.
A mass spectrometric analysis of CF4/O2 plasmas: Effect of oxygen concentration and plasma power

A quadrupole mass analyzer was used to detect the neutral products extracted downstream from a CF4/O2 RF discharge at 80 mtorr. mtorr. Stable discharge products were investigated as a junction of plasma power, residence time, oxygen concentration, and plasma voltage standing-wave ratio. In general, as plasma power increased from 10 to 200 W, production of CO increased while the measured mole fractions of CO2 and COF2 stabilized. The ratio of' CO to CO, decreases! at low plasma powers as the oxygen concentration increased. ,4n increase in the relative conversion of CF4 to oxygenated products occurred at both low plasma powers and low oxygen concentrations. Chemical mechanisms are suggested to account for these results.
Who Benefits From Student Aid? The Economic Incidence of Tax-Based Federal Student Aid

Abstract Federal benefit programs, including federal student aid, are designed to aid targeted populations. Behavioral responses to these programs may alter the incidence of their benefits, a possibility that receives less attention in the literature compared to tax incidence. I demonstrate the importance of benefit incidence analysis by showing that the intended cost reductions of tax-based federal student aid are substantially offset by institutional price increases for a sample of 4-year colleges and universities. Contrary to the goal of policymakers, I find that tax-based aid crowds out institutional aid roughly dollar-for-dollar. Unfortunately, it is not clear how institutions utilize these captured resources, so that the ultimate incidence of the programs is uncertain.
BERYLLIUM AND ALPHA-ELEMENT ABUNDANCES IN A LARGE SAMPLE OF METAL-POOR STARS

The light elements, Li, Be, and B, provide tracers for many aspects of astronomy including stellar structure, Galactic evolution, and cosmology. We have made observations of Be in 117 metal-poor stars ranging in metallicity from [Fe/H] = –0.5 to –3.5 with Keck I/HIRES. Our spectra are high resolution (~42,000) and high signal to noise (the median is 106 per pixel). We have determined the stellar parameters spectroscopically from lines of Fe I, Fe II, Ti I, and Ti II. The abundances of Be and O were derived by spectrum synthesis techniques, while abundances of Fe, Ti, and Mg were found from many spectral line measurements. There is a linear relationship between [Fe/H] and A(Be) with a slope of +0.88 ± 0.03 over three orders of magnitude in [Fe/H]. We find that Be is enhanced relative to Fe; [Be/Fe] is +0.40 near [Fe/H] ~–3.3 and drops to 0.0 near [Fe/H] ~–1.7. For the relationship between A(Be) and [O/H], we find a gradual change in slope from 0.69 ± 0.13 for the Be-poor/O-poor stars to 1.13 ± 0.10 for the Be-rich/O-rich stars. Inasmuch as the relationship between [Fe/H] and [O/H] seems robustly linear (slope = +0.75 ± 0.03), we conclude that the slope change in Be versus O is due to the Be abundance. Much of the Be would have been formed in the vicinity of Type II supernova (SN II) in the early history of the Galaxy and by Galactic cosmic-ray (GCR) spallation in the later eras. Although Be is a by-product of CNO, we have used Ti and Mg abundances as alpha-element surrogates for O in part because O abundances are rather sensitive to both stellar temperature and surface gravity. We find that A(Be) tracks [Ti/H] very well with a slope of 1.00 ± 0.04. It also tracks [Mg/H] very well with a slope of 0.88 ± 0.03. We have kinematic information on 114 stars in our sample and they divide equally into dissipative and accretive stars. Almost the full range of [Fe/H] and [O/H] is covered in each group. There are distinct differences in the relationships of A(Be) and [Fe/H] and of A(Be) and [O/H] for the dissipative and the accretive stars. It is likely that the formation of Be in the accretive stars was primarily in the vicinity of SN II, while the Be in the dissipative stars was primarily formed by GCR spallation. We find that Be is not as good a cosmochronometer as Fe. We have found a spread in A(Be) that is valid at the 4σ level between [O/H] = –0.5 and –1.0, which corresponds to –0.9 and –1.6 in [Fe/H].
Very badly approximable matrix functions

We study in this paper very badly approximable matrix functions on the unit circle \( \mathbb{T}, \) i.e., matrix functions Φ such that the zero function is a superoptimal approximation of Φ. The purpose of this paper is to obtain a characterization of the continuous very badly approximable functions.
Ab-initio pulsar magnetosphere: three-dimensional particle-in-cell simulations of axisymmetric pulsars

We perform ''first-principles'' relativistic particle-in-cell simulations of aligned pulsar magnetosphere. We allow free escape of particles from the surface of a neutron star and continuously populate the magnetosphere with neutral pair plasma to imitate pair production. As pair plasma supply increases, we observe the transition from a charge-separated ''electrosphere'' solution with trapped plasma and no spin-down to a solution close to the ideal force-free magnetosphere with electromagnetically dominated pulsar wind. We calculate the magnetospheric structure, current distribution, and spin-down power of the neutron star. We also discuss particle acceleration in the equatorial current sheet.
Infrared Observations of a Mid-L Dwarf with Strong Hα Emission

We present Spitzer/IRAC observations of the L5 dwarf, 2MASSI J1315309-264951 (2M 1315). This ultracool dwarf is known to display strong emission in the Hα line. The spectral energy distribution (SED) for this object does not show any IR excess that would indicate the presence of an accretion disk. Although the IRAC colors for 2M 1315 are consistent with other L dwarfs, they seem to be redder by ~0.1 mag than the other L5 dwarfs, and more like the late-type L dwarfs. The existing six epochs of spectroscopy suggest that the emission in Hα is not persistent, but shows long-term variability between a flare value of ~100 A and a quiescent value of ~25 A. Chromospheric activity seems to be the most likely cause, which is also indicated by the detection of Na I D lines in emission (Fuhrmeister et al.). We have measured a proper motion of 0.79'' ± 0.06'' yr-1, which corresponds to a tangential velocity of ~81 km s-1 at a distance of ~22 pc. The high Vtan for this object suggests an old age. Evolutionary models indicate lower limits of 3.3 Gyr (Chabrier et al.) or 1.4 Gyr (Burrows et al.) for this magnetically active L dwarf to be a stable hydrogen-burning star. There seem to be no observational differences between this old L dwarf that has Hα emission and the other field L dwarfs without it.
Examination of an Oligocene lacustrine ecosystem using C and N stable isotopes

Abstract The Late Oligocene (25.8 Ma) Enspel Fossillagerstatte in Westerwald, Germany, contains a comprehensive fossil ecosystem preserved with specimens retaining morphological detail and a concentration of organic material. Stable carbon and nitrogen isotope analyses were used to examine the lacustrine ecosystem preserved in one stratigraphic horizon. These data suggest the presence of several trophic levels, including primary producers (diatoms and higher plants), primary consumers (e.g., tadpoles and insects), and secondary consumers (e.g., the fish species Paleorutilus enspelensis ). Terrigenous and aquatic plants were associated with the lowest δ 13 C and δ 15 N values (mean plant = − 26.28‰ ± 0.45, 3.18‰ ± 1.04), primary consumers such as flies are one trophic level higher, and carnivores such as fish are yet another level higher. The δ 15 N values for P. enspelensis also showed enrichment in 15 N with increasing body length, implying a shift in diet or feeding strategy with size. P. enspelensis and tadpole ( Pelobates decheni ) samples showed intraorganism fractionation between ‘muscle’ and ‘bone’ tissues. Stable carbon and nitrogen isotope data from the measurement of components (shale, leaves and seeds) common to a number of different stratigraphic horizons showed significant variation between horizons. A number of the features of the stable isotopic data are similar to those relationships seen in modern ecosystems and therefore suggest that stable isotope analyses can contribute to understanding ancient ecosystems.
Conductors and the moduli of residual perfection

Let A be a complete discrete valuation ring with possibly imperfect residue field. The purpose of this paper is to give a notion of conductor for Galois representations over A which agrees with the classical Artin conductor when the residue field is perfect. The definition rests on two results of perhaps wider interest: there is a moduli space that parametrizes the ways of modifying A so that its residue field is perfect, and any Galois-theoretic object over A can be recovered from its pullback to the (residually perfect) discrete valuation ring corresponding to the generic point of this moduli space. Finally, I show that this conductor extends the non-logarithmic variant of Kato’s conductor to representations of rank greater than one.
The ex-dividend day behavior of American depository receipts

Abstract We compare the ex-dividend day stock returns and trading volume of foreign stocks that trade in US markets as American Depository Receipts (ADRs) with the ex-day returns and volume of a matched sample of US stocks. This experiment allows us to investigate whether differences in the way dividends are paid and/or foreign currency risk affect the stock returns and trading volume of ADRs on the ex-dividend day. If these factors inhibit dividend capture in ADRs, then ADRs should earn larger ex-day returns than US stocks, and their ex-day trading volume should be lower. We present evidence consistent with these hypotheses. The results of a cross-sectional regression analysis of ex-day returns and volume are not consistent with a foreign exchange risk premium suppressing dividend capture in ADRs, however, suggesting that differences in dividend payment policies account for the lower level of dividend capture in ADRs.
Finite subset spaces of graphs and punctured surfaces

The kth nite subset space of a topological space X is the space expkX of non-empty nite subsets of X of size at most k, topologised as aq uotient of X k . The construction is a homotopy functor and may be regarded as a union of conguration spaces of distinct unordered points in X. We calculate the homology of the nite subset spaces of a connected graph , and study the maps (exp k) induced by a map : ! 0 between two such graphs. By homotopy functoriality the results apply to punctured surfaces also. The braid group Bn may be regarded as the mapping class group of an n{punctured disc Dn , and as such it acts on H(exp k Dn). We prove a structure theorem for this action, showing that the image of the pure braid group is nilpotent of class at mostb(n 1)=2c. AMS Classication 54B20; 05C10, 20F36, 55Q52
Total Synthesis of (±)-Cameroonanol

[reaction: see text]The structure and relative stereochemistry of the novel silphiperfolane-type sesquiterpene cameroonan-7alpha-ol (1) were confirmed by a total synthesis of (+/-)-1 from 3,3,5-trimethylbicyclo[3.3.0]oct-1(8)-en-2-one (6) by means of a Sakurai reaction with (Z)-crotylsilane, free radical hydrobromination, base-induced cyclization, and LiAlH4 reduction.
Why Are Hispanic- and Asian-American Homeownership Rates So Low?: Immigration and Other Factors

Abstract The homeownership rates of Hispanic- and Asian-American households are significantly less than that of other demographic groups in the US, especially after accounting for income and other characteristics. This naturally leads to an investigation of the impact of immigration characteristics of various groups on the propensity for homeownership. It is found that being an immigrant has a substantial negative effect on the probability of being a homeowner but that this effect dissipates over time. The relative youth of these two groups in and of itself plays a significant role in lowering their homeownership rate, as does the relatively high rate of residence in areas with high value–rent ratios.
A Strong coupling test of S duality

Abstract By studying the partition function of N =4 topologically twisted supersymmetric Yang-Mills on four-manifolds, we make an exact strong coupling test of the Montonen-Olive strong-weak duality conjecture. Unexpected and exciting links are found with two-dimensional rational conformal field theory.
Synthesis of functionalized polyfluoroalkyl hypochlorites and fluoroxy compounds and their reactions with some fluoroalkenes

Abstract Several new polyfluoroalkyl hypochlorites and fluoroxy compounds containing Cl, H andBr in the alkyl group have been prepared and characterized by 19 F NMR, 1 H NMR andIR spectroscopies and by their reactions with fluoroalkenes to produce new polyfluoroethers.The novel compounds are prepared by the CsF-catalyzed addition of F 2 or ClF to theCO bond in CF 3 C(O)CF 2 Cl, ClCF 2 C(O)CF 2 Cl, and their derivatives HCF 2 C(O)CF 3 andHCF 2 C(O)CF 2 Cl. Compounds containing an α-CF 3 group exhibit enhanced thermal stability. New fluoroxy compounds and hypochlorites have also been prepared from the acidfluorides CF 3 CFXC(O)F (XCl, Br), which are obtained by the ring-opening reactionof hexafluoropropene oxide with (CH 3 ) 3 SiCl, LiBr and (C 2 H 5 ) 3 SiBr. These -OX compoundsbehave similarly to previously known materials with two α-F atoms, decomposing quicklyat room temperature to COF 2 and haloalkanes.
Three-Dimensional Wake Forcing Functions Generated by a High-Speed Rotor

A series of experiments are described that are directed at investigating and quantifying the inherent three-dimensionality and fundamental unsteady-flow characteristics of unsteady aerodynamic forcing functions generated by high-speed compressor rotors for application to forced response. With a midspan rotor-relative inlet Mach number of 0.6, three-component velocity and unsteady-static-pressure data defining the spanwise nature of the rotor wake are acquired and analyzed at two axial locations, in both the inlet guide vane freestream and wake regions. The slanted hot-film technique enables evaluation of the ensemble-averaged-velocity field and the rms of this ensemble-averaged velocity. Data show that the rotor-wake unsteadiness is highest in the blade wake, the vortex regions, and the casing boundary layer. A strip theory approach is used to analyze these three-dimensional data. The rotor-wake data are also correlated with empirical correlations. After Fourier decomposition of the axial and tangential velocity components, a two-dimensional vortical-potential gust splitting analysis is implemented, and the vortical and potential harmonic wake gust forcing functions are determined.
Is the Abnormal Return Following Equity Issuances Anomalous

We examine whether a distinct equity issuer underperformance anomaly exists. In a sample of initial public o!ering (IPO) and seasoned equity o!ering (SEO) "rms from 1975 to 1992, we "nd that underperformance is concentrated primarily in small issuing "rms with low book-to-market ratios. SEO "rms, that underperform these standard benchmarks have time series returns that covary with factor returns constructed from nonissuing "rms. We conclude that the stock returns following equity issues re#ect a more pervasive return pattern in the broader set of publicly traded companies. ( 2000 Elsevier Science S.A. All rights reserved. JEL classixcation: G1; G2
Effect of in-medium properties on heavy ion collisions

The properties of strange hadrons, i.e. of kaons and hyperons, in the nuclear medium--are discussed in connection with neutron star properties and relativistic heavy-ion collisions. Firstly, the relevant medium modifications of a kaon in a medium as provided by heavy-ion collisions is critically examined within a coupled channel calculation. We demonstrate, that particle ratios for kaons are not a sensitive probe of in-medium effects while the K{sup {minus}} flow is more suited to pin down the K{sup {minus}} optical potential in dense matter. Secondly, the interaction between hyperons is studied and may form bound states which can be produced in relativistic heavy-ion collisions. Signals for the detection of strange dibaryons by their decay topology and/or in the invariant mass spectra are outlined.
Testing Event Discrimination over Broad Regions using the Historical Borovoye Observatory Explosion Dataset

We test the performance of high-frequency regional P/S discriminants to differentiate between earthquakes and explosions at test sites and over broad regions using a historical dataset of explosions recorded at the Borovoye Observatory in Kazakhstan. We compare these explosions to modern recordings of earthquakes at the same location. We then evaluate the separation of the two types of events using the raw measurements and those where the amplitudes are corrected for 1-D and 2-D attenuation structure. We find that high-frequency P/S amplitudes can reliably identify earthquakes and explosions, and that the discriminant is applicable over broad regions as long as propagation effects are properly accounted for. Lateral attenuation corrections provide the largest improvement in the 2–4 Hz band, the use of which may successfully enable the identification of smaller, distant events that have lower signal-to-noise at higher frequencies. We also find variations in P/S ratios among the three main nuclear testing locations within the Semipalatinsk Test Site which, due to their nearly identical paths to BRVK, must be a function of differing geology and emplacement conditions.
Flash-vacuum-pyrolytic reorganization of angular [4]phenylene

Flash vacuum pyrolysis of angular [4]phenylene furnishes "biphenylene dimer" on route to coronene.