cssi/SciSciGPT-SciSciNet huggingface dataset:
Magnetization dynamics, Bennett clocking and associated energy dissipation in multiferroic logic.

It has been recently shown that the magnetization of a multiferroic nanomagnet, consisting of a magnetostrictive layer elastically coupled to a piezoelectric layer, can be rotated by a large angle if a tiny voltage of a few tens of millivolts is applied to the piezoelectric layer. The potential generates stress in the magnetostrictive layer and rotates its magnetization by ~ 90? to implement Bennett clocking in nanomagnetic logic chains. Because of the small voltage needed, this clocking method is far more energy efficient than those that would employ spin transfer torque or magnetic fields to rotate the magnetization. In order to assess if such a clocking scheme can also be reasonably fast, we have studied the magnetization dynamics of a multiferroic logic chain with nearest-neighbor dipole coupling using the Landau?Lifshitz?Gilbert (LLG) equation. We find that clock rates of 2.5?GHz are feasible while still maintaining the exceptionally high energy efficiency. For this clock rate, the energy dissipated per clock cycle per bit flip is ~ 52?000?kT at room temperature in the clocking circuit for properly designed nanomagnets. Had we used spin transfer torque to clock at the same rate, the energy dissipated per clock cycle per bit flip would have been ~ 4 ? 108?kT, while with current transistor technology we would have expended ~ 106?kT. For slower clock rates of 1?GHz, stress-based clocking will dissipate only ~ 200?kT of energy per clock cycle per bit flip, while spin transfer torque would dissipate about 108?kT. This shows that multiferroic nanomagnetic logic, clocked with voltage-generated stress, can emerge as a very attractive technique for computing and signal processing since it can be several orders of magnitude more energy efficient than current technologies.
Index sets of computable structures

The index set of a computable structure $$\mathcal{A}$$ is the set of indices for computable copies of $$\mathcal{A}$$ . We determine complexity of the index sets of various mathematically interesting structures including different finite structures, ℚ-vector spaces, Archimedean real-closed ordered fields, reduced Abelian p-groups of length less than ω2, and models of the original Ehrenfeucht theory. The index sets for these structures all turn out to be m-complete Π n 0 , d-Σ n 0 , or Σ n 0 , for various n. In each case the calculation involves finding an optimal sentence (i.e., one of simplest form) that describes the structure. The form of the sentence (computable Πn, d-Σn, or Σn) yields a bound on the complexity of the index set. Whenever we show m-completeness of the index set, we know that the sentence is optimal. For some structures, the first sentence that comes to mind is not optimal, and another sentence of simpler form is shown to serve the purpose. For some of the groups, this involves Ramsey’s theory.
Early diagnosis and treatment of cancer of the lung

EVERY physician who is in active practice shoulders part of the cancer burden. People look to us for advice and help, individually and collectively, if they fall prey to such a terrible disease. Un...
The Use of System Identification Methods to Evaluate the Effects of Slider-Disk Contacts and Disk Micro-Waviness on the Flying Height Modulations

System identification methods have been used to study the response of a magnetic recording slider during contact with a scratch on the disk surface. In addition, the slider response was studied taking into account the effect of disk micro-waviness at various disk rotational speeds. The simulated slider response was compared with the measured slider dynamic behavior. Very good agreement was found between simulated and measured data. The flying height modulation of the slider, due to disk micro-waviness, was found to depend on disk velocity.
New trends in intercalation compounds

We review here some of the recent developments in intercalation compounds generally, with numerous examples taken from the literature on graphite intercalation compounds. Particular emphasis is given to research opportunities and new directions in this rapidly moving research field.
Projective dimension is a lattice invariant

Abstract We show that, for a free abelian group G and prime power pν, every direct sum decomposition of the group G/pνG lifts to a direct sum decomposition of G. This is the key result we use to show that, for R a commutative von Neumann regular ring, and E a set of idempotents in R, then the projective dimension of the ideal E R as an R-module the same as the projective dimension of the ideal EB as a B -module, where B is the boolean algebra generated by E ∪{1} . This answers a 30 year old open question of R. Wiegand.
Short wavelength ion waves upstream of the Earth's bow shock

The identification and explanation of short wavelength antenna interference effects observed in spacecraft plasma wave data have provided an important new method of determining limits on the wavelength, direction of propagation, and Doppler shift of short wavelength electrostatic waves. Using the ISEE-1 wideband electric field data, antenna interference effects have been identified in the ion waves upstream of the earth's bow shock. This identification implies that wavelengths of the upstream ion waves are shorter than the antenna length. The interference effects also provide new measurements of the direction of propagation of the ion waves. The new measurements show that the wave vectors of the ion waves are not parallel to the interplanetary magnetic field (IMF) as previously reported. The direction of propagation does not appear to be controlled by the IMF. In addition, analysis of the Doppler shift of the short wavelength ion waves has provided a measurement of the dispersion relation. The upper limit of the rest frame frequency was found to be on the order of the ion plasma frequency. At this frequency, the wavelength is on the order of a few times the Debye length. The results of this study now provide strong evidence that the ion waves in the upstream region are Doppler-shifted ion acoustic waves. Previously announced in STAR as N83-36328
Enantioselective Synthesis of Cyclopentenones via Rhodium-Catalyzed Kinetic Resolution and Desymmetrization of 4-Alkynals

We have developed two new catalytic processes that provide efficient access to interesting chiral building blocks, cyclopentenones that bear tertiary and quaternary stereocenters, in high enantiomeric excess and very good yield. Structures such as these have potential utility in the synthesis of prostaglandins, pentenomycins, and related compounds.
A Highly Enantio- and Diastereoselective Catalytic Intramolecular Stetter Reaction

A highly enantio- and diastereoselective intramolecular Stetter reaction has been developed. Subjection of α,α-disubstituted Michael acceptors to an asymmetric intramolecular Stetter reaction results in a highly enantioselective conjugate addition and a diastereoselective proton transfer. Available evidence suggests the diastereoselective protonation occurs via intramolecular delivery to the sterically more hindered face of the enolate. The scope of the trisubstituted Michael acceptors has been examined and found to be broad with respect to the size of the α-substituent and nature of the Michael acceptor. Aliphatic and aromatic aldehydes were examined and found to afford the desired product in good overall yield with high enantio- and diastereoselectivity.
Equilibrium Incentives to Acquire Precise Information in Delegated Portfolio Management

This paper investigates how a linear contract offered to a portfolio manager affects her incentives to acquire precise information. I show that increasing the manager's portfolio share increases her demand for precise information. This result contrasts with the existing irrelevance results where the manager's portfolio share does not affect her precision choice. The irrelevance result relies on the manager facing a constant asset price, regardless of her demand. In a noisy rational expectations framework, increasing the manager's share decreases her demand and results in a less informative asset price. Thus, the manager gathers more precise information when offered a larger fraction of portfolio returns.
Practical and Highly Enantioselective Synthesis of β-Alkynyl-β-Amino Esters Through Ag-Catalyzed Asymmetric Mannich Reactions of Silylketene Acetals and Alkynyl Imines

A readily available iso-leucine-based phosphine ligand is used to promote Ag-catalyzed Mannich reactions between silylketene acetals and various alkynyl imines. Reactions can be effected in the presence of 5 mol % catalyst, without the need for rigorous exclusion of air, and with commercially available solvents (without purification) to afford the desired β-alkynyl-β-amino esters in 84−94% ee and 61−91% isolated yield.
Hate groups and hate crime

This paper is the first to investigate the relationship between hate groups and hate crime empirically. We do so using panel data for the U.S. states between 2002 and 2008. Contrary to conventional wisdom, we find little evidence that hate groups are associated with hate crime in the United States. We find somewhat stronger evidence that economic hardship may be related to hate crime. However, evidence for the potential importance of economic factors remains weak. Further, we find that demographic variables are not significantly related to hate crime in the United States. Our results leave the question of what factors may drive hate crime in America unresolved. But they cast doubt on the popular perception that hate groups are among them.
STELLAR BINARY COMPANIONS TO SUPERNOVA PROGENITORS

For typical models of binary statistics, 50%-80% of core-collapse supernova (ccSN) progenitors are members of a stellar binary at the time of the explosion. Independent of any consequences of mass transfer, this has observational consequences that can be used to study the binary properties of massive stars. In particular, the secondary companion to the progenitor of a Type Ib/c SN is frequently (approx50%) the more optically luminous star since the high effective temperatures of the stripped progenitors make it relatively easy for a lower luminosity, cooler secondary to emit more optical light. Secondaries to the lower mass progenitors of Type II SN will frequently produce excess blue emission relative to the spectral energy distribution of the red primary. Available data constrain the models weakly. Any detected secondaries also provide an independent lower bound on the progenitor mass and, for historical SN, show that it was not a Type Ia event. Bright ccSN secondaries have an unambiguous, post-explosion observational signature-strong, blueshifted, relatively broad absorption lines created by the developing SN remnant (SNR). These can be used to locate historical SN with bright secondaries, confirm that a source is a secondary, and, potentially, measure abundances of ccSN ejecta. Luminous, hot secondaries willmore » re-ionize the SNR on timescales of 100-1000 yr that are faster than re-ionization by the reverse shock, creating peculiar H II regions due to the high metallicity and velocities of the ejecta.« less
An efficient method for the synthesis of trifluoromethyl substituted heterocycles

Abstract Trifluoromethyl substituted pyrazoles and isoxazoles have been prepared regiospecifically in high yield from trifluoroacetyl acetylenes.
Effect of probe pressure on cervical fluorescence spectroscopy measurements

Fluorescence spectroscopy is a promising technology for detection of epithelial precancers and cancers. While age and menopausal status influence measurements in the cervix, other variables do not significantly affect the diagnosis. In this study we examine probe pressure as a variable. A fiber optic probe to measure fluorescence spectra at different calibrated levels of pressure was designed and tested. A pilot study was conducted measuring fluorescence excitation emission matrices in 20 patients at light, medium, and firm pressure. Spectroscopic data were pre-processed and analyzed to compare mean peak intensities as a function of pressure. Further statistical analyses tested for differences in intensities at each excitation/emission wavelength pair. Four providers made measurements from 41 sites; 33 yielded good quality spectroscopic data (22 squamous normal, 7 squamous abnormal, 3 columnar normal, 1 transformation zone) from 17 of 20 patients. At all pressure levels, abnormal tissue showed less fluorescence intensity than normal tissue, and post-menopausal patients showed higher fluorescence intensity than premenopausal patients, consistent with previous analyses. A permutation analysis suggests that pressure does not significantly affect fluorescence intensity or lineshape. While other studies are needed to confirm these findings, this study suggests that fluorescence spectroscopy is a robust technology likely not influenced by fiber optic probe pressure.
Optimal transmission policies for energy harvesting two-hop networks

In this paper, a two-hop communication system with energy harvesting nodes is considered. Unlike battery powered wireless nodes, both the source and the relay are able to harvest energy from environment during communication, therefore, both data and energy causality over the two hops need to be considered. Assuming both nodes know the harvested energies in advance, properties of optimal transmission policies to maximize the delivered data by a given deadline are identified. Using these properties, optimal power allocation and transmission schedule for the case in which both nodes harvest two energy packets is developed.
The Luminosity Dependence of Quasar Clustering

We investigate the luminosity dependence of quasar clustering, inspired by numerical simulations of galaxy mergers that incorporate black hole growth. These simulations have motivated a new interpretation of the quasar luminosity function. In this picture, the bright end of the quasar luminosity function consists of quasars radiating nearly at their peak luminosities, while the faint end consists mainly of very similar sources, but at dimmer phases in their evolution. We combine this model with the statistics of dark matter halos that host quasar activity. We find that, since bright and faint quasars are mostly similar sources seen in different evolutionary stages, a broad range in quasar luminosities corresponds to only a narrow range in the masses of quasar host halos. On average, bright and faint quasars reside in similar host halos. Consequently, we argue that quasar clustering should depend only weakly on luminosity. This prediction is in qualitative agreement with recent measurements of the luminosity dependence of the quasar correlation function (Croom et al.) and the galaxy-quasar cross-correlation function (Adelberger & Steidel). Future precision clustering measurements from the Sloan Digital Sky Survey (SDSS) and the Two Degree Field Survey (2dF), spanning a large range in luminosity, should provide a strong test of our model.
Sharp upper bounds on the number of the scattering poles

Abstract We study the scattering poles of a compactly supported “black box” perturbations of the Laplacian in R n , n odd. We prove a sharp upper bound of the counting function N ( r ) modulo o ( r n ) in terms of the counting function of the reference operator in the smallest ball around the black box. In the most interesting cases, we prove a bound of the type N ( r ) ⩽ A n r n + o ( r n ) with an explicit A n . We prove that this bound is sharp in a few special spherically symmetric cases where the bound turns into an asymptotic formula.
Bombs, Ballots, and Coercion: The Madrid Bombings, Electoral Politics, and Terrorist Strategy

In 2004, an al Qaeda affiliate killed 191 civilians in Madrid. Spain's general election three days later confounded pollsters’ expectations; the incumbent Partido Popular was ousted by the challenging Partido Socialista Obrero Espanol ( psoe ), a party committed to withdrawal from Iraq. This manuscript examines the notion that this was a strategic terrorist success. The first strategic form considered is coercive bargaining. The paper finds that al Qaeda is not a credible coercive agent and debunks the popular myth that Spanish voters entered a coercive bargain with the network. The paper also considers the attacks through the strategic frameworks of terrorist advertising, provocation, regime destabilization, and morale building. It finds that the attacks’ only strategic achievement was building morale. Finally, the paper provides a multi-factor explanation of how the Madrid bombings contributed to the psoe victory despite their lack of strategic impact. The upshot of the analysis is that there is little ...
Studying the top quark via the W-gluon fusion process

Abstract We show that studying the single top quark production via the W -gluon fusion process can provide unique information on: (i) the measurement of the decay width Γ ( t → bW + ), (ii) probing the symmetry breaking mechanism by measuring the form factor of t - b - W ; (iii) testing the effective- W approximation prior to supercolliders; (iv) testing CP violation by observing different production rates of p p→ t X and p p→ t X ; (v) testing CP violation from the almost hundred percent longitudinally polarized top quark decay; in addition to the measurement of the top quark mass. In contrast to the recent claim by R.K. Ellis and S. Parke, we show that this process is extremely useful at the Tevatron. With appropriate kinematic cuts, we find there are about 10 top or anti-top events (including the W branching ratio into e or μ) from this process produced at the Tevatron with 100 pb −1 luminosity, S =1.8 TeV and 50% efficiency for tagging a b -quark.
Optical Two-dimensional Fourier-transform Spectroscopy of Semiconductor Quantum Wells

We demonstrate optical two-dimensional Fourier transform spectroscopy of heavy- and light-hole excitons in GaAs quantum wells. This is enabled by active interferometric stabilization of the excitation pulse separation and of a reference pulse.
Effects of speculation and interest rates in a “carry trade” model of commodity prices

Abstract The paper presents and estimates a model of the prices of oil and other storable commodities, a model that can be characterized as reflecting the carry trade. It focuses on speculative factors, here defined as the trade-off between interest rates on the one hand and market participants' expectations of future price changes on the other hand. It goes beyond past research by bringing to bear new data sources: survey data to measure expectations of future changes in commodity prices and options data to measure perceptions of risk. Some evidence is found of a negative effect of interest rates on the demand for inventories and thereby on commodity prices and positive effects of expected future price gains on inventory demand and thereby on today's commodity prices.
Self-similar enstrophy divergence in a shell model of isotropic turbulence

We focus on the early evolution of energy E and enstrophy Z when the dissipation grows in significance from negligible to important. By considering a sequence of viscous shell model solutions we find that both energy and dissipation are continuous functions of time in the inviscid limit. Inviscidly, Z takes only a finite time t* to diverge, where t* depends on initial conditions
SNAr Reactions of 2-haloarylsulfoxides with alkoxides provide a novel synthesis of thiotomoxetine

Abstract A five step synthesis of thiotomoxetine ( 2 ) is described. Installation of the aryl ether was accomplished using a highly efficient S N Ar fragment coupling between amino alcohol ( 4 ) and a 1-halo-2-methylsulfinylbenzene (X = F or Cl) followed by a selective reduction of the arylsulfoxide moiety.
Application of Nicollian-Reisman model to negative point-to-plane corona oxidation of silicon

The expression for silicon oxide growth proposed by Nicollian and Reisman for thermal oxidation is applied to corona discharge oxidation. The model parameter values indicate that at a given temperature the latter is more reaction rate controlled than thermal oxidation. The higher oxidation growth rate for the corona discharge oxidation is attributed to relaxation of the oxide network.
Synthesis and properties of BEDSe-TTF

Abstract We report the synthesis and properties of the π-electron donor molecule 4,5:4′,5′-bis(ethylene-1,2-diseleno)-tetrathiafulvalene (BEDSe-TTF) as well as the properties of a novel charge-transfer (C-T) salt derived from it. BEDSe-TTF was obtained in a 25% overall yield by a three step reaction starting from the organometallic complex, bis(tetrabutylammonium)-bis(2-thione-1,3-dithiole-4,5-diselenolato)nickelate(II). A single crystal X-ray structure determination of BEDSe-TTF showed it to be monoclinic, P21/n, with a = 6.842(2), b = 14.047(5), c = 16.094(5) A and β = 94.49(3)° having a unit cell volume of 1542A3 and four molecules per unit cell. Electrochemical oxidation of BEDSe-TTF gave single crystals of BEDSe-TTF+I3−. The structure of this 1:1 C-T salt was also monoclinic, P21/n, with a = 12.503, b = 10.592, c = 15.842 A and β = 100.12° having a unit cell volume of 2065.4 A3 and four molecules per unit cell.
The Stability Properties and Energy Transformations of the Two-layer Model of Variable Static Stability

The design and performance of simple atmospheric models is briefly reviewed as an introduction to the question of energetic consistency. The two-layer model of Lorenz appears to be the simplest fully-consistent formulation, and the freedom of this model from the constraints upon the Coriolis parameter and static stability characteristic of the usual quasi-geostrophic models is felt to be particularly important. As a prelude to actual numerical integration, the baroclinic stability properties and the energy transformations of this two-layer model are examined. It is found that the perturbations are here significantly more unstable than when the static stability is constrained in the usual manner. For the finite-amplitude disturbances, it is found that some of their available potential energy is transferred to the mean state through the stabilizing action of the systematic rising of the warmer air. These results suggest that the variation of the static stability both promotes the growth of new disturbances and limits the growth of the mature disturbances—effects which would appear to remedy some of the conspicuous performance errors of the conventional two-level models. DOI: 10.1111/j.2153-3490.1961.tb00108.x
Supersymmetry with a chargino NLSP and gravitino LSP

We demonstrate that the lightest chargino can be lighter than the lightest neutralino in supersymmetric models with Dirac gaugino masses as well as within a curious parameter region of the MSSM. Given also a light gravitino, such as from low scale supersymmetry breaking, this mass hierarchy leads to an unusual signal where every superpartner cascades down to a chargino that decays into an on-shell W and a gravitino, possibly with a macroscopic chargino track. We clearly identify the region of parameters where this signal can occur. We find it is generic in the context of the R-symmetric supersymmetric standard model, whereas it essentially only occurs in the MSSM when sign(M1) ≠ sign(M2) = sign(μ) and tan β is small. We briefly comment on the search strategies for this signal at the LHC.
Operant Conditioning for Investigating Speech Sound Discrimination in Aphasic Children

The present study utilized operant conditioning to investigate aphasic children’s speech sound discrimination. Eight aphasic children ranging in age from four to eight years were compared with eigh...
Membrane stratified solar ponds

Abstract The membrane stratified solar pond is a body of liquid utilizing closely spaced transparent membranes to quench convective heat transfer in the top part of the pond. Membranes may be configured as horizontal sheets, vertical sheets or vertical tubes. Several suitable liquids and membrane materials are discussed. Conditions for suppression of convection are described, and transmission of solar radiation through the pond is discussed for each of the three membrane configurations. The steady state thermal efficiency is calculated for the horizontal sheet configuration. Thermal behavior is similar to that of salt gradient solar ponds, but much deeper heat storage layers are feasible. In some cases aquaculture farming may be suitable in the storage layer.
Future directions of multicomponent seismic methods in the marine environment

Several different types of applications of multicomponent data have been demonstrated in both the offshore and onshore environment. To date, however, actual applications have not been as widespread as the potential benefits of the methods may suggest. Barriers to widespread application of the technique are not only limited by the lack of fidelity in the actual recording. Of course, the better the data the more likely the application, but good data—although necessary for successful interpretation—may not be sufficient to lead to universal usage.
Impaired myocardial performance and response to calcium in experimental alcoholic cardiomyopathy.

The effect of chronic consumption of ethanol upon myocardial function has been in dispute. The mechanical performance of isolated left ventricular papillary muscles was studied in a group of eight male rats which had been on a diet in which ethanol provided 36% of total calories for 5 weeks. This group was compared to a pairfed control group of eight rats. Muscles were studied in oxygenated Krebs-Henseleit solution at 28°C, while stretched to Lmax and stimulated at 12/min to contract isometrically. Bath calcium concentrations were varied from 1.25 to 7.5 mm/l. Heart size and chamber weights did not differ between the groups. Peak developed tension, maximum rates of rise and fall of tension, and time to half relaxation were significantly lower in the ethanol group, whereas resting tension and time to peak tension did not differ in the two groups. All parameters except time to half relaxation exhibited a significant dependence on concentration of calcium in the bath. However, the degrees of augmentation of peak developed tension and maximum rates of rise and fall of tension with increase in calcium in the bath from 1.25 to 2.5 mm/l were significantly lower in the ethanol group. In addition to impairment of function with chronic alcohol administration, altered sensitivity to calcium was demonstrated. Thus, isolated muscle studies have defined a defect in defined a defect in myocardial performance not apparent from studies of hemodynamics in the intact animal.
Family symmetry, fermion mass matrices and cosmic texture

Abstract The observed replication of fermions in three families is undoubtedly a reflection of a deeper symmetry underlying the standard model. In this paper we investigate one very elementary possibility, that physics above the grand unification scale is described by the symmetry group G × SU(3)fam with G a gauged grand unified group, and SU(3)fam a global family symmetry. The breaking of this symmetry at the GUT scale produces global texture, providing a mechanism for structure formation in the universe, and sets strong constraints on the low energy fermion mass matrix. With the addition of a 45 Higgs and certain assumptions about the relative strength of Higgs couplings, the simplest SU(5) theory yields an eight-parameter form for the fermion mass matrices, which we show is consistent with the thirteen observable masses and mixing angles. We discuss the natural suppression of flavour-changing neutral currents (FCNCs) and emphasise the rich low energy Higgs sector. With minor assumptions, the theory unifies consistently with the recent LEP data. We consider the extension to G = SO(10), where some simplification and further predictiveness emerges. Finally we discuss the dynamics of SU(3)fam texture and show that the known constraints on unification “predict” a GUT symmetry-breaking scale of the order required for cosmic structure formation, and by the recent detection of cosmic microwave anisotropy by COBE.
Production of Lithium, Beryllium, and Boron from Baryon Inhomogeneous Primordial Nucleosynthesis

We investigate the possibility that inhomogeneous nucleosynthesis may eventually be used to explain the abundances of Li-6, Be-9, and B in Population II stars. The present work differs from previous studies in that we have used a more extensive reaction network. It is demonstrated that in the simplest scenario the abundances of the light elements with A less than or = 7 constrain the separation of inhomogeneities to sufficently small scales that the model is indistinguishable from homogeneous nucleosynthesis and that the abundnace of Li-6, Be-9, and B are then below observations by several orders of magnitude. This conclusion does not depend on the Li-7 constraint. We also examine alternative scenarios which involve a post-nucleosynthesis reprocessing of the light elements to reproduce the observed abundances of Li and B, while allowing for a somewhat higher baryon density (still well below the cosmological critical density). Future B/H measurements may be able to exclude even this exotic scenario and further restrict primirdial nucleosynthesis to approach the homogeneous model conclusions.
Chemical Abundances of H II Regions in the Starburst Galaxy NGC 1705

We report optical spectroscopy of 16 H II regions in NGC 1705 and [O III] λ4363 detections for the first time in five H II regions. The resulting mean oxygen abundance derived directly from measured electron temperatures is 12 + log(O/H) = 8.21 ± 0.05, which corresponds to [O/H] = -0.45, or 35% of the solar value. There are no significant spatial inhomogeneities in [O III] λ4363 oxygen abundances from H II regions at a radius approximately 10'' from the super star cluster. In H II regions where [O III] λ4363 was not measured, oxygen abundances derived with bright-line methods (accurate only to 0.2 dex) are in agreement with direct values of the oxygen abundance. Faint, narrow He II λ4686 emission is found in two H II regions, but the implied contribution from O+3 to the total oxygen abundance is only 0.01 dex. The mean argon-, neon-, and nitrogen-to-oxygen abundance ratios are consistent with mean values for other dwarf irregular galaxies, blue compact dwarf galaxies, and H II galaxies at comparable oxygen abundances. Interestingly, the nitrogen-to-oxygen abundance ratio in the ionized H II gas agrees with the value for the neutral H I, even though the metallicity of the neutral gas may be a factor of 6 lower than that of the ionized gas. This may be indicative of low-metallicity gas in the halo of the galaxy. Extinction values, AV, derived from observed Balmer line ratios along lines of sight to H II regions are in the range between 0 and 0.9 mag. Significant and variable extinction may have important effects on the interpretation of resolved stellar populations and derived star formation histories. With respect to the metallicity-luminosity and metallicity-gas fraction diagnostics, the measured oxygen abundance for NGC 1705 is comparable to those of Local Group dwarf irregular galaxies at a given luminosity and gas fraction. Simple chemical evolution models suggest that the galaxy is quickly evolving into a gas-poor dwarf galaxy.
Acoustics of fluid-structure interactions

Preface 1. Introduction 2. Aerodynamic sound in unbounded flows 3. Sound generation in a fluid with rigid boundaries 4. Sound generation in a fluid with flexible boundaries 5. Interaction of sound with solid structures 6. Resonant and unstable systems References.
The Case Against Cold, Dark Chromospheres

Is the solar chromosphere always hot, with relatively small temperature variations (δT/T ~ 0.1), or is it cold most of the time, with temperature fluctuations that reach δT/T ~ 10 at the top of the chromosphere? Or, equivalently, is the chromosphere heated continually or only for a few seconds once every 3 minutes? Two types of empirical model, one essentially time independent and always hot, the other highly time dependent and mostly cold, come to fundamentally different conclusions. This paper analyzes the time-dependent model of the quiet, nonmagnetic chromosphere by Carlsson & Stein and shows that it predicts deep absorption lines, none of which are observed; intensity fluctuations in the Lyman continuum that are much larger than observed; and time-averaged emission that falls far short of the observed emission. The paper concludes that the solar chromosphere, while time-dependent, is never cold and dark. The same conclusion applies for stellar chromospheres. A complete, time-dependent model of the nonmagnetic chromosphere must describe two phenomena: (1) dynamics, like that modeled by Carlsson & Stein for chromospheric bright points but corrected for the geometrical properties of shocks propagating in an upward-expanding channel, and (2) the energetically more important general, sustained heating of the chromosphere, as described by current time-independent empirical models but modified in the upper photosphere for the formation of molecular absorption lines of CO in a dynamical medium. This model is always hot and, except for absorption features caused by departures from local thermodynamic equilibrium, shows chromospheric lines only in emission.
A text compression scheme that allows fast searching directly in the compressed file

A new text compression scheme is presented in this article. The main purpose of this scheme is to speed up string matching by searching the compressed file directly. The scheme requires no modification of the string-matching algorithm, which is used as a black box; any string-matching procedure can be used. Instead, the pattern is modified; only the outcome of the matching of the modified pattern against the compressed file is decompressed. Since the compressed file is smaller than the original file, the search is faster both in terms of I/O time and precessing time than a search in the original file. For typical text files, we achieve about 30% reduction of space and slightly less of search time. A 30% space saving is not competitive with good text compression schemes, and thus should not be used where space is the predominant concern. The intended applications of this scheme are files that are searched often, such as catalogs, bibliographic files, and address books. Such files are typically not compressed, but with this scheme they can remain compressed indefinitely, saving space while allowing faster search at the same time. A particular application to an information retrieval system that we developed is also discussed.
Equipartitions of Measures by 2-Fans

We study the problem of computing an equitable 2-fan for three masses distributed on the 2-sphere. The existence of an equitable 2-fan was shown by Barany and Matousek. The contribution of this paper is twofold. (i) We prove the existence of an infinite set of equitable 2-fans. (ii) We present an efficient algorithm for finding an equitable 2-fan when the mass distributions are discrete, i.e. finite sets of points. Both (i) and (ii) can be easily extended to mass distributions in the plane instead of the sphere.
Interstellar scattering of the Vela pulsar

The frequency dependence of the parameters of interstellar scattering between 837 and 8085 MHz for the Vela pulsar are consistent with thin-screen models of strong scattering. The magnitudes of the parameters indicate an anomalous turbulence along the path when they are compared with results for other pulsars with comparable column densities of free electrons in the line of sight. This anomaly is due presumably to the Gum Nebula. The decorrelation frequency, appropriately defined, is related to the pulse broadening time by 2 pi as predicted theoretically.
Synthesis of α-amino γ-lactone via a novel tandem three-component reaction of alkenes, glyoxylates and amines

α-Amino γ-lactones were generated by an InCl3-mediated or Sc(OTf)3-catalyzed three-component reaction of alkenes, glyoxylates and amines.
A language for generic programming in the large

Generic programming is an effective methodology for developing reusable software libraries. Many programming languages provide generics and have features for describing interfaces, but none completely support the idioms used in generic programming. To address this need we developed the language G. The central feature of G is the concept, a mechanism for organizing constraints on generics that is inspired by the needs of modern C++ libraries. G provides modular type checking and separate compilation (even of generics). These characteristics support modular software development, especially the smooth integration of independently developed components. In this article we present the rationale for the design of G and demonstrate the expressiveness of G with two case studies: porting the Standard Template Library and the Boost Graph Library from C++ to G. The design of G shares much in common with the concept extension proposed for the next C++ Standard (the authors participated in its design) but there are important differences described in this article.
Evidence of Information Asymmetries in the Market for Residential Condominiums

Previous research (Rutherford et al. 2005; Levitt and Syverson 2005) identify and quantify agency problems in the brokerage of single-family houses. Real estate agents are found to receive a premium when selling their own houses in comparison to similar client-owned houses. Given the homogeneity of the condominium market in comparison to the single-family house market, we use a large sample of condominium transactions to examine if agency problems exist in the condominium market. Controlling for sample selection and endogeneity bias of the data, we find evidence for a similar price premium for agent-owned condominiums. In contrast to the results for single-family houses in the same geographic market, we find that agent-owned condominiums must stay on the market longer to receive a higher price.
Enantioselective Organocatalytic Amine Conjugate Addition

The first enantioselective organocatalytic amine conjugate addition has been successfully developed. The application of LUMO-lowering iminium catalysis has enabled the highly chemo- and enantioselective 1,4-addition of a rationally designed N-silyloxycarbamate nucleophile (HOMO-raised) to α,β-unsaturated aldehydes. Imidazolidinone 2•pTSA was found to catalyze the addition of various orthogonally N-protected silyloxycarbamate nucleophiles to a range of α,β-unsaturated aldehydes, affording synthetically useful β-amino aldehyde intermediates. The synthetic utility of the protocol was demonstrated in the rapid synthesis of enantioenriched β-amino acids in one operation and 1,3-amino alcohol derivatives in three operations.
Chandra X-Ray Observations of NGC 1316 (Fornax A)

We report the results of the Chandra ACIS subarcsecond resolution X-ray observation of the archetypal merger radio galaxy NGC 1316 (Fornax A). We confirm the presence of fine substructures in the hot interstellar medium (ISM). Some of these are likely to result from interaction with the radio jets, while others may be related to a complex intermingling of different phases of the ISM. We detect a low-luminosity X-ray active galactic nucleus (AGN) with LX = 5 × 1039 ergs s-1 (in 0.3-8 keV) and a Γ = 1.7 power-law energy spectrum. We also detect 81 point sources within the 25th magnitude isophotal ellipse of NGC 1316 (LX in the range of 2 × 1037 to 2 × 1039 ergs s-1), with hard (kT ~ 5 keV) X-ray spectra, typical of X-ray binaries, and a spatial radial distribution consistent with that of the optical (i.e., stellar) surface brightness. We derive the X-ray luminosity function (XLF) of these sources, correcting for the incompleteness at the faint end caused by the presence of the diffuse emission from the hot ISM in the central regions of NGC 1316 and by the widening of the Chandra point-spread functions at increasing distance from the aim point. With these corrections, the XLF is well reproduced by a single—unbroken—power law with a slope of -1.3 down to our threshold luminosity of ~3 × 1037 ergs s-1. The hot ISM has temperatures in the 0.5-0.6 keV range, its surface brightness distribution is more centrally concentrated than that of the point sources, and its temperature appears to decrease at larger radii. These properties suggest that the ISM may be subject to partial winds. Taking into account the spectral complexity of the ISM, and the presence of unresolved low luminosity X-ray sources (which can be inferred from the spectra), we constrain the metal abundance of the hot ISM to be Z = 0.25-1.3 Z☉ (90% confidence).
TEMPLATE-PROMOTED DIMERIZATION OF C-ALLYLGLYCINE : A CONVENIENT SYNTHESIS OF (S, S)-2,7-DIAMINOSUBERIC ACID

Abstract ( S , S )-2,7-diaminosuberic acid can be synthesized in a convenient manner using an intramolecular ruthenium-catalyzed ring closing metathesis reaction of BOC-protected C -allylglycine anchored to a catechol template
Enhanced cohesion of matter on a cylindrical surface

We evaluate the cohesive energies ${E}_{b}$ of four systems in which particles move on a cylindrical surface, at fixed distance R from the axis. We find quite nonuniversal dependences of ${E}_{b}$ on R. For the Coulomb binding problem, ${E}_{b}$ is a monotonically decreasing function of R. For three problems involving Lennard-Jones interactions, the behavior is nonmonotonic; ${E}_{b}$ is larger at $R=\ensuremath{\infty}$ than at $R=0.$ The maximum binding corresponds to $R\ensuremath{\sim}0.7\ensuremath{\sigma},$ where $\ensuremath{\sigma}$ is the hard core parameter. Consequences of the enhanced binding are discussed.
Business Unit Reorganization and Innovation in New Product Markets

This paper empirically examines how business unit reorganization affects innovation, and explores how the learning process may mediate this relationship. Unit reorganization is the creation, deletion, or recombination of business units within a firm. Innovation is radical and involves product market entry by a firm into markets in which it was not previously active. I test competing hypotheses that predict either a U-shape or inverted U-shape relationship between reorganization and innovation to determine whether and how learning occurs in the presence of unit-level structural change. Theoretical support is drawn from literature on dynamic capabilities and organizational learning. The sample studied is 250 medical firms belonging to the pharmaceutical, healthcare-service, and medical-device industries, studied over a 20-year period. The findings are twofold. First, reorganization is found to exhibit a U-shape relationship with innovation, supporting learning arguments that stress the importance of experiencing a cohort of multiple events. Second, only reorganization experiences within a current period affect future innovation; past experiences do not impact future innovation, implying that firms may face constraints in organizational memory. The study concludes by exploring the structural origin (i.e., from internal, acquired, or recombined units) of innovative activity within firms.
Pseudofree group actions on spheres

R. S. Kulkarni showed that a finite group acting pseudofreely, but not freely, preserving orientation, on an even-dimensional sphere (or suitable sphere-like space) is either a periodic group acting semifreely with two fixed points, a dihedral group acting with three singular orbits, or one of the polyhedral groups, occurring only in dimension 2. It is shown here that the dihedral group does not act pseudofreely and locally linearly on an actual n-sphere when n is congruent to 0 mod 4. The possibility of such an action when n is congruent to 2 mod 4 and n>2 remains open. Orientation-reversing actions are also considered.
Constructing competitive tours from local information

Abstract We consider the problem of a searcher exploring an initially unknown weighted planar graph G. When the searcher visits a vertex v, it learns of each edge incident to v. The searcher's goal is to visit each vertex of G, incurring as little cost as possible. We present a constant competitive algorithm for this problem.
Total synthesis of (−)-bistatramide C

Abstract The total synthesis of macrocyclic hexapeptide Bistatramide C is reported from enantiomerically pure oxazole and thiazole amino acids.
Geometric angle structures on triangulated surfaces

In this paper we characterize the edge invariant and Delaunay invariant of a spherical angle structure on a triangulated surface. We also characterize the edge invariant of a hyperbolic angle structure on a triangulated surface.
Spectral evolution equation for the sideband instability in a free-electron laser oscillator

Abstract Assuming that the light remains in the optical system while the electrons pass through and are lost, we have derived the evolution equation for an arbitrary optical spectrum in a free electron laser oscillator. The resulting integrodifferential equation includes the effects of linear system losses (due to either mirror reflectivity or clipping), the usual small signal gain term, and a quadratic nonlinear term that includes the effects of saturation and coupling to sideband modes. The effects of detuning and particle beam current and energy variations can easily be included. Results of numerical solutions of the equations for various conditions will be presented.
Higher-order squeezing in a boson-coupled two-mode system.

We consider a model for nondegenerate cavity fields interacting through an intervening boson field. The quantum correltaions introduced in this manner are manifest through their higher-order correlation functions, where a type of squeezed state is identified.
A study of the phase Mg2Cu6Ga5, isotypic with Mg2Zn11. A route to an icosahedral quasicrystal approximant

The new title compound was synthesized by high-temperature means and its X-ray structure refined in the cubic space group Pm3, Z = 3, a = 8.278(1) A. The structure exhibits a 3-D framework made from a Ga14 and Mg network within which large and small cavities are occupied by centered GaCu12 icosahedral and Cu6 octahedral clusters, respectively. The clusters are well bonded within the network. Electronic structure calculations show that a pseudogap exists just above the Fermi energy, and nearly all pairwise covalent interactions remain bonding over a range of energy above that point. Analysis suggests that the compound is hypoelectronic with a four-electron deficiency per unit cell, and such a derivative with Sc substituting for Mg is an appropriate quasicrystal approximant (Im3). Such characteristics seem to be key factors in the formation of icosahedral quasicrystals.
Circular Polarization from Stochastic Synchrotron Sources

The transfer of polarized radiation in stochastic synchrotron sources is explored by means of analytic treatment and Monte Carlo simulations. We argue that the main mechanism responsible for the circular polarization properties compact synchrotron sources is likely to be Faraday conversion and that, contrary to common expectation, a significant rate of Faraday rotation does not necessarily imply strong depolarization. The long-term persistence of the sign of circular polarization, observed in many sources, is most likely due to a small net magnetic flux generated in the central engine, carried along the jet axis and superimposed on a highly turbulent magnetic field. We show that the mean levels of circular and linear polarizations depend on the number of field reversals along the line of sight and that the gradient in Faraday rotation across turbulent regions can lead to correlation depolarization. Our model is potentially applicable to a wide range of synchrotron sources. In particular, we demonstrate how our model can naturally explain the excess of circular over linear polarization in the Galactic center and the nearby spiral galaxy M81 and discuss its application to the quasar 3C 279, the intraday variable blazar PKS 1519-273, and the X-ray binary SS 433.
Laughter, Learning, or Enlightenment? Viewing and Avoidance Motivations Behind The Daily Show and The Colbert Report

This project integrates a uses and gratifications perspective into the study of political satire, to explore the reasons why young people prefer (or avoid) political satire programming, and to unde...