cssi/SciSciGPT-SciSciNet huggingface dataset:
BLACKS AND OTHER RACIAL MINORITIES: THE SIGNIFICANCE OF COLOR IN INEQUALITY

This paper seeks to explain why certain raciavethnic minority groups (i.e., Asians, Hispanics, and Native Americans) have achieved higher socioeconomic statuses than blacks. Data from census reports and previous research suggest that the lower socioeconomic status of blacks is due primarily to greater discrimination against blacks in housing, resulting in a high level of residential segregation, limited suburbanization, and reduced employment and educational opportunities. Unlike members of the other raciavethnic minority groups, blacks cannot expect that future improvements in the social and economic status of blacks will necessarily lead to residential integration and greater suburbanization. The implication is that color- i.e., black color-remains a significant factor in inequality in American society.
Pulsed power for electromagnetic launching

There are system advantages to producing power for electromagnetic propulsion by real time generation rather than by a sequence of generation-storage-switching. The best type of generator for this purpose is the flux compression generator. Different types of flux compression generator which have been developed at Sandia National Laboratories are reviewed and their applications to electric launching are discussed. New experimental facilities for producing more powerful generators are described and cost comparisons are made.
Numerical solution of two-dimensional turbulent blunt body flows with an impinging shock

AN implicit finite-difference method has been developed to compute two-dimensional, turbulent, blunt-body flows with an impinging shock wave. The complete timeaveraged Navier-Stokes equations are solved with algebraic eddy viscosity and turbulent Prandtl number models employed for shear stress and heat flux. The irregular-shaped bow shock is treated as a discontinuity across which the Rankine-Hugoniot equations are applied. A Type III turbulent shock interference flowfield has been computed and the numerical results compare favorably with existing experimental data. Contents The problem of shock interference heating arising from an extraneous shock wave impinging on a blunt body has been studied extensively during the past several years. In the Type III interference pattern, as described by Edney,l a shear layer originates at the intersection of the impinging shock and bow shock and interacts with the wall boundary layer. It has been shown1;2 that the heat transfer is strongly dependent on whether the shear layer is laminar, transitional, or turbulent. A method for computing laminar shock interference flowfields has been developed previously and applied to both two-dimensional3'4 and three-dimensional5 configurations. This method numerically computes the entire shock layer flowfield using the standard, unsplit, MacCormack finitedifference scheme6 to solve the complete set of compressible Navier-Stokes equations. In order to calculate turbulent shock interference flowfields, a turbulence model was added to the method. Unfortunately, this explicit method suffers from the fact that the allowable time step is proportional to the square of the grid spacing in viscous regions. In order to overcome this step size limitation, an implicit, noniterative, approximate-factorization, finite-difference scheme developed by Lindemuth and Killeen,7 McDonald and Briley,8 and Beam and Warming9 is used in the present study to solve the complete time-averaged Navier-Stokes equations. Although this scheme increases the computation time per step over that of the previous explicit scheme by a factor of 1.8 for turbulent calculations, it permits a time step that is many times greater than the explicit time step when fine meshes are
A concise synthesis of α-glycosyl cyanides

Abstract A simple procedure has been developed for the synthesis of α-glycosyl cyanides: reactions of O-benzylated ethyl 1-thio-glycosides of l -fucose and d -glucose, with TMSCN and MeOTF in ether exclusively gave the corresponding α-glycosyl cyanides in good yields.
Are Some Pneumatic Conveying Problems Wicked

Wicked problems are some of the most challenging in the world. World health, global warming, and the energy challenge are some that quickly come to mind. Wicked problems are problems that do not have right and wrong solutions but rather have degrees of good and bad. These problems can be tamed but never totally conquered. Some may say that dilute pneumatic phase conveying is totally solved but some would indicate that there is a subset that is still a big challenge. Dense phase conveying issues are more wicked than dilute phase conveying issues. One can probably take a closer look at such parameters as size, distribution, shape, abrasiveness, hardness, environmental condition, densities, tackiness, and others and define what properties or conditions cause the conveying problem to turn wicked. Industry is always developing new materials and processes that often lessen our confidence in being able to design conveying systems without problems. More stringent conditions are placed on the system whether it is ...
Jørgen Lund: A Perspective on His Contributions to Modern Rotor Bearing Dynamics

This paper presents a perspective on the work of Dr. J. W Lund, in the field of rotor-bearing dynamics. It traces his most influential work in published journals, software, data published in various manuals, government reports, and course notes. It addresses his work in oil bearings, gas bearings, unbalance response of flexible rotors, stability of flexible rotors, squeeze-film dampers, rotor balancing, and modal testing of rotors. It provides a road map for those who would revisit the knowledge base. It shows how Dr Lund's work has permeated the practice of today's suppliers and users of turbomachinery, and industry consultants.
Application of coded apertures in tomographic head scanning

A circular ring tomograph, designated SPRINT, is under development for single photon emission tomography of the human head. Most data to date have been gathered using a single rotating slit inside the detector ring to define ray directions. As an alternative method, we have also investigated the use of multiplexed slit patterns consisting of a pseudorandom binary code. From theoretical considerations, one would expect that the substitution of the code for the single slit would have potential advantages in reducing statistical noise in tomographic images of small objects. It has been our experience that this improvement is marginal at best for the types of source distributions encountered in clinical brain imaging. However, the code shows substantial advantage in suppressing uncorrelated backgrounds and the effects of highly penetrating gamma ray components in the source.
SOI built-in heat spreader with temperature and pressure integrated sensors for cooling optimization and in situ monitoring

Abstract This contribution presents an original solution for sensor integration into a heat spreader which is directly micromachined into the silicon substrate of the device to be cooled. Having both a high thermal conductivity coefficient and a high level of miniaturization, the vapor chamber heat spreader provides a high robustness due to the absence of any moving pumping parts. Simulation results as well as experimental results obtained with a prototype of the heat spreader with integrated temperature and pressure microsensors are presented. The results concerning device cooling optimization using the integrated sensors are highlighting the interest of this approach for accurate in situ monitoring and cooling optimization of silicon-integrated heat spreaders.
Nonequilibrium Thermodynamics of Porous Electrodes

We reformulate and extend porous electrode theory for non-ideal active materials, including those capable of phase transformations. Using principles of non-equilibrium thermodynamics, we relate the cell voltage, ionic fluxes, and Faradaic charge-transfer kinetics to the variational electrochemical potentials of ions and electrons. The Butler-Volmer exchange current is consistently expressed in terms of the activities of the reduced, oxidized and transition states, and the activation overpotential is defined relative to the local Nernst potential. We also apply mathematical bounds on effective diffusivity to estimate porosity and tortuosity corrections. The theory is illustrated for a Li-ion battery with active solid particles described by a Cahn-Hilliard phase-field model. Depending on the applied current and porous electrode properties, the dynamics can be limited by electrolyte transport, solid diffusion and phase separation, or intercalation kinetics. In phase-separating porous electrodes, the model predicts narrow reaction fronts, mosaic instabilities and voltage fluctuations at low current, consistent with recent experiments, which could not be described by existing porous electrode models.
Critical dynamics of contact-line motion.

The velocity V of the contact line where a fluid interface intersects the wall of a tube depends on the applied capillary pressure ${\mathit{P}}_{\mathit{cap}}$. We have used sensitive ac differential-pressure measurements, to study the scaling of ${\mathit{P}}_{\mathit{cap}}$ with V for water-alkane interfaces in tubes that have disordered surfaces. Our results are consistent with a critical depinning transition. The derivative ${\mathit{dP}}_{\mathit{cap}}$/dV\ensuremath{\sim}${\mathit{V}}^{\mathit{x}}$ over two decades in velocity in the critical regime near V=0. We find similar critical exponents for water-hexadecane, x=-0.77(5), and water-decane systems, x=-0.81(5). The exponent does not depend on the direction of flow or on the degree of surface roughness on the tube walls.
Estimation of an Endogenous Switching Regression Model with Discrete Dependent Variables: Monte-Carlo Analysis and Empirical Application of Three Estimators

The performances of alternative two-stage estimators for the endogenous switching regression model with discrete dependent variables are compared, with regard to their usefulness as starting values for maximum likelihood estimation. This is especially important in the presence of large correlation coefficients, in which case maximum likelihood procedures have difficulties to converge. Monte-Carlo simulations indicate that an estimator that corrects for conditional heteroskedasticity of the residuals is superior in almost all instances, and especially when maximum likelihood is problematic. This result is also obtained in an empirical example in which off-farm work participation equations of farm women are conditional on farm work participation status.
Single-electron transistor spectroscopy of InGaAs self-assembled quantum dots

A single-electron transistor (SET) is used to detect tunneling of single electrons into individual InGaAs self-assembled quantum dots (QDs). By using an SET with a small island area and growing QDs with a low density we are able to distinguish and measure three QDs. The bias voltage at which resonant tunneling into the dots occurs can be shifted using a surface gate electrode. From the applied voltages at which we observe electrons tunneling, we are able to measure the electron addition energies of three QDs.
Charge fluctuations at disoriented chiral transition

Abstract The signatures of the creation of a disoriented chiral condensate in heavy-ion collisions are studied in the Ginzburg–Landau description of chiral phase transition. Scaling properties are found that characterize the fluctuations of charged particles. There exists also an explicitly calculable measure that can directly be measured. Experimental procedures needed to find the signatures are discussed.
DIRECT EVIDENCE FOR AN ENHANCEMENT OF HELIUM IN GIANT STARS IN OMEGA CENTAURI

The double main sequence identified in the globular cluster Omega Centauri has been interpreted using isochrones to indicate a large variation in the abundance of helium. If true, a helium enhancement carries strong implications for the chemical and stellar evolutionary history of this cluster. However, only indirect measures currently support this conjecture. We report the discovery of a variation in the line strength of the near-infrared He I 10830 A transition in 12 similar red giants in Omega Centauri observed with PHOENIX on Gemini-S. Abundances of these stars derived from Magellan/MIKE spectra taken at the Las Campanas Observatory show that the helium transition is not detected in the most metal-poor population ([Fe/H] < -1.8), yet is present in the majority of stars with [Fe/H] ≥ ―1.8. These observations give the first direct evidence for an enhancement of helium in Omega Centauri. The appearance of helium appears better correlated with increased [AI/Fe] and [Na/Fe] abundances than as a function of [Fe/H], giving observational support to the presence of high-temperature H burning in a prior generation of stars.
The very small world of the well-connected

Online networks occupy an increasingly larger position in how we acquire information, how we communicate with one another, and how we disseminate information. Frequently, small sets of vertices dominate various graph and statistical properties of these networks and, because of this, they are relevant for structural analysis and efficient algorithms and engineering. For the web overall, and specifically for social linking in blogs and instant messaging, we provide a principled, rigorous study of the properties, the construction, and the utilization of subsets of special vertices in large online networks. We show that graph synopses defined by the importance of vertices provide small, relatively accurate portraits, independent of the importance measure, of the larger underlying graphs and of the important vertices. Furthermore, they can be computed relatively efficiently.
Automated Drill Modeling for Drilling Process Simulation

Accurate models of two-flute conical twist drills are needed for finite element simulations of the drilling process. Existing drill designing methods rely extensively on discretized analytical equations to describe the drill and different sets of equations that need to be formulated as the drill design changes. This paper presents a method to create accurate models of two-flute conical twist drills using solid-modeling techniques, which addresses some of these shortcomings. Boolean operations are used to mimic the drill manufacturing steps and generate the fully designed drill. The drills generated by this method have been used in finite element simulations to study the effect of drill point geometry on burr formation in drilling.
Einstein Gravitation as a Long Wavelength Effective Field Theory

A possible resolution of the difficulties in quantizing general relativity is provided by the suggestion that Einstein gravitation is not a fundamental field theory, but rather is a long-wavelength effective field theory, arising as a scale-symmetry-breaking effect in a renormalizable fundamental theory. In unified theories of this type, Newton's constant will be calculable in terms of fundamental particle masses. The history and current status of these ideas is reviewed. In the conventional picture of the fundamental forces of physics, as recently reviewed in Weinberg ( i98), gravitation appears on a quite different footing from the weak, strong and electromagnetic interactions of the matter fields. The total dynamics, in the usual formulation, is governed by an action functional
Are Minority Areas Disproportionately Targeted for Halfway House Placement

The geographic placement of halfway houses is an important issue in the field of community corrections. Much research has underscored the social justice issues involved with the subsidization and placement of halfway houses within certain communities. A commonly held belief is that state and local governments actively target lower socioeconomic status, minority communities for the placement of houses, as residents have little power to resist. This article uses data collected on Connecticut towns from 2000 to 2008 and reveals that state-subsidized halfway houses are significantly more likely to be sited in non-White communities with high index crime rates.
Rotational invariance in the M(atrix) formulation of type IIB theory

Abstract The matrix model formulation of M-theory can be generalized by compactification to ten-dimensional type II string theory, formulated in the infinite momentum frame. Both the type IIA and IIB string theories can be formulated in this way. In the M-theory and type IIA cases, the transverse rotational invariance is manifest, but in the IIB case, one of the transverse dimensions materializes in a completely different way from the other seven. The full O(8) rotational symmetry then follows in a surprising way from the electric-magnetic duality of supersymmetric Yang-Mills field theory.
The Relationship Between Adsorption and Solid Acidity of Heteropolyacids

Abstract The adsorption energy of a base to a solid acid catalyst is often assumed to correlate with the acid strength of the catalyst. In this study, the influences of adsorbate type, binding configuration and solid acid composition on the adsorption energy are explored using quantum chemical methods. In particular, density functional theory is used to calculate the adsorption energies of functionalized hydrocarbons containing O, N, or S heteroatoms or C C to phosphotungstic (H3PW12O40) and phosphomolybdic (H3PMo12O40) acids. The adsorption energies of the different molecules bound to the same solid acid are not easily predicted by the proton affinity of the adsorbate because the stabilization of the protonated adsorbate also varies with composition. Bond order conservation helps to explain the relatively small variance in adsorption energies among reactants of widely varying base strength. The activation barriers to form carbenium-ion transition states from adsorbed olefins are also calculated over the two heteropolyacids. The stronger adsorption of propylene to phosphotungstic acid compared to phosphomolybdic acid results in a higher activation barrier to form the carbenium-ion transition state. These heteropolyacids are predicted to have higher activation barriers than zeolites for carbenium-ion formation, which is typically thought to be the rate controlling step in many hydrocarbon conversion processes. This contrasts with the ranking of acid strength based solely on the magnitude of the adsorption energy.
Validating measures of scanned information exposure in the context of cancer prevention and screening behaviors.

Individuals may obtain health information, particularly from the mass media, without engaging in purposeful information searches (called scanning). This study used the Seeking and Scanning Behavior Survey of the General Population (SSBG), a nationally representative survey of adults aged 40–70 years (n = 2,489), to validate measures of scanned information exposure about cancer prevention and screening behaviors. Scanned exposure measures concerning specific behaviors (exercise; fruit and vegetable consumption; dieting; and mammogram, prostate-specific antigen (PSA) text, and colonoscopy screening) have good face validity and are convergent across behaviors (mean correlation across six preventive behaviors = 0.50, sd = 0.09). These measures can be discriminated from measures of general media exposure (mean r = 0.23, sd = 0.02) and seeking exposure for the same behaviors (mean r = 0.25, sd = 0.06). Scanned information exposure was associated with weekly volume of newspaper coverage for two of six behaviors,...
THE NEUTRON PEAK IN THE EXTENDED SADDLE POINT MODEL OF HIGH TEMPERATURE SUPERCONDUCTORS

Abstract An explanation is proposed for the maximum at 41 meV in the inelastic spin-flip neutron scattering from YBa 2 Cu 3 O 7− δ , based on the extended saddle point model developed by the author in his previous works. It is shown that, for appearance of the maximum in the imaginary part of the spin susceptibility, close proximity of the Fermi energy to the extended saddle point is necessary. The energy of the maximum is then close to 2 Δ max , in agreement with experiment. Theoretical and experimental evidence concerning the energy of the extended saddle point (flat region) is discussed. Different limiting cases are calculated. A proof is given within the present model that interaction in the final state is small, and hence no collective modes are formed. A general discussion of the experimental situation is presented.
FERROMAGNETIC RESONANCE IN TERFENOL-D AT 17 GHz

Ferromagnetic resonance measurements have been performed on several samples of Terfenol-D (Dy0.73Tb0.27Fe1.95) at 16.95 GHz and over the temperature range 293 to 305 K. We find that the first magnetocrystalline anisotropy constant, obtained from one sample under nearly zero stress, is K1 = (-1.4±1.0)× l06erg/cm3 at 294 K. Our measurement is distinct from quasistatic torque measurements in that the lattice does not deform during the measurement and, hence, the anisotropy contribution due to magnetoelastic strain does not enter. The bare anisotropy constant, unmodified by static elastic strain, is and . The samples exhibited hysteresis; the position of FMR shifted by 4.0 kOe between measurements made with the magnetic field increasing and those made with the field decreasing.
Habitable moons around extrasolar giant planets

Possible planetary objects have now been discovered orbiting nine different main-sequence stars. These companion objects (some of which might actually be brown dwarfs) all have a mass at least half that of Jupiter, and are therefore unlikely to be hospitable to Earth-like life: jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell. Here we argue that rocky moons orbiting these companions could be habitable if the planet-moon system orbits the parent star within the so-called 'habitable zone', where life-supporting liquid water could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion. Such a moon would, however, need to be large enough (>0.12 Earth masses) to retain a substantial and long-lived atmosphere, and would also need to possess a strong magnetic field in order to prevent its atmosphere from being sputtered away by the constant bombardment of energetic ions from the planet's magnetosphere.
New examples of manifolds with completely integrable geodesic flows

Abstract We construct Riemannian manifolds with completely integrable geodesic flows, in particular various nonhomogeneous examples. The methods employed are a modification of Thimm′s method, Riemannian submersions and connected sums.
Stock Price Reaction to Dividend Increases in the Hotel and Restaurant Sector

This study assesses the stock price reaction to announcements of dividend increases by firms in the hospitality industry using a standard event study methodology. Results indicate that dividend increases are favorably received by market participants because a statistically significant positive market reaction is observed. Results of a cross-sectional analysis show that the size of the market reaction across firms is positively related to the magnitude of the dividend increase. These results imply that managers ought to carefully consider the ramifications of a change in dividend policy because such changes appear to be perceived as signals of the firm’s future financial condition.
WIYN Open Cluster Study — XVI. Optical/infrared photometry and comparisons with theoretical isochrones

We present combined optical/near-infrared photometry (BVIK) for six open clusters - M35, M37, NGC 1817, NGC 2477, NGC 2420 and M67. The open clusters span an age range from 150 Myr to 4 Gyr and have metal abundances from[Fe/H] = -0.27 to +0.09 dex. We have utilized these data to test the robustness of theoretical main sequences constructed by several groups as denoted by the following designations - Padova, Baraffe, Y 2 , Geneva and Siess. The comparisons of the models with the observations have been performed in the [M V , (B - V) 0 ], [M V , (V - I) 0 ] and [M V , (V - K) 0 ] colour-magnitude diagrams as well as the distance-independent [(V - K) 0 , (B - V) 0 ] and [(V - K) 0 , (V - I) 0 ] two-colour diagrams. We conclude that none of the theoretical models reproduces the observational data in a consistent manner over the magnitude and colour range of the unevolved main sequence. In particular, there are significant zero-point and shape differences between the models and the observations. We speculate that the crux of the problem lies in the precise mismatch between theoretical and observational colour-temperature relations. These results underscore the importance of pursuing the study of stellar structure and stellar modelling with even greater intensity.
Weak Institutions, Rights Claims and Pathways to Compliance: The Transformative Role of the Peruvian Human Rights Ombudsman

This article examines the contribution of the Peruvian human rights ombudsman towards upholding a stable and enforceable rights framework, an important component of an inclusive democratic political regime. It argues that the human rights ombudsman may play a significant role in advancing social transformation through the articulation and facilitation of rights claims in an institutional terrain informed by the politically contested nature of formal rules. The analysis goes beyond formal legal channels of redress to consider innovative mechanisms to increase social accountability, including a variety of non-judicial remedies such as policy initiatives, media advocacy and conflict mediation. The article suggests the human rights ombudsman is well placed to advance rights claims through legal, institutional and social pathways, with particular focus on the question of compliance—understood as a matter of both enforcement and management.
Efficient Microwave Method for the Oxidative Coupling of Phenols

The tert-butyl peroxide–initiated, oxidative coupling of phenols can frequently promote reactions that otherwise perform poorly under alternative conditions. Despite this utility, peroxide coupling...
Who Initiates Recalls and Who Cares? Evidence from the Automobile Industry

In this paper, we investigate two questions. First, we explore which entity (the NHTSA or the manufacturer) is more likely to initiate a given auto safety recall campaign. Second, we analyze the determinants of owner response rates to safety recalls. Our data spans nineteen years (1980–1998) for the six largest auto manufacturers. We find evidence that the government initiates larger, less hazardous recalls involving older models and financially weak firms. Inexpensive recalls are more likely to be manufacturer initiated. The largest owner repair responses are associated with newsworthy hazardous defects of new domestic vehicles in their inaugural model year.
Management of small polyps detected by screening CT colonography: patient and physician preferences.

Abstract Background Management of small polyps found on computed tomography (CT) colonography is controversial and critical to both cancer outcomes and cost. Patient and physician behavior are influenced by personal beliefs and prior experience. Thus, we aimed to understand patient and physician preferences after finding polyps on CT colonography. Methods Patients were given a validated handout and survey asking for their preference for evaluation of a "pea-sized" polyp found on CT colonography. By using an Internet survey, physicians were asked how they would manage a 5-mm, 8-mm, or 12-mm polyp, or three 5-mm polyps found by CT colonography in a hypothetical 52-year-old patient of average colorectal cancer risk. Survey reliability was assessed using Cronbach's coefficient alpha. Results Of the 305 patient respondents, 95% wanted to know if the polyp found on CT colonography was precancerous, 86% stated they would request endoscopic evaluation, and 85% wanted polypectomy. Of the 277 primary care physicians, 71% would refer a 5-mm sigmoid polyp for endoscopy, 86% would refer an 8-mm polyp, 97% would refer a 12-mm polyp, and 91% would refer three 5-mm polyps. Of the 461 gastroenterologists, 83% would refer a 5-mm sigmoid polyp for endoscopy, 96% would refer an 8-mm polyp, 97% would refer a 12-mm polyp, and 93% would refer three 5-mm polyps. Overall, 75% of physicians indicated the fear of missing a precancerous lesion would prompt referral for colonoscopy. Conclusion Both patients and physicians overwhelmingly preferred to follow up small polyps identified by CT colonography with endoscopy, suggesting that population-based CT colonography screening programs in which polyps are not removed might require significant patient and physician education before implementation.
Organic Metals Containing Tellurium

Abstract Examination of the structural and electronic trends among organic metals and organic superconductors, which are composed of complex salts of heterocyclic π-donors, has been greatly facilitated by the preparation and study of a number of new tellurium containing organic π-donors. These studies required that a number of new synthetic strategies be developed. A brief review of these methods leading up to and including the recent synthesis of tetratellurafulvalene (TTeF) is provided. The increase in electrical conductivity on going from S to Se to Te in the series (TXF-TCNQ) (where X[dbnd]S, Se, Te) is shown to be consistent with the square of the bandwidths or to an increase in intrachain interaction (σ∞WT 2). While TTeF-TCNQ has not been found to undergo a transition to a superconducting state as the temperature is lowered at ambient pressure neither does it undergo a metal to insulator transition as is observed for TTF-TCNQ (Tmax = 59K) or for TSF-TCNQ (Tmax = 40K). This change in behavior is like...
On ultrasonic factors and fracture toughness

Abstract Concurrent to experimental evidences that display certain correlation between ultrasonic (attenuation and velocity) factors and fracture toughness, there have been findings of certain correlation between fracture toughness and material microstructures. In an attempt to provide a mechanics view on the quantitative ultrasonic determination of fracture toughness, the author presented a literature survey. A critical discussion and summary of the survey is given. The elastodynamic fields due to the presence of a pair of inhomogeneities of plate geometry are investigated by the method of equivalent inclusions. The change of stress amplitude as the plane time-harmonic waves pass through the plates is found and the relation between the fracture toughness and the ultrasonic factors is delineated. The approach taken here does not assume the existence of a sharp crack in the material, however, a critical condition at which the ultrasonic factors are measured is implied.
Dioxygen Activation in Soluble Methane Monooxygenase

The controlled oxidation of methane to methanol is a chemical transformation of great value, particularly in the pursuit of alternative fuels, but the reaction remains underutilized industrially because of inefficient and costly synthetic procedures. In contrast, methane monooxygenase enzymes (MMOs) from methanotrophic bacteria achieve this chemistry efficiently under ambient conditions. In this Account, we discuss the first observable step in the oxidation of methane at the carboxylate-bridged diiron active site of the soluble MMO (sMMO), namely, the reductive activation of atmospheric O2. The results provide benchmarks against which the dioxygen activation mechanisms of other bacterial multicomponent monooxygenases can be measured.Molecular oxygen reacts rapidly with the reduced diiron(II) cen-ter of the hydroxylase component of sMMO (MMOH). The first spectroscopically characterized intermediate that results from this process is a peroxodiiron(III) species, P*, in which the iron atoms have identical env...
Consequences of narrow cyclotron emission from Hercules X-1

The implications of the recent observations of a narrow cyclotron line in the hard X-ray spectrum of Hercules X-1 are studied. A Monte Carlo code is used to simulate the X-ray transfer of an intrinsically narrow feature at approximately 56 keV through an opaque, cold magnetospheric shell. The results of this study indicate that if a narrow line can be emitted by the source region, then only about 10% of the photons remain in a narrow feature after scattering through the shell. The remaining photons are scattered into a broad feature (FWHM approximately 30 keV) that peaks near 20 keV. Thus, these calculations indicate that the intrinsic source luminosity of the cyclotron line is at least an order of magnitude greater than the observed luminosity.
Medium effects in high energy heavy-ion collisions

The change of hadron properties in dense matter based on various theoretical approaches are reviewed. Incorporating these medium effects in the relativistic transport model, which treats consistently the change of hadron masses and energies in dense matter via the scalar and vector fields, heavy-ion collisions at energies available from SIS/GSI, AGS/BNL and SPS/CERN are studied. This model is seen to provide satisfactory explanations for the observed enhancement of kaon, antikaon and antiproton yields as well as soft pions in the transverse direction from the SIS experiments. In the AGS heavy-ion experiments, it can account for the enhanced ratio, the difference in the slope parameters of the and transverse kinetic energy spectra and the lower apparent temperature of antiprotons than that of protons. This model also provides possible explanations for the observed enhancement of low-mass dileptons, phi mesons and antilambdas in heavy-ion collisions at SPS energies. Furthermore, the change of hadron properties in hot dense matter leads to new signatures of the quark - gluon plasma to hadronic matter transition in future ultrarelativistic heavy-ion collisions at RHIC/BNL.
The Seiberg–Witten equations and the Weinstein conjecture

Let M denote a compact, oriented 3–dimensional manifold and let a denote a contact 1–form on M; thus a∧da is nowhere zero. This article proves that the vector field that generates the kernel of da has a closed integral curve.
Observation of high energy quark-antiquark elastic scattering with mesonic exchange

Abstract We studied the high energy quark-antiquark elastic scattering with an exchange of a mesonic state in the t channel with −t/Λ QCD 2 a 1 . Two methods are proposed to eliminate the strong background from bare pomeron, reggized gluon and odderon exchange. The feasibility of measuring mesonic reggeon exchange is discussed.
Capital Structure and Dividend Irrelevance with Asymmetric Information

The Modigliani and Miller propositions on the irrelevancy of capital structure and dividends are shown to be valid in a large class of models with asymmetric information. The main assumption is that managerial compensation is chosen optimally. This differs from most of the recent articles on this topic, which impose by fiat a suboptimal contract. Even when imperfections internal to the firm preclude optimal investment, there is a separation between incentives and financing. We conclude that corporations should move toward contracts with better incentives, and that new models should be built that recognize the limitations to optimal contracting. Article published by Oxford University Press on behalf of the Society for Financial Studies in its journal, The Review of Financial Studies.
The Returns to English-Language Skills in India

Abstract India’s colonial legacy and linguistic diversity give English an important role in its economy, and this role has expanded due to globalization in recent decades. In this study, we use individual-level data from the 2005 India Human Development Survey to quantify the effects of English-language skills on wages. After controlling for age, social group, schooling, geography, and proxies for ability, we find that hourly wages are on average 34% higher for men who speak fluent English and 13% higher for men who speak a little English relative to men who do not speak English. The return to fluent English is as large as the return to completing secondary school and half as large as the return to completing a bachelor’s degree. In addition, we find that more experienced and more educated workers receive higher returns to English. The complementarity between English skills and education appears to have strengthened over time—only the more educated among young workers receive a premium for English-speakin...
A Spitzer/IRAC survey of the Orion molecular clouds

We present initial results from a survey of the Orion A and B molecular clouds made with the InfraRed Array Camera (IRAC) onboard the Spitzer Space Telescope. This survey encompasses a total of 5.6 square degrees with the sensitivity to detect objects below the hydrogen burning limit at an age of 1 Myr. These observations cover a number of known star forming regions, from the massive star forming clusters in the Orion Nebula and NGC 2024, to small groups of low mass stars in the L1641. We combine the IRAC photometry with photometry from the 2MASS point source catalog and use the resulting seven band data to identify stars with infrared excesses due to dusty disks and envelopes. Using the presence of an infrared excess as an indicator of youth, we show the distribution of young stars and protostars in the two molecular clouds. We find that roughly half of the stars are found in dense clusters surrounding the two regions of recent massive star formation in the Orion clouds, NGC 2024 and the Orion Nebula.
Domain-wall Supergravities from Sphere Reduction

Abstract Kaluza-Klein sphere reductions of supergravities that admit Ads × Sphere vacuum solutions are believed to be consistent. The examples include the S4 and S7 reductions of eleven-dimensional supergravity, and the S5 reduction of ten-dimensional type IIB supergravity . In this paper we provide evidence that sphere reductions of supergravities that admit instead Domain-wallxSphere vacuum solutions are also consistent, where the background can be viewed as the near-horizon structure of a dilatonic p-brane of the theory. The resulting lower-dimensional theory is a gauged supergravity that admits a domain wall, rather than AdS, as a vacuum solution. We illustrate this consistency by taking the singular limits of certain modulus parameters, for which the originalSn compactifying spheres (n = 4, 5 or 7) becomes Sp × Rq, with p = n − q
Layer potential methods for elliptic homogenization problems

In this paper we use the method of layer potentials to study L 2 boundary value problems in a bounded Lipschitz domain Ω for a family of second-order elliptic systems with rapidly oscillating periodic coefficients. Defining L e = -div(A(e -1 X)∇), under the assumption that A(X) is elliptic, symmetric, periodic, and Holder-continuous, we establish the solvability of the L 2 Dirichlet, regularity, and Neumann problems for L e (u e ) = 0 in Ω with optimal estimates uniform in e > 0.
Bisphosphine-catalyzed mixed double-Michael reactions: asymmetric synthesis of oxazolidines, thiazolidines, and pyrrolidines.

Bisphosphine-catalyzed mixed double-Michael reactions have been developed to afford β-amino carbonyl derivatives of oxazolidines, thiozolidines, and pyrrolidines in excellent yields and with high diastereoselectivities. Efficient reactions between amino-acid-derived pronucleophiles, such as β-amino alcohols, β-amino thiols, and γ-amino diesters, as Michael donors and electron-deficient acetylenes, such as propiolates, acetylacetylene, and tosylacetylene, as Michael acceptors provided access to azolidines containing both diversity of substituents and asymmetry. This methodologythe first examples of mixed double-Michael reactions of acetylenesis operationally simple and involves mild conditions. Mechanistically, it constitutes a rare example of the anchimeric assistance of bisphosphines in organocatalysis.
Photonic crystal microcavities for chip‐based cavity QED

The suitability of recently demonstrated high quality factor (Q), ultra-small mode volume (Veff) graded square lattice photonic crystal microcavities for cavity QED experiments is discussed. In addition to the basic importance of the Q and Veff of such cavities, other issues of both practical and fundamental relevance are considered. Included amongst these are the robustness of the cavity's performance to fabrication errors and the ability to efficiently source and collect light from the cavity through conventional fiber optics. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Total synthesis of the eupomatilones

Full details of the total syntheses of five members of the eupomatilone family of lignans are reported.
AN ALGEBRAIC APPROACH TO INDUCTIVE LEARNING

The paper presents a framework to induction of concept hierarchies based on consistent integration of metric and similarity-based approaches. The hierarchies used are subsumption lattices induced by the least general generalization operator (lgg) commonly used in inductive learning. Using some basic results from lattice theory the paper introduces a semantic distance measure between objects in concept hierarchies and discusses its applications for solving concept learning and conceptual clustering tasks. Experiments with well known ML datasets represented in three types of languages - propositional (attribute-value), atomic formulae and Horn clauses, are also presented.
Novel five-membered ring intermediates in gas phase reactions

This review considers the role of closed-ring intermediates in chemistry, in general, and focuses on recent experimental and theoretical works that provide compelling evidence for a fivemembered ring intermediate in the gas phase. The reactions of oxygen atoms with ethyl iodide and larger alkyl iodides produce HOI and a corresponding ethylenic compound via attack of the oxygen atom at the iodine and closure of the five-membered ring between the oxygen and a hydrogen on the beta-carbon. Detailed results are gathered from infrared chemiluminescence and molecular beam scattering, as well as new kinetics and product yield experiments. The theoretical calculations fully support and characterize the novel reaction mechanism.
The Regge symmetry is a scissors congruence in hyperbolic space

We give a constructive proof that the Regge symmetry is a scissors congruence in hyperbolic space. The main tool is Leibon's con- struction for computing the volume of a general hyperbolic tetrahedron. The proof consists of identifying the key elements in Leibon's construction and permuting them.
Modulated spin and charge densities in cuprate superconductors

Neutron scattering experiments have played a crucial role in characterizing the spin and charge correlations in copper-oxide superconductors. While the data are often interpreted with respect to specific theories of the cuprates, an attempt is made here to distinguish those facts that can be extracted empirically, and the connections that can be made with minimal assumptions.
Parton energy loss at strong coupling and the universal bound

The apparent universality of jet quenching observed in heavy-ion collisions at RHIC for light and heavy quarks, as well as for quarks and gluons, is very puzzling and calls for a theoretical explanation. Recently, it has been proposed that synchrotron-like radiation at strong coupling gives rise to a universal bound on the energy of a parton escaping from the medium. Since this bound appears to be quite low, almost all of the observed particles at high transverse momentum have to originate from the surface of the hot fireball. Here I make a first attempt of checking this scenario against the RHIC data and formulate a “universal-bound model” of jet quenching that can be further tested at RHIC and LHC.
A transfluxor analog memory using frequency modulation

The accurate storage of a continuous voltage has always proven to be a difficult and challenging problem to the designers of electronic analog systems. Most modern analog computer installations include a number of "sample-hold" devices, utilizing high-quality operational amplifiers in combination with special electronic switching circuitry. In such units the voltage is stored as charge on a capacitor, so that leakage and grid currents must be extremely carefully controlled to permit long-time storage with high accuracy. Recently introduced hybrid computer systems have placed an additional requirement upon the analog memory unit: economy. For example, in the discrete-space-discrete-time hybrid computer system now under development at UCLA, 1,000 sample-hold circuits will be required in order to accommodate 1,000 parallel digital-analog channels. Furthermore, hold times of several minutes are desired. Under these conditions conventional capacitor-type analog memories become economically unfeasible. These considerations have stimulated a search for a rapid, accurate and economic analog memory and have resulted in the development of the FM-transfluxor unit described in this paper. Since their introduction by Rajchman in 1955, multiaperture magnetic devices (MAD) have assumed an important place as magnetic logic and memory devices in digital computer applications. The extension of this technique to analog systems has been proposed from time to time, but no fully satisfactory transfluxor analog memory has been described to date.
Low energy description of quantum gravity and complementarity

Abstract We consider a framework in which low energy dynamics of quantum gravity is described preserving locality, and yet taking into account the effects that are not captured by the naive global spacetime picture, e.g. those associated with black hole complementarity. Our framework employs a “special relativistic” description of gravity; specifically, gravity is treated as a force measured by the observer tied to the coordinate system associated with a freely falling local Lorentz frame. We identify, in simple cases, regions of spacetime in which low energy local descriptions are applicable as viewed from the freely falling frame; in particular, we identify a surface called the gravitational observer horizon on which the local proper acceleration measured in the observer's coordinates becomes the cutoff (string) scale. This allows for separating between the “low-energy” local physics and “trans-Planckian” intrinsically quantum gravitational (stringy) physics, and allows for developing physical pictures of the origins of various effects. We explore the structure of the Hilbert space in which the proposed scheme is realized in a simple manner, and classify its elements according to certain horizons they possess. We also discuss implications of our framework on the firewall problem. We conjecture that the complementarity picture may persist due to properties of trans-Planckian physics.
Low-energy quasiparticle states near extended scatterers in d-wave superconductors and their connection with SUSY quantum mechanics

Low-energy quasiparticle states, arising from scattering by single-particle potentials in $d$-wave superconductors, are addressed. Via a natural extension of the Andreev approximation, the idea that sign variations in the superconducting pair potential lead to such states is extended beyond its original setting of boundary scattering to the broader context of scattering by general single-particle potentials, such as those due to impurities. The index-theoretic origin of these states is exhibited via a simple connection with Witten's supersymmetric quantum-mechanical model.
Toward an understanding of data structures

This paper presents a notation and formalism for describing the semantics of data structures. This is based on directed graphs with named edges and transformations on these graphs. In addition, and implementation facility is described which could be part of a programming language, which allows a programmer who has expressed the semantics of an algorithm in terms of the graphs to then specify the implementation of some of his data structures in order to gain efficiency.