cssi/SciSciGPT-SciSciNet huggingface dataset:
Formation of Low-Mass X-Ray Binaries. II. Common Envelope Evolution of Primordial Binaries with Extreme Mass Ratios

We study the formation of low-mass X-ray binaries (LMXBs) through helium star supernovae in binary systems that have each emerged from a common envelope phase. LMXB progenitors must satisfy a large number of evolutionary and structural constraints, including survival through common envelope evolution, through the post-common envelope phase, where the precursor of the neutron star becomes a Wolf-Rayet star, and survival through the supernova event. Furthermore, the binaries that survive the explosion must reach interaction within a Hubble time and must satisfy stability criteria for mass transfer. These constraints, imposed under the assumption of a symmetric supernova explosion, prohibit the formation of short-period LMXBs transferring mass at sub-Eddington rates through any channel in which the intermediate progenitor of the neutron star is not completely degenerate. Barring accretion-induced collapse, the existence of such systems therefore requires that natal kicks be imparted to neutron stars. We use an analytical method to synthesize the distribution of nascent LMXBs over donor masses and orbital periods and evaluate their birthrate and systemic velocity dispersion. Within the limitations imposed by observational incompleteness and selection effects, and our neglect of secular evolution in the LMXB state, we compare our results with observations. However, our principal objective is to evaluate how basic model parameters (common envelope ejection efficiency, rms kick velocity, primordial mass ratio distribution) influence these results. We conclude that the characteristics of newborn LMXBs are primarily determined by age and stability constraints and the efficiency of magnetic braking and are largely independent of the primordial binary population and the evolutionary history of LMXB progenitors (except for extreme values of the average kick magnitude or of the common envelope ejection efficiency). Theoretical estimates of total LMXB birthrates are not credible, since they strongly depend on the observationally indeterminate frequency of primordial binaries with extreme mass ratios in long-period orbits.
Research in clinical nursing

This paper presents a tested and useful method of research in clinical nursing at the doctoral and post-doctoral levels of research skill. Field theory-based, salient variables in patients' experience are inductively arrived at from empirical data. The unitizing of data provides true numbers for measurements of relationships and change in the dependent variable. Descriptive analysis and data-based theory benefit from increased reliability. The authors argue that clinical field research permits a wide choice in designs and observational tools to fit the exigencies of the patient situation under investigation. The method is particularly useful td nurses in direct nursing care situations.
Chemistry and physics of amorphous semiconductors

Our understanding of amorphous semiconductors has been greatly clarified by recent theoretical and experimental work. It is now evident that the electrical properties of these materials are generally controlled by intrinsic defects which are either thermodynamically required or induced via strains during the deposition process. The nature of these defects is intimately related to the chemistry of the constituent atoms.
QM/MM: what have we learned, where are we, and where do we go from here?

This paper briefly reviews the current status of the most popular methods for combined quantum mechanical/molecular mechanical (QM/MM) calculations, including their advantages and disadvantages. There is a special emphasis on very general link-atom methods and various ways to treat the charge near the boundary. Mechanical and electric embedding are contrasted. We consider methods applicable to gas-phase organic chemistry, liquid-phase organic and organometallic chemistry, biochemistry, and solid-state chemistry. Then we review some recent tests of QM/MM methods and summarize what we learn about QM/MM from these studies. We also discuss some available software. Finally, we present a few comments about future directions of research in this exciting area, where we focus on more intimate blends of QM with MM.
Crystallographic analysis of thermochromic, unsolvated tetramesityldisilene at 173 K and 295 K

X-ray crystal structure determinations of tetramesityldisilene (1) at 295 K, where it is bright orange, and at 173 K, where it is pale yellow, were experimentally equivalent. The thermochromism of 1, therefore, is not due to changes in conformation; a vibrational origin is considered. The crystal structure of unsolvated 1 differs substantially from that of the toluene solvate (1·C7H8) because of different crystal packing of the two forms. These two solid-state structures are compared with those of four other disilenes.
Preparation of 5-Substituted 1H-Tetrazoles Catalyzed by Scandium Triflate in Water

Abstract Several 5-substituted 1H-tetrazoles were prepared in water or isopropanol/water mixtures using microwave heating. Good yields were obtained for the [2 + 3] cycloaddition of sodium azide with aryl nitriles, aliphatic nitriles, and vinyl nitriles when catalyzed by scandium triflate. The reactions were typically heated for 1 h at 160 °C in a 3:1 isopropanol/water mixture to obtain the best yields.
Relativistic particle acceleration in plerions

We discuss recent research on the structure and particle acceleration properties of relativistic shock waves in which the magnetic field is transverse to the flow direction in the upstream medium, and whose composition is either pure electrons and positrons or primarily electrons and positrons with an admixture of heavy ions. Particle-in-cell simulation techniques as well as analytic theory have been used to show that such shocks in pure pair plasmas are fully thermalized -- the downstream particle spectra are relativistic Maxwellians at the temperature expected from the jump conditions. On the other hand, shocks containing heavy ions which are a minority constituent by number but which carry most of the energy density in the upstream medium do put approximately 20% of the flow energy into a nonthermal population of pairs downstream, whose distribution in energy space is N(E) varies as E(exp -2), where N(E)dE is the number of particles with energy between E and E+dE. The mechanism of thermalization and particle acceleration is found to be synchrotron maser activity in the shock front, stimulated by the quasi-coherent gyration of the whole particle population as the plasma flowing into the shock reflects from the magnetic field in the shock front. The synchrotron maser modes radiated by the heavy ions are absorbed by the pairs at their (relativistic) cyclotron frequencies, allowing the maximum energy achievable by the pairs to be gamma(sub +/-)m(sub +/-)c squared = m(sub i)c squared gamma(sub 1)/Z(sub i), where gamma(sub 1) is the Lorentz factor of the upstream flow and Z(sub i) is the atomic number of the ions. The shock's spatial structure is shown to contain a series of 'overshoots' in the magnetic field, regions where the gyrating heavy ions compress the magnetic field to levels in excess of the eventual downstream value. This shock model is applied to an interpretation of the structure of the inner regions of the Crab Nebula, in particular to the 'wisps,' surface brightness enhancements near the pulsar. We argue that these surface brightness enhancements are the regions of magnetic overshoot, which appear brighter because the small Larmor radius pairs are compressed and radiate more efficiently in the regions of more intense magnetic field. This interpretation suggests that the structure of the shock terminating the pulsar's wind in the Crab Nebula is spatially resolved, and allows one to measure gamma(sub 1) and a number of other properties of the pulsar's wind. We also discuss applications of the shock theory to the termination shocks of the winds from rotation-powered pulsars embedded in compact binaries. We show that this model adequately accounts for (and indeed predicted) the recently discovered X-ray flux from PSR 1957+20, and we discuss several other applications to other examples of these systems.
Fundamental-mode amplifier performance of the NRL ubitron

Abstract An experimental and theoretical research program to study the ubitron-FEL interaction is in progress at the Naval Research Laboratory, including both fundamental and harmonic modes of operation. Operation of a ubitron-FEL amplifier using the fundamental wiggler harmonic interaction with the TE 11 circular-waveguide mode is reported here. The experiment employs a 190–250 keV electron beam with currents up to 37 A, using a helical wiggler/axial guide-field configuration. Small-signal gains as high as 17–19 dB have been observed in the 13–18 GHz frequency band, corresponding to a gain per free-space wavelength approaching 1.5 dB/λ. These results were obtained using a modified SLAC klystron gun. Improved performance is expected using a higher-current (100 A), higher-quality electron gun currently being installed. The theoretical program includes a nonlinear analysis of the rf and electron beam interaction while propagating through a cylindrical waveguide with a helical-wiggler field and an axial guide field. The analysis includes beam injection into the wiggler, wiggler inhomogenieties, efficiency enhancement by means of tapered wigglers, beam thermal effects and harmonic interactions. The experimental results presented in this paper are in reasonable agreement with the nonlinear simulation of the interaction in the Raman regime.
Temperley-Lieb pfaffinants and Schur $Q$-positivity conjectures

We study pfaffian analogues of immanants, which we call pfaffinants. Our main object is the TL-pfaffinants which are analogues of Rhoades and Skandera's TL-immanants. We show that TL-pfaffinants are positive when applied to planar networks and explain how to decompose products of complementary pfaffians in terms of TL-pfaffinants. We conjecture in addition that TL-pfaffinants have positivity properties related to Schur Q-functions
The Origin and Propagation of Variability in the Outflows of Long-duration Gamma-ray Bursts

We present the results of hydrodynamical simulations of gamma-ray burst (GRB) jets propagating through their stellar progenitor material and subsequently through the surrounding circumstellar medium. We consider both jets that are injected with constant properties in the center of the star and jets injected with a variable luminosity. We show that the variability properties of the jet outside the star are a combination of the variability injected at the base of the jet and the variability caused by the jet propagation through the star. Comparing power spectra for the two cases shows that the variability injected by the engine is preserved even if the jet is heavily shocked inside the star. Such shocking produces additional variability at long timescales, of order several seconds. Within the limited number of progenitors and jets investigated, our findings suggest that the broad pulses of several seconds duration typically observed in GRBs are due to the interaction of the jet with the progenitor, while the short-timescale variability, characterized by fluctuations on timescales of milliseconds, has to be injected at the base of the jet. Studying the properties of the fast variability in GRBs may therefore provide clues to the nature of the inner engine and the mechanisms of energy extraction from it.
A New Algorithm for Supernova Neutrino Transport and Some Applications

We have developed an implicit, multigroup, time-dependent, spherical neutrino transport code based on the Feautrier variables, the tangent-ray method, and accelerated ? iteration. The code achieves high angular resolution, is good to O(v/c), is equivalent to a Boltzmann solver (without gravitational redshifts), and solves the transport equation at all optical depths with precision. In this paper, we present our formulation of the relevant numerics and microphysics and explore protoneutron star atmospheres for snapshot postbounce models. Our major focus is on spectra, neutrino-matter heating rates, Eddington factors, angular distributions, and phase-space occupancies. In addition, we investigate the influence on neutrino spectra and heating of final-state electron blocking, stimulated absorption, velocity terms in the transport equation, neutrino-nucleon scattering asymmetry, and weak magnetism and recoil effects. Furthermore, we compare the emergent spectra and heating rates obtained using full transport with those obtained using representative flux-limited transport formulations to gauge their accuracy and viability. Finally, we derive useful formulae for the neutrino source strength due to nucleon-nucleon bremsstrahlung and determine bremsstrahlung's influence on the emergent ?? and ?? neutrino spectra. These studies are in preparation for new calculations of spherically symmetric core-collapse supernovae, proto-neutron star winds, and neutrino signals.
A new catalyst for exclusive β-hydrosilylation of acrylonitrile

Abstract Acrylonitrile and 2-chloroacrylonitrile react with trichlorosilane in the presence of cobalt chloride and an amine to give the β-adduct in 75–95% yields under mild conditions.
The superchannel scheme for integrated services on multiple access broadcast networks

Abstract Integration of packet voice with data on a multiple access broadcast network (MABN) is an important problem. Several protocols, e.g., real-time control, movable-boundary and Global Queue schemes have been proposed to integrate voice and data traffic on MABNs. Both the movable-boundary and the Global Queue schemes require modifications to existing data stations, and they do not allow voice stations to utilize unused data bandwidth. Also, under the real-time control protocol, data performance will degrade significantly if voice traffic is heavy. In this paper, we propose a scheme for integrated services on MABNs based on the “superchannel” concept and describe a protocol for voice/data integration. The superchannel is a logical channel which is established on existing MABNs, and each such channel can carry a different type of traffic under a special control protocol. The proposed scheme is fully compatible with existing MABNs, i.e., data stations can operate using their original protocol. By introducing a priority boundary, the channel utilization is improved under heavy voice traffic and light data load, while still maintaining a desired level of performance if the combined voice/data traffic load is heavy. Since interference of voice and data traffic only appears at the boundary of the superchannel cycle, the protocol can be relatively easily extended for multiple traffic types. We first describe various operations that need to be performed by voice stations under the superchannel scheme. Then, approximate mathematical models are formulated to analyze the channel overhead, voice loss rate, and data queue length. Finally, various analytical and simulation results are obtained to illustrate some features of the proposed scheme, and these results are compared with previous work.
Consumer expectations and cyclical durations

Abstract Do variations in consumer expectations lead to changes in business-cycle durations? Intuitively, the answer is in the affirmative. In this study it is postulated that expectations are self-fulfilling; optimistic sentiments postpone cyclical peaks and promote cyclical troughs, and pessimistic sentiments result in the opposite combination. First, it is shown that the hypothesis that consumer expectations do not Granger-cause cyclical duration is rejected. Survival analysis is then used to investigate the association between changes in consumer expectations ana business-cycle durations. In particular, it is found that consumers' optimism associates with longer expansion durations, and vice-versa.
Intramolecular photocycloaddition of a tethered bis-2,3-dihydro-4-pyridone: Stereochemistry and reactivity of the cycloadduct

Abstract The photocycloaddition of enantiopure bis-dihydropyridone 4 provided a single cycloadduct in high yield. Treatment of the cycloadduct with SmI2 effected ring opening and intramolecular aldol addition to give pentacyclic β-hydroxyketone 7.
TESTING THE STOCHASTIC STRUCTURE OF PRODUCTION: A FLEXIBLE MOMENT-BASED APPROACH

Conventional production function specifications are shown to impose restrictions on the probability distribution of output that cannot be tested with the conventional models. These restrictions have important implications for firm behavior under uncertainty. A flexible representation of a firm's stochastic technology is developed based on the moments of the probability distribution of output. These moments are a unique representation of the technology and are functions of inputs. Large-sample estimators are developed for a linear moment model that is sufficiently flexible to test the restrictions implied by conventional production function specifications. The flexible moment-based approach is applied to milk production data. The first three moments of output are statistically significant functions of inputs. The cross-moment restrictions implied by conventional models are rejected.
Dynamic Stress Intensity Factors for an Inclined Subsurface Crack

Calcul de ces facteurs pour une fissure dans un demi-espace dont la surface est soumise a une excitation uniforme harmonique dans le temps
Time-Resolved Assembly of Chiral Uranyl Peroxo Cage Clusters Containing Belts of Polyhedra

Two chiral cage clusters built from uranyl polyhedra and (HPO3)2– groups have been synthesized in pure yield and characterized structurally and spectroscopically in the solid state and aqueous solution. Synthesis reactions under ambient conditions in mildly acidic aqueous solutions gave clusters U22PO3 and U28PO3 that contain belts of four uranyl peroxide pentagonal and hexagonal bipyramids, in contrast to earlier reported uranyl peroxide cage clusters that are built from four-, five-, and six-membered rings of uranyl hexagonal bipyramids. U22PO3 and U28PO3 are also the first chiral uranyl-based cage clusters, the first that contain uranyl pentagonal bipyramids that contain no peroxide ligands, and the first that incorporate (HPO3)2– bridges between uranyl ions. They are built from 22 uranyl polyhedra and 20 (HPO3)2– groups, or 28 uranyl polyhedra and 24 (HPO3)2– groups, with the outer and inner surfaces of the cages passivated by the O atoms of uranyl ions. Small-angle X-ray scattering (SAXS) profiles de...
INCENTIVES TO CULTIVATE FAVORED MINORITIES UNDER ALTERNATIVE ELECTORAL SYSTEMS

A simple model is used to compare, under different electoral systems, the incentives for candidates to create inequalities among otherwise homogeneous voters, by making campaign promises that favor small groups, rather than appealing equally to all voters. In this game model, each candidate generates offers for voters independently out of a distribution that is chosen by the candidate, subject only to the constraints that offers must be nonnegative and have mean 1. Symmetric equilibria with sincere voting are analyzed for two-candidate elections and for multicandidate elections under rank-scoring rules, approval voting, and single transferable vote. Voting rules that can guarantee representation for minorities in multiseat elections generate, in this model, the most severely unequal campaign promises.
Photoluminescence Quantum Yields from Crystalline and Amorphous Silicon Nanoparticles

The optical properties of amorphous and crystalline silicon nanoparticles are studied. By tuning the power of the non-thermal plasma reactor, the structure of the particles is adjusted from amorphous to crystalline nanoparticles. The microstructure is studied using transmission electron microscopy, X-ray diffraction, and Raman vibrational spectroscopy. The photoluminescence quantum yields of crystalline nanoparticle samples are consistently higher than those of amorphous nanoparticles.
Intradural endoscope-assisted anterior clinoidectomy: a cadaveric study.

Abstract Objective The anterior clinoid process (ACP) is critically related to the clinoidal portion of the internal carotid artery (ICA). The deep location of the ACP makes treatment of vascular and neoplastic lesions related to the ACP challenging. Removal of the ACP is advocated to facilitate treatment of such lesions. However injury to the clinoidal ICA remains a potential and dreadful complication of ACP removal. The aim of this study was to demonstrate an endoscopic assisted technique to perform intradural removal of the ACP via a pterional approach with continuous visualization of the clinoidal ICA. Methods Sixteen bilateral pterional dissections were performed in 8 glutaraldehyde embalmed, colored silicone injected, adult cadaveric heads. Using a standard pterional approach, we performed drilling of the ACP in 2 stages. Stage 1 consisted of extradural microscopic removal of the sphenoid ridge so as to gain access to the origin of the ACP. Stage 2, the endoscopic stage, consisted of intradural endoscopic removal of the ACP and mobilization of the clinoidal segment of the ICA. We used 2.7 mm, 0° and 30° angled endoscopes. Results In all the specimens we were able to remove the ACP while at the same time continuously visualizing the clinoidal ICA. The exposure of the clinoidal ICA and of adjoining neuro-vascular structures including the intracranial optic nerve was excellent and was accomplished with minimal frontal lobe retraction. Mobilization of the clinoidal ICA led to unhindered exposure of the parasellar region. Conclusions Endoscopic assisted ACP removal with continuous ICA visualization was feasible in our model. Continuous visualization of the clinoidal ICA should theoretically decrease the risk of inadvertent ICA injuries. Clinical studies to validate this laboratory study are necessary.
Oxidation of Benzaldehydes to Benzoate Esters Using Household Bleach and Sodium Iodide in Alcohol Solvents

Abstract Various substituted benzaldehydes were converted into benzoate esters with household bleach and sodium iodide in an alcohol solvent. The reaction works best with methanol. Only 4-chlorobenzaldehyde, 3-nitrobenzaldehyde, and 4-nitrobenzaldehyde reacted completely with 1-propanol under these conditions. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]
Photosensitizers related to purpurin-18-N-alkylimides: a comparative in vivo tumoricidal ability of ester versus amide functionalities.

Abstract For a comparative study, 3-(alkyloxyethyl)-3-devinylpurpurin-18-N-hexylimides with ester and amide functionalities were investigated for tumor selectivity and in vivo photosensitizing efficacy. Compared to amide analogues, the related photosensitizers with ester functionalities were found to be more effective. Among these compounds the 3-devinyl-(3-hexyloxyethyl)-purpurin-18-N-hexylimide as methyl ester 12 Download : Download high-res image (209KB) Download : Download full-size image Scheme 1 . (a) Zn(Br)2/HMDS, hexylamine, toluene, reflux; (b) HBr/AcOH; (c) alkyl alcohol; (d) alkyl amine; (e) CH2N2; (g) MeOH/KOH; (f) aq LiOH/MeOH/THF; (g) DCC/H2N–(CH2)5CH3. showed excellent tumor uptake (tumor versus muscle ratio: 8:1), and produced 100% tumor cure on day 30 at a dose of 1.0 μmol/kg. The mice were treated with light (135 J/cm2, 705 nm) at 24 h post injection of the drug.
Solving the Selesnick-Burrus filter design equations using computational algebra and algebraic geometry

In a recent paper, I. Selesnick and C.S. Burrus developed a design method for maximally flat FIR low-pass digital filters with reduced group delay. Their approach leads to a system of polynomial equations depending on three integer design parameters K,L,M. In certain cases (their ''Region I''), Selesnick and Burrus were able to derive solutions using only linear algebra; for the remaining cases (''Region II''), they proposed using Grobner bases. This paper introduces a different method, based on multipolynomial resultants, for analyzing and solving the Selesnick-Burrus design equations. The results of calculations are presented, and some patterns concerning the number of solutions as a function of the design parameters are proved.
Global claim-staking and latecomer cost in the orbit spectrum resource

Abstract This article first examines some research on and analysis of the origins and magnitude of latecomer cost handicap, and then turns to the claimstaking or land-rush hypothesis. Here a central question is why there should be latecomers in the first place, and further, what the cost consequences seem to be. The article concludes with a brief look at global claim-staking, some illustrative equations on the subject, and finally, at degrees of stability in satellite deployment over time.
Encyclopedic storage of scientific and technical knowledge

Encyclopedic storage is a method of storing knowledge that avoids unnecessary duplication and provides convenient access to the stored materials. This paper discusses a particular approach to encyclopedic storage of scientific and technical information which can now be implemented. Motivation for this approach is developed here by considering first some of the basic properties of the process of knowledge transfer via the written record, leading to the development of a unit of knowledge. In terms of this unit, the `size' of scientific and technical knowledge, and of electrical engineering knowledge is estimated. This unit also becomes the basic building block for the proposed encyclopedic system. A very small experimental version of such a system is now in existence.
Bismuth triflate: An efficient catalyst for the formation and deprotection of tetrahydropyranyl ethers

The tetrahydropyranylation of alcohols under solvent-free conditions is efficiently catalyzed by bismuth triflate (0.1 mol %). The experimental procedure is simple and works well with a variety of alcohols and phenols. The catalyst is insensitive to air and small amounts of moisture, easy to handle and relatively nontoxic. The deprotection of THP ethers is also catalyzed by bismuth triflate (1.0 mol %). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
New experiments with antiprotons

Abstract Fermilab operates the world's most intense source of antiprotons. Recently various experiments have been proposed that can use those antiprotons either parasitically during Tevatron Collider running or after the Tevatron Collider finishes in about 2010. We discuss the physics goals and prospects of the proposed experiments. Fermilab operates the world's most intense antiproton source. Newly proposed experiments can use those antiprotons either parasitically during Tevatron Collider running or after the Tevatron Collider finishes in about 2011. For example, the annihilation of 8 GeV antiprotons might make the world's most intense source of tagged D 0 mesons, and thus the best near-term opportunity to study charm mixing and, via CP violation, to search for new physics. Other potential measurements include sensitive studies of hyperons and of the mysterious X , Y , and Z states. Production of antihydrogen in flight can be used for first searches for antihydrogen CPT violation. With antiproton deceleration to low energy, an experiment using a Penning trap and an atom interferometer could make the world's first measurement of the gravitational force on antimatter.
Higher loops beyond the SU(2) sector

We consider the case of coherent gauge invariant operators in the SU(3) and SO(4) sectors. We argue that in many cases, these sectors can be closed in the thermodynamic limit, even at higher loops. We then use a modification of the Bethe equations which is a natural generalization of a proposal put forward by Serban and Staudacher to make gauge theory predictions for the anomalous dimensions for a certain class of operators in each sector. We show that the predictions are consistent with semiclassical string predictions at two loops but in general fail to agree at three loops. Interestingly, in both cases there is one point in the configuration space where the gauge theory and string theory predictions agree. In the SU(3) case it corresponds to a circular string with R-charge assignment (J,J,J).
Sensitivity of the short- to intermediate-wavelength geoid to rheologic structure in subduction zones

[1] The rheologic structure of subduction zones determines how the negative buoyancy of sinking lithosphere (slabs) couples to the surface to cause surface deformation and plate motion. However, the rheologic structures determined using different methods are inconsistent. Analysis of the geoid and some dynamical models conclude that slabs must be weak, whereas other dynamical models and experimentally determined rheology predict that slabs are strong. Using idealized three-dimensional models of a subduction zone, we show that lateral variations in viscosity (LVVs) within a slab caused by yielding render the geoid insensitive to the viscosity structure outside of the bending region of the slab. Spectral analysis of the geoid up to harmonic degree 360 (features at wavelengths down to 110 km) shows that LVVs cause significant mode coupling with changes to the long-wavelength geoid (>1000 km) caused by short-wavelength (<500 km) changes to dynamic topography. Models with either a uniformly weak slab, or a strong slab with yielding, provide a good match to the observed geoid spectrum and characteristic features of the geoid over subduction zones. Therefore, observations other than the geoid are needed to constrain the strength profile of subducting slabs.
Mixing in the dome region of a staged gas turbine combustor

Author(s): Sowa, WA; Brady, RA; Samuelsen, GS | Abstract: Many modifications to the combustion process are being proposed and evaluated to lower NOr emissions from gas turbine engines in both stationary and propulsion applications. A promising technique is staged combustion, wherein the fuel is mixed into a fuel-rich region and the final air is injected downstream to an overall lean mixture. This article examines the effect of dome design and operational changes on the mixing quality in the fuel-rich region. A statistical analysis is employed to establish the parametric sensitivity in this complex flow. A mixing effectiveness index is defined and used to optimize the gas species uniformity and the extent of reaction at the exit plane of the dome. The results reveal that mixing effectiveness is intimately tied to the fuel and air injection locations, the macroscale structure of the dome aerodynamics, and the level of turbulence. Increases in nozzle/air to fuel ratio, reference velocities, and the dome expansion angle increased the level of turbulence. The optimum configuration featured counterswirling fuel and airstreams and produced a strong torroidal recirculation zone, an effective spray angle of 45 deg, and azimuthal velocities that decayed to zero inside of two duct diameters. Due to the intimate relationship between variables, the response of mixing to changes in any single variable cannot be considered independently of the other variables. The results underscore the system specific nature of mixing optimization. © 1993 by the American Institute of Aeronautics and Astronautics, Inc.
Identity crises and strong compactness

From a proper class of supercompact cardinals, we force and obtain a model in which the proper classes of strongly compact and strong cardinals precisely coincide. In this model, it is the case that no strongly compact cardinal $\kappa$ is $2^\kappa = \kappa^+$ supercompact.
A Predictive Algorithm for Rate Control of Mechanisms Near Singularities

A new kinematic algorithm for the control of mechanisms is described that produces smoother and more accurate control near kinematic singularities than the usual damped least-squares method. The new method predicts the occurence of singularities, evaluates the singular terms of the inverse kinematic function us ing a nonsingular expression, and smoothly interpolates between the singular and nonsingular forms. The desingularized expres sion makes use of the rates of change of the singular vectors and values of the Jacobian matrix; formulas for these derivatives are presented. Simulations of the control of two- and six-joint serial manipulators moving through and near singular configurations are given to illustrate the method.
Developing customer loyalty from e‐tail store image attributes

– The purpose of this paper is to investigate e‐tail store attributes that develop customers' positive perceptions of e‐tail store image, and determines whether or not they develop a sense of loyalty to an e‐tailer., – Acknowledging the importance of customer retention, this paper is designed to examine e‐customer loyalty intentions toward the e‐tailer. To understand the concept of loyalty toward an e‐tailer, this study focuses on the importance of the final stage of the customer decision‐making process: post‐purchase evaluation. This paper develops a model that describes the extent to which e‐tail store image (derived from a set of e‐tail store attributes) indicates patronage intentions and finally predicts customer loyalty. We use the structural equation modeling to test the model and hypotheses., – Results in this paper indicate that e‐tail store image is derived from e‐merchandise, e‐service, and e‐shopping atmosphere attributes, all of which support the way consumers shop. A favorable e‐tail store image positively influences e‐patronage intentions, which thus leads to e‐loyalty., – The research in this paper provides a conceptual model that will help e‐retailers better articulate how and why consumers may be e‐loyal shoppers. Second, the research identifies attributes, unique to online shopping that serve as the basis for conceptualizing e‐tail image as a second order factor.
Flexible backhaul design and degrees of freedom for linear interference networks

The considered problem is that of maximizing the degrees of freedom (DoF) in cellular downlink, under a backhaul load constraint that limits the number of messages that can be delivered from a centralized controller to the base station transmitters. A linear interference channel model is considered, where each transmitter is connected to the receiver having the same index as well as one succeeding receiver. The backhaul load is defined as the sum of all the messages available at all the transmitters normalized by the number of users. When the backhaul load is constrained to an integer level B, the asymptotic per user DoF is shown to equal (4B-1)/(4B), and it is shown that the optimal assignment of messages to transmitters is asymmetric and satisfies a local cooperation constraint and that the optimal coding scheme relies only on zero-forcing transmit beamforming. Finally, an extension of the presented coding scheme is shown to apply for more general locally connected and two-dimensional networks.
A NEW APPROACH TO THE FAMILY STRUCTURE

In this letter, we introduce a new approach to formulate the family structure of the standard model. Trying to mimic the highly constrained representation structure of the standard model while extending the symmetry, we propose an SU(4) ⊗ SU(3) ⊗ SU(2) ⊗ U(1) symmetry with a SM-like chiral spectra basically “derived” from the gauge anomaly constraints. Embedding the SM leads to SU(4)A ⊗ SU(3)C ⊗ SU(2)L ⊗ U(1)X models, which upon the SU(4)A ⊗ U(1)Y symmetry breaking, gives the three families naturally as a result. A specific model obtained from the approach is illustrated. The model, or others from our approach, holds promise of a very interesting phenomenology. We sketch some of the results here. An interesting possibility of supersymmetrizing the model with the EW-Higgses already in the spectrum is noted. A comparison with other approaches is also discussed.
Measuring the Rotation Speed of Giant Stars from Gravitational Microlensing

During some gravitational lensing events, the lens transits the disk of the star. This event causes a shift in the apparent radial velocity of the star proportional to the star's rotation speed. The magnification of such an event is different from that expected for a point source. By measuring both effects, one can determine the rotation parameter v sin i. The method is especially useful for K-giant stars because these stars have turbulent velocities that are typically large compared with their rotation speed. By making a series of radial velocity measurements, one can typically determine v sin i to the same accuracy as the individual radial velocity measurements. There are approximately 10 microlensing transit events per year that would be suitable for these measurements.
Sea ice, high-latitude convection, and equable climates

[1] It is argued that deep atmospheric convection might occur during winter in ice-free high-latitude oceans, and that the surface radiative warming effects of the clouds and water vapor associated with this winter convection could keep high-latitude oceans ice-free through polar night. In such an ice-free high-latitude ocean the annual-mean SST would be much higher and the seasonal cycle would be dramatically reduced - making potential implications for equable climates manifest. The constraints that atmospheric heat transport, ocean heat transport, and CO 2 concentration place on this mechanism are established. These ideas are investigated using the NCAR column model, which has state-of-the-art atmospheric physics parameterizations, high vertical resolution, a full seasonal cycle, a thermodynamic sea ice model, and a mixed layer ocean.
ESPRIT-estimation of signal parameters via rotational invariance techniques

High-resolution signal parameter estimation is a problem of significance in many signal processing applications. Such applications indude direction-of-arrival estimation, system identification, and time series analysis. A novel approach to the general problem of signal parameter estimation is described. Although discussed in the context of directionof- arrival estimation, ESPRIT can be applied to a wide variety of problems. It exploits an underlying rotational invariance among signal subspaces induced by an array of sensors with a translational invariance structure. The technique, when applicable, manifests significant performance and computational advantages over previous algorithms such as Burg's maximum entropy method, Capon's maximum likelihood method, and Schmidt's multiple signal classification.
Conformal Laplacian and Conical Singularities

We study a behavior of the conformal Laplacian operatorLg on a manifold with tame conical singularities: when each singularity is given as a cone over a product of the standard spheres. We study the spectral properties of the operator Lg on such manifolds. We describe the asymptotic of a general solution of the equation Lgu = Qu α with 1 ≤ α ≤ n+2 n−2 near each singular point. In particular, we derive the asymptotic of a Yamabe metric near such singularity.
Photoassisted diversity-oriented synthesis: accessing 2,6-epoxyazocane (oxamorphan) cores.

The modular synthesis of photoprecursors and their photoinduced cyclization into substituted 1-benzazocanes of two distinct topologies is described. The key step producing an extended polyheterocyclic system involves the photogeneration of azaxylylenes and their subsequent intramolecular cycloaddition with furan-containing pendants tethered either via the aniline nitrogen or through the carbonyl group containing arm. The primary photoproducts—secondary or tertiary anilines which are not acylated at the nitrogen atom—undergo facile acid-catalyzed or spontaneous ring-opening–ring-closing rearrangement to yield fused polyheterocyclic structures possessing a 2,6-epoxyazocane (or oxamorphan) core.
Gauge-mediated SUSY breaking with a gluino LSP

Abstract In gauge-mediated SUSY breaking models, messengers transmit SUSY breaking from a partially hidden sector to the standard model sector via common standard model gauge interactions. The minimal set of messengers has quantum numbers of a 5+ 5 of SU(5); identical to the quantum numbers of the minimal Higgs sector of an SU(5) GUT. We show in a simple model with messenger masses of order the GUT scale that Higgs - messenger mixing quite naturally leads to a low energy MSSM with gluinos as the lightest supersymmetric particles [LSP]. We study the phenomenological consequences of such a model.
The DeMeester score overdiagnoses GERD when meals are included in the analysis

Introduction: The DeMeester scoring system is commonly use when interpreting a 24H pH-monitoring study with patients on unrestricted diet. This is based on analysis of the full recording without exclusion of the meals. We believe that meals should be excluded for a more accurate analysis. Aim: Assess the accuracy of diagnosing GERD using DeMeester scoring system with and without meals included. Methods: One hundred forty consecutive normal 24H pH-studies (total time pH less then 4.5) reviewed from our database. Patients were off medication and with no history of past or recent esophagea l surgery. The DeMeester score for the distal esophagus was computed, including and excluding time during meal ingestion. Tota l time pH less then four, total number of episodes and DeMeester score (DS) were analyzed. Results: Ten patients (7%) with normal DS score when meals were excluded became abnormal with meals included. Only one patient had a total percentage time pH<4 changing to abnormal with meal included. The difference in DS is explained by a change in number of episodes, which are a reflux artifact produced by low pH foods (table below). Conclusion: Using the DeMeester score without excluding meals may provide a false positive diagnosis of GERD.
The Lucas Critique, Policy Invariance and Multiple Equilibria

The Lucas Critique of Econometric Policy Evaluation argues that the parameters of econometric models are subject to theoretical cross-equation restrictions which follow from the fact that the endogenous variables of the models are chosen optimally by forward-looking agents. In this paper I argue that these facts alone are insufficient to generate such restrictions. I present an example of a model in which there exist multiple stationary rational expectations equilibria one of which is supported by a process-invariant forecast rule. Immunity to the Lucas Critique is proposed as a selection criterion in models with multiple equilibria.
Equality of streams is a Π0 over 2-complete problem

This paper gives a precise characterization for the complexity of the problem of proving equal two streams defined with a finite number of equations: Π0 over 2. Since the Π 0 over 2 class includes properly both the reursively enumerable and the corecursively enumerable classes, this result implies that neither the set of pairs of equal streams nor the set of pairs of unequal streams is recursively enumerable. Consequently, one can find no algorithm for determining equality of streams, as well as no algorithm for determining inequality of streams. In particular, there is no complete proof system for equality of streams and no complete system for inequality of streams.
Nuclear data sheets for A=234

Abstract The available nuclear structure information for all nuclei with mass number A = 234 is presented. Various decay and reaction data are evaluated and compared. Inconsistencies and discrepancies are indicated. Adopted data, levels, spin, parity and configuration assignments are given.
Optimal consumption-portfolio policies: A convergence from discrete to continuous time models☆

Abstract We establish a convergence of optimal intertemporal consumption and portfolio policies from a sequence of discrete time multivariate and multinomial models to a continuous time multi-dimensional diffusion model.
A refinement of Wilf-equivalence for patterns of length 4

In their paper [6], Dokos et al. conjecture that the major index statistic is equidistributed among 1423-avoiding, 2413-avoiding, and 3214-avoiding permutations. In this paper we confirm this conjecture by constructing two major index preserving bijections, @Q:S"n(1423)->S"n(2413) and @W:S"n(3214)->S"n(2413). In fact, we show that @Q (respectively, @W) preserves numerous other statistics including the descent set, right-to-left maxima (respectively, left-to-right minima), and a statistic we call steps. Additionally, @Q (respectively, @W) fixes all permutations avoiding both 1423 and 2413 (respectively, 3214 and 2413).
Functional precision polymers via ADMET polymerization

Acyclic diene metathesis (ADMET) polymerization is a powerful and versatile technique for creating precision polymers. Specialized and well-defined materials, as well as improved understanding of structure–property relationships, can be achieved by ADMET polymerization of designed symmetrical monomer structures. The introduction of functional groups into ADMET polymers, from polar groups to biodegradable moieties, has resulted in an array of precision functional materials with distinct properties and interesting applications.
Gestational age assessment in preterm neonates weighing less than 1500 grams

Postnatal assessment of gestational age in preterm neonates traditionally has been performed using the methods of Dubowitz and Ballard. This study was designed to determine the accuracy of these methods in a sample of very low birth weight preterm neonates. Dubowitz and Ballard examinations were done on 110 preterm neonates within the first 72 hours of life by a neonatologist masked to the gestational age assessed antenatally. Mean birth weight was 1066 ± 256 g (SD). These data were compared with gestational age assessments using last menstrual period and best obstetric estimate calculated by an obstetrician unaware of the neonatal examination. Mean gestational age using last menstrual period was 28.3±2.9 weeks. Mean differences between last menstrual period and Dubowitz/Ballard were -2.8±2.1 weeks and -2.6±2.2 weeks, respectively. Results using best obstetric estimate were similar. An ophthalmologist examined lens vessels of 89 neonates. A similar pattern toward overestimation of gestational age interval by Dubowitz/Ballard was seen at each lens vessel grade. The Dubowitz and Ballard examinations are inaccurate methods of assessing gestational age in preterm neonates with birth weights less than 1500 g.
A singular stochastic differential equation driven by fractional Brownian motion

Abstract In this paper we study a singular stochastic differential equation driven by an additive fractional Brownian motion with Hurst parameter H > 1 2 . Under some assumptions on the drift, we show that there is a unique solution, which has moments of all orders. We also apply the techniques of Malliavin calculus to prove that the solution has an absolutely continuous law at any time t > 0 .
Symmetries of supergravity black holes

We investigate Killing tensors for various black hole solutions of supergravity theories. Rotating black holes of an ungauged theory, toroidally compactified heterotic supergravity, with NUT parameters and two U(1) gauge fields are constructed. If both charges are set equal, then the solutions simplify, and then there are concise expressions for rank-2 conformal Killing–Stackel tensors. These are induced by rank-2 Killing–Stackel tensors of a conformally related metric that possesses a separability structure. We directly verify the separation of the Hamilton–Jacobi equation on this conformally related metric and of the null Hamilton–Jacobi and massless Klein–Gordon equations on the 'physical' metric. Similar results are found for more general solutions; we mainly focus on those with certain charge combinations equal in gauged supergravity but also consider some other solutions.