cssi/SciSciGPT-SciSciNet huggingface dataset:
Formulation of the Quantum-Mechanical Many-Body Problem in Terms of One- and Two-Particle Functions

A self-consistent procedure is presented for the determination of the properties of a many-fermion system, taking into account all two-particle correlations. We consider a system of $N$ fermions, interacting through two-body forces and write the wave function in the form, $\ensuremath{\Psi}={\ensuremath{\Psi}}_{0}+\ensuremath{\Sigma}{\mathrm{ij}}^{}{f}^{(2)}(\mathrm{ij})$, where ${\ensuremath{\Psi}}_{0}$ is a determinant of one-particle wave functions and ${f}^{(2)}(\mathrm{ij})$ is an antisymmetrized product of ($N\ensuremath{-}2$) one-particle functions and of one two-particle function. By introducing two-particle functions for each electron pair, all two-particle correlations are taken into account. It is shown that for the best one- and two-particle functions a system of coupled integrodifferential equations can be derived. These equations are derived by varying the expectation value of the Hamiltonian with respect to the one- and two-particle functions, taking into account the normalization and orthogonality as subsidiary conditions. After eliminating the Lagrangian multipliers, we have obtained the following result. We obtained $N$ one-particle equations for the $N$ one-particle wave functions and one-particle orbital parameters. These equations are characterized by a potential (and exchange operator) in which, besides the Hartree-Fock type potential terms, there are also the potentials arising from the two-particle functions, where the latter occur in diagonal, as well as in nondiagonal form. For the two-particle functions and the orbital parameters associated with them, we have obtained two-particle equations in which the equation for the function ${\ensuremath{\varphi}}_{\mathrm{ij}}$ contains all one-particle functions and all the other two-particle functions. It is shown that the system of coupled one- and two-particle equations can be solved with a self-consistent procedure. The method can be applied to systems with any number of particles.
Contact Process in a Wedge

We prove that the supercritical one-dimensional contact process survives in certain wedge-like space-time regions, and that when it survives it couples with the unrestricted contact process started from its upper invariant measure. As an application we show that a type of weak coexistence is possible in the nearest-neighbor “grass-bushes-trees” successional model introduced in Durrett and Swindle (Stoch. Proc. Appl. 37:19–31, 1991).
An Investigation of the Transient Thermal Analysis of Spur Gears

A finite element computer program has been developed for evaluating the transient behavior of surface temperature in high performance spur gears. The program is an extension of a previously developed code that was limited to steady-state behavior. The time dimension is implemented using two- and three-point finite difference schemes. The different schemes are provided to the user for the purpose of numerical stability and convergence studies. A detailed explanation of the gear cooling process leading to the establishment of a modified Blok model is also included. Other conventional models for approximating the heat transfer coefficients are available for comparison. Preliminary results are given showing snap shots of gear temperature contours at the initial stages of tooth engagement.
Diversity of dynamics and morphologies of invasive solid tumors

Complex tumor-host interactions can significantly affect the growth dynamics and morphologies of progressing neoplasms. The growth of a confined solid tumor induces mechanical pressure and deformation of the surrounding microenvironment, which in turn influences tumor growth. In this paper, we generalize a recently developed cellular automaton model for invasive tumor growth in heterogeneous microenvironments [Y. Jiao and S. Torquato, PLoS Comput. Biol.7, e1002314 (2011)] by incorporating the effects of pressure. Specifically, we explicitly model the pressure exerted on the growing tumor due to the deformation of the microenvironment and its effect on the local tumor-host interface instability. Both noninvasive-proliferative growth and invasive growth with individual cells that detach themselves from the primary tumor and migrate into the surrounding microenvironment are investigated. We find that while noninvasive tumors growing in “soft” homogeneous microenvironments develop almost isotropic shapes, both high pressure and host heterogeneity can strongly enhance malignant behavior, leading to finger-like protrusions of the tumor surface. Moreover, we show that individual invasive cells of an invasive tumor degrade the local extracellular matrix at the tumor-host interface, which diminishes the fingering growth of the primary tumor. The implications of our results for cancer diagnosis, prognosis and therapy are discussed.
Cache memory systems for multiprocessor architecture

The performances of two types of multiprocessor systems with cache memories dedicated to each processor are analyzed. It is demonstrated that by appropriate cache system design, adequate memory system speed can be achieved to keep the processors busy. A write through algorithm is used for each cache to minimize directory searching and several main memory modules are used to provide interleaved write. In large memories a cost performance analysis shows that with an increase in per bit costs of 5 to 20 percent, the memory throughput can be enhanced by a factor of 10 and by a factor of 3 or more over simple interleaving of the modules for random memory requests. Experimental evidence indicates smaller cache memories are required for dedicated processors than for standard processors. All memories and buses can be of modest speed.
Structure of an archaeal‐type phosphoenolpyruvate carboxylase sensitive to inhibition by aspartate

The crystal structure of an archaeal-type phosphoenolpyruvate carboxylase from Clostridium perfringens has been determined based on X-ray data extending to 3 Ǻ. The asymmetric unit of the structure includes two tetramers (each a dimer-of-dimers) of the enzyme. The precipitant, malonate, employed for the crystallization is itself a weak inhibitor of phosphoenolpyruvate carboxylase and a malonate molecule is seen in the active-site in the crystal structure. The allosteric binding sites for aspartate (an inhibitor) and glucose-6-phosphate (an activator) observed in the Escherichia coli and Zea mays phosphoenolpyruvate carboxylase structures, respectively, are not conserved in the C. perfringens structure. Aspartate inhibits the C. perfringens enzyme competitively with respect to the substrate, Mg++.phosphoenolpyruvate. A mechanism for inhibition is proposed based on the structure and sequence comparisons with other archaeal-type phosphoenolpyruvate carboxylases with differing sensitivity to inhibition by aspartate.
Bentham’s Sanction Typology and Restrictive Deterrence A Study of Young, Suburban, Middle-Class Drug Dealers

Restrictive deterrence is the process whereby offenders limit the frequency, magnitude, or seriousness of their offenses to avoid pain. Prior research on drug dealing and restrictive deterrence largely focuses on the effect of formal control, or political sanction. Bentham, however, suggests there are four other types of sanction that may deter offenses: moral, sympathetic, religious, and physical. This paper explores whether and how each sanction type restricts drug sales among a sample of 29 young, suburban, middle-class drug sellers. We conclude by discussing the usefulness of studying interconnections between the sanctions and by outlining the reasons to choose Bentham's sanction typology in future work. Language: en
Bismuth telluride hexagonal nanoplatelets and their two-step epitaxial growth.

We report a synthesis of discrete, single-crystal, defect-free, and hexagonal Bi2Te3 nanoplatelets using a high-temperature organic solution approach, and we demonstrate a two-step epitaxial growth of the cylindrical strings of Bi2Te3 nanoplatelets on the surface of the Te rod by packing them along c-axis in a top−bottom−top−bottom sequence. This type of building-up provides additional opportunity for the exploration of novel thermoelectric properties from such quantum-confined materials, in which the boundary scattering of phonons is anticipated to enhance.
Projecting the Effect of Changes in Smoking and Obesity on Future Life Expectancy in the United States

We estimate the effects of declining smoking and increasing obesity on mortality in the United States over the period 2010–2040. Data on cohort behavioral histories are integrated into these estimates. Future distributions of body mass indices are projected using transition matrices applied to the initial distribution in 2010. In addition to projections of current obesity, we project distributions of obesity when cohorts are age 25. To these distributions, we apply death rates by current and age-25 obesity status observed in the National Health and Nutrition Examination Survey, 1988–2006. Estimates of the effects of smoking changes are based on observed relations between cohort smoking patterns and cohort death rates from lung cancer. We find that changes in both smoking and obesity are expected to have large effects on U.S. mortality. For males, the reductions in smoking have larger effects than the rise in obesity throughout the projection period. By 2040, male life expectancy at age 40 is expected to have gained 0.83 years from the combined effects. Among women, however, the two sets of effects largely offset one another throughout the projection period, with a small gain of 0.09 years expected by 2040. Electronic supplementary material The online version of this article (doi:10.1007/s13524-013-0246-9) contains supplementary material, which is available to authorized users.
Iron Lewis acid catalyzed reactions of phenyldiazomethane with aromatic aldehydes

Abstract The iron Lewis acid 1 was found to catalyze reactions of phenyldiazomethane and aromatic aldehydes to give cis -epoxides along with the corresponding ketones. The yield of the epoxide increased with electron-withdrawing substituents on the aldehyde, while little or no epoxide was formed with electron-donating substituents. The reaction was found to go through the coordination of the aldehyde to the iron Lewis acid instead of a carbene intermediate.
New Evidence on Optimal Asset Allocation

Brocato and Steed (1998) showed that portfolio rebalancing based on NBER business cycle turning points substantially improves in-sample Markowitz efficiency. In a similar vein, we investigate potential improvements from rebalancing based on turning points in the monetary cycle. We find that the monetary cycle has greater influence than the business cycle on the variance/covariance structure of multiple asset classes. Furthermore, we find substantial improvements in in-sample efficiency beyond a buy-and-hold strategy and the business-cycle approach. Importantly, our indicator of monetary cycle turning points has a practical advantage over NBER business cycle turning points, in that it relies only on ex ante information. In out-of-sample tests, we continue to find superior portfolio performance after transactions costs using the monetary cycle to time portfolio rebalancing.
Unpowered Approach and Landing Guidance Using Trajectory Planning

A guidance scheme that employs a trajectory-planning algorithm has been developed for the approach and landing phase of an unpowered reusable launch vehicle. The trajectoryplanning scheme computes a reference flight profile by piecing together several flight segments that are defined by a small set of geometric parameters. A feasible reference profile that brings the vehicle from its current state to a desired landing condition is obtained by iterating on a single geometric parameter, and the flight-path angle at the start of the flare is selected as the iteration variable. Open- and closed-loop guidance commands are readily available once the reference trajectory is obtained. The trajectory-planning algorithm is able to quickly generate new reference profiles for test cases with large variations in winds, vehicle energy, and vehicle drag. The effectiveness of the tr ajectoryplanning algorithm is demonstrated by several numerical simulations, which show that the guided vehicle is able to land successfully with adequate energy margin.
Practical data-swapping: the first steps

The problem of statistical database confidentiality in releasing microdata is addressed through the use of approximate data-swapping. Here, a portion of the microdata is replaced with a database that has been selected with approximately the same statistics. The result guarantees the confidentiality of the original data, while providing microdata with accurate statistics. Methods for achieving such transformations are considered and analyzed through simulation.
Ultrahigh-energy neutrinos

The ultrahigh energy neutrino cross section is well understood in the standard model for neutrino energies up to 1012 GeV, Tests of neutrino oscillations (νμ ↔ ντ) from extragalactic sources of neutrinos are possible with large underground detectors. Measurements of horizontal air shower event rates at neutrino energies above 1010 GeV will be able to constrain nonstandard model contributions to the neutrino-nucleon cross section, e.g., from mini-black hole production.
Inductive Measurement of Plasma Jet Electrical Conductivity

An inductive probing scheme, originally developed for shock tube studies, has been adapted to measure explosive plasma jet conductivities. In this method, the perturbation of an applied magnetic field by a plasma jet induces av oltage in a search coil, which, in turn, can be used to infer electrical conductivity through the inversion of a Fredholm integral equation of the first kind. A 1-in. (25.4-mm)-diam probe was designed and constructed, and calibration was accomplished by firing an aluminum slug through the probe using a light-gas gun. Exploratory laboratory experiments were carried out using plasma jets expelled from 15-g high-explosive shaped charges. Measured conductivities were in the range of 3 kS/m for unseeded octol charges and 20 kS/m for seeded octol charges containing 2% potassium carbonate by mass.
FANO MANIFOLDS, CONTACT STRUCTURES, AND QUATERNIONIC GEOMETRY

Let Z be a compact complex (2n+1)-manifold which carries a complex contact structure, meaning a codimension-1 holomorphic sub-bundle D⊂TZ which is maximally non-integrable. If Z admits a Kahler-Einstein metric of positive scalar curvature, we show that it is the Salamon twistor space of a quaternion-Kahler manifold (M4n, g). If Z also admits a second complex contact structure , then Z=CP2n+1. As an application, we give several new characterizations of the Riemannian manifold HPn= Sp(n+1)/(Sp(n)×Sp(1)).
A Tale of Three Schools: Insights on Autocorrelations of Short-Horizon Stock Returns

This article reexamines the autocorrelation patterns of short-horizon stock returns. We document empirical results which imply that these autocorrelations have been overstated in the existing literature. Based on several new insights, we provide support for a market efficiency-based explanation of the evidence. Our analysis suggests that institutional factors are the most likely source of the autocorrelation patterns.
Kindred Narratives Reflections of Southern Black Orality in Sweetwater

Durham reinterprets home and reimagines the storied lives of Black women by fusing her experience with those described by author Robin Boylorn in Sweetwater. Boylorn privileges African diasporic storytelling traditions, such as orality. Durham employs them and provides a complementary performance narrative to recount southern Black girlhood in Sweetwater (North Carolina) and Tidewater (Virginia).
Information Acquisition at the Nanoscale: Fundamental Considerations

Reliable extraction of information from a physical system requires some combination of redundancy, state distinguishable, and access time. This has obvious implications for any prospective nanoelectronic technology that would require rapid extraction of information from small numbers of electrons through nanoscale access volumes. In this paper, we explore this issue through consideration of fundamental physical limits on information acquisition from electronic systems. We outline our general approach, obtain the required accessible information bounds for multipartitie information-bearing systems, and present model calculations that illustrate loss of accessible information at nanoscale access volumes and low particle densities in a simple tight-binding molecular wire. This approach, fully developed, could provide both useful physical insight and practical tools for the assessment of emerging electronic information processing technologies.
SPECTROPHOTOMETRY OF THE HUYGENS REGION OF THE ORION NEBULA, THE EXTENDED ORION NEBULA, AND M 43: SCATTERED LIGHT SYSTEMATICALLY DISTORTS CONDITIONS DERIVED FROM EMISSION LINES

We report on medium resolution spectrophotometry of the Orion Nebula region, including for the first time the Extended Orion Nebula (EON) and the nearby M 43. The 49 long-slit observations were divided into 99 smaller samples, which have allowed determinations of the amount of extinction, extinction-corrected Hβ surface brightness, electron temperatures (from [S II], [N II], and [O III]), and electron densities (from [S II] and [Cl III]) throughout much of this complex region. We verify an earlier conclusion from a radio/optical study that beyond about 5' from θ1Ori C local emission begins to be contaminated by scattering of light from the much brighter central Huygens region of M 42, and this scattered light component becomes dominant at large distances. This contamination means that the derived properties for the outer regions are not accurate. From comparison of the light from the dominant star in M 43 with the continuum of that nebula (which is almost entirely scattered starlight), it is determined that scattered light is enhanced in the blue, which can lead to observed Balmer line ratios that are theoretically impossible and erroneous electron temperatures. This blue scattering of emission lines is important even in the Huygens region because it means that at anything except very high spectroscopic resolution the observed lines are a blend of the original and scattered light, with shorter wavelength lines being artificially enhanced. This can lead to overestimates of the electron temperatures derived from the nebular and auroral line ratios of forbidden lines. This phenomenon is probably applicable to many other H II regions. We have been able to use extinction-insensitive line ratios, the extinction-corrected surface brightness in Hβ, and the equivalent width of the continuum to create for the first time a three-dimensional model of the entire M 42, EON, and M 43 region. This is an irregular concave blister of ionized gas bounded on the outside by apparent walls where the ionization front has curved almost to the direction of the observer. M 43 is seen to be shielded from illumination by θ1Ori C by the northeast portion of the wall bounding M 42.
Symmetric and asymmetric cleavage of the lighter boron hydrides and of metal salts – the role of the dielectric constant

Abstract Evidence is presented to support the premise that when a base reacts with diborane at low temperatures (−77 to −80°C) the variable which determines whether the product will be an ionic substance such as [H 2 B(Base) 2 ] + [BH 4 − ] or a non-ionic substance such as H 3 B(Base) is the dielectric constant of the base and the medium. In most cases steric factors do not play a dominant role in the outcome of these direct reactions.
Stabilization of the Ti3Co5B2-type structure for Ti3−xSixRu5B2 through Si–Ti substitution

We report a route for designing and synthesizing Ti{sub 3}Co{sub 5}B{sub 2}-type compounds in the Ti–Ru–B system by using chemical substitution of Si for Ti to decrease the d-electron-based antibonding interactions that it is argued would otherwise drive an instability in this structure for unsubstituted Ti{sub 3}Ru{sub 5}B{sub 2}. Ti{sub 3−x}Si{sub x}Ru{sub 5}B{sub 2} with x=0.75, 1.00 and 1.25 nominal compositions crystalizes in the Ti{sub 3}Co{sub 5}B{sub 2} structure type using arc melting methods, whereas at lower doping levels (x=0.0, 0.25 and 0.50) the more complex Zn{sub 11}Rh{sub 18}B{sub 8}-type structure is stable. Electronic structure calculations show that in hypothetical, unsubstituted Ti{sub 3}Ru{sub 5}B{sub 2} with the Ti{sub 3}Co{sub 5}B{sub 2}-type structure, the antibonding interactions are strong around the Fermi level between the Ti and Ru in the structure that form tetragonal prisms. We propose that weakening these strong interactions through the partial substitution of isovalent Si for Ti leads to the observed stability of the Ti{sub 3}Co{sub 5}B{sub 2}-type structure for Ti{sub 3−x}Si{sub x}Ru{sub 5}B{sub 2} for x≈1. - Graphical abstract: We present the designing and synthesizing of Ti{sub 3}Co{sub 5}B{sub 2}-type compounds in the Ti–Ru–B system by using chemical substitution of Si for Ti to decrease the d-electron-basedmore » antibonding interactions that would otherwise drive an instability in this structure for unsubstituted Ti{sub 3}Ru{sub 5}B{sub 2}. Electronic structure calculations show that in hypothetical, unsubstituted Ti{sub 3}Ru{sub 5}B{sub 2} with the Ti{sub 3}Co{sub 5}B{sub 2}-type structure, the antibonding interactions are strong around the Fermi level between the Ti and Ru in the structure that form tetragonal prisms. We propose that weakening these strong interactions through the partial substitution of isovalent Si for Ti leads to the observed stability of the Ti{sub 3}Co{sub 5}B{sub 2}-type structure for Ti{sub 3−x}Si{sub x}Ru{sub 5}B{sub 2} for x≈1. - Highlights: • New quaternary phase Ti{sub 3−x}Si{sub x}Ru{sub 5}B{sub 2} in Ti{sub 3}Co{sub 5}B{sub 2}-type structure is reported. • Chemical substitution of isovalent Si for Ti is used to stabilize the phase. • Decreasing the d-electron-based antibonding interactions is proved by calculation. • Physical properties of Ti{sub 3−x}Si{sub x}Ru{sub 5}B{sub 2} are presented down to 0.4 K.« less
Measure Concentration for Compound Poisson Distributions

We give a simple development of the concentration properties of compound Poisson measures on the nonnegative integers. A new modification of the Herbst argument is applied to an appropriate modified logarithmic-Sobolev inequality to derive new concentration bounds. When the measure of interest does not have finite exponential moments, these bounds exhibit optimal {em polynomial} decay. Simple new proofs are also given for earlier results of Houdr{'e} (2002) and Wu (2000).
Collective behavior of optically trapped neutral atoms

We describe experiments that show collective behavior in clouds of optically trapped neutral atoms. This collective behavior is demonstrated in a variety of observed spatial distributions with abrupt bistable transitions between them. These distributions include stable rings of atoms around a small core and clumps of atoms rotating about the core. The size of the cloud grows rapidly as more atoms are loaded into it, implying a strong long-range repulsive force between the atoms. We show that a force arising from radiation trapping can explain much of this behavior.
Speculative execution in a distributed file system

Speculator provides Linux kernel support for speculative execution. It allows multiple processes to share speculative state by tracking causal dependencies propagated through interprocess communication. It guarantees correct execution by preventing speculative processes from externalizing output, for example, sending a network message or writing to the screen, until the speculations on which that output depends have proven to be correct. Speculator improves the performance of distributed file systems by masking I/O latency and increasing I/O throughput. Rather than block during a remote operation, a file system predicts the operation's result, then uses Speculator to checkpoint the state of the calling process and speculatively continue its execution based on the predicted result. If the prediction is correct, the checkpoint is discarded; if it is incorrect, the calling process is restored to the checkpoint, and the operation is retried. We have modified the client, server, and network protocol of two distributed file systems to use Speculator. For PostMark and Andrew-style benchmarks, speculative execution results in a factor of 2 performance improvement for NFS over local area networks and an order of magnitude improvement over wide area networks. For the same benchmarks, Speculator enables the Blue File System to provide the consistency of single-copy file semantics and the safety of synchronous I/O, yet still outperform current distributed file systems with weaker consistency and safety.
Frustration and packing in curved-filament assemblies: from isometric to isomorphic bundles

Densely packed bundles of filaments (filamentous proteins) are common and critical structural elements in range of biological materials. While most bundles form from intrinsically straight filaments, there are notable examples of protein filaments possessing a natural, or intrinsic, curvature, such as the helical bacterial flagellum. Here, we study the non-linear interplay between the thermodynamic preference for dense and regular inter-filament packing and the mechanical preference for uniform filament shape in bundles of helically curved filaments. Geometric constraints in bundles make perfect inter-filament (constant spacing, or isometric) packing incompatible with perfect intra-filament (constant shape, or isomorphic) packing. As a consequence, we predict that bundle packing exhibits a strong sensitivity to bundle size, evolving from the isometric packing at small radii to an isomorphic packing at large radii. The nature of the transition between these extremal states depends on thermodynamic costs of packing distortion, with packing in elastically constrained bundles evolving smoothly with size, while packing in osmotically compressed bundles may exhibit a singular transition from the isometric packing at a finite bundle radius. We consider the equilibrium assembly of bundles in a saturated solution of filaments and show that mechanical cost of isomorphic packing leads to self-limited equilibrium bundle diameters, whose size and range of stability depend both on condensation mechanism, as well as the helical geometry of filaments.
Covering spaces and Q-gradings on Heegaard Floer homology

Heegaard Floer homology, first introduced by P. Ozsvath and Z. Szabo in [OS04b], associates to a 3-manifold Y a family of relatively graded abelian groups HF (Y, t), indexed by Spin structures t on Y . In the case that Y is a rational homology sphere, Ozsvath and Szabo lift the relative Z-grading to an absolute Q-grading [OS06]. This induces a relative Q-grading on ⊕ t∈Spin(Y ) HF (Y, t). In this paper we describe an alternate construction of this relative Q-grading by studying the Heegaard Floer homology of covering spaces.
Enantioselective synthesis of pyrroloindolines by a formal [3 + 2] cycloaddition reaction.

(R)-BINOL•SnCl_4 was found to catalyze a formal [3 + 2] cycloaddition reaction between C(3)-substituted indoles and 2-amidoacrylates to provide pyrroloindolines. A variety of pyrroloindolines were prepared with high enantioselectivity in one step from simple precursors. This methodology is expected to facilitate the total synthesis of pyrroloindoline alkaloids, an important class of biologically active natural products.
Direct Bandgap, Ionizing-Radiation Insensitive, Photodiode Structures

This paper reports on photodiode structures designed and fabricated to reduce unwanted ionizing-radiation induced noise currents without significantly reducing the optical sig-nal currents. For the optical wavelength range from 0.7 µm to 1.4 μm, we have studied three types of photodiode structures fabricated from GaAlAs/GaAs, GaAlSb, and InGaAsP compound semiconductor materials. In addition, we compare the results of testing these specially designed direct bandgap photodiodes with commercially available direct and indirect hand qap photodiodes in an ionizing-radiation environment.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Navier-Stokes Analysis of Flowfield Characteristics of an Ice-Contaminated Aircraft Wing

An analytical study was performed as part of the NASA Lewis support of a National Transportation Safety Board (NTSB) aircraft accident investigation. The study was focused on the performance degradation associated with ice contamination on the wing of a commercial turbo-prop-powered aircraft. Based upon the results of an earlier numerical study conducted by the authors, a prominent ridged-ice formation on the subject aircraft wing was selected for detailed flow analysis using 2-dimensional (2-D), as well as, 3-dimensional (3-D) Navier-Stokes computations. This configuration was selected because it caused the largest lift decrease and drag increase among all the ice shapes investigated in the earlier study. A grid sensitivity test was performed to find out the influence of grid spacing on the lift, drag, and associated angle-of-attack for the maximum lift (C(sub lmax)). This study showed that grid resolution is important and a sensitivity analysis is an essential element of the process in order to assure that the final solution is independent of the grid. The 2-D results suggested that a severe stability and control difficulty could have occurred at a slightly higher angle-of-attack (AOA) than the one recorded by the Flight Data Recorder (FDR). This stability and control problem was thought to have resulted from a decreased differential lift on the wings with respect to the normal loading for the configuration. The analysis also indicated that this stability and control problem could have occurred whether or not natural ice shedding took place. Numerical results using an assumed 3-D ice shape showed an increase of the angle at which this phenomena occurred of about 4 degrees. As it occurred with the 2-D case, the trailing edge separation was observed but started only when the AOA was very close to the angle at which the maximum lift occurred.
Low-Threshold Stimulated Emission Using Colloidal Quantum Wells

The use of colloidal semiconductor nanocrystals for optical amplification and lasing has been limited by the need for high input power densities. Here we show that colloidal nanoplatelets produce amplified spontaneous emission with thresholds as low as 6 μJ/cm2 and gain as high as 600 cm–1, both a significant improvement over colloidal nanocrystals; in addition, gain saturation occurs at pump fluences 2 orders of magnitude higher than the threshold. We attribute this exceptional performance to large optical cross-sections, slow Auger recombination rates, and narrow ensemble emission line widths.
Computation of Near-Minimum-Time Maneuvers of Flexible Structures by Parameter Optimization

Near-minimum-time attitude maneuvers of space structures as well as ground-based test articles are consid- ered. The switching nature of the controls for rigid-body maneuvers is illustrated using a control cube and a crit- ical control axis. The presence of torque smoothing and, where appropriate, gravitational effects and connections to other bodies are explicitly included in the mathematical models of the systems to be optimized. A maximum fuel consumption constraint is included along with the required terminal conditions on attitude and angular velocities. The switch times, maximum thrust magnitudes, and smoothing parameters are determined using the sequential quadratic programming method for parameter optimization. Results indicating attitude and angular velocity histories, thruster forces, and structural vibrations are presented for three, four, and five switch maneu- vers, as well as maneuvers that involve large coasting arcs. A variety of performance indices based on torque, power, and time have been considered. Except for Refs. 12 and 13, applications to flexible spacecraft models have been limited to single-axis maneuvers. A recent survey article on time-optimal attitude maneuvers is pre- sented in Ref, 18. Solution to the optimization problem usually proceeds by invoking Pontryagin's principle, which leads to a two- point boundary-value problem (TPBVP).19 This is solved using either direct (gradient) or indirect (shooting) methods. The switch- time optimization algorithm (STO)20 is a direct method available for the solution of time-optimal control problems. Adaptation of a shooting method to solve time-optimal maneuver problems is given by Li and Bainum.21 Bilimoria and Wie22 considered the specific problem of time- optimal control of a sphere with three orthogonal control inputs, each bounded by ±1. They also restricted their attention to attitude boundary conditions that could otherwise be achieved by single- axis rotations about an Euler axis. Their results show that Euler- axis rotations are not time optimal in general; there are two types of switching sequences: five switches for rotation angles greater than 73 deg and seven switches for angles less than 73 deg. The switches are sequential, i.e., no control switches for the second time before all others switch. Li and Bainum21 present results for rest-to-rest maneuvers of nearly symmetric spacecraft that show similar behavior. However, for highly unsymmetric spacecraft and arbitrary attitude boundary conditions, the number and sequence of switches are not predictable as they are for spherical bodies. Byers and Vadali23 and Byers et al.24 used the STO algorithm to compare the Euler-axis, five-switch, and seven-switch maneuvers for Euler- axis boundary conditions and found that the differences in the maneuver times are insignificant for practical implementations. A suboptimal control strategy was developed in Ref. 23 by assuming a five-switch control sequence and an approximate solution to the Euler parameter differential equation. This switching structure also
17O NMR studies of local structure and phase evolution for materials in the Y2Ti2O7–ZrTiO4 binary system

Abstract 17 O MAS NMR and XRD studies of precursor-derived Y 1.6 Zr 0.4 Ti 2 O 7.2 and Y 1.2 Zr 0.8 Ti 2 O 7.4 have been performed to investigate the development of local and long-range order in these materials as they evolve from a metastable amorphous state upon heating. Zirconium titanate (ZrTiO 4 ) was also investigated to help interpret the 17 O NMR spectra of the ternary compositions. Consistent with earlier studies, crystallization was observed at 800 °C to form a fluorite structure and a small amount of rutile; weak broad reflections were also observed which were ascribed to the presence of small pyrochlore-like ordered domains or particles within the fluorite phase. As the temperature was increased further, the sizes of these domains grew along with the concentration of rutile. At the highest temperature studied (1300 °C), the reflections of the thermodynamic phases, pyrochlore and zirconium titanate (ZrTiO 4 ), dominated the XRD pattern. The 17 O NMR spectra revealed a series of different peaks that were assigned to different 3- and 4-coordinate O local environments. The data were consistent with the formation of a metastable phase Y 2− x Zr x Ti 2− y Zr y O 7+ x with pyrochlore-like ordering but with Zr substitution on both cation sites of the pyrochlore structure. At low temperatures, doping on the A (Y 3+ ) sites predominates (i.e., x > y ), consistent with the fact that the pyrochlore develops out of a more disordered fluorite-like, phase. As the temperature is raised, the Zr doping on the A site decreases and the metastable phase at this temperature can now be written as Y 2− x ′ Zr x ′ Ti 2− y ′ Zr y ′ O 7+ x ′ (i.e., x ′ y ′); TiO 2 is also observed, consistent with this suggestion. At high temperatures, doping on the B site decreases and the resonances due to the stoichiometric pyrochlore yttrium titanate (Y 2 Ti 2 O 7 ) dominate the NMR spectra. Weaker 17 O NMR resonances due zirconium titanate (ZrTiO 4 ) are also observed.
Individual Agents, Firms, and the Real Estate Brokerage Process

This study examines how individual agents affect house selling prices and time on the market while controlling for brokerage firm-specific effects as well as supply and demand conditions that vary by neighborhood. Firm size effects disappear once firm specialization and agent characteristics are taken into account but geographic concentration by firms leads to higher selling prices. For individual agents, neither sex nor selling own listings affects price or selling time, but there are gains from partnering transactions across firms. Agents who specialize in listing properties obtain higher prices for their sellers while those who specialize in selling obtain lower prices for their buyers. Houses nearer to other transactions of an agent sell for higher prices. Finally, greater scale of listing and selling activity by an agent tends to lower selling price or lengthen the time on the market.
Formation of Co3+ octahedra and tetrahedra in YBaCo4O8.1

Abstract High-resolution neutron and synchrotron X-ray powder diffraction experiments were performed, at 300 and 10 K, for the determination of the structure of YBaCo 4 O 8.1 , which was prepared by controlled oxidation of the Kagome lattice compound YBaCo 4 O 7 . Our diffraction data demonstrate that YBaCo 4 O 8.1 crystallizes in the orthorhombic Pbc2 1 space group with the formation of a large superstructure ( a =12.790 A, b =10.845 A, c =10.149 A), with respect to the parent trigonal YBaCo 4 O 7 material. The Co ions occupy both corner-sharing tetrahedral and edge-sharing octahedral sites, in contrast to YBaCo 4 O 7 , which has only corner-sharing tetrahedra. The octahedral sites form by the addition of two extra oxygen atoms and the drastic displacements of some of the original O atoms relative to the parent. The edge-sharing octahedra form isolated zigzag chains parallel to the c -axis linked to one another via tetrahedra. While found in a few phosphates, silicates and germanates, this motif appears unique to YBaCo 4 O 8.1 among mixed-metal oxides. No structural phase transition or long range antiferromagnetic ordering are observed at 10 K.
Diels-Alder reactions of vinylbicyclo[4.1.0]heptenes

Abstract Efficient syntheses of 1,3-dimethy1-2-vinylbicyclo[4.1.0]hept-2-ene (1) and 2,2-ethylenedioxy-4,6-dimethyl-5-vinylbicyclo[4.1.0]hept-4-ene (2) are described. These dienes, which undergo Diels-Alder reactions with p -benzoquinones readily, may serve as versatile intermediates for terpenoid synthesis.
Infrared factorization in inclusive B meson decays

Abstract We perform infrared factorization of differential rates of rediative and semileptonic inclusive decays of the B meson in the end-point region of photon and charged lepton spectrum, respectively, in the leading heavy quark mass limit. We find that the differential rates are expressed in terms of hard, jet and soft functions, which satisfy evolution equations. Solving these equations, we find expressions for the moments of the differential rates in their end-point regions, which take into account all leading and nonleading logarithmic corrections in perturbation theory, as well as large nonperturbative power corrections. Expanded to the one-loop level, our predictions coincide with the results of existing lowest order calculations for B→γXs and B →l v X u . Nonperturbative corrections appear in our formalism from the boundary value of the soft function in the evolution equation. The soft function is a universal process-independent function, which describes the distribution of the b quark in the B meson. Its behavior in the end-point region is governed by the nonperturbative asymptotics of a Wilson line expectation value. By considering the contributions of infrared renormalons, we find an ansatz for the Wilson line, which leads to a Gaussian model for the heavy quark distribution function.
Performance Implications of Peer Monitoring

Peer monitoring, which occurs when individuals notice and respond to their peers' behavior or performance results, is an informal organizational control that has not been extensively studied. Agency theory suggests that peer monitoring should be associated with higher performance because it allows workers whose interests are aligned with those of the organization to encourage their peers to perform well and deters inappropriate behavior by increasing the chances that it would be detected. This paper considers two research questions. The first is, “What is peer monitoring?” We found two types of peer monitoring. Direct peer monitoring occurs when workers notice their peers' behavior or results and respond in a forthright way, such as correcting coworkers who make mistakes. Indirect peer monitoring occurs when workers gossip about or avoid poorly performing peers. The second research question is, “Is peer monitoring associated with higher work-unit performance?” We examined the effects of both types of peer...
The time-sharing monitor system

The IBM Advanced Systems Development Division is currently operating the Time-Shared Monitor System (TSM), an experimental, general-purpose, time-sharing system based on the IBM 7090 Data Processing System. This system is capable of serving 24 remote users simultaneously. It requires a minimum of computing equipment, and gives the remotely located user a maximum amount of control over the 7090 itself; and over the content of his program files within it.
Hierarchical video classification with mixed media cues

A hierarchical semantic tree for sport video analysis by incorporating mixed media cues form video, audio and caption texts is proposed in this research. It allows queries form users at different granularity of semantic meanings. A set of classification functions, which associate the low-level features with video high-level semantic meanings for various applications, are learned by supervised learning algorithms at each node. Experimental results show our proposed scheme and classification system is effective and promising.
Measurement of lung tumor motion using respiration-correlated CT

Purpose We investigate the characteristics of lung tumor motion measured with respiration-correlated computed tomography (RCCT) and examine the method's applicability to radiotherapy planning and treatment. Methods and materials Six patients treated for non–small-cell lung carcinoma received a helical single-slice computed tomography (CT) scan with a slow couch movement (1 mm/s), while simultaneously respiration is recorded with an external position-sensitive monitor. Another 6 patients receive a 4-slice CT scan in a cine mode, in which sequential images are acquired for a complete respiratory cycle at each couch position while respiration is recorded. The images are retrospectively resorted into different respiration phases as measured with the external monitor (4-slice data) or patient surface displacement observed in the images (single-slice data). The gross tumor volume (GTV) in lung is delineated at one phase and serves as a visual guide for delineation at other phases. Interfractional GTV variation is estimated by scaling diaphragm position variations measured in gated radiographs at treatment with the ratio of GTV:diaphragm displacement observed in the RCCT data. Results Seven out of 12 patients show GTV displacement with respiration of more than 1 cm, primarily in the superior-inferior (SI) direction; 2 patients show anterior-posterior displacement of more than 1 cm. In all cases, extremes in GTV position in the SI direction are consistent with externally measured extremes in respiration. Three patients show evidence of hysteresis in GTV motion, in which the tumor trajectory is displaced 0.2 to 0.5 cm anteriorly during expiration relative to inspiration. Significant (>1 cm) expansion of the GTV in the SI direction with respiration is observed in 1 patient. Estimated intrafractional GTV motion for gated treatment at end expiration is 0.6 cm or less in all cases; however; interfraction variation estimates (systematic plus random) are more than 1 cm in 3/9 patients. Conclusion Respiration-correlated CT can be performed with currently available CT equipment and acquisition settings. RCCT provides not only three-dimensional information on intrafractional tumor motion and deformation, but also allows estimates of interfractional tumor variation when combined with radiographic measurements of diaphragm position variation during treatment.
Infinite dimensional multiplicity free spaces III: matrix coefficients and regular functions

In earlier papers we studied direct limits (G, K ) = lim → (Gn, Kn) of two types of Gelfand pairs. The first type was that in which the Gn/Kn are compact Riemannian symmetric spaces. The second type was that in which Gn = NnKn with Nn nilpotent, in other words pairs (Gn, Kn) for which Gn/Kn is a commutative nilmanifold.IneachweworkedoutamethodinspiredbytheFrobenius-SchurOrthog- onality Relations to define isometric injections ζm,n : L 2 (Gn/Kn )� → L 2 (Gm/Km) for m n and prove that the left regular representation of G on the Hilbert space directlimit L 2 (G/K ) := lim → L 2 (Gn/Kn)ismultiplicity-free.Thisleftopenquestions concerning the nature of the elements of L 2 (G/K ). Here we define spacesA(Gn/Kn) of regular functions on Gn/Kn and injections νm,n : A(Gn/Kn) → A(Gm/Km) for m n related to restriction by νm,n( f )|Gn /Kn = f . Thus the direct limit A(G/K ) := lim → {A(Gn/Kn), νm,n} sits as a particular G-submodule of the much larger inverse limit lim − {A(Gn/Kn),restriction}. Further, we define a pre Hilbert space structure on A(G/K ) derived from that of L 2 (G/K ). This allows an interpretation of L 2 (G/K ) as the Hilbert space completion of the concretely defined function space A(G/K ), and also defines a G-invariant inner product on A(G/K ) for which the left regular representation of G is multiplicity-free.
Calculation of chemical reaction energies using the AM05 density functional

We present results that compare the accuracy of the AM05 density functional (Armiento and Mattsson, Phys Rev B 2005, 72, 085108; Mattsson et al., J Chem Phys 2008, 128, 084714) to a set of chemical reaction energies. The reactions were generated from the singlet species in the well-known G2 test suite (Curtiss et al., J Chem Phys 1991; Curtiss et al., J Chem Phys 1997; 106, 1063). Our results show that, in general, the AM05 functional performs nearly as well as the other “pure” density functionals, but none of these perform as well as the hybrid B3LYP functional. These results are nonetheless encouraging because the AM05 functional arises from very simple assumptions, and does not require the calculation of the Hartree-Fock exchange integrals. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010
Overview of Laser Applications to Chemistry

This overview addresses three general areas: spectroscopy; molecular interactions and reaction dynamics; interrelation of chemistry and laser development. The various topics and specific chemical examples contained in the overview are by no means exhaustive, but are chosen simply to give the reader a flavor of the role of lasers in chemistry.
Design Optimization of Variable Stroke Compressors to Minimize Vibration by Using Asymptotic Analysis

A design optimization of a variable displacement compressor that minimizes its crankshaft vibra tion is presented. A vibration mount installed between the flywheel and crankshaft is used as the opt...