cssi/SciSciGPT-SciSciNet huggingface dataset:
Superfluid to normal phase transition in strongly correlated bosons in two and three dimensions

Using quantum Monte Carlo simulations, we investigate the finite-temperature phase diagram of hard-core bosons ($XY$ model) in two- and three-dimensional lattices. To determine the phase boundaries, we perform a finite-size-scaling analysis of the condensate fraction and/or the superfluid stiffness. We then discuss how these phase diagrams can be measured in experiments with trapped ultracold gases, where the systems are inhomogeneous. For that, we introduce a method based on the measurement of the zero-momentum occupation, which is adequate for experiments dealing with both homogeneous and trapped systems, and compare it with previously proposed approaches.
Phase Diagram Visualization via Continuously-Fed Crystallization: Experiments and Model

A protein’s atomic level three-dimensional structure is typically determined by X-ray diffraction of a high-quality protein crystal (Figure 1a). The X-ray bream is diffracted inside the crystal producing spots at various locations (Figure 1b) which can be used to back out the location of the electron cloud of the protein which is used to solve the structure (Figure 1c). The current bottleneck in these structural determination projects is in growing a diffraction quality protein crystal. Current growth methods involve testing hundreds of conditions in this multi-parametric process without knowledge of the protein phase diagram (PD). In this work, a microfluidic crystallization chamber is manufactured to allow phase diagram visualization to predict the PD of a protein in a single experiment. This phase diagram visualizer (PDV) screens a large range of protein and salt concentrations by controlling the transport mechanism (convection and diffusion) of both salt and protein. The PDV has been fabricated and its flow and concentration profiles have been determined using a computational model. The PDV has predicted the metastable line of the phase diagram for tetragonal lysozyme (known PD) and the solubility line for triclinic lysozyme (unknown PD).Copyright © 2009 by ASME
A note on E-strings

We study BPS states in type IIA string compactification on a local Calabi-Yau 3-fold which are related to the BPS states of the E-string. Using Picard-Lefshetz transformations of the 3-cycles on the mirror manifold we determine automorphisms of the K-theory of the compact divisor of the Calabi-Yau which maps certain D-brane configurations to a bound state of single D4-brane with multiple D0-branes. This map allows us to write down the generating functions for the multiplicity of these BPS states.
MOLECULAR STRUCTURE OF FLUORO DERIVATIVES OF ANIONIC PENTACOORDINATED GERMANIUM. A NEW GEOMETRICAL FORM FOR GERMANIUM

Abstract The X-ray structures of tetraethylammonium bis(1,2-benzenediolato)fluorogermanate, [(C2H5)4N]+[(C6H4O2)2GeF]- (3), and the related monosolvate of methyltriphenylphosphonium bis(4methyl-1,2-benzenedithiolato)fluorogermanate, [(CH3)PPh3]+ [(C7H6S2)2GeF]-.CH3CN (4), lie along the Berry C 2t, coordinate connecting the idealized trigonal bipyramid with the rectangular pyramid. The structure of 3 is placed about 81% along this coordinate toward the rectangular pyramid and that for 4 is about 40% along this coordinate. 3 crystallizes in the monoclinic space group P21,/c with a = 12.886 (2) A, b = 14.870 (2) A, c = 10.912 (1) A, β = 100.29 (1)°, and Z = 4. 4 crystallizes in the monoclinic space group P21/n with a = 17.108 (6) A, b = 10.566 (3) A c = 20.630 (6) A, β = 114.01 (2)°, and Z = 4. The final conventional unweighted residuals were 0.035 and 0.058 for 3 and 4, respectively. The greater displacement of the pentacoordinated oxa compound 3 toward the RP is rationalized in terms of reduced electron-pa...
A disiloxane equilibration approach to the preparation and characterization of 5,5′-(1,1,3,3,-tetramethyldisiloxane-1,3-diyl) bisbicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride

Abstract The preparation of 5,5′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bisbicyclo[2.2.1]heptene-2,3-dicarboxylic anhydride, 3 , by a novel synthetic approach was found to be an effective method to isolate this disiloxane which is difficult to purify. The structure of the diastereomerically mixed produced was confirmed by a combination of nuclear resonance spectroscopic and liquid chromatographic studies and correlated to the X-ray structure from the d,l -isomer. The hydrosilation of bicyyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride 1 by 1,1,3,3,-tetramethyldisiloxane and pentamethyldisiloxane is compared.
On the sign problem in 2D lattice super Yang-Mills

In recent years a new class of supersymmetric lattice theories have been proposed which retain one or more exact supersymmetries for non-zero lattice spacing. Recently there has been some controversy in the literature concerning whether these theories suffer from a sign problem. In this paper we address this issue by conducting simulations of the $ \mathcal{N} $ = (2, 2) and $ \mathcal{N} $ = (8, 8) supersymmetric Yang-Mills theories in two dimensions for the U(N ) theories with N = 2, 3, 4, using the new twisted lattice formulations. Our results provide evidence that these theories do not suffer from a sign problem in the continuum limit. These results thus boost confidence that the new lattice formulations can be used successfully to explore non-perturbative aspects of four-dimensional $ \mathcal{N} $ = 4 supersymmetric Yang-Mills theory.
The political economy of deposit insurance

The author uses a political economy framework to analyze cross-country differences in deposit insurance coverage. He finds supporting evidence of the significance of private interest theories in explaining coverage of deposit insurance. Deposit insurance coverage is significantly higher in countries where poorly capitalized banks dominate the market and in countries where depositors are poorly educated. The author does not find that coverage is significantly related to political-institutional variables, such as the degree of democracy or restraints on the executive, or to proxies for the general level of institutional development, such as per capita income or property rights. These results provide evidence in support of the private interest view, according to which risky banks lobby for extensive coverage.
Transport Properties of Bi2S3 and the Ternary Bismuth Sulfides KBi6.33S10 and K2Bi8S13

We have studied transport properties (resistivity, Hall effect, thermopower, and thermal conductivity) of Bi2S3 and two new ternary bismuth sulfides, KBi6.33S10 and K2Bi8S13, to explore their potential for thermoelectric applications. While both Bi2S3 and K2Bi8S13 display an essentially metallic conduction, KBi6.33S10 has a distinctly semiconducting character. From the Hall measurements it follows that the dominant carriers in all three compounds are electrons and that the carrier density in K2Bi8S13 is almost 2 orders of magnitude larger than in Bi2S3 and KBi6.33S10 over the whole temperature range from 4 to 300 K. While the room temperature thermopowers of KBi6.33S10 and K2Bi8S13 are comparable (∼−100 μV/K), the thermopower of Bi2S3 is a factor of 3 larger. All three compounds are poor conductors of heat, in particular the thermal conductivity of KBi6.33S10 is some 25% lower than the thermal conductivity of Bi2Te3, the benchmark thermoelectric material. To make these materials useful thermoelectrics, wa...
Modeling the Hydroclimatology of Kuwait: The Role of Subcloud Evaporation in Semiarid Climates

Abstract A new subcloud layer evaporation scheme is incorporated into Regional Climate Model, version 3 (RegCM3), to better simulate the rainfall distribution over a semiarid region around Kuwait. The new scheme represents subcloud layer evaporation of convective as well as large-scale rainfall. Model results are compared to observations from rain gauge data networks and satellites. The simulations show significant response to the incorporation of subcloud layer evaporation as a reduction by as much as 20% in annual rainfall occurs over the region. As a result, the new model simulations of annual rainfall are within 15% of observations. In addition, results indicate that the interannual variability of rainfall simulated by RegCM3 is sensitive to the specification of boundary conditions. For example, forcing RegCM3’s lateral boundary conditions with the 40-yr ECMWF Re-Analysis (ERA-40) data, instead of NCEP–NCAR’s Reanalysis Project 2 (NNRP2), reduces interannual variability by over 25%. Moreover, with sub...
The influence of spin uncoupling on the lowest-energy rydberg transitions of methyl iodide

Abstract The analysis of the rotational sub-band structure in the B bandsystem of methyl iodide by Mulliken and Teller has been extended to all four states of the …4 a 1 2 2 e 3 6 sa 1 Rydberg (R6 s ) configuration. All available one- and two-photon absorption data can be reproduced using a single set of molecular constants and selection rules derived by generalizing the frame transformation of the quantum defect theory to a symmetric top molecule. It is shown that electronic—nuclear interactions in addition to the electronic Coriolis coupling term must be included in an interpretation of the rotational structure of the R6 s states. In particular, uncoupling of the spin of the Rydberg electron from the molecular axis is a key element in understanding the results. Molecular constants obtained by fitting experimental bandshapes of the R6 s origins are shown to be those of the alternative levels of the freely-rotating, electronically-degenerate molecular ion core, CH 3 I + ( 2 E 3 2 , 1 2 ).
Broker Compensation Patterns and Trends: 2005–2009

Changes in the mortgage industry have been swiftly effected over the past few years. Many of the changes have come about as a response to the high level of observed delinquencies and defaults on residential mortgages as house prices plummeted, and others have evolved from continuing concerns about the treatment of borrowers during the mortgage origination process. The segmented mortgage industry of the early part of the decade, with loans being originated in the prime, subprime and government mortgage sectors, has been largely replaced with a bifurcated system. By year end 2010, the FHA/VA (government sector) combined with the conventional, conforming market share of originations was 90.8 %. In this paper, we examine some of the observed trends and changes in the types and levels of broker compensation that existed before the regulatory change that brought about the implementation of the Federal Reserve Board’s (FRB) new loan officer compensation rule. Among other questions, we examine the variance in broker compensation across geographies, across lenders, across borrower types, and across loan products. The intent of this ex post analysis is to provide an understanding of the potential impacts of the declining broker industry on both access to mortgage loans and on the pricing of mortgage originations.
An Uneventful Horizon in Two Dimensions

We investigate the possibility of firewalls in the Einstein-dilaton gravity model of CGHS. We use the results of the numerical simulation carried out by Ashtekar et al. to demonstrate that firewalls are absent and the horizon is drama free. We show that the lack of a firewall is consistent because the model does not satisfy one of the postulates of black hole complementarity. In particular, we elaborate on previous work showing that the Hawking radiation is not pure, and is completely entangled with a long-lived remnant beyond the last ray.
Gauge Theory of CP Nonconservation

It is proposed that $\mathrm{CP}$ nonconservation arises purely from the exchange of Higgs bosons.
A New Navy Classification Criterion for Insulation Life

Meaningful thermal classification of insulating systems or magnet wires is based on the expected useful life at a given temperature. The Navy had established and used for more than a decade 40000 and 20000 hours as the minimum extrapolated test life at the rating temperature for varnish imaregnated and non-varnish impregnated insulation systems and magnet wires respectively. Following the setting of these standards, the Navy has continued to obtain and analyze aging data from new systems and wires with emphasis on the polyester types. The results of the continued research have led to a major modification in the Navy's classification criterion.
Violation of Bell's inequality with photons from independent sources.

We report a violation of Bell's inequality using one photon from a parametric down-conversion source and a second photon from an attenuated laser beam. The two photons were entangled at a beam splitter using the postselection technique of Shih and Alley [Phys. Rev. Lett. 61, 2921 (1988)]. A quantum interference pattern with a visibility of $91%$ was obtained using the photons from these independent sources, as compared with a visibility of $99.4%$ using two photons from a central parametric down-conversion source.
Fractional-power-filter-based multiobject joint transform correlation

A fractional power filter based joint transform correlator (JTC) for multiple target detection is presented and analyzed. The proposed technique can be used for real time multiple target detection using classical matched filtering, inverse filtering and/or phase-only filtering. An efficient JTC architecture is developed for optical implementation of the proposed technique and simulation results axe presented to validate the performance of this technique
Rapid, General Access to Chiral β-Fluoroamines and β, β-Difluoroamines via Organocatalysis

A rapid, general route to enantiopure β-fluoroamines and β,β-difluoroamines has been developed employing organocatalysis in both a two-pot and a one-pot procedure. Both chemical yields (64−82%) and enantioselectivity (94−98% ee) were excellent and represent a significant improvement in the art of preparing chemically diverse β-fluoroamines from readily available precursors.
Special biserial coalgebras and representations of quantum SL(2)

Abstract We develop the theory of special biserial and string coalgebras and other concepts from the representation theory of quivers. These tools are then used to describe the finite-dimensional comodules and Auslander–Reiten quiver for the coordinate Hopf algebra of quantum SL ( 2 ) at a root of unity. We also compute quantum dimensions and the stable Green ring.
Rees algebras of square-free monomial ideals

We determine the defining equations of the Rees algebra of an ideal $I$ in the case where $I$ is a square-free monomial ideal such that each connected component of the line graph of the hypergraph corresponding to $I$ has at most $5$ vertices. Moreover, we show in this case that the non-linear equations arise from even closed walks of the line graph, and we also give a description of the defining ideal of the toric ring when $I$ is generated by square-free monomials of the same degree. Furthermore, we provide a new class of ideals of linear type. We show that when $I$ is a square-free monomial ideal with any number of generators and the line graph of the hypergraph corresponding to $I$ is the graph of a disjoint union of trees and graphs with a unique odd cycle, then $I$ is an ideal of linear type.
Salomon brothers and the May 1991 Treasury auction: Analysis of a market corner

Abstract In May 1991, the Treasury sold $12.29 billion in two-year notes. Through improper bidding, Salomon Brothers gained control of at least 86 percent of the issue. This study investigates the impact of Salomon's attempted corner by examining the postauction price behaviour of the two-year note. Based on a no-arbitrage relation, the results show that the two-year note was substantially overpriced for approximately six weeks following the auction. The typical mispricing during this period is estimated at 0.16 to 0.25 percent of par. In dollar terms, the aggregate misvaluation averaged $20–$30 million, and, by controlling the supply of the issue, Salomon stood to gain substantially from the squeeze.
Partially localized quasimodes in large subspaces

We consider spaces of high-energy quasimodes for the Laplacian on a compact hyperbolic surface, and show that when the spaces are large enough, one can find quasimodes that exhibit strong localization phenomena. Namely, take any constant c, and a sequence of cr j -dimensional spaces S j of quasimodes, where $$\frac{1}{4} + r_j^2 \to \infty $$ is an approximate eigenvalue for S j . Then we can find a sequence of vectors ψ j ∈ S j , such that any weak-* limit point of the microlocal lifts of |ψ j |2 localizes a positive proportion of its mass on a singular set of codimension 1. This result is sharp, in light of the QUE result of [BL12] for certain joint quasimodes that include spaces of size o(r j ), with arbitrarily slow decay.
Single stop production at hadron colliders

Abstract We analyze the production of a single top squark at hadron colliders: p p /pp→ t 1 +X . The total cross sections and the transverse momentum distributions are presented in next-to-leading order QCD. The higher-order corrections render the predictions theoretically stable with respect to variations of the factorization and renormalization scales. The transverse momentum distribution is resummed to estimate effects of the small transverse momentum regime on possible analyses. Since the corrections increase the cross sections and reduce the theoretical uncertainty, the discovery range for these particles is extended in the refined analysis.
Matching and the Changing Properties of Accounting Earnings over the Last 40 Years

ABSTRACT: We present a theory that poor matching manifests as noise in the economic relation of advancing expenses to earn revenues. As a result, poor matching decreases the correlation between contemporaneous revenues and expenses, increases earnings volatility, decreases earnings persistence, and induces a negative autocorrelation in earnings changes. The empirical tests document these effects in a sample of the 1,000 largest U.S. firms over the last 40 years. We find a clear and economically substantial trend of declining contemporaneous correlation between revenues and expenses, increased volatility of earnings, declining persistence of earnings, and increased negative autocorrelation in earnings changes. The combined evidence suggests that accounting matching has become worse over time and that this trend has a pronounced effect on the properties of the resulting earnings. This evidence also suggests that the standard-setters’ stated goal of moving away from matching and toward more fair-value accoun...
Global nanotechnology research literature overview

Abstract Text mining was used to extract technical intelligence from the open source global nanotechnology and nanoscience research literature (SCI/SSCI databases). Identified were: (1) the nanotechnology/nanoscience research literature infrastructure (prolific authors, key journals/institutions/countries, most cited authors/journals/documents); (2) the technical structure (pervasive technical thrusts and their inter-relationships); (3) nanotechnology instruments and their relationships; (4) potential nanotechnology applications, (5) potential health impacts and applications; and (6) seminal nanotechnology literature. Our results are summarized in this paper.
An economical method for calculating the discrete Fourier transform

With the advent of digital computers it became possible to compute the Discrete Fourier Transform for a large number of input points in relatively reasonable times. However, for certain uses a demand developed to compute the Discrete Fourier Transform in a very short time or even in real time. Also, a demand developed for computing the Fourier Transform for a very large number of input points. These demands resulted in a requirement for computing the Fourier Transform in the fastest time possible. A very economical way for computing the Fourier Transform was developed a few years ago and is known as the Cooley-Tukey Algorithm. This article describes another algorithm for computing the Discrete Fourier Transform where the required number of additions and subtractions is the same as in the Cooley-Tukey Algorithm; but the required number of multiplications is only one half of that in the Cooley-Tukey Algorithm.
Experiences applying formal approaches in the development of swarm-based space exploration systems

NASA is researching advanced technologies for future exploration missions using intelligent swarms of robotic vehicles. One of these missions is the Autonomous Nano-Technology Swarm (ANTS) mission that will explore the asteroid belt using 1,000 cooperative autonomous spacecraft. The emergent properties of intelligent swarms make it a potentially powerful concept, but at the same time more difficult to design and ensure that the proper behaviors will emerge. NASA is investigating formal methods and techniques for verification of such missions. The advantage of using formal methods is the ability to mathematically verify the behavior of a swarm, emergent or otherwise. Using the ANTS mission as a case study, we have evaluated multiple formal methods to determine their effectiveness in modeling and ensuring desired swarm behavior. This paper discusses the results of this evaluation and proposes an integrated formal method for ensuring correct behavior of future NASA intelligent swarms.
Errors-and-Erasures Decoding for Block Codes With Feedback

Inner and outer bounds are derived on the optimal performance of fixed-length block codes on discrete memoryless channels with feedback and errors-and-erasures decoding. First, an inner bound is derived using a two-phase encoding scheme with communication and control phases together with the optimal decoding rule for the given encoding scheme, among decoding rules that can be represented in terms of pairwise comparisons between the messages. Then, an outer bound is derived using a generalization of the straight-line bound to errors-and-erasures decoders and the optimal error-exponent tradeoff of a feedback encoder with two messages. In addition, upper and lower bounds are derived, for the optimal erasure exponent of error-free block codes in terms of the rate. Finally, a proof is provided for the fact that the optimal tradeoff between error exponents of a two-message code does not improve with feedback on discrete memoryless channels (DMCs).
Ab initio and semiempirical molecular orbital studies of surface enhanced and bulk hyper‐Raman scattering from pyridine

Ab initio and semiempirical molecular orbital methods have been used to calculate the bulk and surface Raman and hyperRaman spectra of pyridine. Similar calculations for benzene are also reported. For both molecules, we compare the results with available bulk and surface experiments. In all calculations, the polarizability and hyperpolarizability derivatives are evaluated using normal coordinates that are obtained from Hartree–Fock (HF) calculations. The Raman results are somewhat sensitive to the basis set used in determining the normal coordinates, and the hyper‐Raman spectra are strongly sensitive. The Raman and hyper‐Raman spectra have been calculated at zero frequency using HF methods (GAUSSIAN 90), and finite frequency using INDO (intermediate neglect of differential overlap) methods (zindo). The frequency dependence of the results is found to be minor. Comparisons with experiment indicate that the inclusion of diffuse basis functions is crucial to the accuracy of the HF calculations. For such basis sets, the benzene Raman and hyper‐Raman spectra provided by HF are in excellent agreement with experiment. Raman spectra from HF for pyridine also agree well, but hyper‐Raman spectra agree only in part. Changes in Raman and hyper‐Raman spectra calculated in going from bulk to surface generally agree with observations. The corresponding bulk and surface spectra from zindo are usually less accurate, especially the hyper‐Raman spectra, and especially the out of plane modes. Estimates of the surface hyper‐Raman enhancement factor are in the range 1011–1012 for pyridine on silver electrodes.
Scaffolding Catalysis: Expanding the Repertoire of Bifunctional Catalysts.

Inducing an intramolecular reaction is a powerful means of accelerating reactions. Though this mechanism of catalysis is common in enzymes, it is underutilized in synthetic catalysts. This article outlines our group’s recent efforts to use reversible covalent bonding to induce an intramolecular reaction, allowing for rate acceleration as well as control of the selectivity in the desymmetrization of 1,2-diols.
Experimental study of plate buckling induced by spatial temperature gradients

An experimental study of plate buckling induced by spatial temperature gradients is described. A rectangular Hastelloy-X plate is subjected to local line heating by a focused quartz heat lamp. Two ...
Ionospheric irregularities produced by internal atmospheric gravity waves

Abstract A perturbation treatment is used to determine the nature and magnitude of the effects of internal atmospheric gravity waves on the ambient rates of production, chemical loss, and motion of the ionization. The relative and absolute importance of these effects in the creation of ionospheric irregularities are assessed. This assessment yields several conclusions of particular interest. Firstly, in the F 2-region the dominant effect of the gravity waves is that of imparting the motion of the neutral gas parallel to the magnetic field to the ionization through collisional interaction. Secondly, at heights at or below the height of the F1 -ledge, chemical effects, in particular the effect of gravity waves on the rate of photoionization, are quite important. Thirdly, gravity waves affect the rate of photoionization at a given point by changing both the neutral gas number density and the ionizing radiation flux at that point, and this latter effect, hitherto ignored, is in some respects the more important of the two. Fourthly, as a result of the interplay of a number of factors, certain Fourier components of that portion of the gravity-wave spectrum permitted at ionospheric heights are more successful than others in creating observable disturbances. Finally, gravity waves creating neutral gas velocities of the order of 20 m sec −1 seem capable under the right conditions of creating TID's of the largest magnitudes observed.
Does consent bias research

Researchers increasingly rely on large data sets of health information, often linked with biological specimens. In recent years, the argument has been made that obtaining informed consent for conducting records-based research is unduly burdensome and results in "consent bias." As a type of selection bias, consent bias is said to exist when the group giving researchers access to their data differs from the group denying access. Therefore, to promote socially beneficial research, it is argued that consent should be unnecessary. After analyzing the biostatistics evidence and bioethics arguments, the article concludes that (1) claims about the amount of consent bias are overstated; (2) commonly used statistical methods usually can account for consent bias; and (3) any residual effects of consent bias are below an acceptable level of imprecision and constitute a reasonable social cost for conducting ethically responsible research.
Incorporation of an Amino Function in a (1S,2S,3R)-3-Hydroxy-2-methoxy-1-cyclohexane Carboxylic Acid

Abstract (1S,2S,3R)-3-Hydroxy-2-methoxy-1-cyclohexanecarboxylic acid was synthesized for the construction of an amino acid to be used in a constrained ring didemnin B analog ( 2 ). The amine functionality was introduced into the cyclohexane ring by reductive amination using sodium triacetoxyborohydride or by oxime formation followed by reduction.
Example of lumped parameter modeling of a quantum optics circuit

Is it possible for a simple lumped parameter model of a circuit to yield correct quantum mechanical predictions of its behavior, when there is quantum entanglement between components of that circuit? This paper shows that it is possible in a simple but important example – the circuit of the original Bell’s Theorem experiments, for ideal polarizers. Correct predictions emerge from two alternative simple models, based on classical Markov Random Fields (MRF) across spacetime. Exact agreement with quantum mechanics does not violate Bell’s Theorem itself, because the interplay between initial and final outcomes in these calculations does not meet the classical definition of time-forwards causality. Both models raise interesting questions for future research. The final section discusses several possible directions for following up on these results, both in lumped system modeling and in more formal and general approaches. It describes how a new triphoton experiment, not yet performed, may be able to discriminate between MRF models and the usual measurement formalism of Copenhagen quantum mechanics.
A TALE OF TWO EFFECTS

Abstract This paper investigates the relationship between nominal interest rates and prices using nearly two centuries of data from ten industrial countries. Both a positive relationship between interest rates and price levels (that is, a positive Gibson effect) and a negative relationship between interest rates and subsequent price changes (that is, a negative Fama-Fisher effect) prevailed until World War I. We propose a simple explanation wherein this doubly paradoxical juxtaposition of effects arises when money is supplied inelastically and prices are flexible. This double paradox disappeared after World War II when economies became mostly characterized by elastic money and sticky prices. During that period, a positive Fama-Fisher effect emerged while the Gibson effect largely dissipated.
Steady fluid flows and symplectic geometry

Abstract We show that for an even-dimensional fluid there exists a strong relation, via the Morse theory and symplectic geometry, between the topology of the vorticity function and the existence of a stationary solution of Euler's equation. In particular, it turns out that there is no smooth steady flow on the disc provided that the vorticity function is Morse, positive and has both a local maximum and minimum in the interior of the disc. As we show, the structure of four-dimensional steady flows is similar to that of three-dimensional flows described in Arnold's theorem. Namely, under certain hypotheses, an analytic four-dimensional steady flow is fibered into invariant tori and annuli, for such a flow gives rise to an integrable Hamiltonian system on a symplectic four-manifold. It is also proved that an odd-dimensional chaotic steady flow is always a Beltrami flow, i.e., its velocity and vorticity fields are proportional.
Infeasible path optimal design methods with applications to aerodynamic shape optimization

We consider optimal design of physical systems described by a nonlinear boundary value problem. We propose a sequential quadratic programming method specifically tailored to the solution of this class of design problems. A particular representation of the null space of the constraint Jacobian that exploits its specific structure is employed. The resulting method avoids resolution of nonlinear behavior at the optimization iterations while keeping the size of the problem as small as that of conventional approaches. Three variants of the method are developed and discussed. These entail the solution of either two or three linear systems involving the Jacobian matrix of the discretized form of the boundary value problem. The method is used to solve aerodynamic design problems involving nonlinear transonic flow. No special provisions are made for treating discontinuities, and therefore the present implementation of the method is limited to problems with no shocks. Problems with up to 90 shape design variables are solved. Numerical results demonstrate a substantial performance improvement over conventional methods.
Chern-Simons terms and Bosonic strings

Abstract We discuss the coupling of background chiral vector gauge fields to closed Bose strings. The appearance of Chern-Simons terms in such couplings is elucidated.
LEFT VENTRICULAR FUNCTION, AORTIC VELOCITY AND LATE GADOLINIUM ENHANCEMENT ASSESSED BY REAL-TIME AND SINGLE SHOT CMR IS COMPARABLE TO BREATH-HELD SEGMENTED IMAGING: a prospective STUDY

Widespread use of CMR has been hampered by long exam times that limit cost-effectiveness, and limited reliability in patients with irregular rhythm and/or inability to breath-hold. These limitations result from the use of segmented sequences requiring breath-holding and regular rhythm. Single-shot (
Pressure-induced amorphization of crystalline silica

The crystalline-to-amorphous transformation in the solid state is currently the subject of intense study. With the seminal discovery of amorphization of H2O ice I under pressure1, interest has focused on the possible occurrence of pressure-induced amorphization in other systems, the thermodynamic and mechanistic basis of the process, and the relationship between amorphization by pressure and by other means2–5. Here we report in situ synchrotron X-ray diffraction measurements of α-quartz and coesite in a diamond-anvil cell that demonstrate that these crystalline materials transform to amorphous solids at 25–35 GPa and 300 K. We show that an internally consistent thermodynamic description of the process is possible, extending into the pressure domain recent thermodynamic calculations of thermally-induced amorphization of silica polymorphs4. The measurements provide constraints on the equations of state and melting relations in this system at high pressures, shed light on the mechanism for glass formation in SiO2 in laboratory shock-wave experiments and meteorite-impact events, and provide insights into the thermoelastic stability of tetrahedral network structures at high compression.
An experimental analysis of the effects of automated mitigation procedures on investment and prices in wholesale electricity markets

In this paper we report the findings of an economic experiment that examines the effects of an automated mitigation procedure (AMP) on prices and capacity investment choices of suppliers in a wholesale electricity market. Specifically, we examine the effects of different market power incentives on markets with and without an AMP. While we find that the AMP does not affect overall investment in capacity, the most significant determinant of long-run prices is investment in new capacity. The AMP also does not reduce long-run prices relative to markets without an AMP. Furthermore, our participants successfully manipulated the AMP’s trigger price.
Ages and Metallicities of Extragalactic Globular Clusters from Spectral and Photometric Fits of Stellar Population Synthesis Models

Spectra of galaxies contain an enormous amount of information about the relative mixture of ages and metallicities of constituent stars. We present a comprehensive study designed to extract the maximum information from spectra of data quality typical in large galaxy surveys. These techniques are not intended for detailed stellar population studies that use high-quality spectra. We test techniques on a sample of globular clusters, which should consist of single stellar populations and provide good test cases, using the Bruzual-Charlot high-resolution stellar population synthesis models to simultaneously estimate the ages and metallicities of 101 globular clusters in M31 and the Magellanic Clouds. The clusters cover a wide range of ages and metallicities, 4 Myr < tage < 20 Gyr and -1.6 < [Fe/H] < +0.3, estimated by other methods in the literature. We compare results from model fits to both the spectra and photometry and find that fits to continuum-normalized spectra over the entire range available, typically 3500 A to 1 μm for this sample, provide the best results. For clusters older than 1 Gyr we agree with literature ages to 0.16 dex (35%) and [Fe/H] to 0.12 dex. For younger clusters we agree with literature ages to 0.3 dex (63%) but cannot constrain the metallicity. It is particularly important to use the entire continuum-normalized spectrum to avoid problems with model continua for young objects and to break age-metallicity degeneracies of broadband photometry. Our required S/N is 15-30 A-1 for 20% age uncertainties and 30-55 A-1 for 10% uncertainties over spectral resolutions of Δλ = 5-25 A. This technique should work well for the age-metallicity parameter space expected for early-type galaxies at z ~ 1, although individual galaxy spectral S/N may require the co-addition of a few like objects.
The Education and Development of Managers for Future Decades

* A major report, "Managers for the XXI Century: Their Education and Development," emanated from a landmark international conference in Paris in June 1980, sponsored jointly by the American Assembly of Collegiate Schools of Business (AACSB) and the European Foundation for Management Development (EFMD).1 The report was published in the Fall of 1981 but, thus far, has received little notice from academicians although it culminated a 3-year effort, "Management and Management Education in a World of Changing Expectations," by the AACSB and the EFMD to establish a frame-work to prepare managers better for the forthcoming decades.2 In this article, we present a personal interpretation of the ideas on management education that emerged from the Paris meeting. The various ideas on changes in the direction of management education are certainly worthy of widespread analysis, discussion, and consideration on the part of teachers, researchers, and educators in management-a response that has not occurred up to this time.
Spectral Classification of Quasars in the Sloan Digital Sky Survey: Eigenspectra, Redshift, and Luminosity Effects

We study 16,707 quasar spectra from the Sloan Digital Sky Survey (SDSS) (an early version of the First Data Release; DR1) using the Karhunen-Loeve transform (or principal components analysis). The redshifts of these quasars range from 0.08 to 5.41, the i-band absolute magnitudes from -30 to -22, and the resulting rest-frame wavelengths from 900 to 8000 A. The quasar eigenspectra of the full catalog reveal the following: first order—the mean spectrum; second order—a host-galaxy component; third order—the UV-optical continuum slope; fourth order—the correlations of Balmer emission lines. These four eigenspectra account for 82% of the total sample variance. Broad absorption features are found not to be confined in one particular order but to span a number of higher orders. We find that the spectral classification of quasars is redshift and luminosity dependent; as such there does not exist a compact set (i.e., less than ≈10 modes) of eigenspectra (covering 900–8000 A) that can describe most variations (i.e., greater than ≈95%) of the entire catalog. We therefore construct several sets of eigenspectra in different redshift and luminosity bins. From these eigenspectra we find that quasar spectra can be classified (by the first two eigenspectra) into a sequence that is defined by a simple progression in the steepness of the slope of the continuum. We also find a dependence on redshift and luminosity in the eigencoefficients. The dominant redshift effect is a result of the evolution of the blended Fe II emission (optical) and the Balmer continuum (the "small bump," λrest ≈ 2000–4000 A). A luminosity dependence is also present in the eigencoefficients and is related to the Baldwin effect—the decrease of the equivalent width of an emission line with luminosity, which is detected in Lyα, Si IV+O IV], C IV, He II, C III] and Mg II, while the effect in N V seems to be redshift dependent. If we restrict ourselves to the rest-wavelength regions 1150–2000 A and 4000–5500 A, the eigenspectra constructed from the wavelength-selected SDSS spectra are found to agree with the principal components by Francis et al. and the well-known "Eigenvector-1" of Boroson & Green, respectively. ASCII formatted tables of the eigenspectra are available.
Photolysis of 1,1,2,2-tetramethyl-1,2-bis-(2′-thienyl)disilane

Photolysis of 1,1,2,2-tetramethyl-1,2-bis-(2′-thienyl)disilane (I) in methanol/benzene leads to dimethyl-bis-(2′-thienyl)silane (III), 2-methoxydimethylsilylthiophene (IV) and 2-dimethylsilylthiophene (V) as a major products. The mechanism of this reaction, has been explored by use of methanol-d4. The predominant pathway leading to IV and V appears to involve direct reaction of methanol with the photoexcited state of I.
An efficient and convenient synthesis of formamidines

Abstract A set of new reagents, aryl sulfonyl chlorides, were used as coupling agents in the syntheses of formamidines from primary amines and N,N-dimethyl formamide in excellent yields.
Magnetic and Gravitational Disk-Star Interactions: An Interdependence of PMS Stellar Rotation Rates and Spin-Orbit Misalignments

The presence of giant gaseous planets that reside in close proximity to their host stars, i.e., hot Jupiters, may be a consequence of large-scale radial migration through the protoplanetary nebulae. Within the framework of this picture, significant orbital obliquities characteristic of a substantial fraction of such planets can be attributed to external torques that perturb the natal disks out of alignment with the spin axes of their host stars. Therefore, the acquisition of orbital obliquity likely exhibits sensitive dependence on the physics of disk-star interactions. Here, we analyze the primordial excitation of spin-orbit misalignment of Sun-like stars in light of disk-star angular momentum transfer. We begin by calculating the stellar pre-main-sequence rotational evolution, accounting for spin-up due to gravitational contraction and accretion as well as spin-down due to magnetic star-disk coupling. We devote particular attention to angular momentum transfer by accretion, and show that while generally subdominant to gravitational contraction, this process is largely controlled by the morphology of the stellar magnetic field (that is, specific angular momentum accreted by stars with octupole-dominated surface fields is smaller than that accreted by dipole-dominated stars by an order of magnitude). Subsequently, we examine the secular spin-axis dynamics of disk-bearing stars, accounting for the time-evolution of stellar and disk properties, and demonstrate that misalignments are preferentially excited in systems where stellar rotation is not overwhelmingly rapid. Moreover, we show that the excitation of spin-orbit misalignment occurs impulsively through an encounter with a resonance between the stellar precession frequency and the disk-torquing frequency. Cumulatively, the model developed herein opens up a previously unexplored avenue toward understanding star-disk evolution and its consequences in a unified manner.
Anomalous Spin-Orbit Effects in a Strained InGaAs/InP Quantum Well Structure

There is currently a large effort to explore spin-orbit effects in semiconductor structures with the ultimate goal of manipulating electron spins with gates. A search for materials with large spin-orbit coupling is therefore important. We report results of a study of spin-orbit effects in a strained InGaAs/InP quantum well. The spin-orbit relaxation time, determined from the weak antilocalization effect, was found to depend nonmonotonically on gate voltage. The spin-orbit scattering rate had a maximum value of 5×1010 s−1 at an electron density of n=3×1015 m−2. The scattering rate decreased from this for both increasing and decreasing densities. The smallest measured value was approximately 109 s−1 at an electron concentration of n=6×1015 m−2. This behavior could not be explained by either the Rashba or the bulk Dresselhaus mechanisms but is attributed to asymmetry or strain effects at dissimilar quantum well interfaces.
Thermal fluctuations and anomalous elasticity of homogeneous nematic elastomers

We present a unified formulation of a rotationally invariant nonlinear elasticity for a variety of spontaneously anisotropic phases, and use it to study thermal fluctuations in nematic elastomers and spontaneously anisotropic gels. We find that in a thermodynamic limit homogeneous nematic elastomers are universally incompressible, are characterized by a universal ratio of shear moduli, and exhibit an anomalous elasticity controlled by a nontrivial low-temperature fixed-point perturbative in D = 3 − dimensions. In three dimensions, we make predictions that are asymptotically exact.
On the Maximally Clustered Elements of Coxeter Groups

We continue the study of the maximally clustered elements for simply laced Coxeter groups which were recently introduced by Losonczy. Such elements include as a special case the freely braided elements introduced by Losonczy and the author, which in turn constitute a superset of the iji-avoiding elements of Fan. Our main result is to classify the MC-finite Coxeter groups, namely, those Coxeter groups having finitely many maximally clustered elements. Remarkably, any simply laced Coxeter group having finitely many iji-avoiding elements also turns out to be MC-finite.
Vertical-coupled high-efficiency tunable III–V- CMOS SOI hybrid external-cavity laser

We demonstrate a hybrid III-V/SOI laser by vertically coupling a III-V RSOA chip with a SOI-CMOS chip containing a tunable wavelength selective reflector. We report a waveguide-coupled wall-plug-efficiency of 5.5% and output power of 10 mW. A silicon resistor-based microheater was integrated to thermally tune a ring resonator for precise lasing wavelength control. A high tuning efficiency of 2.2 nm/mW over a range of 18 nm was achieved by locally removing the SOI handler substrate. C-band single mode lasing was confirmed with a side mode suppression ratio of 35 dB. This grating coupler based vertical integration approach can be scaled up in two dimensions for efficient multi-wavelength sources in silicon photonics.
Enantioselective Copper-Catalyzed Carboetherification of Unactivated Alkenes

Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein reported is a highly efficient copper-catalyzed cyclization of γ-unsaturated pentenols which terminates in CC bond formation, a net alkene carboetherification. Both intra- and intermolecular CC bond formations are demonstrated, thus yielding functionalized chiral tetrahydrofurans as well as fused-ring and bridged-ring oxabicyclic products. Transition-state calculations support a cis-oxycupration stereochemistry-determining step.
Neutral buoyancy evaluation of extravehicular activity assembly of a large precision reflector

A procedure that enables astronauts in extravehicular activity (EVA) to perform efficient on-orbit assembly of large paraboloidal precision reflectors is presented. The procedure and associated hardware are verified in simulated Og ~ (neutral buoyancy) assembly tests of a 14m-diameter precision reflector mockup. The test article represents a precision reflector having a reflective surface which is segmented into 37 individual panels. The panels are supported on a doubly curved tetrahedral truss consisting of 315 struts. The entire truss and seven reflector panels were assembled in three hours and seven minutes by two pressure-suited test subjects. The average time to attach a panel was two minutes and three seconds. These efficient assembly times were achieved because all hardware and assembly procedures were designed to be compatible with EVA assembly capabilities.
No forbidden landscape in string/M-theory

Scale invariant but non-conformal field theories are forbidden in (1 + 1) dimension, and so should be the corresponding holographic dual gravity theories. We conjecture that such scale invariant but non-conformal field configurations do not exist in the string/M-theory. We provide a proof of this conjecture in the classical supergravity limit when the space-time is trivially fibered over the compact space. Our proof does also apply in higher dimensional scale invariant but non-conformal field configurations, which suggests that scale invariant but non-conformal field theories may be forbidden in higher dimensions as well.