cssi/SciSciGPT-SciSciNet huggingface dataset:
The Elastic Properties of Composite Materials

The determination of the elastic properties of composite materials (multiphase aggregates, polycrystals, and porous or cracked solids) from the elastic properties of the components may be approached in several ways. The problem may be treated statistically, via scattering theory, through variational principles, or by the assumption of specific geometries for the material under consideration. Each of these methods is reviewed in turn. The widely used Voigt-Reuss-Hill average can be a poor approximation for both two-phase composites and polycrystals, and its replacement by the two Hashin-Shtrikman bounds is recommended. For pore-containing or crack-containing media, specific geometry models must be considered if useful results are to be obtained. If aggregate theory is used to estimate the moduli of individual components of a composite whose bulk properties are known, the shear moduli of the component phases must be matched (within a factor of 2 or 3) for the method to be useful. Results for nonlinear composites (which allow calculation of the pressure variation of aggregate moduli) have been obtained for only a few special cases.
Spanning trees and Khovanov homology

The Jones polynomial can be expressed in terms of spanning trees of the graph obtained by checkerboard coloring a knot diagram. We show that there exists a complex generated by these spanning trees whose homology is the reduced Khovanov homology. The spanning trees provide a filtration on the reduced Khovanov complex and a spectral sequence that converges to its homology. For alternating links, all differentials on the spanning tree complex are zero and the reduced Khovanov homology is determined by the Jones polynomial and signature. We prove some analogous theorems for (unreduced) Khovanov homology.
Substituted 2,5'-Bi-1H-benzimidazoles: topoisomerase I inhibition and cytotoxicity.

Several 2‘-aryl-5-substituted-2,5‘-bi-1H-benzimidazole derivatives were synthesized and evaluated as topoisomerase I poisons and for their cytotoxicity toward the human lymphoblast cell line RPMI 8402. This study focused on 18 2,5‘-bi-1H-benzimidazole derivatives which contained either a 5-cyano, a 5-(aminocarbonyl), or a 5-(4-methylpiperazinyl) group. Among these bibenzimidazoles, the pharmacological activity of 2‘-phenyl derivatives and the influence of the different positional isomers of either a 2‘-tolyl group or a 2‘-naphthyl moiety on cytotoxicity and topoisomerase I inhibitory activity were determined.
Suspension Processing of Al2O3/SiC Whisker Composites

Homogeneous Al2O3 powder/SiC whisker compacts were prepared by suspension processing. By optimizing the conditions for particle/whisker codispersion, castable suspensions could be prepared at total-solids concentrations 50 vol%. Green bodies with high relative density (∼66% to 70%) were obtained with SiC whisker contents in the range of 5 to 30 vol%. Although densification was severely inhibited by the SiC whiskers, significantly higher sintered densities were obtained by suspension processing compared to dry processing.
Digital holographic logic

Abstract Theoretically optical computers should be capable of performing 1014 multiplications per sec. Some, in fact, have attained actual operating speeds of 1011 multiplications per sec in applications involving data analysis in military radar systems. These computers suffer from the disadvantage of being fixed-program systems, and practical limitations in optical design and optical physics limit precision and accuracy. To take advantage of the high computing rates available in the optical computer and provide accuracy and flexibility optical computers are needed which are (1) digital in nature and (2) functionally programmable. This paper proposes a digital optical computer technology using holographic programming. A simple laboratory demonstration is given where the Identity Function and the Exclusive-OR are generated using this technology. An extension into the practical realm of pattern recognition using acoustically programmed holograms is also mentioned.
Transient Thermal Response of Turbulent Compressible Boundary Layers

A numerical method is developed with the capability to predict transient thermal boundary layer response under various flow and thermal conditions. The transient thermal boundary layer variation due to a moving compressible turbulent fluid of varying temperature was numerically studied on a two-dimensional semi-infinite flat plate. The compressible Reynolds-averaged boundary layer equations are transformed into incompressible form through the Dorodnitsyn–Howarth transformation and then solved with similarity transformations. Turbulence is modeled using a two-layer eddy viscosity model developed by Cebeci and Smith, and the turbulent Prandtl number formulation originally developed by Kays and Crawford. The governing differential equations are discretized with the Keller-box method. The numerical accuracy is validated through grid-independence studies and comparison with the steady state solution. In turbulent flow as in laminar, the transient heat transfer rates are very different from that obtained from quasi-steady analysis. It is found that the time scale for response of the turbulent boundary layer to far-field temperature changes is 40% less than for laminar flow, and the turbulent local Nusselt number is approximately 4 times that of laminar flow at the final steady state.
Variational modeling of ionic polymer plate structures

Ionomeric polymers are a promising class of intelligent material which exhibit electromechanical coupling similar to that of piezoelectric bimorphs. Ionomeric polymers are much more compliant than piezoelectric ceramics or polymers and have been shown to produce actuation strain on the order of 5% at operating voltages between 1 V and 5 V. This performance indicates the potential for self-actuating devices manufactured from ionomeric polymers, such as deformable mirrors or low pressure pump diaphragms. This paper presents a variational approach to the dynamic modeling of ionic polymer plates in rectangular coordinates. A linear matrix equation, which relates displacement and charge to applied forces and voltage, is developed to determine the response of the structure to applied forces and applied potentials. The modeling method is based on the incorporation of empirically determined material properties, which have been shown to be highly frequency dependent. The matrices are calculated at discrete frequencies and solved frequency-by-frequency to determine the response of the ionomeric plate structures. A model of a thin rectangular plate is developed and validated experimentally. Simulated frequency response functions are compared to experimental results for several locations on the plate. The response of the plate at certain frequencies is computed and compared to experimentally-determined response shapes. The results demonstrate the validity of the modeling approach in predicting the dynamic response of the ionomeric plate structure. These spatial solutions are also compared to experimentally determined response shapes.
Optimization of low-energy resonant hopping transfers between planetary moons

Abstract In response to the scientific interest in Jupiter's Galilean moons, NASA and ESA have plans to send orbiting missions to Europa and Ganymede, respectively. The inter-moon transfers of the Jovian system offer obvious advantages in terms of scientific return, but are also challenging to design and optimize due in part to the large, often chaotic, sensitivities associated with repeated close encounters of the planetary moons. The approach outlined in this paper confronts this shortcoming by exploiting the multi-body dynamics with a patched three-body model to enable multiple “resonant-hopping” gravity assists. Initial conditions of unstable resonant orbits are pre-computed and provide starting points for the elusive initial guess associated with the highly nonlinear optimization problem. The core of the optimization algorithm relies on a fast and robust multiple-shooting technique to provide better controllability and reduce the sensitivities associated with the close approach trajectories. The complexity of the optimization problem is also reduced with the help of the Tisserand–Poincare (T–P) graph that provides a simple way to target trajectories in the patched three-body problem. Preliminary numerical results of inter-moon transfers in the Jovian system are presented. For example, using only 59 m/s and 158 days, a spacecraft can transfer between a close resonant orbit of Ganymede and a close resonant orbit of Europa.
Risk aversion and CO2 regulatory uncertainty in power generation investment: Policy and modeling implications

Abstract We consider a simulation of risk-averse producers when making investment decisions in a competitive energy market, who face uncertainty about future regulation of carbon dioxide emissions. Investments are made under regulatory uncertainty; then the regulatory state is revealed and producers realize returns. We consider anticipated taxes, grandfathered permits and auctioned permits and show that some anticipated policies increase investment in the relatively dirty technology. Beliefs about the policy instrument that will be used to price carbon may be as important as certainty that carbon will be priced. More generally, a failure to consider risk aversion may bias policy analysis for the power sector.
New Compounds: Isoquinoline Derivatives as Simple Emetine Models

Several new isoquinolines were prepared using Reissert compounds. A few compounds were screened, and they exhibited no antineoplastic activity.
Asymmetric exclusion process and extremal statistics of random sequences

A mapping is established between sequence alignment, one of the most commonly used tools of computational biology, at a certain choice of scoring parameters and the asymmetric exclusion process, one of the few exactly solvable models of nonequilibrium physics. The statistical significance of sequence alignments is characterized through studying the total hopping current of the discrete time and space version of the asymmetric exclusion process.
Recent advances in solvation models for stationary phase characterization and the prediction of retention in gas chromatography

Rapid progress has been made in the last few years in the development of solvation models for gas chromatography. These models are based on the free energy of transfer of a solute from the gas phase to solution consisting of the additive processes of cavity formation and solute-solvent interactions expressed as dispersion, orientation, induction and hydrogen-bond formation. The adaptation of these models to characterize solvent selectivity for a wide range of common stationary phases and to the prediction of retention is critically discussed. The need to use high quality retention data in the further elaboration of solvation models is also demonstrated.
Performance of low-complexity greedy scheduling policies in multi-channel wireless networks: Optimal throughput and near-optimal delay

In this paper, we focus on the scheduling problem in multi-channel wireless networks, e.g., the downlink of a single cell in fourth generation (4G) OFDM-based cellular networks. Our goal is to design efficient scheduling policies that can achieve provably good performance in terms of both throughput and delay, at a low complexity. While a recently developed scheduling policy, called Delay Weighted Matching (DWM), has been shown to be both rate-function delay-optimal (in the many-channel many-user asymptotic regime) and throughput-optimal (in general non-asymptotic setting), it has a high complexity O(n5), which makes it impractical for modern OFDM systems. To address this issue, we first develop a simple greedy policy called Delay-based Queue-Side-Greedy (D-QSG) with a lower complexity O(n3), and rigorously prove that D-QSG not only achieves throughput optimality, but also guarantees near-optimal rate-function-based delay performance. Specifically, the rate-function attained by DQSG for any fixed integer threshold b > 0, is no smaller than the maximum achievable rate-function by any scheduling policy for threshold b-1. Further, we develop another simple greedy policy called Delay-based Server-Side-Greedy (D-SSG) with an even lower complexity O(n2), and show that D-SSG achieves the same performance as D-QSG. Thus, we are able to achieve a dramatic reduction in complexity (from O(n5) of DWM to O(n2)) with a minimal drop in the delay performance. Finally, we conduct numerical simulations to validate our theoretical results in various scenarios. The simulation results show that our proposed greedy policies not only guarantee a near-optimal rate-function, but also empirically are virtually indistinguishable from the delay-optimal policy DWM.
Experiments with Laser-Produced Plasmas: Electrons, Ions, and Neutrons

Experimental results, particularly x-ray bremsstrahlung and ion time-of-flight measurements, obtained from plasmas generated with a 10 J, 25 psec Nd:YAG-Nd:glass (1.06 μm) laser delivering focal spot intensities of greater than 1016 W/cm2 are reviewed. Preliminary experiments with a 10 J, 1 nsec CO2 (10.6 μm) laser delivering ~ 1014 W/cm2 to a target are briefly discussed. Both sets of experiments yield high-energy (tens of keV) electrons and ions. Experimental evidence indicates that neutron emission can be explained by electron heating and a consequent ion acceleration. Therefore, neutron production in laser-produced plasmas can be a delusive diagnostic.
Antimatter in the Universe.

The evidence for cosmologically significant amounts of antimatter in the Universe is reviewed. There is no compelling evidence, either theoretical or experimental, for a baryon-symmetric Universe. The possibility is not completely ruled out, however.
State-selective cross section scalings for electron capture collisions

The classical-trajectory Monte Carlo method is used to calculate total and final nf state-selective electron capture cross sections for various fully stripped ions, ranging from He2+ to Ne10+, incident on H(ni = 1-4) and Li(2s and 2p) targets over the collision energies of 1-100 keV u-1. Theoretical derivations of two scaling laws for state-selective electron capture cross sections as a function of collision energy, initial and final bound electron states and projectile charge are presented. The new scaling rules reduce the state-selective capture cross sections to very distinct universal curves. Curve fits to the state-selective cross sections are presented to provide additional information about the peak locations and magnitudes as well as the behaviour of the reduced cross sections as a function of collision energy. The scaling laws developed in this report allow for the prediction of state-selective electron capture cross sections in low-energy regions where experimental data have been limited or non-existent.
Mechanically modulated tunneling resistance in monolayer MoS2

We report on the modulation of tunneling resistance in MoS2 monolayers using a conductive atomic force microscope (AFM). The resistance between the conductive AFM probe and the bottom electrode separated by a monolayer MoS2 is reversibly reduced by up to 4 orders of magnitude, which is attributed to enhanced quantum tunneling when the monolayer is compressed by the tip force. Under the Wentzel-Kramers-Brillouim approximation, the experimental data are quantitatively explained by using the metal-insulator-metal tunneling diode model. As an ideal tunneling medium, the defect-free, nanometer-thick MoS2 monolayer can serve as the active layer for non-impacting nano-electro-mechanical switches.
A Comparison of Fiscal Consequences for Tax and Expenditure Limitation Proposals

Three constitutional tax and expenditure limitation proposals are analyzed for historical consequences. The first and second allowed 32% less state spending and $710 million less in local government aid compared to actual. The first proposal also imposed limits on local government units and allowed property taxes to increase about 5% more than actual. The second proposal covered state revenues only and would have required a 29.7% increase in property taxes to fully replace the reduction in local government aid. A third proposal excluded local government aid but effectively covered only half of the state general fund revenues.
The challenges of investor communication The case of CUC International, Inc.

Abstract We examine investor communication issues using the experience of CUC International. CUC had difficulty convincing investors that its marketing outlays were profitable investments, leading to stock misvaluation over an extended period. To resolve this problem, CUC adopted an accounting change and then underwent a leveraged recapitalization. Subsequently, it accelerated recap debt repayments and initiated a stock repurchase. CUC's experience suggests that accounting reports are not always effective in investor communication. While financial signals are more effective, their impact is not as immediate as predicted by prior research. The CUC case suggests that investor communications is a rich area for future research.
Utilization of the hydroxyalkylation reaction to prepare bis(benzocrown ethers).

Abstract The hydroxyalkylation reaction has been used to condense benzocrown ethers with various aldehydes and ketones. The condensation reactions are catalyzed by triflic or sulfuric acid. The products from the reactions are bis(benzocrown ethers) and they are formed in good yields (42–98%, 13 examples).
New recursions for genus-zero Gromov–Witten invariants

Abstract New relations among the genus-zero Gromov–Witten invariants of a complex projective manifold X are exhibited. When the cohomology of X is generated by divisor classes and classes “with vanishing one-point invariants,” the relations determine many-point invariants in terms of one-point invariants.
Q-switched ruby laser therapy of nevus of Ota.

• Background. —The Q-switched ruby laser has been demonstrated to provide selective photothermolysis of pigmented tissue at a wavelength of 694 nm and a pulse width of 40 ns with dermal penetration. It was used to treat 15 patients with nevus of Ota involving the face with an age range of 6 to 52 years. Other methods of treatment for the nevus of Ota have either left scarring or were ineffective. The clinical efficacy of this laser treatment was evaluated in a comparative photographic analysis. Observations. —Complete clearing was noted in four of the 15 patients and a minimum of 50% lightening of the original color in the remaining 11. Ten of the 15 patients were Asian, two were white, two were Hispanic, and one was Indian. The energy fluence used varied between 6 and 10 J/cm 2 , and the number of treatments ranged from 1 to 7. Significant lightening or clearing was found at the higher energy ranges of 9 to 10 J/cm 2 with significantly less lightening noted at the lower energy range of 6 to 8.5 J/cm 2 . No scarring was noted in any of the 15 patients, and some isolated hypopigmentation was noted in one of the subjects. Transient postinflammatory hyperpigmentation of 2 months' duration was noted in only one patient. Conclusion. —Q-switched ruby selective photothermolysis appears to be an effective and safe method of lightening or removing nevus of Ota.
Performance of phosphor-coated LED optics in ray trace simulations

In commercial high brightness phosphor coated (PC) LED packages the phosphor is put down on the die in the center of the hemispherical encapsulation, representing a quasi-point source that provides convenient optical control in lighting fixture design. However, specific applications may benefit from other package geometries and beam shapes regarding efficiency, color uniformity and thermal management. In order to examine optical arrangements the solid model of an InGaN LED die and the optical system including the phosphor were simulated using Monte-Carlo forward ray tracing technique. Photoluminescence was implemented as two separate processes: short wavelength LED emission and phosphor absorbtion was traced first, followed by re-emission of the down-converted radiation by the phosphor layer, optical properties of existing phosphors were used. Output parameters of the two ray traces were combined and evaluated for the geometries examined.
Fast roll inflation

We show that in the simplest theories of spontaneous symmetry breaking one can have a stage of a fast-roll inflation. In this regime the standard slow-roll condition |m^2| << H^2 is violated. Nevertheless, this stage can be rather long if |m| is sufficiently small. Fast-roll inflation can be useful for generating proper initial conditions for the subsequent stage of slow-roll inflation in the very early universe. It may also be responsible for the present stage of accelerated expansion of the universe. We also make two observations of a more general nature. First of all, the universe after a long stage of inflation (either slow-roll or fast-roll) cannot reach anti-de Sitter regime even if the cosmological constant is negative. Secondly, the theories with the potentials with a 'stable' minimum at V(\phi)<0 in the cosmological background exhibit the same instability as the theories with potentials unbounded from below. This instability leads to the development of singularity with the properties practically independent of V(\phi). However, the development of the instability in some cases may be so slow that the theories with the potentials unbounded from below can describe the present stage of cosmic acceleration even if this acceleration occurs due to the fast-roll inflation.
The Local Void is Really Empty

Are voids in the distribution of galaxies only places with reduced matter density and low star formation efficiency or are they empty of matter? There is now compelling evidence of expansion away from the Local Void at very high velocities. The motion is most reasonably interpreted as an evacuation of the void, which requires that the void be very large and very empty.
A new thermoelectric material: CsBi4Te6.

The highly anisotropic material CsBi4Te6 was prepared by the reaction of Cs/Bi2Te3 around 600 °C. The compound crystallizes in the monoclinic space group C2/m with a = 51.9205(8) A, b = 4.4025(1) A, c = 14.5118(3) A, β = 101.480(1)°, V = 3250.75(11) A3, and Z = 8. The final R values are R1 = 0.0585 and wR2 = 0.1127 for all data. The compound has a 2-D structure composed of NaCl-type [Bi4Te6] anionic layers and Cs+ ions residing between the layers. The [Bi4Te6] layers are interconnected by Bi−Bi bonds at a distance of 3.2383(10) A. This material is a narrow gap semiconductor. Optimization studies on the thermoelectric properties with a variety of doping agents show that the electrical properties of CsBi4Te6 can be tuned to yield an optimized thermoelectric material which is promising for low-temperature applications. SbI3 doping resulted in p-type behavior and a maximum power factor of 51.5 μW/cm·K2 at 184 K and the corresponding ZT of 0.82 at 225 K. The highest power factor of 59.8 μW/cm·K2 at 151 K was o...
Practical Asymmetric Conjugate Alkynylation of Meldrum’s Acid-Derived Acceptors: Access to Chiral β-Alkynyl Acids

The enantioselective conjugate addition of alkynyl nucleophiles has been a long-standing challenge in synthetic chemistry. This paper describes a highly practical asymmetric conjugate alkynylation of Meldrum's acid-derived acceptors using cinchonidine (<$100/kg) as the chiral mediator. The process provides practical access to chiral beta-alkynyl acids. Noteworthy attributes of the method are its broad scope, high functional-group compatibility, and ease of scalability.
Halide Coordination of Perhalocyclohexasilane Si6X12 (X = Cl or Br)

The addition of halide anions (X' = Cl(-), Br(-), or I(-)) to perhalocyclohexasilane Si(6)X(12) (X = Cl or Br) led to the formation of complexes comprising [Si(6)X(12)X'(2)](2-) dianions. An upfield shift in the (29)Si NMR spectra was noted upon coordination, and structural determination by X-ray crystallography showed that the dianions adopt an "inverse sandwich" structure where the six cyclic silicon atoms form a planar hexagon with the two halide anions X' located on the 6-fold axis equally disposed above and below the plane of the Si(6) ring. Additionally, these apical X' atoms are within the van der Waals bonding distance to the silicon ring atoms, indicating a strong interaction between X' and silicon atoms. These results detail crystallographic variations within the halogen series providing further insight into the nature of the Lewis acid sites above and below the Si(6)X(12) ring, where interactions with hard Lewis bases such as halide anions are observed. Interestingly, the stereochemistry of the silicon atoms in [Si(6)X(12)X'(2)](2-) is not affected much by the size or electronegativity of the halogen atoms.
Depinning and dynamic phases in driven three-dimensional vortex lattices in anisotropic superconductors

We use three-dimensional molecular dynamics simulations of magnetically interacting pancake vortices to study the dynamic phases of vortex lattices in highly anisotropic materials such as BSCCO. Our model treats the magnetic interactions of the pancakes exactly, with long-range logarithmic interactions both within and between planes. The pancake vortices decouple at low drives and show two-dimensional plastic flow. The vortex lattice both recouples and reorders as the driving current is increased, eventually forming a recoupled crystalline-like state at high drives. We construct a phase diagram as a function of interlayer coupling and show the relationship between the recoupling transition and the single-layer reordering transitions.
Ten facts of life for distant supersoft sources

Abstract First discovered in the Magellanic Clouds and in the Milky Way, the largest pools of luminous supersoft X-ray sources (SSSs) now known lie in M31 and in more distant galaxies. Hundreds of newly-discovered SSSs are helping us to test models for Type Ia supernovae and to identify SSSs that may represent a wider range of physical systems, including accreting intermediate-mass black holes. In this short report we list ten intriguing facts about distant SSSs.
The labor market, education and armed conflict in Tajikistan

Shortly following its independence in 1991, Tajikistan suffered a violent civil war. This study explores the effect of this conflict on education and labor market outcomes for men and women. The results are based on the data from the 2003 and 2007 Tajik Living Standards Measurement Surveys that were separated from the 1992-1998 Tajik civil war by five and nine years, respectively. The regression analysis that controls for the cohort and regional-level exposure points toward a persistent and lasting gap in the educational attainment by women who were of school age during the war and lived in the more conflict-affected regions as compared with women the same age who lived in the lesser affected regions and also to the older generation. These empirical results support the anecdotal and observational evidence about the decline in female educational attainment in Tajikistan. Interestingly, this group of young women is more likely to hold a job as compared with the rest of the analytical sample. Conditional on being employed, men and women in the more conflict-affected areas do not receive wages that are significantly different from wages received by men and women in the lesser affected areas.
Dark Matter Properties and the Structure of Galaxy Clusters

Laboratory experiments, large-scale computer simulations and observational cosmology have begun to make progress in the campaign to identify the particle responsible for gravitationally-inferred dark matter. We report results from an astrophysical program to measure dark matter particle properties. We use a sample of carefully-selected, highly-relaxed galaxy clusters to constrain the strength of dark matter self-interaction. We also report structural parameters for this cluster sample and discuss the implications for cold dark matter cosmology.
Possible Detection of a Pair Instability Supernova in the Modern Universe, and Implications for the First Stars

SN 2006gy radiated far more energy in visual light than any other supernova so far, and potential explanations for its energy demands have implications for galactic chemical evolution and the deaths of the first stars. It remained bright for over 200 days, longer than any normal supernova, and it radiated more than 1051 ergs of luminous energy at visual wavelengths. I argue that this Type IIn supernova was probably the explosion of an extremely massive star like Eta Carinae that retained its hydrogen envelope when it exploded, having suffered relatively little mass loss during its lifetime. That this occurred at roughly Solar metallicity challenges current paradigms for mass loss in massive‐star evolution. I explore a few potential explanations for SN2006gy's power source, involving either circumstellar interaction, or instead, the decay of 56Ni to 56Co to 56Fe. If SN 2006gy was powered by the conversion of shock energy into light, then the conditions must be truly extraordinary and traditional interactio...
On inflation with non-minimal coupling

A simple realization of inflation consists of adding the following operators to the Einstein-Hilbert action: (∂ϕ)2, λϕ 4, and ξϕ 2 R , with ξ a large non-minimal coupling. Recently there has been much discussion as to whether such theories make sense quantum mechanically and if the inflaton ϕ can also be the Standard Model Higgs. In this work we answer these questions. Firstly, for a single scalar ϕ, we show that the quantum field theory is well behaved in the pure gravity and kinetic sectors, since the quantum generated corrections are small. However, the theory likely breaks down at ~m Pl /ξ due to scattering provided by the self-interacting potential λϕ 4. Secondly, we show that the theory changes for multiple scalars $ \overrightarrow \phi $ with non-minimal coupling $ \xi \overrightarrow \phi \cdot \overrightarrow \phi \mathcal{R} $ , since this introduces qualitatively new interactions which manifestly generate large quantum corrections even in the gravity and kinetic sectors, spoiling the theory for energies ≳ m Pl /ξ. Since the Higgs doublet of the Standard Model includes the Higgs boson and 3 Goldstone bosons, it falls into the latter category and therefore its validity is manifestly spoiled. We show that these conclusions hold in both the Jordan and Einstein frames and describe an intuitive analogy in the form of the pion Lagrangian. We also examine the recent claim that curvature-squared inflation models fail quantum mechanically. Our work appears to go beyond the recent discussions.
Unusual reactivity of pentafluorobenzyl aromatic ethers under friedel-crafts reaction conditions

Abstract A pentafluorobenzyl (PFBz) ether of 2,6-dimethylphenol undergoes a PFBz rearrangement, which appears to be intermolecular, yielding a 2:3 ratio of meta to para migration. Only ether bond cleavage takes place in a corresponding PFBz ether of 2,6-difluorophenol. Both sets of products are unusual, and it is suggested that they are both due to high reactivity of the PFBz-oxy moiety with the AlCl 3 catalyst.
Almost isometric actions, property (T), and local rigidity

Let Γ be a discrete group with property (T) of Kazhdan. We prove that any Riemannian isometric action of Γ on a compact manifold X is locally rigid. We also prove a more general foliated version of this result. The foliated result is used in our proof of local rigidity for standard actions of higher rank semisimple Lie groups and their lattices in [FM2].
Syndetic sets, paving and the Feichtinger conjecture

We prove that if a Bessel sequence in a Hilbert space that is indexed by a countably infinite group in an invariant manner can be partitioned into finitely many Riesz basic sequences, then each of the sets in the partition can be chosen to be syndetic. We then apply this result to prove that if a Fourier frame for a measurable subset of a higher dimensional cube can be partitioned into Riesz basic sequences, then each subset can be chosen to be a syndetic subset of the corresponding higher dimensional integer lattice. Both of these results follow from a result about syndetic pavings of elements of the von Neumann algebra of a discrete group.
Staggered fermions and their O( a) improvements

Expanding upon the arguments of Sharpe, we explicitly implement the Symanzik improvement program demonstrating the absence of order a terms in the staggered fermion action. We propose a general program to improve fermion operators to remove O(a) corrections from their matrix elements, and demonstrate this program for the examples of matrix elements of fermion bilinears and BK. We also determine the additional operators which must be added to improve the standard staggered fermion currents.
Comparison of Aircraft Noise-Contour Prediction Programs

A comparison was made of Version 1.3 of the FAA Integrated Noise Model (INM) and Version 3.4 of the USAF/NOISEMAP computer programs. Those programs are widely used to predict the location of aircraft noise contours around airports and to determine the size of the areas enclosed. Large differences were found in the noise data bases. There were also differences in flight-profile data bases, ground attenuation factor, and in the way the change in noise duration is handled for curved flight paths. The two programs were used to calculate sound exposure level contours produced by individual operations of various air-carrier and general-aviation jets. The programs were also used to calculate contours of cumulative day-night average sound level around a hypothetical average major intercontinental airport (AVPORT). Large differences in contour areas and shapes were found.
NEW GENETIC APPROACHES : ESTABLISHING RESOURCES FOR RESEARCH

The National Heart, Lung, and Blood Institute (NHLBI) is committed to a broad-ranging program of research that builds on past achievements and capitalizes on the most promising new approaches and technologies. Molecular genetics constitutes an area of particular interest because it has potential to directly enhance our mastery over cardiovascular, lung, and blood diseases. Moreover, an understanding of the molecular genetics of disease will provide vital new information to extend further the considerable contributions that have come from more traditional disciplines. To guide its efforts in this emerging area, the Institute called upon an Expert Panel on Genetic Strategies for Heart, Lung, and Blood Diseases to formulate a Master Plan for the implementation of major research opportunities and strategies (see December 1993 Circulation ). In this column, we highlight the development of two major initiatives recommended in the Master Plan: “Mammalian Genotyping Service” and “Genetic Map and Large Insert Library for the Rat Genome.” The Master Plan identified the need for an efficient, rapid genotyping service to support projects that exploit genetic linkage analyses, association studies, and mutational analysis in an effort to identify the genetic …
INTACS for keratoconus.

BACKGROUND INTACS are two, arc like, PMMA segments which were designed to be surgically inserted into the deep corneal stroma to flatten the central cornea. Their original application was for the refractive correction of mild myopia (−1 to −3D). However, because of the superior accuracy and familiarity with the excimer laser by refractive surgeons, they are rarely used for this indication, except in patients with forme fruste keratoconus or extremely thin corneas with less than 3D of Myopia (1,2). Dr. Joseph Colin in France first conceived of the concept of using INTACS to treat patients with keratoconus and published his first report on the safety and efficacy for this indication in 2001(3). At 1 year, all 10 patients he operated became contact lens tolerant and demonstrated an improvement in both uncorrected and best-corrected acuity (4). Since his pioneering work, corneal surgeons throughout the word have adopted this technology to treat patients with mild to moderate keratoconus who are contact lens intolerant and/or who desire a modest improvement in uncorrected and best-corrected visual acuity (5-14). In the United States 0.25mm, 0.275mm, 0.30mm, 0.325mm and 0.35mm segments are available for use. They are approved in the United States by the FDA under an Human Devise Exemption for compassionate therapeutic use. Outside of the United States .40mm and 0.45mm sized segments are also available. Competitive devices the Ferrara ring and the Keraring are also sold and marketed outside of the United States since they do not have FDA approval in the USA. The main difference between these two devices is that with INTACS the optical zone is approximately 7mm while the Ferrara and Kerarings have an optical zone of the order of 4.5 to 5mm. Recently Intacs SK was introduced outside of the United States. They have an optical zone of 6 mm and have a round design to minimize glare. They may be used to correct larger myopic and astigmatic refractive errors than INTACS because of their design and closer proximity to the visual axis(15)
Capital Accumulation Games of Infinite Duration

Abstract Consider a market in which firms accumulate capital according to the Nerlove-Arrow capital accumulation equation. Each player chooses a path of investment and thus an induced path of capital to maximize his total discounted profits which depend on his own capital and the capital stocks of his rivals. Existence is proved for such a nonzero sum, infinite horizon differential game and conditions under which the game converges to a particular stationary point, regardless of the initial conditions are shown. Thus, the game possesses the property of conditional global asymptotic stability.
Using dimethylether as a drift gas in a high precision drift tube detector

Excellent spatial resolution (34 microns) has been obtained using dimethylether, (CH3)2O at 1 atm in a small drift tube detector. This is better by at least a factor of 2 compared to previous work (about 80 microns) with a conventional gas (a 50-50 argon-ethane mixture) in the same detector. The Lorentz angle and the gas amplification have been measured over a wide range of electric and magnetic fields.
High-Resolution Center-to-Limb Variation of the Quiet Solar Spectrum near Mg II

The accurate determination of the center-to-limb variation of the quiet solar spectrum is of fundamental importance to our understanding of both spatially resolved solar spectral radiance as well as full-disk spectral irradiance. Previous studies have examined the center-to-limb variation at various spectral resolutions using both observations and calculations. Here we derive the center-to-limb variation near Mg II at 2800 A from observations made by the HRTS-9 rocket-spectrograph at both high spatial (1'') and spectral (0.2 A) resolution. This region of the solar spectrum is important because of its impact on the terrestrial atmosphere and its use in generating the Mg II index. The initial part of this paper presents the correction methods used to determine the center-to-limb variation, including the determination of the vignetting properties of the HRTS-9 instrument. This latter correction accounts for the intensity variation along the slit axis of the observed spectrogram. The resulting center-to-limb variation is employed in a model of solar spectral irradiance near Mg II. Using these results and calibrated solar spectra, the absolute intensity calibration is determined for the HRTS-9 spectra. An important aspect of the high-resolution center-to-limb variation is the presence of many spectral features illustrating the differences between the wings and cores of the numerous Fraunhofer lines in the 2765-2875 A region. Also, both the Mg I and Mg II lines in this spectral region have broad, smooth wings that vary differently than the nearby line-blanketed continuum. The results of this study will provide a good source of comparison for detailed models of the quiet solar spectrum.
EVIDENCE ON DELTA HEDGING AND IMPLIED VOLATILITIES FOR THE BLACK‐SCHOLES, GAMMA, AND WEIBULL OPTION PRICING MODELS

Modifying the distributional assumptions of the Black-Scholes model is one way to accommodate the skewness of underlying asset returns. Simple models based on the compensated gamma and Weibull distributions of asset prices are shown to produce some improvements in option pricing. To evaluate these assertions, I construct and compare delta hedges of all S&P 500 options traded on the Chicago Board Options Exchange between September 2001 and October 2003 for the Weibull, Black-Scholes, and gamma models. I also compare implied volatilities and their smiles (i.e., nonlinearities) among the three models. None of the three models improves over the others as far as delta hedging is concerned. Volatilities implied by all three models exhibit statistically significant smiles.
Attendance Policies, Student Attendance, and Instructor Verbal Aggressiveness

The authors utilized an experimental design across six sections of a managerial communications course (N = 173) to test the impact of instructor verbal aggressiveness and class attendance policies on student class attendance. The experimental group received a policy based on the principle of social proof (R. B. Cialdini, 2001), which indicated that for similar students, class attendance was linked to high academic performance. Students also assessed their instructor's level of verbal aggressiveness (D. A. Infante, 1979). Results suggest that instructor verbal aggressiveness did not influence class attendance. However, social proof did positively influence class attendance rates under certain circumstances. The authors discuss the study implications.
Formation and Quasi-Periodic Behavior of Outer Spiral Rainbands in a Numerically Simulated Tropical Cyclone*

AbstractThe formation and quasi-periodic behavior of outer spiral rainbands in a tropical cyclone simulated in the cloud-resolving tropical cyclone model version 4 (TCM4) are analyzed. The outer spiral rainbands in the simulation are preferably initiated near the 60-km radius, or roughly about 3 times the radius of maximum wind (RMW). After initiation, they generally propagate radially outward with a mean speed of about 5 m s−1. They are reinitiated quasi-periodically with a period between 22 and 26 h in the simulation. The inner spiral rainbands, which form within a radius of about 3 times the RMW, are characterized by the convectively coupled vortex Rossby waves (VRWs), but the formation of outer spiral rainbands (i.e., rainbands formed outside a radius of about 3 times the RMW) is much more complicated. It is shown that outer spiral rainbands are triggered by the inner-rainband remnants immediately outside the rapid filamentation zone and inertial instability in the upper troposphere. The preferred rad...
Degenerate four-wave mixing in triply resonant Kerr cavities

We demonstrate theoretical conditions for highly efficient degenerate four-wave mixing in triply resonant nonlinear (Kerr) cavities. We employ a general and accurate temporal coupled-mode analysis in which the interaction of light in arbitrary microcavities is expressed in terms of a set of coupling coefficients that we rigorously derive from the full Maxwell equations. Using the coupled-mode theory, we show that light consisting of an input signal of frequency ${\ensuremath{\omega}}_{0}\ensuremath{-}\ensuremath{\Delta}\ensuremath{\omega}$ can, in the presence of pump light at ${\ensuremath{\omega}}_{0}$, be converted with quantum-limited efficiency into an output shifted signal of frequency ${\ensuremath{\omega}}_{0}+\ensuremath{\Delta}\ensuremath{\omega}$, and we derive expressions for the critical input powers at which this occurs. We find the critical powers in the order of 10 mW, assuming very conservative cavity parameters (modal volumes $~10$ cubic wavelengths and quality factors $~1000$). The standard Manley-Rowe efficiency limits are obtained from the solution of the classical coupled-mode equations, although we also derive them from simple photon-counting ``quantum'' arguments. Finally, using a linear stability analysis, we demonstrate that maximal conversion efficiency can be retained even in the presence of self- and cross-phase modulation effects that generally act to disrupt the resonance condition.
Ammonolysis of anilides promoted by ethylene glycol and phosphoric acid

Ethylene glycol (EG) and phosphoric acid have been found to promote the ammonolysis of a variety of diverse anilides as well as N-aryl carbamate, phthalimide, and urea substrates in the absence of transition metals or other Lewis acid promoters.
What did structural adjustment adjust?: The association of policies and growth with repeated IMF and World Bank adjustment loans

Abstract Analysis of adjustment loans often overlooks their repetition to the same country. Repetition changes the nature of the selection problem. None of the top 20 recipients of repeated adjustment lending over 1980–99 were able to achieve reasonable growth and contain all policy distortions. About half of the adjustment loan recipients show severe macroeconomic distortions regardless of cumulative adjustment loans. Probit regressions for an extreme macroeconomic imbalance indicator and its components fail to show robust effects of adjustment lending or time spent under IMF programs. An instrumental variables regression for estimating the causal effect of repeated adjustment lending on policies fails to show any positive effect on policies or growth.
X-Ray Observations of Gravitationally Lensed Quasars: Evidence for a Hidden Quasar Population

X-ray observations are presented of gravitationally lensed (GL) quasars with redshifts ranging between 1 and 4. The large magnification factors of GL systems allow us to investigate the properties of quasars with X-ray luminosities that are substantially lower than those of unlensed ones and also provide an independent means of estimating the contribution of faint quasars to the hard X-ray component of the cosmic X-ray background. Spectral indices have been estimated in the rest-frame energy bands 0.5-1 keV (soft), 1-4 keV (mid), and 4-20 keV (hard). Our spectral analysis indicates a flattening of the spectral index in the hard band for two radio-loud quasars in the GL quasar sample for which the data have moderate signal-to-noise ratio. These results are consistent with the reported spectral properties of nonlensed radio-loud quasars; however, there are no indications of spectral hardening toward fainter X-ray fluxes. We have identified a large fraction of broad absorption line (BAL) quasars among the GL quasar population. We find that approximately 35% of radio-quiet GL quasars contain BAL features, which is significantly larger than the 10% fraction of BAL quasars presently found in optically selected flux-limited quasar samples. We present a simple model that estimates the effects of attenuation and lens magnification on the luminosity function of quasars and that explains the observed fraction of GL BAL quasars. These observations suggest that a large fraction of BAL quasars are missed from flux-limited optical surveys. Modeling of several X-ray observations of the GL BAL quasar PG 1115+080 suggests that the observed large X-ray variability may be caused in part by a variable intrinsic absorber consistent with previously observed variability of the BAL troughs in the UV band. The observed large X-ray flux variations in PG 1115+080 offer the prospect of considerably reducing errors in determining the time delay with future X-ray monitoring of this system and hence constraining the Hubble constant H0.
Evidence and Implications of Increases in Trading Volume Around Exchange Listings

After controlling for market volume trends and differences in volume measurement between the Nasdaq and the exchanges, we find that mean trading volumes increase significantly for Nasdaq stocks that list on the Amex or the NYSE. Furthermore, stocks with low (high) pre-listing volume tend to realize the largest volume increases (decreases) as well as the best (worst) post-listing performance. Our results support the hypothesis that stocks with high past trading volumes tend to experience lower future returns, and shed new light on the nature and possible causes of poor post-listing stock performance.