cssi/SciSciGPT-SciSciNet huggingface dataset:
Deconcentration without a "clean break"

This report reviews recent papers which argue that urbanization trends in the US show a reversal of past patterns. The review suggests that a reversal is not obvious and may simply appear as a result of a statistical artifact: urbanization which has spilled over metropolitan boundaries may simply be more of the same outward growth but would show up as a metropolitan-to-nonmetropolitan growth shift. A new data file for eighteen other developed countries is examined. These data are suitable for computations of various versions of the Hoover index of population concentration. Such calculations suggest that the eighteen countries examined are experiencing more traditional urban outward expansion. This adds to scepticism of the reversal or ‘clean break’ hypothesis.
Growing Live Disks within Cosmologically Assembling Asymmetric Halos: Washing Out the Halo Prolateness

We study the growth of galactic disks in live triaxial dark matter (DM) halos. The halos have been assembled using the constrained realizations method and evolved from the linear regime using cosmological simulations. The "seed" disks have been inserted at redshift z = 3 and increased in mass tenfold over various time periods, ~1-3 Gyr, with the halo responding quasi-adiabatically to this process. We follow the dynamical and secular evolution of the disk-halo system and analyze changes in the most important parameters, such as three-dimensional DM shapes, stellar (disk) and DM (halo) radial density profiles, and stellar bar development. We find that a growing disk is responsible for washing out the halo prolateness (in the disk plane) and for diluting its flatness over a period of time comparable to the disk growth. Moreover, we find that a disk that contributes more to the overall rotation curve in the system is also more efficient in axisymmetrizing the halo, without accelerating the halo figure rotation. The observational corollary is that the maximal disks probably reside in nearly axisymmetric halos, while disks whose rotation is dominated by the halo at all radii are expected to reside in more prolate halos. The halo shape is sensitive to the final disk mass, but is independent of how the seed disk is introduced into the system, abruptly or quasi-adiabatically. It is weakly sensitive to the timescale of the disk growth. We also expect that the massive disks are subject to a bar instability, while in light disks this instability is damped by the halo triaxiality. Implications of these results for the cosmological evolution of disks embedded in asymmetric halos are discussed and so are the corollaries for the observed fraction of stellar bars. Finally, the halo responds to the stellar bar by developing a gravitational wake—a "ghost" bar of its own, which is almost in phase with that in the disk.
The Hubble Diagram to Redshift >6 from 69 Gamma-Ray Bursts

One of the few ways to measure the properties of dark energy is to extend the Hubble diagram (HD) to higher redshifts with gamma-ray bursts (GRBs). GRBs have at least five properties (their spectral lag, variability, spectral peak photon energy, time of the jet break, and the minimum rise time) that have correlations to the luminosity of varying quality. In this paper I construct a GRB HD with 69 GRBs over a redshift range from 0.17 to >6, with half the bursts having a redshift larger than 1.7. This paper uses over 3.6 times as many GRBs and 12.7 times as many luminosity indicators as any previous GRB HD work. For the gravitational lensing and Malmquist biases, I find that the biases are small, with an average of 0.03 mag and an rms scatter of 0.14 mag in the distance modulus. The GRB HD is well behaved and nicely delineates the shape of the HD. The reduced χ2 for the fit to the concordance model is 1.05, and the rms scatter about the concordance model is 0.65 mag. This accuracy is just a factor of 2.0 times that gotten for the same measure from all the big supernova surveys. I fit the GRB HD to a variety of models, including where the dark energy has its equation of state parameter varying as w(z) = w0 + waz/(1 + z). I find that the concordance model is consistent with the data, that is, the dark energy can be described well as a cosmological constant that does not change with time.
Numerical simulations of a loop quantum cosmos: robustness of the quantum bounce and the validity of effective dynamics

A key result of isotropic loop quantum cosmology is the existence of a quantum bounce which occurs when the energy density of the matter field approaches a universal maximum close to the Planck density. Though the bounce has been exhibited in various matter models, due to severe computational challenges, some important questions have so far remained unaddressed. These include the demonstration of the bounce for widely spread states, its detailed properties for the states when matter field probes regions close to the Planck volume and the reliability of the continuum effective spacetime description in general. In this manuscript we rigorously answer these questions using the Chimera numerical scheme for the isotropic spatially flat model sourced with a massless scalar field. We show that, as expected from an exactly solvable model, the quantum bounce is a generic feature of states even with a very wide spread, and for those which bounce much closer to the Planck volume. We perform a detailed analysis of the departures from the effective description and find some expected, and some surprising results. At a coarse level of description, the effective dynamics can be regarded as a good approximation to the underlying quantum dynamics unless the states correspond to small scalar field momenta, in which case they bounce closer to the Planck volume or are very widely spread. Quantifying the amount of discrepancy between the quantum and the effective dynamics, we find that the departure between them depends in a subtle and non-monotonic way on the field momentum and different fluctuations. Interestingly, the departures are generically found to be such that the effective dynamics overestimates the spacetime curvature, and underestimates the volume at the bounce.
γ-Fluorophenyl-GABA derivatives from fluorobenzonitriles in high diastereomeric and enantiomeric excess

Abstract An enantioselective synthesis of α-fluoroaryl homoallylic amines in 52–71% yields and 76–93% enantioselectivities has been achieved via the allylboration of the corresponding fluorinated N -aluminobenzaldimines with B -allyldiisopinocampheylborane in the presence of methanol, followed by alkaline hydrogen peroxide workup. Crotylboration of these aluminobenzaldimines with potassium B -methoxy B - E - or - Z -crotyldiisopinocampheylborinate provided the corresponding β- anti- or - syn -methyl α-fluoroarylhomoallylamines, respectively in high de and ee. Similarly, alkoxyallylboration with lithium B -methoxy B -γ-OMEMallyldiisopinocampheylborinate provided the corresponding β- syn -alkoxyhomoallylamines in excellent de and ee. Representatives of these amino alkenes were converted to the corresponding optically active N -Boc-protected fluorinated amino alcohols via hydroboration-oxidation. Further chromium-mediated oxidation provided N -Boc-protected γ-fluorophenyl-γ-aminobutyric acids, which upon deprotection provided the corresponding γ-lactams.
Picosecond Energy Transfer in Quantum Dot Langmuir - Blodgett Nanoassemblies

We study spectrally resolved dynamics of Forster energy transfer in single monolayers and bilayers of semiconductor nanocrystal quantum dots assembled using Langmuir−Blodgett (LB) techniques. For a single monolayer, we observe a distribution of transfer times from ∼50 ps to ∼10 ns, which can be quantitatively modeled assuming that the energy transfer is dominated by interactions of a donor nanocrystal with acceptor nanocrystals from the first three “shells” surrounding the donor. We also detect an effective enhancement of the absorption cross section (up to a factor of 4) for larger nanocrystals on the “red” side of the size distribution, which results from strong, interdot electrostatic coupling in the LB film (the light-harvesting antenna effect). By assembling bilayers of nanocrystals of two different sizes, we are able to improve the donor−acceptor spectral overlap for engineered transfer in a specific (“vertical”) direction. These bilayers show a fast, unidirectional energy flow with a time constant ...
Using Field Measurements of Air Filter Performance and HVAC Fan Energy Measurements to Select Air Filters with Lowest Life Cycle Cost

ABSTRACT Properly selected and maintained, building air filters provide a simple and often overlooked opportunity for significant reductions in electric energy use. These savings can be achieved while maintaining or enhancing indoor air quality (IAQ) by filtration of incoming and recirculated air in building HVAC systems. This article reviews the technologies behind air filtration in buildings and describes methods to select air filters and to measure electric energy use from fans and blowers, as well as the field performance of particulate air filters. Using the criteria described, air filters and energy use are evaluated in several common settings, including offices and mixed-use buildings, manufacturing plants, laboratories, and hospitals. Several case studies are briefly described, showing in-situ filtration performance, electrical energy measurements, life cycle cost calculations, and total cost of ownership for air filters of various designs and qualities. Air filter performance is characterized usi...
Effects of Blowing on Delta Wing Vortices During Dynamic Pitching

An experimental investigation was conducted in a water tunnel to identify the effects of apex blowing on two delta wing models undergoing constant pitch-rate motion. One wing was of 60-deg sweep and the other was of 76-deg sweep. Flow visualization methods were utilized to determine vortex burst locations for a range of pitchup and pitch-down rates, apex jet strengths, and blowing directions. Results indicate, individually, that blowing direction on the 60-deg wing and blowing rate on the 76-deg wing have the greatest effect on vortex behavior under both static and dynamic pitch-up conditions. Vortex improvements, for any blowing direction or rate examined, are most dramatic during dynamic pitch-down conditions. In this case, the use of blowing resulted in the reformation of unburst vortices with significant length.
Heavy quarkonia results from CLEO

The latest experimental results in bottomonium and charmonium spectroscopy from CLEO are presented.
A Successful Targeted Search for Hypervelocity Stars

Hypervelocity stars (HVSs) travel with velocities so extreme that dynamical ejection from a massive black hole is their only suggested origin. Following the discovery of the first HVS by Brown and collaborators, we have undertaken a dedicated survey for more HVSs in the Galactic halo and present here the resulting discovery of two new HVSs: SDSS J091301.0+305120 and SDSS J091759.5+672238, traveling with Galactic rest-frame velocities of at least +558 ± 12 and +638 ± 12 km s-1, respectively. Assuming the HVSs are B8 main-sequence stars, they are at distances of ~75 and ~55 kpc, respectively, and have travel times from the Galactic center consistent with their lifetimes. The existence of two B8 HVSs in our 1900 deg2 survey, combined with the Yu & Tremaine HVS rate estimates, is consistent with HVSs drawn from a standard initial mass function but inconsistent with HVS drawn from a truncated mass function like the one in the top-heavy Arches cluster. The travel times of the five currently known HVSs provide no evidence for a burst of HVSs from a major infall event at the Galactic center in the last ~160 Myr.
An Investigation of Oxidation-Resistant Solid Lubricant Materials

Wear tests of oxide and fluoride oxidation resistant solid lubricants for use in high temperature gaseous environments
Effects of Anomalous Rotor Joints on Turbomachine Dynamics

Mechanisms simulating rotor joint restoring moments different from the common axisymmetric elastic hinge are derived and their effects on the dynamics of a complete turbomachine are calculated by impressing equivalent perturbing moments. A mechanism for locking subsynchronous whirl to a fractional frequency is described and supporting experimental observations are discussed. Sample analysis shows the possibility of self-sustained synchronous whirl due to preload asymmetry.Copyright © 1983 by ASME
PSEUDODUALITY IN SUPERSYMMETRIC SIGMA MODELS

We study the pseudoduality transformation in supersymmetric sigma models. We generalize the classical construction of pseudoduality transformation to supersymmetric case. We perform this both by component expansion method on manifold and by orthonormal coframe method on manifold . The component expansion method yields the result that pseudoduality tranformation is not invertible at all points and occurs from all points on one manifold to only one point where Riemann normal coordinates are valid on the second manifold. Torsion of the sigma model on must vanish while it is nonvanishing on , and curvatures of the manifolds must be constant and the same. In the case of super-WZW sigma models, pseudoduality equations result in three different pseudoduality conditions; identity, chiral and antichiral pseudoduality.
Warranties as a device to extract rent from low‐risk users of a product

We develop a simple model that provides a new rationale for why a monopolist should bundle its product with a warranty even when all parties are risk neutral. In our model, a risk-neutral monopolist faces two types of risk-neutral consumers—low-risk users that are unlikely to cause product failure and high-risk users that are more likely to cause product failure. We find that when the firm fails to provide a warranty, a low-risk user acquires a strictly positive rent by pretending to be a high-risk user and receiving a price discount. By imposing a warranty, however, the monopolist can increase the price to high-risk users, which in turn removes the incentive for a low-risk user to pretend to be a high-risk user, and the firm successfully extracts rent from the low-risk user. Copyright © 2007 John Wiley & Sons, Ltd.
Chandra Observation of the Interaction of the Radio Source and Cooling Core in Abell 2063

We present the results of a Chandra observation of the cooling core cluster Abell 2063. Spectral analysis shows that there is cool gas (2 keV) associated with the cluster core, which is more than a factor of 2 cooler than the outer cluster gas (4.1 keV). There also is spectral evidence for a weak cooling flow, ≈ 20 M☉ yr-1. The cluster exhibits a complex structure in the center that consists of several bright knots of emission, a depression in the emission to the north of the center of the cluster, and a shell of emission surrounding it. The depression in the X-ray emission is coincident with the position of the northeastern radio lobe of the radio source associated with the cluster central galaxy. The shell surrounding this region appears to be hotter, which may be the result of a shock that has been driven into the gas by the radio source. The power output of the radio source appears to be sufficient to offset the cooling flow, and heating of the gas through shocks is a possible explanation of how the energy transfer is established.
Energy demand in the transportation sector of Mexico

Abstract This paper report results of an analysis of the demand for energy in the Mexican transport sectors, focusing on the railroad, air transport and motor vehicle modes. The approach is an econometric one with emphasis placed on the structure for each mode. For two of the modes a two-stage approach is employed where in the first stage demands for services from the particular mode are modeled, and in the second stage demand is treated as a derived demand from these transport services. For the motor vehicle mode, gasoline demand is considered as the product of gasoline consumption per vehicle times the total number of vehicles, and then these components are related to economic and structural variables. Diesel demand of motor vehicles is modeled in a more reduced from approach. The principal finding is that changes in income play a more important role in affecting energy demand than do changes in energy prices, especially in the railroad and air transport sectors. For the gasoline and diesel fuel demand in the monitor vehicle sector, however, price is of substantial importance.
An Intentions-Based Model of Entrepreneurial Teams’ Social Cognition*

Research has identified crucial antecedents of corporate entrepreneurship. Research has also identified crucial antecedents of entrepreneurial thinking. This article uses lessons from social cognition to explicitly link these two issues. We adapt an intentions-based model of how to promote entrepreneurial thinking from its original domain of individual entrepreneurship and translate that model to the domain of corporate entrepreneurship. From our intentions-based model of the social cognition of entrepreneurial teams, we emphasize the importance of perceptions of desirability and feasibility and that these perceptions are from the team as well as the individual perspective. This leads to three propositions about entrepreneurial teams and an outline of the opportunities for future research.
Long Term Observations of CYG X-3 with Vela 5B

We present long-term (1969–1979) observations of Cygnus X-3, obtained by the Vela 5B satellite. The 3–12 keV light curve has 10 day time resolution. Cyg X-3 is a peculiar high-luminosity X-ray source, radiating from the radio region to hard gamma rays of more than 1016 eV. It has a 4.8 hour period, probably orbital, which is not resolved by our present analysis. Long term periodicities of ~17, 20, and 33–34 days have been reported by several authors, and explained as the effects of apsidal motion, precession, or an eccentric orbit. We do not observe the ~17 and 33–34 day variations, and set upper limits significantly lower than the reported amplitude of the 33–34 day variation. There is weak evidence for a 20 day flux variation. The light curve shows high and low states which alternate with a characteristic timescale of ~1 year. There is no counterpart, at this time resolution, of the giant radio outburst of 1972 September.
Thiolates, selenolates, and tellurolates of the s-block elements

Abstract The potential of alkali and alkaline earth metal chalcogenolates in synthetic chemistry and various technical applications has sparked the recent interest in the chemistry of alkali and alkaline earth metal thiolates, selenolates and tellurolates. As a result, an increasing body of work concerned with exploring synthetic routes to the target compounds, analyzing the influence of metal, ligand and donor on the structural chemistry, and correlating structure and function has appeared in the literature, most of which during the last few years. This article describes recent trends in this area of alkali and alkaline earth chemistry, by discussing synthetic access routes, analyzing structure determining factors such as metal, donor and ligand influence, comparing structural similarities and disparities in alkali and alkaline earth chemistry, and discussing structure–function relationships.
From cycloheptatriene to enantiopure sugars: synthesis of 2-deoxyhexoses

Abstract meso -Diol 3 , prepared from cycloheptatriene, was desymmetrized with Pseudomonas cepacia lipase and isopropenyl acetate to provide enantiopure 4 . The latter, through a series of stereocontrolled oxidation reactions, followed by ring cleavage by ozonolysis and oxidative cleavage of a terminal diol with periodate, provided of 2-deoxy- d - xylo -hexose ( 1 ) and 2-deoxy- d - arabino -hexose ( 2 ), which were characterized as the corresponding alditol pentaacetates.
Meeting U.S. liquid transport fuel needs with a nuclear hydrogen biomass system

The two major energy challenges for the United States are replacing crude oil in our transportation system and eliminating greenhouse gas emissions. A domestic-source greenhouse-gas-neutral nuclear hydrogen biomass system to replace oil in the transportation sector is described. Some parts of the transportation system can be electrified with electricity supplied by nuclear energy sources that do not emit significant quantities of greenhouse gases. Other components of the transportation system require liquid fuels. Biomass can be converted to greenhouse-gas-neutral liquid fuels; however, the conversion of biomass-to-liquid fuels is energy intensive. There is insufficient biomass to meet U.S. liquid fuel demands and provide the energy required to process the biomass-to-liquid fuels. With the use of nuclear energy to provide heat, electricity, and hydrogen for the processing of biomass-to-liquid fuels, the liquid fuel production per unit of biomass is dramatically increased, and the available biomass could meet U.S. liquid fuel requirements.
TEM sample preparation by single-sided low-energy ion beam etching

Conventional FIB ex-situ lift-out is the most common technique for TEM sample preparation. However, the scaling of semiconductor device structures poses great challenge to the method since the critical dimension of device becomes smaller than normal TEM sample thickness. In this paper, a technique combining 30 keV FIB milling and 3 keV ion beam etching is introduced to prepare the TEM specimen. It can be used by existing FIBs that are not equipped with low-energy ion beam. By this method, the overlapping pattern can be eliminated while maintaining good image quality.
HEREDITARY SENSORY NEUROPATHY TYPE I: HAPLOTYPE ANALYSIS SHOWS FOUNDERS IN SOUTHERN ENGLAND AND EUROPE

Hereditary sensory neuropathy type I (HSN1) is the most common dominantly inherited degenerative disorder of sensory neurons. The gene mutation was mapped to chromosome 9 in a large Australian family, descended from an ancestor from southern England who was a convict. Dawkins et al. recently reported gene mutations in the SPTLC1 gene, in this and other families. The first description of hereditary sensory neuropathy, by Hicks, was in a family from London and Exeter. To determine if the families in the present study that have SPTLC1 mutations are related to English families with HSN1 and, possibly, to the family studied by Hicks, we performed haplotype analysis of four Australian families of English extraction, four English families, and one Austrian family. Three Australian families of English extraction and three English families (two of whom have been described elsewhere) had the 399TG SPTLC1 mutation, the same chromosome 9 haplotype, and the same phenotype. The Australian and English families may therefore have a common founder who, on the basis of historical information, has been determined to have lived in southern England prior to 1800. The sensorimotor neuropathy phenotype caused by the 399TG SPTLC1 mutation is the same as that reported by Campbell and Hoffman and, possibly, the same as that originally described by Hicks.
Another way to enumerate rational curves with torus actions

A new proof of the mirror conjecture for Fano and Calabi-Yau complete intersections in P^n is given, using only the circle action on the graph space. The proof applies to projective bundles as well, with applications to "linear" relative Calabi-Yau's and to Schubert calculus.
Concentration of Competing Retail Stores

Abstract The geographical concentration of stores that sell similar commodities is analyzed using a two-dimensional spatial competition model. A higher concentration of stores attracts more consumers with taste uncertainty and low price expectations (a market-size effect), while it leads to fiercer price competition (a price-cutting effect). Our model is general enough to allow for the coexistence of multiple (possibly) asymmetric clusters of stores. We provide sufficient conditions for the nonemptiness of equilibrium store location choices in pure strategies. Through numerical examples, we illustrate the trade-off between the market-size and price-cutting effects, and provide agglomeration patterns of stores in special cases.
Why Are There So Few Perovskite Ferroelectrics

We use a combination of symmetry arguments and first-principles calculations to explore the connection between structural distortions and ferroelectricity in the perovskite family of materials. We explain the role of octahedral rotations in suppressing ferroelectricity in these materials and show that, as the tolerance factor decreases, rotations alone cannot fully suppress ferroelectricity. Our results show that it is cation displacements (“hidden” in Glazer notation) that accompany the rotations, rather than the rotations themselves, that play the decisive role in suppressing ferroelectricity in these cases. We use the knowledge gained in our analysis of this problem to explain the origin of ferroelectricity in R3c materials such as FeTiO3 and ZnSnO3 and to suggest strategies for the design and synthesis of new perovskite ferroelectrics. Our results have implications not only for the fundamental crystal chemistry of the perovskites but also for the discovery of new functional materials.
Observation of relativistic effects in collective Thomson scattering.

We observe relativistic modifications to the Thomson scattering spectrum in a traditionally classical regime: ${v}_{\mathrm{osc}}/c=e{E}_{0}/cm{\ensuremath{\omega}}_{0}\ensuremath{\ll}1$ and ${T}_{e}l1\text{ }\text{ }\mathrm{keV}$. The modifications result from scattering off electron-plasma fluctuations with relativistic phase velocities. Normalized phase velocities $v/c$ between 0.03 and 0.12 have been achieved in a ${N}_{2}$ gas-jet plasma by varying the plasma density from $3\ifmmode\times\else\texttimes\fi{}{10}^{18}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}3}$ to $7\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}3}$ and electron temperature between 85 and 700 eV. For these conditions, the complete temporally resolved Thomson scattering spectrum including the electron and ion features has been measured. A relativistic treatment of the Thomson scattering form factor shows excellent agreement with the experimental data.
Dilemmas of Justice and Reconciliation: Rwandans and the Gacaca Courts

Following the 1994 genocide, several justice initiatives were implemented in Rwanda, including a tribunal established by the United Nations, Rwanda's national court system and Gacaca, a ‘traditional’ community-run conflict resolution mechanism adapted to prosecute genocide perpetrators. Since their inception in 2001, the Gacaca courts have been praised for their efficiency and for widening participation, but criticised for lack of due process, trained personnel and attention to atrocities committed by the Rwandan Patriotic Front (RPF). To evaluate these criticisms, we present preliminary findings from a survey of 227 Rwandans and analyse their attitudes towards Gacaca in relation to demographic characteristics such as education, residence and loss of relatives during the genocide.
Doctoral Education in Design: Problems and Prospects

This paper considers the status of design research and underlines the importance of setting up clear objectives for doctoral programs within this discipline. For this reason, it compiles a list of key considerations in order to advance towards a consensus in respect to these type of academic programs.
Component segregation in model chemically amplified resists

We have applied chemical force microscopy (CFM) to probe the surface roughness of partially developed model resist materials in order to understand the fundamental materials properties of the resists leading to line edge roughness (LER). CFM is capable of providing simultaneous information about surface topography and chemical heterogeneity of partially developed resist films. We have used CFM to study ESCAP type resists that are used in 248 nm and extreme ultraviolet (EUV) lithography. We observe changes in both the innate material roughness and chemical heterogeneity of the resist with the introduction of photoacid generator (PAG) and with exposure and post exposure bake (PEB). We find several mechanisms by which chemical heterogeneity can contribute to increasing the innate material roughness of the resist.
Analytic Solution of the Spencer-Lewis Angular-Spatial Moments Equations.

A closed-form solution for the angular-spatial moments of the Spencer-Lewis equation is presented that is valid for infinite homogeneous media. From the moments, the electron density distribution as a function of position and path length (energy) is reconstructed for several sample problems involving plane isotropic sources of electrons in aluminium. The results are in excellent agreement with those determined numerically using the streaming ray method. The primary use of the closed form solution will most likely be to generate accurate electron transport benchmark solutions. In principle, the electron density as a function of space, path length, and direction can be determined for planar sources of arbitrary angular distribution.
Solution of the one-dimensional Dirac equation with a linear scalar potential

We solve the Dirac equation in one spatial dimension for the case of a linear, Lorentz-scalar potential. This extends earlier work of Bhalerao and Ram [Am. J. Phys. 69 (7), 817–818 (2001)] by eliminating unnecessary constraints. The spectrum is shown to match smoothly to the nonrelativistic spectrum in a weak-coupling limit.
Some Approximation Concepts for Structural Synthesis

An efficient automated minimum weight design procedure is presented which is applicable to sizing structural systems that can be idealized by truss, shear panel, and constant strain triangles. Static stress and displacement constraints under alternative loading conditions are considered. The optimization algorithm is an adaptation of the method of inscribed hyperspheres and high efficiency is achieved by using several approximation concepts including temporary deletion of noncritical constraints, design variable linking, and Taylor series expansions for response variables in terms of design variables. Optimum designs for several planar and space truss examples problems are presented. The results reported support the contention that the innovative use of approximation concepts in structural synthesis can produce significant improvements in efficiency.
Simplified design of composite materials

Abstract An internally consistent theory of micro- and macromechanics has been formulated to link materials, geometric and environmental parameters that affect the stiffness and strength ofstructural elements made of multidirectional composite laminates. Design simplifications are presented and other unique features ofthis integrated framework are discussed. The framework has been implemented on a personal computer in a spreadsheetformat and validated using organic fibre-matrix composite materials data.
Synthesis and properties of a stable, cationic, rhodium Lewis-acid catalyst for hydrosilation, Mukaiyama aldol and cyclopropanation reactions

The remarkably stable cationic, three-coordinate, 14-electron rhodium complex 1 has been synthesized, isolated and used as a catalyst for hydrosilation, Mukaiyama aldol and cyclopropanation reactions.
Copper on chitosan: a recyclable heterogeneous catalyst for azide–alkyne cycloaddition reactions in water

Copper sulfate has been immobilized over chitosan by simply stirring an aqueous suspension of chitosan in water with copper sulfate; the ensuing catalyst has been utilized for the azide–alkyne cycloaddition in aqueous media and it can be recycled and reused many times without losing its activity.
Synthesis, characterization, and electrochemical studies of iron, cobalt, and nickel complexes of polyphosphine ligands

The reaction of (M(CH/sub 3/CN)/sub 6/) (BF/sub 4/)/sub 2/ (where M = Fe, Co, and Ni) with P(CH/sub 2/CH/sub 2/PPh/sub 2/)/sub 3/ (PP/sub 3/), PhP(CH/sub 2/CH/sub 2/PPh/sub 2/)/sub 2/ (PP/sub 2/), and Ph/sub 2/PCH/sub 2/CH/sub 2/PPh/sub 2/ (dppe) results in the formation of (Fe(PP/sub 3/)(CH/sub 3/CN)/sub 2/) (BF/sub 4/)/sub 2/, (Fe(PP/sub 2/)(CH/sub 3/CN)/sub 3/) (BF/sub 4/)/sub 2/, (Fe(dppe)/sub 2/(CH/sub 3/CN)/sub 2/) (BF/sub 4/)/sub 2/, (Co(PP/sub 3/)(CH/sub 3/CN)) (BF/sub 4/)/sub 2/, (Co(dppe)/sub 2/(CH/sub 3/CN)) (BF/sub 4/)/sub 2/, (Ni(PP/sub 3/)(CH/sub 3/CN)) (BF/sub 4/)/sub 2/, (Ni(PP/sub 2/)(CH/sub 3/CN))(BF/sub 4/)/sub 2/, and (Ni(dppe)/sub 2/)(BF/sub 3/)/sub 2/, respectively. Electrochemical studies have been carried out on these complexes to examine the influence of the nature of the polyphosphine ligand on the redox properties of each metal. For (Fe(PP)(CH/sub 3/CN)/sub 2/)(BF/sub 4/)/sub 2/ the reversibility of both the Fe(II/III) and Fe(I/0) couples are enhanced relative to those of (Fe(dppe)/sub 2/(CH/sub 3/CN)/sub 2/)(BF/sub 4/)/sub 2/. For (Co(PP/sub 3/)(CH/sub 3/CN))(BF/sub 4/)/sub 2/ the lowest oxidation state accessible in CH/sub 3/CN is +1, while for (Co(dppe)/sub 2/(CH/sub 3/CN))(BF/sub 4/)/sub 2/ the -1 oxidation state can be observed. The Ni(I/0) couple is reversible for (Ni(dppe)/sub 2/)(BF/sub 4/)/sub 2/ and irreversible for (Ni(PP/sub 2/)(CH/sub 3/CN))(BF/sub 4/)/sub 2/ and (Ni(PP/sub 3/)(CH/sub 3/CN))(BF/sub 4/)/submore » 2/. The electrochemical studies of the latter complex have led to the synthesis of a Ni(0) dimer, (Ni(PP/sub 3/))/sub 2/.« less
Palladium-catalyzed 1,4-difunctionalization of butadiene to form skipped polyenes.

A palladium-catalyzed 1,4-addition across the commodity chemical 1,3-butadiene to afford skipped polyene products is reported. Through a palladium σ → π → σ allyl isomerization, two new carbon–carbon bonds are formed with high regioselectivity and trans stereoselectivity of the newly formed alkene. The utility of this method is highlighted by the successful synthesis of the ripostatin A skipped triene core.
“Hidden” Seyfert 2 Galaxies and the X-Ray Background

Obscured active galactic nuclei, which are classified optically as type 2 (narrow line) Seyfert galaxies in the local universe, are by far the most promising candidates for the origin of the hard (2-10 keV) X-ray background radiation. However, optical follow-up observations of faint X-ray sources in deep Chandra images have revealed surprising numbers of apparently normal galaxies at modest redshift. Such objects represent ~40%-60% of the sources classified in deep Chandra surveys, raising the possibility that the X-ray galaxy population has evolved with cosmic time. Alternatively, most of the faint X-ray galaxies in question are so distant that their angular diameters are comparable to the slit widths used in ground-based spectroscopic observations; thus, their nuclear spectral features may be overwhelmed ("hidden") by host galaxy light. To test this hypothesis, we have obtained integrated spectra of a sample of nearby, well-studied Seyfert 2 galaxies. The data, which accurately simulate observations of distant Chandra sources, demonstrate convincingly that the defining spectral signatures of Seyfert 2s can be hidden by light from their host galaxies. In fact, 60% of the observed objects would not be classified as Seyfert 2s on the basis of their integrated spectra, similar to the fraction of faint X-ray sources identified with "normal" galaxies. Thus, the numbers of narrow-line active galaxies in deep Chandra surveys (and perhaps all ground-based spectroscopic surveys of distant galaxies) are likely to have been underestimated.
A cylindrical reformulation of Heegaard Floer homology

We reformulate Heegaard Floer homology in terms of holomorphic curves in the cylindrical manifold U a0;1c R, where U is the Heegaard surface, instead of Sym g .U/. We then show that the entire invariance proof can be carried out in our setting. In the process, we derive a new formula for the index of the @‐operator in Heegaard Floer homology, and shorten several proofs. After proving invariance, we show that our construction is equivalent to the original construction of Ozsvath‐Szabo. We conclude with a discussion of elaborations of Heegaard Floer homology suggested by our construction, as well as a brief discussion of the relation with a program of C Taubes.
Functionalization of Hydrocarbons by a New Free Radical Based Condensation Reaction

The Br. radical is the chain carrier of a new highly selective allylation of hydrocarbons (and other substrates): It abstracts a hydrogen atom from R−H to yield R.. Addition of R. to substituted allyl bromide (to form a β-bromo radical) followed by β-cleavage regenerates Br. and provides the product. Reaction yields and kinetic chain lengths for this reaction are highest when the allyl bromide contains a radical-stabilizing substituent.
COMMENTS ON THE REVIEW OF CP VIOLATION IN THE PARTICLE DATA BOOK

Rephasing invariant formalism for the $K^0-\bar K^0$ system is recommended for the Particle Data Group. This formalism is accurate and prevents possible errors in generalizing the formalism to other systems, as well as in using CKM matrices not included in the Particle Data Book.
A stereochemical study on the intramolecular hydrosilylation of α,β-unsaturated esters

Abstract The intramolecular hydrosilylation of several 3-methyl-4-siloxy-2-butenoates afforded cis disubstituted lactones after desilylation. The diastereoinduction was sensitive to the bulk of the allylic substituent, but not to the groups on silicon. The origin of asymmetric induction is believed to be the A1,2 strain from the β-methyl group.
A new robust low-scatter X-ray mass indicator for clusters of galaxies

We present a comparison of X-ray proxies for the total cluster mass, M_(500), including the spectral temperature (T_X), gas mass measured within r_(500) (M_(g,500)), and the new proxy, Y_X, which is a simple product of T_X and M_(g,500) and is related to the total thermal energy of the ICM. We use mock Chandra images constructed for a sample of clusters simulated with the Eulerian N-body+gasdynamics adaptive mesh refinement ART code in the concordance ΛCDM cosmology. The simulations achieve high spatial and mass resolution and include radiative cooling, star formation, and other processes accompanying galaxy formation. Our analysis shows that simulated clusters exhibit a high degree of regularity and tight correlations between the considered observables and total mass. The normalizations of the M_(500)-T_X, M_(g,500)-T_X, and M_(500)-Y_X relations agree to better than ≈10%-15% with the current observational measurements of these relations. Our results show that Y_X is the best mass proxy with a remarkably low scatter of only ≈5%-7% in M500 for a fixed Y_X, at both low and high redshifts and regardless of whether clusters are relaxed or not. In addition, we show that redshift evolution of the Y_(X)-M_(500) relation is close to the self-similar prediction, which makes Y_X a very attractive mass indicator for measurements of the cluster mass function from X-ray-selected samples.
Coding and equalization for PPM on wireless infrared channels

We analyze the performance of trellis-coded pulse-position modulation with block decision-feedback equalization (BDFE) and parallel decision-feedback decoding (PDFD) on indoor, wireless infrared channels. We show that the reduced complexities of BDFE and PDFD as compared to maximum-likelihood sequence detection allow for better codes whose increased coding gain more than compensates for the penalty due to suboptimal detection. We quantify these net gains in performance over a range of dispersive channels, indicating where BDFE and PDFD provide the best performance. Finally, we present Monte Carlo simulation results to verify our analysis.
MEMS microswitch arrays for reconfigurable distributed microwave components

A novel MEMS switch design for use in microwave circuits is presented. The microswitch is capable of being configured in a multi-element X-Y array for use in tunable distributed circuits. Circuit design concepts using microswitch arrays and measurements of single microswitch performance are given.
SYMMETRIES AND EXOTIC SMOOTH STRUCTURES ON A K3 SURFACE

Smooth and symplectic symmetries of an infinite family of distinct exotic K3 surfaces are studied, and a comparison with the corresponding symmetries of the standard K3 is made. The action on the K3 lattice induced by a smooth finite group action is shown to be strongly restricted, and, as a result, the nonsmoothability of actions induced by a holomorphic automorphism of prime order at least 7 is proved, and the nonexistence of smooth actions by several K3 groups is established (included among which is the binary tetrahedral group T 24 that has the smallest order). Concerning symplectic symmetries, the fixed-point set structure of a symplectic cyclic action of prime order at least 5 is explicitly determined, provided that the action is homologically nontrivial.
Towards an understanding of the physical nature of MgII absorption systems

We discuss issues concerning the physical nature of intervening MgII quasar absorption systems in light of results from our recent surveys using SDSS EDR QSO spectra and data obtained at the MMT. These surveys indicate an excess of weak $W_0^{\lambda2796} \lesssim 0.3$\AA) systems relative to the exponential dN/dW distribution of stronger systems. The incidence of intermediate-strength lines shows remarkably little evolution with redshift, thereby constraining models for the nature of the clouds comprising these absorbers. The total distribution does evolve, with the incidence decreasing with decreasing redshift in a $W_0^{\lambda2796}$-dependent rate (the strongest systems evolve the fastest). This suggests that multiple populations that evolve at different rates contribute to the incidence in a $W_0^{\lambda2796}$-dependent manner. We also present two images of fields containing unprecedented ``ultra-strong'' ($W_0^{\lambda2796} \ge 4.0$\AA) MgII absorbers.
Do Informed Citizens Receive More…or Pay More? The Impact of Radio on the Government Distribution of Public Health Benefits

The government provision of free or subsidized bed nets to combat malaria in Benin allows us to identify new channels through which mass media affect public policy outcomes. Prior research has concluded that governments provide greater private benefits to better-informed individuals. We show, for the first time, that governments can also respond by exploiting informed individuals’ greater willingness to pay for these benefits. Using a “natural experiment” in radio markets in northern Benin, we find that media access increases the likelihood that households pay for the bed nets they receive from government, rather than getting them for free. Households more exposed to radio programming on the benefits of bed nets and the hazards of malaria place a higher value on bed nets. Local government officials exercise significant discretion over bed net pricing and respond to higher demand by selling bed nets that they could have distributed for free. Mass media appears to change the private behavior of citizens — in this case, to invest more of their own resources on a public health good (bed nets) — but not their ability to extract greater benefits from government.
The Caffarelli Alternative in Measure for the Nondivergence Form Elliptic Obstacle Problem with Principal Coefficients in VMO

We study the obstacle problem with an elliptic operator in nondivergence form with principal coefficients in VMO. We develop all of the basic theory of existence, uniqueness, optimal regularity, and nondegeneracy of the solutions. These results, in turn, allow us to begin the study of the regularity of the free boundary, and we show existence of blowup limits, a basic measure stability result, and a measure-theoretic version of the Caffarelli alternative proven in [3].
Observations and mitigation of RFI in ALOS PALSAR SAR data: Implications for the DESDynI mission

Initial examination of ALOS PALSAR synthetic aperture radar (SAR) data has indicated significant radio frequency interference (RFI) in several geographic locations around the world. RFI causes significant reduction in image contrast, introduces periodic and quasi-periodic image artifacts, and introduces significant phase noise in repeat-pass interferometric data reduction. The US National Research Council Decadal Survey of Earth Science has recommended DESDynI, a Deformation, Ecosystem Structure, and Dynamics of Ice satellite mission comprising an L-band polarimetric radar configured for repeat-pass interferometry. There is considerable interest internationally in other future L-band and lower frequency systems, as well. Therefore, the issues of prevalence and possibilities of mitigation of RFI in these crowded frequency bands are of considerable interest. RFI is observed in ALOS PALSAR in California and Hawaii, USA, and in southern Egypt in data examined to date. Application of several techniques for removing it from the data prior to SAR image formation, ranging from straight-forward spectral normalization to time-domain, multi-phase filtering techniques, are considered. Considerable experience has been gained from the removal of RFI from P-band acquired by the GeoSAR system. These techniques applied to the PALSAR data are most successful when the bandwidth of any particular spectral component of the RFI is narrow. Performance impacts for SAR imagery and interferograms are considered in the context of DESDynI measurement requirements.
An interactive Bayesian geostatistical inverse protocol for hydraulic tomography

[1] Hydraulic tomography is a powerful technique for characterizing heterogeneous hydrogeologic parameters. An explicit trade-off between characterization based on measurement misfit and subjective characterization using prior information is presented. We apply a Bayesian geostatistical inverse approach that is well suited to accommodate a flexible model with the level of complexity driven by the data and explicitly considering uncertainty. Prior information is incorporated through the selection of a parameter covariance model characterizing continuity and providing stability. Often, discontinuities in the parameter field, typically caused by geologic contacts between contrasting lithologic units, necessitate subdivision into zones across which there is no correlation among hydraulic parameters. We propose an interactive protocol in which zonation candidates are implied from the data and are evaluated using cross validation and expert knowledge. Uncertainty introduced by limited knowledge of dynamic regional conditions is mitigated by using drawdown rather than native head values. An adjoint state formulation of MODFLOW-2000 is used to calculate sensitivities which are used both for the solution to the inverse problem and to guide protocol decisions. The protocol is tested using synthetic two-dimensional steady state examples in which the wells are located at the edge of the region of interest.
Robust controller synthesis for a large flexible space antenna

The linear-quadratic Gaussian/loop-transfer-recovery method is used to synthesize a fine-pointing control system for a large space antenna. A finite-element model for the 122-m hoop/column antenna is employed, and a compensator, utilizing attitudes sensors and torque actuators, is designed which achieves pointing performance while maintaining stability robustness to unmodeled dynamics. Inclusion of the rigid-body modes plus the first three elastic modes is found to be necessary to achieve a 0.1-rad/s bandwidth. Results are obtained by employing a modification of the standard robustness recovery procedure, which reduces the conservative nature of the design methodology. Performance degradation is encountered due to the presence of unavoidable invariant zeros within the design bandwidth.
Models of fermion mass matrices based on a flavor- and generation-dependent U(1) gauge symmetry

Abstract We study models of fermion mass matrices based on a flavor- and generation-dependent string-motivated U(1) A gauge symmetry and report two new classes of solutions to the requisite consistency conditions. In particular, we explore the idea that the fundamental reason underlying the striking feature m b , m r ⪡ m t is that all of the elements of the down-quark and charged lepton effective Yukawa matrices actually arise from higher-dimension operators, suppressed by inverse powers of the Planck mass. We construct an explicit model embodying this idea, in which only the jk = 33 element of the Q = 2 3 effective Yukawa matrix Y jk u arises from dimension-4 operators.