cssi/SciSciGPT-SciSciNet huggingface dataset:
Influence of Fuel Chemical Properties on Soot Emissions from Gas Turbine Combustors

Abstract The influence of fuel composition on soot emissions from continuous flow combustors is examined. A study of the combustion characteristics of a wide range of aviation fuels suggests that smoke point provides a better indication of sooting tendency than does hydrogen content. It is concluded from this study that the best empirical relationship between fuel chemical composition and soot emissions is one which combines two fuel composition parameters—smoke point and naphthalene content—into a single parameter which is shown to correlate successfully soot emissions data acquired from several different fuels burning in a variety of gas turbine and model combustors.
Optogenetics: development and application

Integrating microbial opsins and solid-state optics allows millisecond-precision bidirectional control of defined cell types in freely behaving mammals. Following the introduction of the microbial opsin genes ChR2 and NpHR to neurobiology, genomic strategies allowed the discovery and adaptation for neuroscience of a third major optogenetic tool, namely a cation channel (VChR1) with action spectrum significantly redshifted relative to ChR2, to allow tests of the combinatorial interaction of cell types in circuit computation or behavior. We also have developed genetic targeting tools for versatile use of microbial opsins with existing resources including cell type-specific promoter fragments or Cre-LoxP mouse driver lines suitable for a wide variety of neuroscience investigations, and developed integrated fiberoptic and solid-state optical approaches to provide the complementary technology to allow specific cell types, even deep within the brain, to be controlled in freely behaving mammals.
Uniqueness and non-uniqueness in inverse radiative transfer

We characterize the non-uniqueness in the inverse problem for the stationary transport model, in which the absorption a and the scattering coefficient k of the media are to be recovered from the albedo operator. We show that "gauge equivalent" pairs (a, k) yield the same albedo operator, and that we can recover uniquely the class of the gauge equivalent pairs. We apply this result to show unique determination of the media when the absorption a depends on the line of travel through each point while the scattering k obeys a symmetry property. Previously known results concerned the directional independent absorption a.
Inverse mean curvature flows in the hyperbolic 3-space revisited

This note revisits the inverse mean curvature flow in the 3-dimensional hyperbolic space. In particular, we show that the limiting shape is not necessarily round after scaling, thus resolving an inconsistency in the literature. The same conclusion is obtained for n-dimensional hyperbolic space as well.
SURFACE COMPLEXITY COMPONENT OF LIDAR POINT CLOUD ERROR CHARACTERIZATION

Abstract. There are several data product characterization methods to describe LiDAR data quality. Typically based on guidelines developed by government or professional societies, these techniques require the statistical analysis of vertical differences at known checkpoints (surface patches) to obtain a measure of the vertical accuracy. More advanced methods attempt to also characterize the horizontal accuracy of the LiDAR point cloud, using measurements at LiDAR-specific targets or other man-made objects that can be distinctly extracted from both horizontal and vertical representation in the LiDAR point cloud. There are two concerns with these methods. First, the number of check points/features is relatively small with respect to the point cloud size that is typically measured, at least, in millions. Second, these locations are usually selected in relatively benign areas, such as hard flat surfaces at easily accessible locations. The problem with this characterization is that it is not likely that a statistically representative analysis can be obtained from a limited number of points at locations that may not properly represent the overall object space composition. There is an ongoing effort to address these issues, and some of the newer methods to characterize LiDAR data include an average points spacing measure, computed from the LiDAR point cloud. Clearly, it is an important step forward but it ignores the surface complexity. The objective of this study is to elaborate only on the requirements for adequate surface representation in combination with the LiDAR error characterization techniques to identify the relation between the two surfaces, the measured and reference (ideal), and thus, to support better LiDAR or, in general, point cloud error characterization.
A matroid invariant via the K-theory of the Grassmannian

Abstract Let G ( d , n ) denote the Grassmannian of d-planes in C n and let T be the torus ( C ∗ ) n / diag ( C ∗ ) which acts on G ( d , n ) . Let x be a point of G ( d , n ) and let T x ¯ be the closure of the T-orbit through x. Then the class of the structure sheaf of T x ¯ in the K-theory of G ( d , n ) depends only on which Plucker coordinates of x are nonzero – combinatorial data known as the matroid of x. In this paper, we will define a certain map of additive groups from K ○ ( G ( d , n ) ) to Z [ t ] . Letting g x ( t ) denote the image of ( − 1 ) n − dim T x [ O T x ¯ ] , g x behaves nicely under the standard constructions of matroid theory, such as direct sum, two-sum, duality and series and parallel extensions. We use this invariant to prove bounds on the complexity of Kapranov's Lie complexes [M. Kapranov, Chow quotients of Grassmannians I, Adv. Soviet Math. 16 (2) (1993) 29–110], Hacking, Keel and Tevelev's very stable pairs [P. Hacking, S. Keel, E. Tevelev, Compactification of the moduli space of hyperplane arrangements, J. Algebraic Geom. 15 (2006) 657–680] and the author's tropical linear spaces when they are realizable in characteristic zero [D. Speyer, Tropical linear spaces, SIAM J. Discrete Math. 22 (4) (2008) 1527–1558]. Namely, in characteristic zero, a Lie complex or the underlying ( d − 1 ) -dimensional scheme of a very stable pair can have at most ( n − i − 1 ) ! ( d − i ) ! ( n − d − i ) ! ( i − 1 ) ! strata of dimensions n − i and d − i , respectively. This prove the author's f-vector conjecture, from [D. Speyer, Tropical linear spaces, SIAM J. Discrete Math. 22 (4) (2008) 1527–1558], in the case of a tropical linear space realizable in characteristic 0.
Compressing Phasor Measurement data

Phasor Measurement units (PMU's) are becoming standard equipment in electrical grids around the world. They are capable of generating a significant amount of data on a continuous basis from distribution and transmission networks. Several months of data from 2 PMU's situated on a distribution network were captured in raw format. This data was separated by measurement type and compressed using a number of standard compression algorithms. The results show the compressibility of PMU data for these algorithms and are used to estimate the space requirements for storing a day of data from a single PMU.
SYNTHESIS OF SELENIUM-DERIVATIZED NUCLEOSIDES AND OLIGONUCLEOTIDES FOR X-RAY CRYSTALLOGRAPHY

We report here the synthesis of nucleoside and oligonucleotide analogs containing selenium, which serves as an anomalous scattering center to enable MAD phase determination in nucleotide X-ray crystallography. We have developed a phase transfer approach to introduce the selenium functionality in A, C, G, T, and U nucleosides at 5′-positions. In the incorporation of the selenium functionality, the leaving groups (bromide, mesyl, and tosyl) were readily displaced by sodium selenide, sodium diselenide, and sodium methyl selenide with yields higher than 90%. Selenium-derivatized oligonucleotides have been synthesized via phosphoramidite chemistry.
Simple conversion of aryl bromides to arylmethylphosphonates

Abstract Aryl bromides in tetrahydrofuran when combined with t -butyllithium and then with cuprous iodide and diethyl chloromethylphosphonate give diethyl arylmethylphosphonates.
Computational Experience With Confidence Regions and Confidence Intervals for Nonlinear Least Squares

We present the results of a Monte Carlo study of the leading methods for constructing approximate confidence regions and confidence intervals for parameters estimated by nonlinear least squares. We examine three variants of the linearization method, the likelihood method, and the lack-of-fit method. The linearization method is computationally inexpensive, produces easily understandable results, and is widely used in practice. The likelihood and lack-of-fit methods are much more expensive and more difficult to report. In our tests, both the likelihood and lack-of-fit methods perform very reliably. All three variants of the linearization method, however, often grossly underestimate confidence regions and sometimes significantly underestimate confidence intervals. The linearization method variant based solely on the Jacobian matrix appears preferable to the two variants that use the full Hessian matrix because it is less expensive, more numerically stable, and at least as accurate. The Bates and Watts curvat...
Metal-CO2 Propulsion for Mars Missions : Current Status and Opportunities

*† Metal-CO2 propulsion is less known than other Mars in-situ resource utilization (ISRU) technologies. This concept, based on using Martian carbon dioxide as an oxidizer in jet or rocket engines, offers the advantage of no chemical processing for CO2 and thus requires less power consumption than ISRU alternatives. In this paper, we review various aspects of metal-CO2 propulsion, such as combustion of magnesium and aluminum in CO2, engine types and characteristics, production of liquid CO2 and metal fuel on Mars, and potential missions. Lunar and terrestrial applications are also discussed. I. Introduction N-SITU Resource Utilization (ISRU) is recognized as an enabling technology for exploration of Mars, which can significantly reduce the mass, cost, and risk of robotic and human missions. The critical element in future missions is the large mass of propellant for a Mars ascent vehicle, while power and propellant to accommodate a long stay and mobility on Mars are also important. Transportation of propellant from Earth to Mars requires tremendous increase in the initial mass of hardware in low Earth orbit (and hence mission cost) as compared to prior no-return missions. Fortunately, Mars possesses resources that can be used for propellant production. The Martian atmosphere consisting of 95% CO2 is the obvious and most promising in-situ resource. I
Optical trapping of dielectric nanoparticles in resonant cavities

We theoretically investigate the opto-mechanical interactions between a dielectric nanoparticle and the resonantly enhanced optical field inside a high Q, small-mode-volume optical cavity. We develop an analytical method based on open system analysis to account for the resonant perturbation due to particle introduction and predict trapping potential in good agreement with three-dimensional (3D) finite-difference time-domain (FDTD) numerical simulations. Strong size-dependent trapping dynamics distinctly different from free-space optical tweezers arise as a consequence of the finite cavity perturbation. We illustrate single nanoparticle trapping from an ensemble of monodispersed particles based on size-dependent trapping dynamics. We further discover that the failure of the conventional dipole approximation in the case of resonant cavity trapping originates from a new perturbation interaction mechanism between trapped particles and spatially localized photons.
Efficiency and nash equilibria in a scrip system for P2P networks

A model of providing service in a P2P network is analyzed. It is shown that by adding a scrip system, a mechanism that admits a reasonable Nash equilibrium that reduces free riding can be obtained. The effect of varying the total amount of money (scrip) in the system on efficiency (i.e., social welfare) is analyzed, and it is shown that by maintaining the appropriate ratio between the total amount of money and the number of agents, efficiency is maximized. The work has implications for many online systems, not only P2P networks but also a wide variety of online forums for which scrip systems are popular, but formal analyses have been lacking.
THE RATE OF RETURN ON SAVINGS AND LOAN ASSETS

Using Cointegration Tests, Granger‐Causality Tests, and OLS, this study empirically investigates the determinants of the rate of return on savings and loan assets over the 1965–1991 period. It is found that it is determined by the mortgage rate, the capital/asset ratio, the price of imported crude oil, the cost of deposits, and the ceiling on federal deposit insurance.
SUPPLY RESPONSE WITH STOCHASTIC TECHNOLOGY AND PRICES IN AUSTRALIA'S RURAL EXPORT INDUSTRIES

Risky output prices and production characterise Australian agriculture. Exports are vitally important, sometimes relying heavily on a particular market. In this study a model is developed to include explicitly both output price and technological risks as well as multiple output relationships. It is used to show that changes in US beef import policy generating a 10 per cent beef price fall could reduce Australian beef supply by 3.5 per cent and grazing industry net revenue by 8.4 per cent, despite some switching from beef production to other enterprises.
Enantioselective Iodolactonization of Disubstituted Olefinic Acids Using a Bifunctional Catalyst

The enantioselective iodolactonizations of a series of diversely substituted olefinic carboxylic acids are promoted by a BINOL-derived, bifunctional catalyst. Reactions involving 5-alkyl- and 5-aryl-4(Z)-pentenoic acids and 6-alkyl- and 6-aryl-5(Z)-hexenoic acids provide the corresponding γ- and δ-lactones having stereogenic C–I bonds in excellent yields and >97:3 er. Significantly, this represents the first organocatalyst that promotes both bromo- and iodolactonization with high enantioselectivities. The potential of this catalyst to induce kinetic resolutions of racemic unsaturated acids is also demonstrated.
Refined filtering of image noise using local statistics

An effective algorithm for digital image noise filtering is presented in this paper. Mostnoise filtering techniques such as Kalman filter and transform domain methods require extensive image modeling and produce filtered images with considerable contrast loss. The algorithm proposed in this paper is an extension of Lee's local statistics method modified to utilize local gradient information. It does not require image modeling, and it will not smear edges and subtle details. For both the additive and multiplicative noise cases, the local mean and variance are computed from a reduced set of pixels depending on the orientation of the edge. Consequently, noise along the edge is removed, and the sharpness of the edge is enhanced. For practical applications when the noise variance is spatially varying and unknown, an adaptive filtering algorithm is developed. Experiments show its good potential for processing real-life images. Examples on images containing 256×256 pixels are given to substantiate the theoretical development.
Theoretical and experimental studies of the 3-aza-Claisen rearrangement

Abstract Semiempirical calculations support a spin-paired chair-like TS for the 3-aza-Claisen rearrangement, and yield the prediction that an anionic substituent on the nitrogen atom reduces the activation energies for the rearrangement. Attempts to demonstrate this experimentally have been unsuccessful.
Saddles, twists, and curls: shape transitions in freestanding nanoribbons

Efforts to modulate the electronic properties of atomically thin crystalline nanoribbons requires precise control over their morphology. Here, we perform atomistic simulations on freestanding graphene nanoribbons (GNRs) to first identify the minimal shapes as a function of ribbon width, and then develop a core-edge framework based on classical plate theory to explore the effect of size and ribbon elasticity in more general systems. The elastic edge-edge interactions are central to stabilization of the flat phase in ultra-narrow ribbons, and their bifurcation to twisted and bent shapes at critical widths that vary inversely with edge stress. In the case of compressive edge stress, we uncover hitherto ignored saddle shapes that are energetically indistinguishable with twisted shapes in the vicinity of the bifurcation yet dominate the morphological space with increasing width. At much larger widths with negligible edge-edge interactions, rippling instabilities set in, i.e. edge ripples and midline dimples for compressive and tensile edge stresses, respectively. Simulations of tapering GNRs reveal the dynamics of these shape transitions. Our results capture the interplay between geometry and mechanics that sets the morphology of crystalline nanoribbons and also highlight the utility of the core-edge framework in developing a unified understanding of the interplay.
A harmonic retrieval framework for discontinuous motion estimation

Motion discontinuities arise when there are occlusions or multiple moving objects in the scene that is imaged. Conventional regularization techniques use smoothness constraints but are not applicable to motion discontinuities. In this paper, we show that discontinuous (or multiple) motion estimation can be viewed as a multicomponent harmonic retrieval problem. From this viewpoint, a number of established techniques for harmonic retrieval ran be applied to solve the challenging problem of discontinuous (or multiple) motion. Compared with existing techniques, the resulting algorithm is not iterative, which not only implies computational efficiency but also obviates concerns regarding convergence or local minima. It also adds flexibility to spatio-temporal techniques which have suffered from lack of explicit modeling of discontinuous motion. Experimental verification of our framework on both synthetic data as well as real image data is provided.
Overlap for Majorana-Weyl fermions

Abstract The power of the overlap formalism is illustrated by regularizing theories based on Majorana-Weyl fermions.
Area minimization among marginally trapped surfaces in Lorentz–Minkowski space

We study an area minimization problem for spacelike zero mean curvature surfaces in four dimensional Lorentz–Minkowski space. The areas of these surfaces are compared of with the areas of certain marginally trapped surfaces having the same boundary values.
Sensitivity of the Astrometric Technique in Detecting Outer Planets

With the advent of optical interferometers that will be coming on line in the next decade, radial velocity searches for extrasolar planets will be complemented by high angular resolution astrometric measurements. In this paper, we explore the sensitivity of the astrometric technique, and develop an analytical understanding of the sensitivity in the regime where the orbital period is longer than the time baseline of the survey. As in an earlier paper that dealt with the radial velocity technique, our analysis of the astrometric technique utilizes both the orbital amplitude and phase.
Physicalism and the Fallacy of Composition

Physicalism, as I treat it here, holds that every instance of causationreported by the special sciences is shadowed, even rivalled, by causation atthe level of microphysics. The reported ‘cause’ is embodied in one massive collection of microparticle events; the ‘event’ in another; the former brings about the latter in accordance with the laws of microphysics. I argue that while individual events in the ‘cause’ collection bring about individual events in the ‘effect’ collection, it does not follow, and typically is unbelievable, that the ‘cause’ collection itself brings anything about. For typically that collection is too sprawling and disconnected from the standpoint of microphysics to do anything. Causings reported by the special sciences can be traced only at that level. This is actually unsurprising, since the objects of such sciences are not mere parcels of microparticles, but genuine wholes with natures of their own.
X-rays from quasars and active galaxies

We review some of the most important theoretical ideas and observations for quasars and the nuclei of active galaxies, and suggest areas of future research. Emphasis is on the nature of the power source, the radiation processes, and the mechanism for formation and collimation of jets. Phenomena that produce X-rays are of particular concern. Particular topics discussed are the observed and expected time variability, the gas supply mechanisms and luminosity evolution, thermal and nonthermal radiation processes, observed and theoretical spectra, criteria for thermalization of electrons and ions, effects of electron-positron pairs on relativistic plasmas, hydrodynamic, electrodynamic and inertial methods for producing and confining jets. We conclude with a list of needed observations.
RESULTS FROM PHENIX AT RHIC WITH IMPLICATIONS FOR LHC

Results from the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) in nucleus-nucleus and proton-proton collisions at c.m. energy {radical}s{sub NN} = 200 GeV are presented in the context of the methods of single and two-particle inclusive reactions which were used in the discovery of hard-scattering in p-p collisions at the CERN ISR in the 1970's. These techniques are used at RHIC in A + A collisions because of the huge combinatoric background from the large particle multiplicity. Topics include J/{Psi} suppression, jet quenching in the dense medium (sQGP) as observed with {pi}0 at large transverse momentum, thermal photons, collective flow, two-particle correlations, suppression of heavy quarks at large p{sub T} and its possible relation to Higgs searches at the LHC. The differences and similarities of the measurements in p-p and A + A collisions are presented. The two discussion sessions which followed the lectures on which this article is based are included at the end.
Multiplicative noise: Applications in cosmology and field theory

Physical situations involving multiplicative noise arise generically in cosmology and field theory. In this paper, the focus is first on exact nonlinear Langevin equations, appropriate in a cosmological setting, for a system with one degree of freedom. The Langevin equations are derived using an appropriate time-dependent generalization of a model due to Zwanzig. These models axe then extended to field theories and the generation of multiplicative noise in such a context is discussed. Important issues in both the cosmological and field theoretic cases are the fluctuation-dissipation relations and the relaxation time scale. Of some importance in cosmology is the fact that multiplicative noise can substantially reduce the relaxation time. In the field theoretic context such a noise can lead to a significant enhancement in the nucleation rate of topological defects.
Thermal loads on tokamak plasma-facing components during normal operation and disruptions

Abstract Power loadings experienced by tokamak plasma-facing components during normal operation and during off-normal events are discussed. A model for power and particle flow in the tokamak boundary layer is presented and model predictions are compared to infrared measurements of component heating. The inclusion of the full three-dimensional geometry of the component and of the magnetic flux surface is very important in the modeling. Experimental measurements show that misalignment of component armour tile surfaces by only a millimeter can lead to significant localized heating. An application to the design of plasma-facing components for future machines is presented. Finally, thermal loads expected during tokamak disruptions are discussed. The primary problems are surface melting and vaporization due to localized intense heating during the disruption thermal quench and volumetric heating of the component armour and structure due to localized impact of runaway electrons.
Stock price effects of the allowance of LIFO for tax purposes

Abstract I investigate stock price behavior associated with the allowance of LIFO for tax purposes. The analysis is structured as an event study of the Revenue Acts of 1938 and 1939. The results indicate a positive net market reaction to legislative events leading to LIFO's incorporation into the US tax code for the sample firms having the largest estimated LIFO tax benefits. I conclude the market revised its probabilities that firms most likely to benefit would avail themselves of the opportunity to use LIFO and defer taxes on inventory profits.
Inconsistencies of massive charged gravitating higher spins

We examine the causality and degree-of-freedom (DoF) problems encountered by charged, gravitating, massive higher spin fields. For spin s = 3/2, making the metric dynamical yields improved causality bounds. These involve only the mass, the product eMP of the charge and Planck mass and the cosmological constant Λ. The bounds are themselves related to a gauge invariance of the timelike component of the field equation at the onset of acausality. While propagation is causal in arbitrary E/M backgrounds, the allowed mass ranges of parameters are of Planck order. Generically, interacting spins s > 3/2 are subject to DoF violations as well as to acausality; the former must be overcome before analysis of the latter can even begin. Here we review both difficulties for charged s = 2 and show that while a g-factor of 1/2 solves the DoF problem, acausality persists for any g. Separately we establish that no s = 2 theory — DoF preserving or otherwise — can be tree unitary.
Physical model for vaporization

Based on two assumptions, the surface layer is flexible, and the internal energy of the latent heat of vaporization is completely utilized by the atoms for overcoming on the surface resistance of the liquid, the enthalpy of vaporization was calculated for 45 elements. The theoretical values were tested against experiments with positive result.
Potential flow downstream of the heliospheric terminal shock: A non-spherical shock

We have solved for the potential flow downstream of the terminal shock of the solar wind in the limit of small departures from a spherical shock due to a latitudinal ram pressure variation in the supersonic solar wind. The solution connects anisotropic streamlines at the shock to uniform streamlines down the heliotail because we use a non-slip boundary condition on the heliopause at large radii. The rotational velocity about the heliotail in the near-field solution decays as the fourth power of distance from the shock. The polar divergence of the streamlines will have consequences for the previously discussed magnetic pressure ridge that may build-up just inside the heliopause.
Standardizing the MR image intensity scales: Making MR intensities have tissue specific meaning

One of the major drawbacks of Magnetic Resonance Imaging (MRI) has been the lack of a standard and quantifiable interpretation of image intensities. Unlike in other modalities such as x-ray computerized tomography, MR images taken for the same patient on the same scanner at different times may appear different from each other due to a variety of scanner-dependent variations, and therefore, the absolute intensity values do not have a fixed meaning. We have devised a two-step method wherein all images can be transformed in such a way that for the same protocol and body region, in the transformed images similar intensities will have similar tissue meaning. Standardized images can be displayed with fixed windows without the need of per case adjustment. More importantly, extraction of quantitative information with fixed windows without the need of per case adjustment. More importantly, extraction of quantitative information about healthy organs or about abnormalities can be considerably simplified. This paper introduces and compares new variants of this standardizing method that can help to overcome some of the problems with the original method.
OB associations: Massive stars in context

Massive stars are important in a variety of contexts: individually they are examples of stars that undergo significant mass loss which is driven by line radiation pressure; as denizens of the Galaxy they play a significant role in the galactic recycling effort; a ensembles of stars they contain clues to massive star evolution in general and the question of supernova progenitors in particular. Finally, under extreme conditions of pathological star formation massive stars participate in the star burst phenomena seen in some galaxies. If we wish to understand starbursts, we must first understand locally observed variations in the mas spectrum. But all of these diverse areas of study rely on certain fundamental parameters of the stars themselves--here we include temperature, luminosity, mass, and chemical composition. And central to accurate determinations of these parameters are the distances to the stars. This review will focus on what is known about hte loose clustering of massive stars termed OB associations. These associations ontain many, but byno means all, of the stars with masses greater than about 15 solar masses. Most of our knowledge of the stellar content of the OB associations in our own Galaxy is surprisingly sketchy due to their large angular size, but large-field CCD detectors are changing this. Magellanic Cloud associations can now be compared with OB associations in our own Galaxy, and the initial mass function shows suprising variations. The physical cause of these variations is still unknown. Another development is the study of embedded star clusters: infrared array detectors have been probing the buried stars in molecular clouds and finding an unexpectedly large population of these objects. Both these young IR clusters, and a springling of evolved red supergiants, suggest that the star formation history of OB associations may be more complicated than we have supposed.
Effects of DNase production, plasmid size, and restriction barriers on transformation of Vibrio cholerae by electroporation and osmotic shock

Attempts to transform wilt type strains of V. cholerae with plasmid DNA by traditional osmotic shock methods were note successful. A mutant of V. cholerae that was deficient in extracellular DNase was transformed with plasmid DNA by osmotic shock, demonstrating directly that extracellular DNase is a major barrier to transformation of V. cholerae. Transformation of wild type of DNase-negative strains of V. cholerae was accomplished by electroporation. Efficiency of transformation by electroporation increased with field strength, decreased with plasmid size, and was relatively insensitive to changes in the electrolyte composition of the buffer as long as isotonic sucrose was present. Host-controlled modification/restriction systems also affected transformation efficiency in V. cholerae.
Optofluidic assembly of microdisk lasers on a silicon chip

A room-temperature optofluidic assembly process to integrate III-V microdisk lasers on a silicon chip is demonstrated. The assembly is accomplished using lateral-field optoelectronic tweezers, which achieves an unoptimized placement accuracy of approximately plusmn 0.25 mum.
Theory of metal insulator transition in strongly correlated electron systems

Abstract A comprehensive theory of the correlation driven metal insulator transition in 1D and 2D strongly correlated electron systems is given. In both the 1D and 2D Hubbard model the metal insulator transition encountered close to half filling is of Pokrovsky-Talapov type. An important consequence of this in the 2D Hubbard model is the break down of the Fermi liquid theory. We also describe in detail the properties of the Pokrovsky-Talapov transition in 2D ferroelectrics.
Combinatorics of rank jumps in simplicial hypergeometric systems

Let A be an integer d x n matrix, and assume that the convex hull conv(A) of its columns is a simplex of dimension d - 1 not containing the origin. It is known that the semigroup ring C[NA] is Cohen-Macaulay if and only if the rank of the GKZ hypergeometric system H A (β) equals the normalized volume of conv(A) for all complex parameters β ∈ C d (Saito, 2002). Our refinement here shows that H A (β) has rank strictly larger than the volume of conv(A) if and only if β lies in the Zariski closure (in C d ) of all Z d -graded degrees where the local cohomology ⊕ i<d H i m (C[NA]) is nonzero. We conjecture that the same statement holds even when conv(A) is not a simplex.
Constructing all self-adjoint matrices with prescribed spectrum and diagonal

The Schur---Horn Theorem states that there exists a self-adjoint matrix with a given spectrum and diagonal if and only if the spectrum majorizes the diagonal. Though the original proof of this result was nonconstructive, several constructive proofs have subsequently been found. Most of these constructive proofs rely on Givens rotations, and none have been shown to be able to produce every example of such a matrix. We introduce a new construction method that is able to do so. This method is based on recent advances in finite frame theory which show how to construct frames whose frame operator has a given prescribed spectrum and whose vectors have given prescribed lengths. This frame construction requires one to find a sequence of eigensteps, that is, a sequence of interlacing spectra that satisfy certain trace considerations. In this paper, we show how to explicitly construct every such sequence of eigensteps. Here, the key idea is to visualize eigenstep construction as iteratively building a staircase. This visualization leads to an algorithm, dubbed Top Kill, which produces a valid sequence of eigensteps whenever it is possible to do so. We then build on Top Kill to explicitly parametrize the set of all valid eigensteps. This yields an explicit method for constructing all self-adjoint matrices with a given spectrum and diagonal, and moreover all frames whose frame operator has a given spectrum and whose elements have given lengths.
Variables separated equations: Strikingly different roles for the Branch Cycle Lemma and the finite simple group classification

Davenport’s Problem asks: What can we expect of two polynomials, over Z, with the same ranges on almost all residue class fields? This stood out among many separated variable problems posed by Davenport, Lewis and Schinzel. By bounding the degrees, but expanding the maps and variables in Davenport’s Problem, Galois stratification enhanced the separated variable theme, solving an Ax and Kochen problem from their Artin Conjecture work. Denef and Loeser applied this to add Chow motive coefficients to previously introduced zeta functions on a diophantine statement. By restricting the variables, but leaving the degrees unbounded, we found the striking distinction between Davenport’s problem over Q, solved by applying the Branch Cycle Lemma, and its generalization over any number field, solved by using the simple group classification. This encouraged Thompson to formulate the genus 0 problem on rational function monodromy groups. Guralnick and Thompson led its solution in stages. We look at two developments since the solution of Davenport’s problem. We use these to consider: Going beyond the simple group classification to handle imprimitive groups, and what is the role of covers and correspondences in going from algebraic equations to zeta functions with Chow motive coefficients.
Semiclassical approach for multiparticle production in scalar theories

We propose a semiclassical approach to calculate multiparticle cross sections in scalar theories, which have been strongly argued to have the exponential form exp(λ−1 F(λn, ϵ)) in the regime λ → 0, λn, ϵ = fixed, where λ is the scalar coupling, n is the number of produced particles, and ϵ is the kinetic energy per final particle. The formalism is based on singular solutions to the field equation, which satisfy certain boundary and extremizing conditions. At low multiplicities and small kinetic energies per final particle we reproduce in the framework of this formalism the main perturbative results. We also obtain a lower bound on the tree-level cross section in the ultra-relativistic regime.
A new SISO algorithm with application to turbo equalization

In this paper we propose a new soft-input soft-output equalization algorithm, offering very good performance/complexity tradeoffs. It follows the structure of the BCJR algorithm, but dynamically constructs a simplified trellis during the forward recursion. In each trellis section, only the M states with the strongest forward metric are preserved, similar to the M-BCJR algorithm. Unlike the M-BCJR, however, the remaining states are not deleted, but rather merged into the surviving states. The new algorithm compares favorably with the reduced-state BCJR algorithm, offering better performance and more flexibility, particularly for systems with higher order modulations
Anionic Oxy-Claisen Rearrangement of a Tricyclic α-Allyloxy Ketone

Abstract Preparatively useful reaction conditions for the anionic oxy-Claisen rearrangement of an α-allyloxy ketone ( 6 ) possessing acidic α - and α′-hydrogens are described. The reaction rate and efficiency are strongly influenced by both solvent and counterion. The product, 8 , although formally the product of [3,3]-sigmatropic rearrangement of enolate 7 , may in fact arise via a [2,3]-Wittig followed by one or more [1,2]-acyloin rearrangements.
Design and analysis of Toeplitz preconditioners

The solution of symmetric positive definite Toeplitz systems Ax=b by the preconditioned conjugate gradient (PCG) method was recently proposed by Strang (1986) and analyzed by Chan (1989) and Chan and Strang (1989). The convergence rate of the PCG method depends on the choice of preconditioners for the given Toeplitz matrices. The authors present a general approach to the design of Toeplitz preconditioners based on the idea to approximate a partially characterized linear deconvolution with circular deconvolutions. All resulting preconditioners can therefore be inverted via various fast transform algorithms with O(N log N) operations. For a wide class of problems, the PCG method converges in a finite number of iterations independent of N so that the computational complexity for solving these Toeplitz systems is O(N log N). >
Stack inspection: Theory and variants

Stack inspection is a security mechanism implemented in runtimes such as the JVM and the CLR to accommodate components with diverse levels of trust. Although stack inspection enables the fine-grained expression of access control policies, it has rather a complex and subtle semantics. We present a formal semantics and an equational theory to explain how stack inspection affects program behavior and code optimisations. We discuss the security properties enforced by stack inspection, and also consider variants with stronger, simpler properties.
Tests for assessment of agreement using probability criteria

Abstract For the assessment of agreement using probability criteria, we obtain an exact test, and for sample sizes exceeding 30, we give a bootstrap- t test that is remarkably accurate. We show that for assessing agreement, the total deviation index approach of Lin [2000. Total deviation index for measuring individual agreement with applications in laboratory performance and bioequivalence. Statist. Med. 19, 255–270] is not consistent and may not preserve its asymptotic nominal level, and that the coverage probability approach of Lin et al. [2002. Statistical methods in assessing agreement: models, issues and tools. J. Amer. Statist. Assoc. 97, 257–270] is overly conservative for moderate sample sizes. We also show that the nearly unbiased test of Wang and Hwang [2001. A nearly unbiased test for individual bioequivalence problems using probability criteria. J. Statist. Plann. Inference 99, 41–58] may be liberal for large sample sizes, and suggest a minor modification that gives numerically equivalent approximation to the exact test for sample sizes 30 or less. We present a simple and accurate sample size formula for planning studies on assessing agreement, and illustrate our methodology with a real data set from the literature.
Algebraic Nonlinear Collective Motion

Abstract Finite-dimensional Lie algebras of vector fields determine geometrical collective models in quantum and classical physics. Every set of vector fields on Euclidean space that generates the Lie algebra sl(3, R) and contains the angular momentum algebra so(3) is determined. The subset of divergence-free sl(3, R) vector fields is proven to be indexed by a real numberΛ. TheΛ=0 solution is the linear representation that corresponds to the Riemann ellipsoidal model. The nonlinear group action on Euclidean space transforms a certain family of deformed droplets among themselves. For positiveΛ, the droplets have a neck that becomes more pronounced asΛincreases; for negativeΛ, the droplets contain a spherical bubble of radius |Λ|1/3. The nonlinear vector field algebra is extended to the nonlinear general collective motion algebra gcm(3) which includes the inertia tensor. The quantum algebraic models of nonlinear nuclear collective motion are given by irreducible unitary representations of the nonlinear gcm(3) Lie algebra. These representations model fissioning isotopes (Λ>0) and bubble and two-fluid nuclei (Λ
A gas that sinks in a liquid-the first helium experiment published by Kamerlingh Onnes.

The year 1906 was a year of many remarkable achievements in the laboratory of Kamerlingh Onnes and his staff. They put into operation a hydrogen liquefier producing 4 l h−1, followed by a liquid-hydrogen cryostat for work below 21 K. They prepared their first sample of 2 l of helium gas. Pressure–volume–temperature measurements down to 54 K were in progress for hydrogen, and initiated for helium, in order to obtain an estimate for the critical temperature of helium; this estimate was urgently needed for design of a helium liquefier. Towards the end of 1906, Kamerlingh Onnes performed the first helium experiment at liquid-hydrogen temperature: a test of the phase behaviour of a mixture of hydrogen and helium. In the process, he discovered what he termed the barotropic effect: at increasing pressure, the helium-rich vapour phase sank to the bottom, having become heavier than the hydrogen-rich liquid phase. This paper describes the experiment and the resulting flurry of activity by Van der Waals, Kamerlingh Onnes, Keesom and Van Laar, all trying to understand and model the curious phase behaviour, as well as earlier relevant work by Van der Waals, Korteweg, Kuenen and Van Laar.
Post-Main-Sequence Changes in Rotational Velocities

For 1377 dwarfs and 381 giants of types B and A, we present mean observed projected rotational velocities for normal plus abnormal spectral types combined. For the dwarfs, V sin i is statistically constant at 127 ± 15 km s-1 from B0 V to A5 V. Using the interior models of Bertelli et al., we predict the rotational velocities of the giants. We assume an age of 30 × 106 yr for the observed dwarfs. The predicted giant rotational velocities agree well with the observed values if angular momentum is conserved in rigid-body rotation; the observed minus the computed is -7 ± 4 km s-1. Significant loss of angular momentum by mass loss (stellar winds) cannot occur because the observed rotational velocities of the giants are already at the maximum level allowed by either conservation mechanism. Comparison with three other studies indicates that angular momentum is conserved by rigid-body rotation if the expansion is less than a factor of 4, but conserved in shells if the expansion is more.
The relationship of RSV-specific immunoglobulin E antibody responses in infancy, recurrent wheezing, and pulmonary function at age 7-8 years.

In order to determine if respiratory syncytial virus (RSV)-specific IgE responses at the time of bronchiolitis in infancy are related to recurrent wheezing and pulmonary function at 7–8 years of age, a cohort of 43 infants was identified at the time of their initial RSV bronchiolitis episode. RSV-specific IgE responses in nasopharyngeal secretions were determined, and patients were then followed prospectively with notation of the number of wheezing episodes and exposure to cigarette smoke at home. At 7–8 years of age the patients underwent skin testing to 7 environmental allergens and pulmonary function testing, including pulse oximetry and methacholine challenge. Pulmonary function following inhalation of bronchodilating agents was compared to baseline pulmonary function results in order to determine if abnormalities of pulmonary function were reversible. Recurrent wheezing following bronchiolitis was associated with the initial RSV-IgE response, as well as with a family history of asthma. Current wheezing at age 7–8 years was associated with 2 or more positive skin tests (P < 0.01), a history of exercise-induced wheezing (P = 0.01). and increased sensitivity to methacholine (P < 0.01). Pulmonary function test results were similar for groups with and without recurrent wheezing following bronchiolitis. For the entire study group, RSV-IgE specific responses were unrelated to pulmonary function, but small airway dysfunction was associated with passive smoking (P < 0.025), and both large airway dysfunction and increased airway reactivity were associated with the number of positive skin tests (P < 0.025). Reduced small airway function improved following bronchodilator inhalation. The degree of improvement was inversely related to the degree of baseline dysfunction (P < 0.01), and was correlated with passive smoking (P < 0.01). These findings suggest that decreased pulmonary function following bronchiolitis is related to atopy and passive cigarette smoke exposure and may be reversible. © 1993 Wiley-Liss, Inc.
An investigation of the scales in transitional boundary layers under high free-stream turbulence conditions

The scales in a transitional boundary layer subject to high (initially 8%) free-stream turbulence and strong acceleration (K as high as 9×10−6) were investigated using wavelet spectral analysis and conditional sampling of experimental data. The boundary layer shows considerable evolution through transition, with a general shift from the lower frequencies induced by the free-stream unsteadiness to higher frequencies associated with near-wall-generated turbulence. Within the non-turbulent zone of the intermittent flow, there is considerable self-similarity in the spectra from the beginning of transition to the end, with the dominant frequencies in the boundary layer remaining constant at about the dominant frequency of the free-stream. The frequencies of the energy-containing scales in the turbulent zone change with streamwise location and are significantly higher than in the non-turbulent zone. When normalized on the local viscous length scale and velocity, however, the turbulent zone spectra also show good self-similarity throughout transition. Turbulence dissipation occurs almost exclusively in the turbulent zone. The velocity fluctuations associated with dissipation are isotropic, and their normalized spectra at upstream and downstream stations are nearly identical. The distinct differences between the turbulent and non-turbulent zones suggest the potential utility of intermittency based transition models in which these zones are treated separately. The self-similarity noted in both energy containing and dissipation scales in both zones suggests possibilities for simplifying the modeling for each zone.
Stochastic competitive learning

Competitive learning systems are examined as stochastic dynamical systems. This includes continuous and discrete formulations of unsupervised, supervised, and differential competitive learning systems. These systems estimate an unknown probability density function from random pattern samples and behave as adaptive vector quantizers. Synaptic vectors, in feedforward competitive neural networks, quantize the pattern space and converge to pattern class centroids or local probability maxima. A stochastic Lyapunov argument shows that competitive synaptic vectors converge to centroids exponentially quickly and reduces competitive learning to stochastic gradient descent. Convergence does not depend on a specific dynamical model of how neuronal activations change. These results extend to competitive estimation of local covariances and higher order statistics. >