cssi/SciSciGPT-SciSciNet huggingface dataset:
On the inverse scattering problem for Jacobi matrices with the spectrum on an interval, a finite system of intervals or a cantor set of positive length

When solving the inverse scattering problem for a discrete Sturm–Liouville operator with a rapidly decreasing potential, one gets reflection coefficients s ± and invertible operators , where is the Hankel operator related to the symbol s ±. The Marchenko–Faddeev theorem [8] (in the continuous case, for the discrete case see [4, 6]), guarantees the uniqueness of the solution of the inverse scattering problem. In this article we ask the following natural question – can one find a precise condition guaranteeing that the inverse scattering problem is uniquely solvable and that operators are invertible? Can one claim that uniqueness implies invertibility or vise versa? Moreover, we are interested here not only in the case of decreasing potential but also in the case of asymptotically almost periodic potentials. So we merge here two mostly developed cases of the inverse problem for Sturm–Liouville operators: the inverse problem with (almost) periodic potential and the inverse problem with the fast decreasing potential.
From Separate and Unequal to Integrated and Equal? School Desegregation and School Finance in Louisiana

Abstract School desegregation might have induced unintended behavioral responses of white families as well as state and local governments. This paper examines these responses and is the first to study the effects of desegregation on the finances of school districts. Desegregation induced white flight from blacker to whiter public school districts and to private schools, but the local property tax base and local revenue were not adversely affected. The state legislature directed significant new funding to districts where whites were particularly affected by desegregation. Desegregation therefore appears to have achieved its intended goal of improving resources available in schools that blacks attended.
A decomposition technique for integrable functions with applications to the divergence problem

Abstract Let Ω ⊂ R n be a bounded domain that can be written as Ω = ⋃ t Ω t , where { Ω t } t ∈ Γ is a countable collection of domains with certain properties. In this work, we develop a technique to decompose a function f ∈ L 1 ( Ω ) , with vanishing mean value, into the sum of a collection of functions { f t − f ˜ t } t ∈ Γ subordinated to { Ω t } t ∈ Γ such that supp ( f t − f ˜ t ) ⊂ Ω t and ∫ f t − f ˜ t = 0 . As an application, we use this decomposition to prove the existence of a solution in weighted Sobolev spaces of the divergence problem div u = f and the well-posedness of the Stokes equations on Holder- α domains and some other domains with an external cusp arbitrarily narrow. We also consider arbitrary bounded domains. The weights used in each case depend on the type of domain.
Concurrent esterification and N-acetylation of amino acids with orthoesters: A useful reaction with interesting mechanistic implications

Abstract The concurrent esterification and N-acetylation of amino acids has been studied with triethyl orthoacetate (TEOA) and triethyl orthoformate (TEOF). In a surprising finding, only 1 equiv of TEOA in refluxing toluene was necessary to convert l -proline and l -phenylalanine into the corresponding N-acetyl ethyl esters in good yield. The same transformation using TEOF was not effective. Stereochemical outcome and stoichiometric studies as well as structural variation of the amino acids in this reaction provided unexpected mechanistic insight.
Orphan Therapies: Making Best Use of Postmarket Data

BACKGROUND Postmarket surveillance of the comparative safety and efficacy of orphan therapeutics is challenging, particularly when multiple therapeutics are licensed for the same orphan indication. To make best use of product-specific registry data collected to fulfill regulatory requirements, we propose the creation of a distributed electronic health data network among registries. Such a network could support sequential statistical analyses designed to detect early warnings of excess risks. We use a simulated example to explore the circumstances under which a distributed network may prove advantageous.
Un)Informed Charitable Giving

Abstract Evidence suggests little informed giving. To understand this behavior, we examine voluntary provision of a discrete public good with independent private values that can be ascertained at a cost. We find that an individual who considers a smaller contribution is less likely to learn her value, and thus the percentage of informed giving diminishes as the population grows. We also find that a direct grant to the charity exacerbates crowding-out by discouraging information acquisition whereas a matching grant increases donations by encouraging it. We further show that with costly information, a (first-order) stochastic increase in values can decrease donations; and that facilitating private acquisition of information can be a better fund-raising strategy than directly supplying it.
The effect of propargyl oxygen substituents in the carbene-chromium/alkyne cycloaddition

Abstract The usual reaction of alkalynes with arylcarbene chromium complexes is deflected by hte presence of propargylic alkoxy groups, especially in the case of the 2,5-dimethoxypnenyl carbene ligand; indenes and furans become significant products.
ROSAT and ASCA Observations of the Crab-like Supernova Remnant N157B in the Large Magellanic Cloud

We report the results of ROSAT and ASCA X-ray observations of the supernova remnant N157B (or 30 Dor B, SNR 0539-69.1) in the Large Magellanic Cloud. For comparison, we also briefly describe the results on SNR 0540-69.3, the only confirmed Crab-like remnant in the Cloud. The X-ray emission from N157B can be decomposed into a bright comet-shaped feature, superposed on a diffuse emission region with a dimension of ~20 pc. The flat and nearly featureless spectrum of the remnant is distinctly different from those of young shell-like remnants, suggesting a predominantly Crab-like nature of N157B. Characterized by a power law with an energy slope of ~1.5, the spectrum of N157B above ~2 keV is, however, considerably steeper than that of SNR 0540-69.3, which has a slope of ~1.0. At lower energies, the spectrum of N157B presents marginal evidence for emission lines, which if real most likely arise in hot gas of the diffuse emission region. The hot gas has a characteristic thermal temperature of 0.4-0.7 keV. No significant periodic signal is detected from N157B in the period range of 3×10-3-2000 s. The pulsed fraction is 9% (99% confidence) in the 2-7 keV range. We discuss the nature of the individual X-ray components. In particular, we suggest that the synchrotron radiation of relativistic particles from a fast-moving (~103 km s-1) pulsar explains the size, morphology, spectrum, and energetics of the comet-shaped X-ray feature. We infer the age of the remnant as ~5 × 103 yr. The lack of radio polarization of the remnant may be due to Faraday dispersion by foreground H II gas.
Classical photoabsorption sum rules

Abstract We use a quantum loop expansion to derive sum rule constraints on polarized photoabsorption cross sections in the Standard Model, generalizing earlier results obtained by Altarelli, Cabibbo, and Maiani. We show that the logarithmic integral of the spin-dependent photoabsorption cross section ∫ v th ∞ dv v δωBonn(v) vanishes foror any 2 → 2 process γa → bc in the classical, tree-graph approximation in the Standard Model, supersymmetric gauge theories, and other quantum field theories where the Drell-Hearn-Gerasimov sum rule is valid. Here ν = p · q M and Δσ ( ν ) = σ P ( ν ) f - σ A ( ν ) is the difference between the photoabsorption cross section for parallel and antiparallel photon and target helicities. Tests of the sum rule for the reactions γe → Wν and γγ → W + W f - can provide new tests of the canonical magnetic and quadrupole couplings of the Standard Model. We also extend the sum rule to certain virtual photon processes.
Continuous wavelet transform of 1-D signals by Fourier filtering

A true continuous wavelet transform (CWT) must be continuous in both shift and scale. By a continuous anamorphic transformation of a one-dimensional (1D) signal and a suitable choice of kernel or filter, we can allow a normal two-dimensional (2D) optical Fourier transform image processor to perform a CWT.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Direct, Catalytic Hydroaminoalkylation of Unactivated Olefins with N-Alkyl Arylamines

A tantalum-catalyzed addition of N-alkyl arylamine α-C−H bonds across olefins is reported. These reactions occur with mono- and 2,2-disubstituted olefins to form the branched insertion products in high yield and regioselectivity. The reactions encompass additions of the α-C−H bonds of cyclic and acyclic amines, as well as intramolecular additions. NMR studies indicate that the starting homoleptic, Ta(NMe2)5 precatalyst converts to bis- and tris(N-methylanilide) complexes (among others) in solution. Deuterium-labeling studies suggest that reversible ortho-metalation of the arene substituent occurs under the reaction conditions. However, several experiments imply that this ortho-metalation does not lie on the reaction pathway. Instead, these complexes are proposed to eliminate amine to form N-aryl imine complexes, which insert olefins into the Ta−C bond and undergo protonolysis to regenerate the active catalyst and eliminate the addition product.
A General Methodology for the Synthesis of Transition Metal Pnictide Nanoparticles from Pnictate Precursors and Its Application to Iron−Phosphorus Phases

Nanoparticles of iron phosphide have been prepared through a new strategy involving the reductive annealing of nanoparticulate iron phosphate precursors cast onto atomically flat mica surfaces. This route appears to be general for a range of transition metals and pnicogens and avoids the use of highly toxic and pyrophoric agents such as Pn(SiMe3)3 (Pn = P, As), which are commonly employed in the synthesis of pnictide nanoparticles.
Large volatility-stabilized markets

Abstract We investigate the behavior of systems of interacting diffusion processes, known as volatility-stabilized market models in the mathematical finance literature, when the number of diffusions tends to infinity. We show that, after an appropriate rescaling of the time parameter, the empirical measure of the system converges to the solution of a degenerate parabolic partial differential equation. A stochastic representation of the latter in terms of one-dimensional distributions of a time-changed squared Bessel process allows us to give an explicit description of the limit.
Strong-Lensing Time Delay: A New Way of Measuring Cosmic Shear

The phenomenon of cosmic shear, or distortion of images of distant sources unaccompanied by magnification, is an effective way of probing the content and state of the foreground universe, because light rays do not have to pass through matter clumps in order to be sheared. It is shown that the delay in the arrival times between two simultaneously emitted photons that appear to be arriving from a pair of images of a strongly lensed cosmological source contains not only information about the Hubble constant, but also the long-range gravitational effect of galactic-scale mass clumps located away from the light paths in question. This is therefore also a method of detecting shear. Data on time delays among a sample of strongly lensed sources can provide crucial information about whether extra dynamics beyond gravity and dark energy are responsible for the global flatness of space. If the standard ΛCDM model is correct, there should be a large dispersion in the value of H0 as inferred from the delay data by (the usual procedure of) ignoring the shear from all other mass clumps except the strong lens itself. The fact that there has not been any report of a significant deviation from the h = 0.7 mark during any of the H0 determinations by this technique may already be pointing to the absence of the random effect discussed here.
Congruences for the Fishburn numbers

The Fishburn numbers, (n); are dened by a formal power series expansion 1 X n=0 (n)q n = 1 + 1 X n=1 n Y j=1
Organoactinide-Mediated Hydrothiolation of Terminal Alkynes with Aliphatic, Aromatic, and Benzylic Thiols

Atom-efficient organoactinide-catalyzed intermolecular hydrothiolation of terminal alkynes is achieved by Th(IV) and U(IV) complexes to yield vinyl sulfides. The conversion is highly Markovnikov selective and is capable of utilizing aromatic, benzylic, and aliphatic thiols. Kinetic measurements of the transformation mediated by Me(2)SiCp(2)''Th[CH(2)(TMS)](2) (1a; Cp'' = eta(5)-Me(4)C(5)) shows the reaction is zero-order in [thiol], first-order in [1a], first-order in [alkyne] at lower alkyne concentrations, and zero-order at higher [alkyne]. The proposed catalytic cycle invokes turnover-limiting insertion of the alkyne into the Th-S bond followed by a rapid Th-C bond protonolysis. All reactions except entries 7 and 8 are quantitative by (1)H NMR.
Nonlinear Adaptive Control of Spacecraft Maneuvers

A novel method is presented to carry out near-minimum-time maneuvers of a spacecraft of unknown inertia. The formulation assumes the presence of three orthogonal reaction wheels located near the system mass center and oriented arbitrarily with respect to the spacecraft principal axes. Modie ed Rodrigues parameters along with their shadow set are used as the primary attitude coordinates. Open-loop maneuver laws are designed while solving the equations of motion by inversedynamics approach. This approach permits theapproximateimposition of the maximum saturation torque constraint. The torque proe les are near-bang-bang, with the instantaneous switches replaced by cubicsplinesof specie edduration.An adaptivetrackingcontrollawisdeveloped to determine perturbations to the nominal open-loop torque commands that will ensure the actual motion to follow the nominal motion in the presence of uncertainty in the inertia matrix and errors in the initial attitude. Global stability of the overall closed-loop controller is proved analytically and demonstrated by numerical simulations.
Regularization dependence of running couplings in softly broken supersymmetry

Abstract We discuss the dependence of running couplings on the choice of regularization method in a general softly-broken N = 1 supersymmetric theory. Regularization by dimensional reduction respects supersymmetry, but standard dimensional regularization does not. We find expressions for the differences between running couplings in the modified minimal subtraction schemes of these two regularization methods, to one-loop order. We also find the two-loop renormalization group equations for gaugino masses in both schemes, and discuss the application of these results to the Minimal Supersymmetric Standard Model.
Weak state routing for large-scale dynamic networks

Forwarding decisions in routing protocols rely on information about the destination nodes provided by routing table states. When paths to a destination change, corresponding states become invalid and need to be refreshed with control messages for resilient routing. In large and highly dynamic networks, this overhead can crowd out the capacity for data traffic. For such networks, we propose the concept of weak state, which is interpreted as a probabilistic hint, not as absolute truth. Weak state can remain valid without explicit messages by systematically reducing the confidence in its accuracy. Weak State Routing (WSR) is a novel routing protocol that uses weak state along with random directional walks for forwarding packets. When a packet reaches a node that contains a weak state about the destination with higher confidence than that held by the packet, the walk direction is biased. The packet reaches the destination via a sequence of directional walks, punctuated by biasing decisions. WSR also uses random directional walks for disseminating routing state and provides mechanisms for aggregating weak state. Our simulation results show that WSR offers a very high packet delivery ratio (≥ 98%). Control traffic overhead scales as O(N), and the state complexity is Θ(N3/2), where N is the number of nodes. Packets follow longer paths compared to prior protocols (OLSR [2], GLS-GPSR [3], [4]), but the average path length is asymptotically efficient and scales as O(√N). Despite longer paths, WSR's end-to-end packet delivery delay is much smaller due to the dramatic reduction in protocol overhead.
Synthesis and characterization of transition metal complexes of (2-(2-methoxyethoxy)ethyl)diphenylphosphine and (2-(2-methoxyethoxy)ethyl)dimethylarsine

Abstract Two new, potentially tridentate ligands, Ph 2 P(CH 2 CH 2 O) 2 Me (POO) and Me 2 As(CH 2 CH 2 O) 2 Me(AsOO), have been synthesized and characterized by multinuclear NMR spectroscopy. Mononuclear complexes of these ligands, cis -(CO) 4 Mo(EOO) 2 (E = P, As), cis,cis,trans - and cis,trans,cis -(CO) 2 Cl 2 Ru(POO) 2 , [(1,5-cod)Rh(POO) 2 ][ClO 4 ] and Cl 2 M(POO) 2 , (M = Pd and Pt), have also been prepared and characterized by multinuclear NMR and IR spectroscopy. In all cases, these ligands are coordinated only through the group 15 donor atom. Different procedures have been developed to give either the cis,cis,trans or cis,trans,cis isomers of Cl 2 (CO) 2 Ru(POO) 2 complex in high yields. The latter isomer is unusual and has not previously been reported with ligands of this type. The reactions of the cis -(CO) 4 Mo(EOO) 2 complexes with methyllithium have been examined. The carbonyl ligands in these complexes do not react with methyllithium at room temperature. These results are in direct contrast to those of Powell and coworkers who reported facile reactions between methyllithium and the carbonyl ligands in similar cis -(CO) 4 Mo(Ph 2 PO(CH 2 CH 2 O) 3 PPh 2 complexes. These results confirm Powell's conclusions that the number and type of the hard donor atoms in these complexes greatly affect the reactivity of methyllithium towards the carbonyl ligands.
Minimum-rank optimal update of elemental stiffness parameters for structural damage identification

A new optimal update method for the correlation of dynamic structural finite element models with modal data is presented. The method computes a minimum-rank solution for the perturbations of the elemental stiffness parameters while constraining the connectivity of the global stiffness matrix. The resulting model contains a more accurate representation of the dynamics of the test structure, and the changes between the original model and the updated model can be interpreted as modeling errors or as changes in the structure resulting from damage. The motivation for the method is presented in the context of existing optimal matrix update procedures. This method is distinct from past minimum-rank optimal update procedures because it computes minimum-rank updates directly to the elemental stiffness parameters. The method is demonstrated numerically on a spring-mass system and is also applied to experimental data from the NASA Langley Research Center eight-bay truss damage detection experiment. The results demonstrate that the proposed procedure may be useful for updating elemental stiffness parameters in the context of damage detection and model refinement.
Fermions in Bosonic String Theories

We generalize the Jackiw-Rebbi-Hasenfratz-'t Hooft construction of fermions from bosons to demonstrate the fermionic nature of certain bound states involving SU(N) instantons in even spatial dimensions and SO(N) instantons in 8k+1 spatial dimensions. We use this result to identify several fermionic excitations in various perturbatively bosonic string theories. In some examples we are able to identify these fermions as excitations in known conformal field theories and independently confirm their fermionic nature. Examples of the fermions we find include certain 3-string junctions in type-0B theory, excitations of the 0-p system in type-0A theory, excitations of the stable D-particle of type-0 theory, and a rich spectrum of fermions in the bosonic string compactified on the SO(32) group lattice.
On Combinatorics of Quiver Component Formulas

Buch and Fulton [9] conjectured the nonnegativity of the quiver coefficients appearing in their formula for a quiver cycle. Knutson, Miller and Shimozono [24] proved this conjecture as an immediate consequence of their "component formula". We present an alternative proof of the component formula by substituting combinatorics for Grobner degeneration [23, 24]. We relate the component formula to the work of Buch, Kresch, Tamvakis and the author [10] where a "splitting" formula for Schubert polynomials in terms of quiver coefficients was obtained. We prove analogues of this latter result for the type BCD-Schubert polynomials of Billey and Haiman [4]. The form of these analogues indicate that it should be interesting to pursue a geometric context that explains them.
Thermal emission from cometary dust

Abstract The thermal emission from the dust coma of a comet can be analyzed to yield the flux and size distribution of the dust grains and the relative abundance of silicate and absorbing grains.
Criteria for the stability of p -linear maps and p -powers

The main purpose of this paper is to report on the use of a theorem, which extends to multilinear maps the Banach-Steinhaus principle of uniform boundedness, in providing a solution to the problem of determining conditions on the kernel l such that the operator H is stable in the sense that it takes L∞ into itself
Loss of stability and emergence of chaos in dynamical systems

Abstract The purpose of these notes is to give a brief overview of some of the basic ideas involved in studying the breakdown of stability in finite dimensional dynamical systems. We will at the end arrive at one frontier of modern research: the problem of determining how ‘chaotic’ invariant sets can come into existence in such dynamical systems. We emphasize the relation between chaotic properties and hyperbolicity in dynamical systems.
Paving the way or crowding out? The impact of the rise of climate change on environmental issue agendas

Climate change has emerged as a salient issue within the USA. In response, many environmental organizations have pushed climate change to the top of their agendas. As a consequence, critics have charged that environmentalists have decreased attention to—or abandoned altogether—traditional issues such as biodiversity. This research provides empirical data to evaluate such claims. I assess the degree to which climate change has come to dominate US environmental group agendas, using data from organizational websites, financial statements, and interviews. I find that climate change has moved to the top of group agendas, emerging as a key priority and commanding a significant percentage of organizational funding. However, rather than being associated with the neglect of other issues, analysis shows that groups tend to work on a greater number of issues after they prioritize climate change. Moreover, the nature of environmental campaigns has evolved as attention to climate change has increased.
Matrix model superpotentials and ADE singularities

We use F. Ferrari’s methods relating matrix models to Calabi-Yau spaces in order to explain much of Intriligator and Wecht’s ADE classification of N = 1 superconformal theories which arise as RG fixed points of N = 1 SQCD theories with adjoints. We find that ADE superpotentials in the Intriligator–Wecht classification exactly match matrix model superpotentials obtained from Calabi-Yaus with corresponding ADE singularities. Moreover, in the additional b O, b A, b D and b E cases we find new singular geometries. These ‘hat’ geometries are closely related to their ADE counterparts, but feature non-isolated singularities. As a byproduct, we give simple descriptions for small resolutions of Gorenstein threefold singularities in terms of transition functions between just two coordinate charts. To obtain these results we develop an algorithm for blowing down exceptional P 1 s, described in the appendix.
Symmetry-Based Indexing of Image Databases

The use of shape as a cue for indexing into pictorial databases has been traditionally based on global invariant statistics and deformable templates, on the one hand, and local edge correlation on the other. This paper proposes an intermediate approach based on a characterization of the symmetry in edge maps. The use of symmetry matching as a joint correlation measure between pairs of edge elements further constrains the comparison of edge maps. In addition, a natural organization of groups of symmetry into a hierarchy leads to a graph-based representation of relational structure of components of shape that allows for deformations by changing attributes of this relational graph. A graduated assignment graph matching algorithm is used to match symmetry structure in images to stored prototypes or sketches. The results of matching sketches and grey-scale images against a small database consisting of a variety of fish, planes, tools, etc., are promising.
Boundary Partitions in Trees and Dimers

Given a finite planar graph, a grove is a spanning forest in which every component tree contains one or more of a specified set of vertices (called nodes) on the outer face. For the uniform measure on groves, we compute the probabilities of the different possible node connections in a grove. These probabilities only depend on boundary measurements of the graph and not on the actual graph structure, i.e., the probabilities can be expressed as functions of the pairwise electrical resistances between the nodes, or equivalently, as functions of the Dirichlet-to-Neumann operator (or response matrix) on the nodes. These formulae can be likened to generalizations (for spanning forests) of Cardy’s percolation crossing probabilities, and generalize Kirchhoff’s formula for the electrical resistance. Remarkably, when appropriately normalized, the connection probabilities are in fact integer-coefficient polynomials i n the matrix entries, where the coefficients have a natural algebraic interpretation and canbe computed combinatorially. A similar phenomenon holds in the so-called double-dimer model: connection probabilities of boundary nodes are polynomial functions of certain boundary measurements, and as formal polynomials, they are specializations of the grove polynomials. Upon taking scaling limits, we show that the double-dimer connection probabilities coincide with those of the contour lines in the Gaussian free field with certain natural boundary conditions. These results have direct application to connection probabilities for multiple-strand SLE2, SLE8, and SLE4.
Direct activation of relatively unstrained carbon–carbon bonds in homogeneous systems

New modes of chemical reactivity are of high value to synthetic organic chemistry. In this vein, carbon–carbon (C–C) activation is an emerging field that offers new possibilities for synthesizing valuable complex molecules. This review discusses the pioneering stoichiometric discoveries in this field up to the most recent synthetic applications that apply catalytic transformations. Specifically, the review focuses on C–C activation in relatively unstrained systems, including stoichiometric reactions, chelation-directed and chelation-free catalytic reactions. While the field of C–C activation of relatively unstrained systems is underdeveloped, we expect that this review will provide insight into new developments and pave the path for robust, practical applications.
Planarity-preserving clustering and embedding for large planar graphs

In this paper we present a novel approach for cluster-based drawing of large planar graphs that maintains planarity. Our technique works for arbitrary planar graphs and produces a clustering which satisfies the conditions for compound-planarity (c-planarity). Using the clustering, we obtain a representation of the graph as a collection of O(log n) layers, where each succeeding layer represents the graph in an increasing level of detail. At the same time, the difference between two graphs on neighboring layers of the hierarchy is small, thus preserving the viewer's mental map. The overall running time of the algorithm is O(n log n), where n is the number of vertices of graph G.
Universal scaling of the valence quark mass dependence of the chiral condensate

Abstract Recently, the Columbia group obtained the valence quark mass dependence of the chiral condensate for lattice QCD simulations with dynamical fermions for a series of couplings close to the critical temperature. In this letter we show that the data for temperatures below T c and sufficiently small valence quark masses can be rescaled to fall on a universal curve. Using chiral random matrix theory we obtain an exact analytical expression for the shape of this curve. We also discuss the universal scaling behavior of the mass dependence of the mass derivatives of the chiral condensate (scalar susceptibilities).
Tunneling and energy splitting in Ising models

Abstract The energy splitting E 0a in two- and four-dimensional Ising models is measured in a cylindrical geometry on finite lattices. By comparing to exact results in the two-dimensional Ising model we demonstrate that E 0a can be extracted very reliably from Monte Carlo calculations in practice. In four dimensions we compare the measured E 0a with two different theoretical predictions on the finite-size behavior of the energy splitting. We find that our numerical data are in favor of the predictions based on the semiclassical dilute instanton gas approximation.
Maximum-likelihood sequence decoding of digital image watermarking

ABSTRACT This paper explores possible methods to detect the watermark signal. We show how using sequence detection tech- niques, such as maximum likelihood sequence detection (MLSD), can provide the same performance as conventionally used correlation detection while simplifying the detection process. As a result, we can increase the dimension of thewatermark signal (achieving higher capacity), and keep the increase in computational complexity manageable. Wewill also show that with MLSD, we can have a measure of confidence level of the detected signal that is directlydependent on the watermark signal to noise ratio (SNRwm).Keywords: Digital Image Watermarking, Data Hiding, Multimedia Applications, Sequence Detection of DigitalImage Watermarking 1. INTRODUCTION Recent research in digital image watermarking has concentrated on issues such as the robustness of the watermarking algorithm,' limitations and implications,2 and the modeling of the watermarking problem.3 In4 we proposed anapproach for embedding meaningful information in the watermark signal. With this approach, the total availablebits in the watermark signal N are divided into in
Alternative implementations of the Monte Carlo power method

We compare nominal efficiencies, i.e., variances in power shapes for equal running time, of different versions of the Monte Carlo (MC) eigenvalue computation. The two main methods considered here are 'conventional' MC and the superhistory method. Within each of these major methods, different variants are available for the main steps of the basic MC algorithm. Thus, for example, different treatments of the fission process may vary in the extent to which they follow, in analog fashion, the details of real-world fission, or they may vary in details of the methods by which they choose next-generation source sites. In general the same options are available in both the superhistory method and conventional MC, but there seems not to have been much examination of the special properties of the two major methods and their minor variants. We find, first, that the superhistory method is just as efficient as conventional MC and, second, that use of different variants of the basic algorithms may, in special cases, have a surprisingly large effect on MC computational efficiency.
Simulations of early galaxy formation

Abstract We present the predictions for the photometric and emission line properties of galaxies present during the latter stages of reionization from z = 8 → 6. These preliminary predictions are made from cosmological hydrodynamic simulations that include star formation and feedback, but not the effects of radiative transfer. We find significant numbers of galaxies that have stellar masses exceeding 10 8 M ⊙ by z = 8, with metallicities in the range of one-tenth solar. These galaxies are just beyond the reach of current near-infrared surveys, but should be found in large numbers by next-generation programs. The Lyα luminosity function does not evolve much from z = 6 to z = 8, meaning that it should also be possible to detect these objects in significant numbers with upcoming narrow band surveys, unless the escape fraction of Lyα evolves significantly between those epochs.
Synthesis and in vitro cytotoxicity of 6-vinyluridine and related compounds

Abstract The 6-alkenyluracil nucleosides ( 7a–e ) and bases ( 14a–i ) were synthesized and evaluated for their ability to inhibit the growth of mouse leukemia L1210 cells in vitro . While several of the free bases are cytotoxic, with IC 50 values in the 1 – 5 μM range, the corresponding β- d -ribofuranosyl nucleosides are not significantly active.
AGN Environments in the Sloan Digital Sky Survey. I. Dependence on Type, Redshift, and Luminosity

We explore how the local environment is related to the redshift, type, and luminosity of active galactic nuclei (AGNs). Recent simulations and observations are converging on the view that the extreme luminosity of quasars is fueled in major mergers of gas-rich galaxies. In such a picture, quasars are expected to be located in regions with a higher density of galaxies on small scales where mergers are more likely to take place. However, in this picture, the activity observed in low-luminosity AGNs is due to secular processes that are less dependent on the local galaxy density. To test this hypothesis, we compare the local photometric galaxy density on kiloparsec scales around spectroscopic type I and type II quasars to the local density around lower luminosity spectroscopic type I and type II AGNs. To minimize projection effects and evolution in the photometric galaxy sample we use to characterize AGN environments, we place our random control sample at the same redshift as our AGNs and impose a narrow redshift window around both the AGNs and control targets. We find that higher luminosity AGNs have more overdense environments compared to lower luminosity AGNs on all scales out to our 2 h70−1 Mpc limit. In addition, in the range 0.3 ≤ z ≤ 0.6, type II quasars have similarly overdense environments to those of bright type I quasars on all scales out to our 2 h70−1 Mpc limit, while the environment of dimmer type I quasars appears to be less overdense than the environment of type II quasars. We see increased overdensity for type II AGNs compared to type I AGNs on scales out to our limit of 2 h70−1 Mpc in overlapping redshift ranges. We also detect marginal evidence for evolution in the number of galaxies within 2 h70−1 Mpc of a quasar with redshift.
Galileo Probe Heat Shield Ablation Experiment

The Galileo probe deceleration module contained an experiment which measured the recession of the forebody heat shield during the ablative probe entry into the Jovian atmosphere. A detailed description of the experiment, reduction of the probe data, reconstruction of the heat-shield shape, and comparisons with preflight predictions are presented. Data quality is good during the second half of recession, but excessive noise levels at the onset of ablation prevented the experiment from meeting two of three performance requirements. The recession distribution is surprisingly dissimilar from preflight predictions. Measured recession was less than predicted near the stagnation point, but exceeded predictions over most of the frustum. (Author)
An Observationally Motivated Framework for AGN Heating of Cluster Cores

The cooling flow problem is a long-standing puzzle that has received considerable recent attention, in part because the mechanism that quenches cooling flows in galaxy clusters is likely to be the same mechanism that sharply truncates the high end of the galaxy luminosity function. Most of the recent models for halting cooling in clusters have focused on AGN heating, but the actual heating mechanism has remained mysterious. Here we present a framework for AGN heating derived from a Chandra survey of gas entropy profiles within cluster cores. This set of observations strongly suggests that the inner parts of cluster cores are shock-heated every ~108 yr by intermittent AGN outbursts, driven by a kinetic power output of ~1045 ergs s-1 and lasting at least 107 yr. Beyond ~30 kpc these shocks decay to sound waves, releasing buoyant bubbles that heat the core's outer parts. Between heating episodes, cooling causes the core to relax toward an asymptotic pure cooling profile. The density distribution in this asymptotic profile is sufficiently peaked that the AGN shock does not cause a core entropy inversion, allowing the cluster core to retain a strong iron abundance gradient, as observed.
Robust and efficient Cartesian mesh generation for component-based geometry

This work documents a new method for rapid and robust Cartesian mesh generation for component-based geometry. The new algorithm adopts a novel strategy that first intersects the components to extract the wetted surface before proceeding with volume mesh generation in a second phase. The intersection scheme is based on a robust geometry engine that uses adaptive precision arithmetic and automatically and consistently handles geometric degenerades with an algorithmic tie-breaking routine. The intersection procedure has worst-case computational complexity of O(N log N) and is demonstrated on test cases with up to 121 overlapping and intersecting components, including a variety of geometric degeneracies. The volume mesh generation takes the intersected surface triangulation as input and generates the mesh through cell division of an initially uniform coarse grid. In refining hexagonal cells to resolve the geometry, the new approach preserves the ability to directionally divide cells that are well aligned with local geometry. The mesh generation scheme has linear asymptotic complexity with memory requirements that total approximately 14-17 words/cell. The mesh generation speed is approximately 10 6 cells/minute on a typical engineering workstation
Synthesis, structures and properties of CaGa, YGa and Y(Ga,Z) phases: a model for the transformation of a CrB to a MoB-type structure in doped YGa phases

Abstract RGa compounds for R=Ca, Y and Y(Ga 1− x Z x ) for Z=Cu or Zn have been synthesized by either arc-melting or direct reactions in sealed Ta containers. The CrB structures of the binary phases have been identified by Guinier powder diffraction, and the MoB-type structure of the new ternary line phase Y(Ga 0.8 Zn 0.2 ) has been refined by single crystal means: I 4 1 / amd , Z =8, a =4.1787(5), c =21.856(4) A, R ( F )/ R w =3.8/2.7%. A comparable compound is obtained for YGa 0.8 Cu 0.2 , but not for Z=Cd or for RGa(Zn) with R=Tb or Er. Resistivity and magnetic susceptibility measurements on the CrB-type CaGa and YGa demonstrate their metallic properties and the non-applicability of a literal Zintl phase assignment of oxidation states to the latter. A qualitative bonding model is developed for the transformation of CrB-type YGa into the MoB structure of Y(Ga 0.8 Zn 0.2 ) in terms of interchain σ* interactions of the π-states on the separate chains.
Structural health monitoring using active sensors and wavelet transforms

Health monitoring methods using active sensors (e.g. piezoelectric transducers) and wavelet transforms are being developed in the Department of Mechanical Engineering at the University of South Carolina. In these methods, wave propagation signals are collected using arrays of piezoelectric transducers placed on or embedded in a structure. The collected signals are analyzed using appropriate wavelet transforms. The final interpretation of the sensor signals is based on signal patterns uncovered by the wavelet transforms in correlation with elastic-wave propagation theory. A number of specimens have been instrumented and tested, which include simple steel beams and actual composite aircraft panels. Impact tests simulating low velocity impact by foreign-object have been conducted and will be used to illustrate the wavelet-based methods.
The distributional effects of the Federal Energy Tax Act

This paper examines the distributional consequences of the tax credits implemented by the Federal Energy Tax Act of 1978. The distributional effects are of interest both for their own sake, and because they have implications for the cost-effectiveness of the credits. If rates of return to conservation are higher for individuals who consume less housing, as earlier evidence suggests, then conservation incentive programs can achieve larger benefits for a given cost if they are distributionally more progressive. We explain the amount of credit claimed by taxpayers using a tobit model, in which credits claimed are a function of variables that affect the net benefit of weatherization. We estimate the model using data from the 1979 Taxpayer Compliance Measurement Program conducted by the Internal Revenue Service. We find that credits claimed are significantly higher where winters are more severe, where energy prices are high or rising rapidly, and where individuals have higher incomes and spend more on housing. Progressivity indices based on Lorenz-Gini measures of inequality reveal that the tax credits were somewhat regressive, even holding climate and energy prices constant. This suggests that the credits may have been ineffectively targeted. In addition, we find no evidence that the credits had a measurable incentive effect, suggesting that they have largely provided windfall gains to households who would have insulated anyway.
Questions concerning matrix algebras and invariance of spectrum

LetA andB be unital Banach algebras withA a subalgebra ofB. Denote the algebra of alln xn matrices with entries fromA byM n (A). In this paper we prove some results concerning the open question: IfA is inverse closed inB, then isM n (A) inverse closed inM n (B)? We also study related questions in the setting where A is a symmetric Banach *-algebra.
Homology of iterated semidirect products of free groups

Abstract Let G be a group which admits the structure of an iterated semidirect product of finitely generated free groups. We construct a finite, free resolution of the integers over the group ring of G . This resolution is used to define representations of groups which act compatibly on G , generalizing classical constructions of Magnus, Burau, and Gassner. Our construction also yields algorithms for computing the homology of the Milnor fiber of a fiber-type hyperplane arrangement, and more generally, the homology of the complement of such an arrangement with coefficients in an arbitrary local system.
Split Vibration Modes in Acoustically-Coupled Disk Stacks

Vibration of an array of stacked annular plates, in which adjacent plates couple weakly through an acoustic layer, is investigated through experimental and theoretical methods. Such acoustic coupling manifests itself through split natural frequencies, beating in the time responses of adjacent or separated plates, and system-level modes in which plates in the array vibrate in- or out-of-phase at closely-spaced frequencies. Laboratory measurements, including a technique in which the frequency response function of all in-phase modes but no out-of-phase modes, or visa versa, is measured, demonstrate the contribution of coupling to the natural frequency spectrum, and identify the combinations of design parameters for which it is important. For the lower modes of primary interest here, the natural frequencies of the out-of-phase system modes decrease as the air layer becomes thinner, while those of the in-phase mode remain sensibly constant at the in vacuo values. A vibration model comprising N classical thin plates that couple through the three-dimensional acoustic fields established in the annular cavities between plates is developed, and its results are compared with measurements of the natural frequencies and mode shapes.
Probing peptide-nanomaterial interactions.

Peptide enabled synthesis of nanomaterials offer the ability to control size distributions; morphologies; and provide a range of surface functionalities. Invariably, these qualities are determined by how well peptides are able to interact with nanomaterials via their primary amino acid sequence and/or secondary structure. At present, though, the effect of the primary and secondary peptide structure on peptide–nanomaterial interactions is not well understood and lacks precise characterization with regard to peptide binding interactions. This shortcoming is even further complicated due to the fact that each peptide–nanomaterial interaction is unique for a given set of peptides and nanoparticles. As a result, the behavior of peptides in the presence of nanomaterials requires a separate study and individual consideration on a peptide per peptide basis. Because of this, the effectiveness of peptide–nanoparticle complexes is often “hit or miss” under experimental conditions and when challenged with large sets of potential nanoparticle-binding peptides. In the following tutorial review, we highlight relevant peptide–nanoparticle interactions, describe binding and structural data for these interactions, and provide a general description of appropriate biochemical and physical characterization techniques adopted from materials science, structural biology, and biochemistry to probe synthetically produced peptide–nanoparticle complexes.
Real Estate Investment Trusts and Stock Price Reversals

A trigger value of −5% is used to identify a sample of real estate trusts (REITS) that experience substantial one-day price declines. Abnormal returns are then calculated for the subsequent two-day period. The results of this study suggest stock price reversals are associated with extreme stock price declines for REITS. Hence, it appears the market overreacts at the time unfavorable information about REITS is disseminated. The degree of reversal across the sample is assessed according to variables such as the initial price decline (day 0), pre-event leakage (day −1), size (capitalization), the type of real estate investment trust, and relative trading volume.
Molecular-beam optothermal spectroscopy of the 9.6-μm ν14 band of benzene

Author Institution: Nolecular Physics Division, National Institute of Standards and Technology
Irreducible Julia sets of rational functions

We prove that a polynomial Julia set which is a finitely irreducible continuum is either an arc or an indecomposable continuum. For the more general case of rational functions, we give a topological model for the dynamics when the Julia set is an irreducible continuum and all indecomposable subcontinua have empty interior.
Three new bioactive styryllactones from goniothalamus giganteus (Annonaceae)

Three new styryllactones, goniobutenolides A (1) and B (3) and goniofupyrone (5), have been isolated from the bark of Goniothalamusgiganteus (Annonaceae). The structures were elucidated by ir, ms, 1H nmr, 13C nmr, 1H-1H COSY, nOe difference, and NOESY spectra. These compounds are marginally cytotoxic to human tumor cells in culture.
On a Furstenberg-Katznelson-Weiss Type Theorem over Finite Fields

Using Fourier analysis, Covert, Hart, Iosevich, and Uriarte-Tuero (2008) showed that if the cardinality of a subset of the 2-dimensional vector space over a finite field with q elements is ≥ ρq2, with \({q^{-1/2} \ll \rho \leq 1}\) then it contains an isometric copy of ≥ cρq3 triangles. In this note, we give a graph theoretic proof of this result.