cssi/SciSciGPT-SciSciNet huggingface dataset:
On the Complexity of Network Synchronization

We show that if a minimal-time solution to a fundamental distributed computation primitive, synchronizing a network path of finite-state processors, exists on the three-dimensional, undirected grid, then we can conclude the purely complexity-theoretic result $P = NP$. Every previous result on network synchronization for various network topologies either demonstrates the existence of fast synchronization solutions or proves that a synchronization solution cannot exist at all. To date, it is unknown whether there is a network topology for which there exists a synchronization solution but for which no minimal-time synchronization solution exists. Under the assumption that $P \neq NP$, this paper solves this longstanding open problem in the affirmative.
HiMAT onboard flight computer system architecture and qualification

Two highly maneuverable aircraft technology (HiMAT) remotely piloted research vehicles (RPRV's) are being flight tested at NASA Dryden Flight Research Center, Edwards, California, to demonstrate and evaluate a number of technological advances applicable to future fighter aircraft. Closed-loop primary flight control is performed from a ground-based cockpit utilizing a digital computer and up/down telemetry links. A backup flight control system for emergency operation resides in one of two onboard computers. Other functions of the onboard computer system are uplink processing, downlink processing, engine control, failure detection, and redundancy management. This paper describes the architecture, functions, and flight qualification of the HiMAT onboard flight computer systems.
Efficient moral hazard

Abstract This paper presents an infinite-horizon, discounted dynamic programming model of the endogenous opportunity costs of an agent’s effort that is allocated among an endogenous number of principals. An agent allocates effort between evaluating new principals and attending to current principals. Since each principal’s return is not maximized by the agent’s optimal allocation, moral hazard occurs in equilibrium. However, since the agent maximizes the total expected value of all undertaken projects, the agent’s allocation of effort is efficient. If the agent chooses a single principal, then moral hazard does not occur and the allocation is efficient. These results are contrary to the inefficient moral hazard results in bilateral principal-agent (P-A) and common agency (C-A) models.
MODELING PROPERTIES OF CHROMOSPHERIC EVAPORATION DRIVEN BY THERMAL CONDUCTION FRONTS FROM RECONNECTION SHOCKS

Magnetic reconnection in the corona results in contracting flare loops, releasing energy into plasma heating and shocks. The hydrodynamic shocks produced in this manner drive thermal conduction fronts (TCFs) which transport energy into the chromosphere and drive upflows (evaporation) and downflows (condensation) in the cooler, denser footpoint plasma. Observations have revealed that certain properties of the transition point between evaporation and condensation (the "flow reversal point" or FRP), such as temperature and velocity-temperature derivative at the FRP, vary between different flares. These properties may provide a diagnostic tool to determine parameters of the coronal energy release mechanism and the loop atmosphere. In this study, we develop a one-dimensional hydrodynamical flare loop model with a simplified three-region atmosphere (chromosphere/transition region/corona), with TCFs initiated by shocks introduced in the corona. We investigate the effect of two different flare loop parameters (post-shock temperature and transition region temperature ratio) on the FRP properties. We find that both of the evaporation characteristics have scaling-law relationships to the varied flare parameters, and we report the scaling exponents for our model. This provides a means of using spectroscopic observations of the chromosphere as quantitative diagnostics of flare energy release in the corona.
The critical Ising model on trees, concave recursions and nonlinear capacity

We consider the Ising model on a general tree under various boundary conditions: all plus, free and spin-glass. In each case, we determine when the root is influenced by the boundary values in the limit as the boundary recedes to infinity. We obtain exact capacity criteria that govern behavior at critical temperatures. For plus boundary conditions, an L 3 capacity arises. In particular, on a spherically symmetric tree that has n α b n vertices at level n (up to bounded factors), we prove that there is a unique Gibbs measure for the ferromagnetic Ising model at the relevant critical temperature if and only if α ≤ 1/2. Our proofs are based on a new link between nonlinear recursions on trees and L p capacities.
Hadronic Transitions between Quark-Antiquark Bound States

A multipole expansion of the color gauge field is shown to yield selection rules and rate estimates for hadronic transitions between nonrelativistic quark-antiquark bound states. The non-Abelian character of the field is of critical importance in determining the selection rules for the leading (“allowed”) transition.
Toda hierarchy with indefinite metric

Abstract We consider a generalization of the full symmetric Toda hierarchy where the matrix L of the Lax pair is given by L = LS , with a full symmetric matrix L and a nondegenerate diagonal matrix S. The key feature of the hierarchy is that the inverse scattering data are given by a class of noncompact groups of matrices including O(p,q). We give an explicit formula for the solution to the initial value problem of this hierarchy by generalizing the orthogonalization procedure of Szego. The formula also provides an explicit solution of the HR flows introduced by Watkins. Based upon the explicit formula, we also study the behaviors of the solutions. Generically, there are two types of solutions, having either sorting property or blowing up to infinity in finite time. The τ-function structure for the tridiagonal hierarchy is also studied.
Cohomology of Frobenius Algebras and the Yang-Baxter Equation

A cohomology theory for multiplications and comultiplications of Frobenius algebras is developed in low dimensions, in analogy with Hochschild cohomology of bialgebras, based on deformation theory. Concrete computations are provided for key examples. Skein theoretic constructions give rise to solutions to the Yang-Baxter equation, using multiplications and comultiplications of Frobenius algebras, and 2-cocycles are used to obtain deformations of R-matrices thus obtained.
Finite, connected, semisimple, rigid tensor categories are linear

Fusion categories are fundamental objects in quantum algebra, but their definition is narrow in some respects. By definition a fusion category must be k-linear for some field k, and every simple object V is strongly simple, meaning that (V) = k. We prove that linearity follows automatically from semisimplicity: Every connected, finite, semisimple, rigid, monoidal category \C is k-linear and finite-dimensional for some field k. Barring inseparable extensions, such a category becomes a multifusion category after passing to an algebraic extension of k. The proof depends on a result in Galois theory of independent interest, namely a finiteness theorem for abstract composita.
A New High-Frequency Injection Method for Sensorless Control of Doubly Fed Induction Machines

This paper introduces a new method to solve the sensorless control problem for a grid-connected doubly fed induction machine (DFIM). The proposed method is based on high-frequency signal injection and the fact that the rotor of a DFIM can be seen as the rotating secondary of an induction transformer. The commonly used sensorless technique based on stator-flux linkage, aside from being parameter sensitive, does not work during fault ride through (FRT) conditions. Nevertheless, the proposed method is parameter independent and remains fully functional during FRT conditions. Moreover, as opposed to other high-frequency injection methods, the proposed method does not require rotor saliency. The mathematical principle of the proposed technique and its implementation are presented. Computer simulations and initial experimental results are also included for verification.
The relativistic heavy ion collider at Brookhaven

Abstract An overview of the RHIC project, recent project, status, and R&D progress on its superconducting magnets are presented. Also discussed are the current construction and experimental programming plans at RHIC, including an announcement for a call for letters of intent for experiments.
Effect of Modification to Tongue and Impeller Geometry on Unsteady Flow, Pressure Fluctuations, and Noise in a Centrifugal Pump

Particle Image Velocimetry (PIV), pressure, and noise measurements are used to study the effect of modifications to tongue and impeller geometries on the flow structure and resulting noise in a centrifugal pump. It is demonstrated that the primary sources of noise are associated with interactions of the nonuniform outflux from the impeller (jet/wake phenomenon) with the tongue. Consequently, significant reduction of noise is achieved by increasing the gap between the tongue and the impeller up to about 20 percent of the impeller radius. Further increase in the gap affects the performance adversely with minimal impact on the noise level. When the gap is narrow, the primary sources of noise are impingement of the wake on the tip of the tongue, and tongue oscillations when the pressure difference across it is high. At about 20 percent gap, the entire wake and its associated vorticity trains miss the tongue, and the only (quite weak) effect of nonuniform outflux is the impingement of the jet on the tongue. An attempt is also made to reduce the nonuniformity in outflux from the impeller by inserting short vanes between the blades. They cause reduction in the size of the original wakes, but generate an additional jet/wake phenomenon of their own. Both wakes are weak to a level that their impacts on local pressure fluctuations and noise are insignificant. The only remaining major contributor to noise is tongue oscillations. This effect is shown to be dependent on the stiffness of the tongue.
Recognition and reaction of metallointercalators with DNA.

The design of small complexes that bind and react at specific sequences of DNA becomes important as we begin to delineate, on a molecular level, how genetic information is expressed. A more complete understanding of how to target DNA sites with specificity will lead not only to novel chemotherapeutics but also to a greatly expanded ability for chemists to probe DNA and to develop highly sensitive diagnostic agents.
Supersymmetric Wilson lines and loops, and super non-Abelian Stokes theorem

Abstract We generalize the standard product integral formalism to incorporate Grassmann valued matrices and show that the resulting supersymmetric product integrals provide a natural framework for describing supersymmetric Wilson lines and Wilson loops. We use this formalism to establish the supersymmetric version of the non-Abelian Stokes' theorem.
An Econometric Method of Correcting for Unit Nonresponse Bias in Surveys

Past approaches to correcting for unit nonresponse in sample surveys by re-weighting the data assume that the problem is ignorable within arbitrary subgroups of the population. Theory and evidence suggest that this assumption is unlikely to hold, and that household characteristics such as income systematically affect survey compliance. The authors show that this leaves a bias in the re-weighted data and they propose a method of correcting for this bias. The geographic structure of nonresponse rates allows them to identify a micro compliance function, which they then use to re-weight the unit-record data. An example is given for the U.S. Current Population Surveys, 1998-2004. The authors find, and correct for, a strong household income effect on response probabilities.
Rolling circle amplification of metazoan mitochondrial genomes

Here we report the successful use of rolling circle amplification (RCA) for the amplification of complete metazoan mt genomes to make a product that is amenable to high-throughput genome sequencing techniques. The benefits of RCA over PCR are many and with further development and refinement of RCA, the sequencing of organellar genomics will require far less time and effort than current long PCR approaches.
Madey's theorems for free-electron devices, spontaneous emission, and applications

Two theorems due to Madey occupy a central position in free-electron laser physics: one relates the gain to the derivative of the spontaneous emission line shape and the other one relates it to the derivative of the electron energy spread in stimulated emission. We use quantum mechanical perturbation thoery of first order in the radiation field to give a general derivation of the theorems based on(a) the hermiticity of the electronfield interaction,(b) the applicability of lowest order perturbation theory, and(c) the assumption that the emitted photon have a sufficiently low energy. Assumption(b) restricts the validity of the theorems to the small-signal weak-field regime,(c) to the small recoil regime where the gain is classical. We use scalar quantum electrodynamics in the Furry picture in order to keep effects which are nonlinear in the undulator field, e.g. higher harmonic emission. We consider a fairly general one-dimensional (i.e. not having transverse variations) monochromatic undulator field (magnetic or optical undulator, linear or circular polarization, possible presence of a diffractive medium). An appendix considers nonmonochromatic fields. We derive explicit results for the linearly polarized and the helical undulator allowing for an arbitrary orientation of the undulator axis, the electron beam and the emitted radiation with respect to each other. In particular, we discuss the case of Gaussian modes where the applicability of the first theorem has been questioned. It turns out that the theorem is applicable provided that spontaneous emission into the Gaussian mode in question is considered (more generally, into whatever mode is of interest for the gain).
Synthesis and electrochemical properties of Pt(II) 5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraaza[14]annulene: Factors affecting the electropolymerization rates

Abstract The Pt complex of platinum dibenzotetraaza[14]annulene has been prepared from the reaction of the free base ligand with bis(dimethylsulfoxide)platinum(II) chloride. This represents one of the first 14 membered tetraazaannulene macrocyclic complexes reported. The electrochemical properties of platinum 5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraaza[14]annulene were characterized by cyclic voltammetry. The platinum tetraazaannulene as well as a Pd(II) analog, have been found to form films on electrode surfaces during cyclic voltammetry. These films form either by constant potential electrolysis at +1.4 V, by cycling from 0.0 to +1.4 V, or by cycling from +1.4 to −2.0 V (versus SCE). Films can be made to form on several electrode surfaces as well as in various solvents and with a variety of tetraalkylammonium salts as electrolytes. The amount of film grown depends on the method of deposition, the solvent and the rate of cycling. As part of the study, a quantitative analyses of the effects of solvents, scan rate, electrode, scan range and electrolytes or the amount of film actually formed on the electrode was carried out.
Charge redistribution at GaN–Ga2O3 interfaces: a microscopic mechanism for low defect density interfaces in remote-plasma-processed MOS devices prepared on polar GaN faces

Abstract Interfacial defect densities are typically two orders of magnitude higher at [III–V]–dielectric interfaces than at Si–SiO2 interfaces. This paper demonstrates GaN devices with significantly reduced interfacial defect densities using a two-step remote plasma process to form the GaN–dielectric interface and then deposit the dielectric film. Separate plasma oxidation and deposition steps have previously been used for fabrication of aggressively scaled Si devices. Essentially, the same 300°C remote plasma processing has been applied to GaN metal–oxide–semiconductor (MOS) capacitors and field effect transistors (FETs). This paper (i) discusses the low-temperature plasma process for GaN device fabrication, (ii) briefly reviews GaN device performance, and then (iii) presents a chemical bonding model that provides a basis for the improved interface electrical properties.
Self-similar growth of a compound layer in thin-film binary diffusion couples

The diffusion controlled growth of a compound phase AnB between two thin films of material A and B is studied with the nonlinear Kirkendall effect included. This growth process is important in electronic materials processing and in synthesis of high-temperature materials using multilayer films. Previous models of the growth rate do not solve the diffusion equation, and thus do not fully utilize the predictive capability. This paper describes a self-similar transformation that reduces the nonlinear, time-dependent diffusion equation with two free boundaries into a nonlinear ordinary differential equation, which is solved numerically by a shooting method. It is found that the intrinsic diffusion coefficients of A and B in AnB can be determined from the positions of the interfaces without using the concentration profile. This provides a simpler method for measuring intrinsic diffusion coefficients. An asymptotic solution valid for small concentration gradients is derived and agrees with the numerical results.
Searching and bargaining with middlemen

We study decentralized markets which include middlemen, producers and consumers connected via a trading network. We develop a model for trade in such settings based on non-cooperative bargaining with search frictions. Our goal is to investigate how the structure of the trading network and the role of middlemen influence the market's efficiency and fairness. To this end, we introduce the concept of limit stationary equilibrium which characterizes the trading patterns that emerge in a general trading network with a large population of agents. We use this concept to analyze how competition among middlemen is influenced by the network structure, how endogenous delay emerges in trade and how surplus is shared between producers and consumers.
Oxonia-cope prins cyclizations: A facile method for the synthesis of tetrahydropyranones bearing quaternary centers

A new cationic cascade reaction has been developed that produces 4-tetrahydropyranones in good yield. The reaction is based on the facile 2-oxonia Cope rearrangement of allyl-substituted oxocarbenium ions. In the presence of a more nucleophilic silyl enol ether, such systems rearrange and cyclize to produce tetrahydropyranones. The substrates were prepared by silyl ketene acetal addition to ketenes. The rearrangement is compatible with tetrasubstituted silyl enol ethers, which result in the diastereoselective introduction of quaternary centers at the C3 position of the tetrahydropyran ring. The oxonia-Cope Prins rearrangement is a versatile new route to tetrahydropyrans.
High Data Density Four-Color Liquid Crystal Display

A very high resolution and high contrast laser-addressed liquid crystal color display has been developed for use in the acquisition and exploitation of high density alphanumeric and graphic data. The display system consists of two smectic liquid crystal light valves (SLCLV) which are thermally addressed by a single laser selectively. Each light valve is capable of generating 2048 X2048 addressable pixels within a 1 in. X1 in. data format. There are 8 X106 pixels available for data presentation. The laser writing system consists of the laser, a modulator which enables the formation of discrete data elements on the SLCLV, a two-axis galvanometer deflection unit, and beam splitting optics designed to multiplex the writing laser on each SLCLV. A closed-loop galvanometer deflection system can position the focused laser beam to an accuracy of 0.01 % across the screen. The laser focus lens is an f/8.0 telecentric designed to produce a 2.54 cm X2.54 cm (1 in. X1 in.) data format on the SLCLV with spot size less than 10 ,um (0.0004 in.). Color images from each light valve are superimposed onto ' the screen by a wide angle f/8.0 projection lens with 48X magnification which relays the combined color image to a 1.2 m X 1.2 m (48 in. X48 in.) screen with less than 0.1 % of distortion. The possible contrast of the display is up to 60 to 1. The overall dimension of the rear projected color display is 1.52 m X3.2 m X0.74 m (60 in. X52 in. X29 in.).
CREDIT CYCLES REDUX

Theoretical studies have shown that under unorthodox assumptions on preferences and production technologies, collateral constraints can act as a powerful amplification and propagation mechanism of exogenous shocks. We investigate whether or not this result holds under more standard assumptions. We find that collateral constraints typically generate small output amplification. Large amplification is obtained as a “knife-edge” type of result.
Stochastic crack growth analysis methodologies for metallic structures

Abstract Stochastic crack growth analysis methodologies are proposed and evaluated for predicting the statistical crack growth damage accumulation in metallic structures. These new methodologies have several practical applications for metallic airframes, including: (1) ensuring U.S. Air Force damage tolerance and/or durability design requirements, (2) reliability centered maintenance, and (3) structural reliability based designs. They can easily be implemented using deterministic crack growth analysis results and an estimate of the crack growth life dispersion. Two different stochastic crack growth approaches are proposed (i.e. “general” and “analytical”). The “general” approach uses a numerically defined deterministic (median) crack growth curve directly. Whereas, the “analytical” approach approximates the median crack growth curve with one or more compatible crack growth segments. Analytical predictions for both approaches are correlated with experimental test results. Good correlations are obtained for a wide range of crack sizes. These proposed approaches represent a new contribution to the state-of-the-art in the applications of statistical crack growth damage predictions for metallic structures in service.
Polymers in Curved Boxes

We apply results derived in other contexts for the spectrum of the Laplace operator in curved geometries to the study of an ideal polymer chain confined to a spherical annulus in arbitrary space dimension D and conclude that the free energy compared to its value for an uncurved box of the same thickness and volume is lower when D 3. Thus, confining an ideal polymer chain to a cylindrical shell lowers the effective bending elasticity of the walls and might induce spontaneous symmetry breaking, i.e. bending. (Actually, the above mentioned results show that any shell in D = 3 induces this effect, except for a spherical shell.) We compute the contribution of this effect to the bending rigidities in the Helfrich free energy expression.
New Spectral Classification Technique for X‐Ray Sources: Quantile Analysis

We present a new technique, quantile analysis, to classify the spectral properties of X-ray sources with limited statistics. Quantile analysis is superior to conventional approaches, such as X-ray hardness ratio or X-ray color analysis, for studying relatively faint sources or investigating a certain phase or state of a source in detail, where poor statistics do not allow spectral fitting using a model. Instead of working with predetermined energy bands, we determine the energy values that divide the detected photons into predetermined fractions of the total counts, such as the median (50%), terciles (33% and 67%), and quartiles (25% and 75%). We use these quantiles as an indicator of the X-ray hardness or color of the source. We show that the median is an improved substitute for the conventional X-ray hardness ratio. The median and other quantiles form a phase space, similar to the conventional X-ray color-color diagrams. The quantile-based phase space is more evenly sensitive over various spectral shapes than the conventional color-color diagrams, and it is naturally arranged to properly represent the statistical similarity of various spectral shapes. We demonstrate the new technique in the 0.3-8 keV energy range using the Chandra ACIS-S detector response function and a typical aperture photometry involving background subtraction. The technique can be applied in any energy band, provided the energy distribution of photons can be obtained.
A robust link-translating proxy server mirroring the whole web

Link-translating proxies are widely used for anonymous browsing, policy circumvention and WebVPN functions. These are implemented by encoding the destination URL in the path of the URL submitted to the proxy and rewriting all links before returning the document to the client. Commonly these are based on the CGIProxy implementation or a variant. While popular, broken links and very slow load times are common. This is so, since the use of scripting languages makes finding and translating links (the essential task of such a proxy) very difficult. Some web-sites become entirely non-functional when loaded.This paper proposes a novel architecture for a link-translating proxy. By using a sub-domain mapping technique we entirely eliminate the need to translate (or even find") relative links in content. This makes the link rewriting algorithm very simple and robust. We have implemented, deployed, and tested the proxy extensively. We conducted a comparison between the our proxy and CGIProxy. Both the theoretical analysis and experimental evaluation show that our proxy is significantly better in terms of robustness, performance, and security. We call our system Address Bar Only Proxy or ABOProxy. We suggest several novel applications.
Lang's Universal molecule algorithm

Robert Lang's Universal Molecule algorithm, a landmark in modern computational origami, is the main component of his widely used TreeMaker program for origami design. It computes a crease pattern of a convex polygonal region, starting with a compatible metric tree. Although it has been informally described in several publications, neither the full power nor the inherent limitations of the method are well understood. In this paper we introduce a rigorous mathematical formalism to relate the input metric tree, the output crease pattern and the folded uniaxial origami base produced by the Universal Molecule algorithm. We characterize the family of tree-like 3D shapes that are foldable from the computed crease patterns and give a correctness proof of the algorithm.
Addressing Missing Data Mechanism Uncertainty using Multiple-Model Multiple Imputation: Application to a Longitudinal Clinical Trial

We present a framework for generating multiple imputations for continuous data when the missing data mechanism is unknown. Imputations are generated from more than one imputation model in order to incorporate uncertainty regarding the missing data mechanism. Parameter estimates based on the different imputation models are combined using rules for nested multiple imputation. Through the use of simulation, we investigate the impact of missing data mechanism uncertainty on post-imputation inferences and show that incorporating this uncertainty can increase the coverage of parameter estimates. We apply our method to a longitudinal clinical trial of low-income women with depression where nonignorably missing data were a concern. We show that different assumptions regarding the missing data mechanism can have a substantial impact on inferences. Our method provides a simple approach for formalizing subjective notions regarding nonresponse so that they can be easily stated, communicated, and compared.
Surfaces and interfaces for controlled defect engineering

The behavior of point defects within silicon can be changed significantly by controlling the chemical state at the surface. In ultrashallow junction applications for integrated circuits, such effects can be exploited to reduce transient enhanced diffusion, increase dopant activation, and reduce end-of-range damage.
A generalised area law for hadronic string reinteractions

Abstract A new model for hadronic string reinteractions based on a generalised area law is presented. The model describes both the hadronic final states in e + e − annihilation and the diffractive structure function in deep inelastic scattering. The model also predicts a shift in the W-mass reconstructed from hadronic decays of W-pairs of the order 65 MeV.
Cu-catalyzed fluorination of diaryliodonium salts with KF.

A mild Cu-catalyzed nucleophilic fluorination of unsymmetrical diaryliodonium salts with KF is described. This protocol preferentially fluorinates the smaller aromatic ligand on iodine(III). The reaction exhibits a broad substrate scope and proceeds with high chemoselectivity and functional group tolerance. DFT calculations implicate a CuI/CuIII catalytic cycle.
Leap forward virtual clock: a new fair queuing scheme with guaranteed delays and throughput fairness

We describe an ejjicient fair queuing scheme, Leap Forward Virtual Clock, that provides end-to-end delay bounds simdar to WFQ, along with throughput fairness. Our scheme can be implemented with a worstca.se time O (log log N) per packet (inclusive of sorting costs), which improves upon all previously known schemes that guarantee delay and throughput fairness similar to WFQ. Interestingly, both the classical virtual clock and the Self- Clocked Fair Queuing schemes can be thought of as special cases of our scheme, by setting the leap forward parameter appropriately.
Converting an atomic fermi gas into a long-lived molecular bose gas

We have converted a quantum degenerate Fermi gas of 6Li atoms into an ultracold gas of 6Li2 molecules using a Feshbach resonance. Up to 1.5 times 105 molecules are produced with 50% efficiency, and optically confined for up to 1 s
A Rational Approach to Solid State Synthesis—The Zintl Concept

Abstract There are a wide variety of ternary compounds, AxMyXz, where A = alkali or alkaline earth metal, M = semimetal or main group element and X = pnictide, that have been synthesized. For example the compounds Ba3AlSb3, Ca3AlSb3, Ca3AlSb3 and Ca5Al2Sb6 have been synthesized and their structures can be understood via the Zintl formalism which can be simply stated as the octet rule for all atoms. The structures can be generally formulated as A− + [(MX)−] so that the anionic units in these examples may be written as: (Al2Sb6)12-; (AlSb3)6- chains; a (Al2Sb6)10- network; and [(AlSb9- 4) + 4Sb3- + Sb7- 3). The Zintl concept has also been applied to ternary transition metal compounds such as the lanthanum transition metal pnictides and ternary transition metal chalcogenides. These structures and their related properties can be understood in terms of cations and complex polyatomic anionic units. The Zintl concept, as it applies to ternary pnictide compounds, will be presented and its extension to ternary tra...
Chip scale thermal management of high brightness LED packages

ABSTRACT The efficiency and reliability of the solid-state lighting devices strongly depend on successful thermal management. Light emitting diodes, LEDs, are a strong candidate for the next generation, general illumination applications. LEDs are making great strides in terms of lumen performance and reliability, however the barrier to widespread use in general illumination still remains the cost or $/Lumen. LED packaging designers are pushing the LED performance to its limits. This is resulting in increased drive currents, and thus the need for lower thermal resistance packaging designs. As the power density continues to rise, the integrity of the package electrical and thermal interconnect becomes extremely important. Experimental results with high brightness LED packages show that chip attachment defects can cause significant thermal gradients across the LED chips leading to premature failures. A numerical study was also carried out with parametric models to understand the chip active layer temperature profile variation due to the bump defects. Finite element techniques were utilized to evaluate the effects of lo calized hot spots at the chip active layer. The importance of zero defects in one of the more popular interconnect schemes; the epi down soldered flip chip configuration is investigated and demonstrated. Keywords: High brightness LEDs, Infrared imaging, Microscopic IR, Bump defects, Finite element analysis.
Orthogonal Polynomials with Respect to Self-Similar Measures

We study experimentally systems of orthogonal polynomials with respect to self-similar measures. When the support of the measure is a Cantor set, we observe some interesting properties of the polynomials, both on the Cantor set and in the gaps of the Cantor set. We introduce an effective method to visualize the graph of a function on a Cantor set. We suggest a new perspective, based on the theory of dynamical systems, for studying families Pn (x) of orthogonal functions as functions of n for fixed values of x.
A survey of debris trails from short-period comets

Abstract We observed 34 comets using the 24 μm camera on the Spitzer Space Telescope. Each image contains the nucleus and covers at least 10 6 km of each comet's orbit. Debris trails due to mm-sized or larger particles were found along the orbits of 27 comets; 4 comets had small-particle dust tails and a viewing geometry that made debris trails impossible to distinguish; and only 3 had no debris trail despite favorable observing conditions. There are now 30 Jupiter-family comets with known debris trails, of which 22 are reported in this paper for the first time. The detection rate is > 80 % , indicating that debris trails are a generic feature of short-period comets. By comparison to orbital calculations for particles of a range of sizes ejected over 2 yr prior to observation, we find that particles comprising 4 debris trails are typically mm-sized while the remainder of the debris trails require particles larger than this. The lower-limit masses of the debris trails are typically 10 11 g , and the median mass loss rate is 2 kg/s. The mass-loss rate in trail particles is comparable to that inferred from OH production rates and larger than that inferred from visible-light scattering in comae.
On the estimation of doubly-selective fading channels

Coherent communications over doubly-selective fading channels are attracting increasing research interests because of the performance advantage over their noncoherent counterparts. In this paper, we use a simple windowing and dewindowing technique to improve the accuracy of an existing basis expansion model (BEM) and develop a windowed least-squares (WLS) estimator for doubly-selective fading channels. We also design the optimum pilot pattern for the WLS estimator. Our designs can considerably improve the channel estimation performance. Simulations are provided to corroborate our theoretical analysis.
Visualization of force fields in protein structure prediction

The force fields used in molecular computational biology are not mathematically defined in such a way that their mathematical representation would facilitate the straightforward application of volume visualization techniques. To visualize energy, it is necessary to define a spatial mapping for these fields. Equipped with such a mapping, we can generate volume renderings of the internal energy states in a molecule. We describe our force field, the spatial mapping that we used for energy, and the visualizations that we produced from this mapping. We provide images and animations that offer insight into the computational behavior of the energy optimization algorithms that we employ.
In situ observations of sigma phase dissolution in 2205 duplex stainless steel using synchrotron X-ray diffraction

Synchrotron radiation was used to directly observe the transformation of ferrite, austenite and sigma phases during heating and cooling of 2205 duplex stainless steel. Sigma formed during the initial stages of heating, dissolved as the temperature was increased, and reformed on cooling. The dissolution temperature of sigma was measured to be 985 ± 2.8 °C at a heating rate of 0.25 °C/s, and the kinetics of sigma formation at 850 °C was determined to be slower after dissolving at 1000 °C than before.
Metal complexes as diagnostic tools

Abstract This review summarizes some of the developments of metal complexes and metal-complex-bioconjugates for the diagnosis of disease states that have occurred over the past 10 years. The diagnostic imaging modalities discussed are gamma scintigraphy, positron emission tomography (PET) and magnetic resonance imaging (MRI). Metal complexes are utilized in all three imaging modalities to image a broad array of diseases, including heart disease, brain disorders and cancer. There are a wide variety of different radiometals that have been utilized in the synthesis of coordination compounds for gamma scintigraphy and PET, and these will be discussed individually. The field of metal-complex-bioconjugate chemistry is covered extensively, describing radiometals labeled to biomolecules such as receptor ligands for diseases such as neurological disorders and cancer. A section is devoted to the development of coordination compounds for MRI enhancement agents, and specifically details the agents that have been evaluated in vivo, both in animal models and in humans. Overall, the goal of this review is to demonstrate the significant progress made in the field of coordination chemistry as it applies to the development of diagnostic imaging agents.
Tight-binding study of high-pressure phase transitions in titanium: Alpha to omega and beyond

We use a tight-binding total-energy method, with parameters determined from a fit to first-principles calculations, to examine the newly discovered γ phase of titanium. Our parameters were adjusted to accurately describe the αTi-ωTi phase transition, which is misplaced by density-functional calculations. We find a transition from ωTi to γTi at 102 GPa, in good agreement with the experimental value of 116 GPa. Our results suggest that current density-functional calculations will not reproduce the ωTi-γTi phase transition, but will instead predict a transition from ωTi to the bcc βTi phase.
EVIDENCE ON THE MARKET FOR PROFESSIONAL DIRECTORS

Using the temporary increase in the supply of directors associated with successful tender offers, we examine characteristics of directors who are valuable in the market for board seats. We find that after a takeover, professional directors are three times more likely to receive new appointments than other types of directors released from their respective boards. We find that the proportion of professional directors in above-average performing targets is significantly greater than that in underperforming targets. Our results indicate that professional directors generally have valuable general human capital that more than offsets the costs of multiple directorships.
Costly Trade Liberalizations: Durable Goods and Capital Mobility

The social costs of a temporary liberalization policy in the context of an economy with infinitely lived individuals and no intertemporal consumption substitution are studied. Importable goods, however, can be stored, and storability is the central source of distortions. Possible welfare costs of the induced inventory accumulation are shown to be significant. It is also argued that temporariness is formally equivalent to "lack of credibility." Because international capital mobility is the vehicle that magnifies these distortions, the results suggest that an optimal trade liberalization without full credibility could call for controls on international capital mobility.
Physician demographics and the risk of medical malpractice

Abstract purpose: This study was undertaken to clarify which, if any, physician demographic characteristics are associated with an increased rate of medical malpractice claims. methods: We analyzed the malpractice experience of 9,250 physicians insured for at least 2 years from 1977 to 1987 in the state of New Jersey. After adjusting for years at risk, physician claims per year was categorized into low, medium, and high. results: Male physicians were three times as likely to be in the high-claims group as female physicians, even after adjusting for other demographic variables (relative risk, 3.1; 99% confidence interval, 2.2 to 4.4). Specialty was strongly associated with claims rate, with neurosurgery, orthopedics, and obstetrics/gynecology having 7 to 12 times the number of claims per year as psychiatry, the specialty with the fewest claims. The rate of claims varied with age (p conclusion: Male physicians are three times as likely to be in a high-claims category as female physicians. We suspect that the most likely explanation for this finding is that women interact more effectively with patients. Understanding the reasons for the variation in claim rates between physicians may lead to the development of methods to reduce the overall rate of malpractice claims.
Isotropic conductive adhesives: Future trends, possibilities and risks

This brief summary of the questions facing isotropic conductive adhesives is intended to provoke discussion in the research community, and suggest future research priorities. The primary impediment to widespread industrial adoption of the technology is a lack of confidence in its reliability, specifically in its drop-test performance. The key to solving any such technical problem is to fully understand the technology, but at this point there are still far too many fundamental questions on multiple aspects of it to inspire confidence. Some basic research questions are identified, the answers to which should lead to improved product performance.
Regioselective synthesis of various prodrugs of ganciclovir

Abstract High-yield regioselective syntheses of 9-[(1,3-dihydroxy-2-propoxy)methyl]guanine mono-, di- and tri-substitution derivatives as potential prodrugs were accomplished via one or multisteps. Two amino acid esters of ganciclovir were synthesized as water-soluble prodrugs, which form protonated cations in pH 7.4 phosphate buffer.
A ground state tri-π-methane rearrangement☆

An example of a ground state tri-p-methane rearrangement is described. © 2000 Elsevier Science Ltd.
CAN WE PREDICT EARTHQUAKES

(This is an unsensational statement on the earthquake problem by one of America's leading seismologists. Is there danger of earthquake in California, New England, and elsewhere in the United States? Dr. Willis states the facts and the reader can draw his own conclusions.)
A Concise Asymmetric Synthesis of cis-2,6-Disubstituted N-Aryl Piperazines via Pd-Catalyzed Carboamination Reactions

A concise, modular, asymmetric synthesis of cis-2,6-disubstituted piperazines from readily available amino acid precursors is described. The key step in the synthesis is a Pd-catalyzed carboamination of a N1-aryl-N2-allyl-1,2-diamine with an aryl bromide. The products are obtained in 14−20:1 dr, with >97% ee, and the key cyclizations are the first examples of six-membered ring formation via Pd-catalyzed carboamination reactions of unsaturated amines with aryl halides.
Risk Diversification in the Credit Portfolio: An Overview of Country Practices

This paper reviews the rules in place in selected countries to limit risk concentrations in the credit portfolio. The paper focuses on a number of issues suggested by international organizations for countries and bank supervisors to consider in imposing standards for risk diversification in the credit portfolio. The issues reviewed for each country are the large exposure limits, the definition of credit exposure (including application on a consolidated basis), and the definition of a group of related borrowers. The paper concludes that most of the countries reviewed set limits on large exposures for banks and define a related group of borrowers in line with recommended international standards. The major differences identified among countries include how to determine the credit exposure, the application of the exposure limits on a consolidated basis, and whether to impose limits on exposure to a specific sector.
Seeking conceptual clarity in the action modalities

This article begins with the presumption that action learning has not made as deep an impact in promoting participatory social change as its supporters may have hoped for, but nor has its cousin action modalities, such as action research and action science. These action strategies have evolved separately along distinct traditions and, rather than focus on their commonalities, their proponents have tended to cite their differences from one another. As a result, they have seldom stood together to advocate for their shared epistemology based on practice as the fundamental unit of analysis. Accordingly, after briefly summarizing the history and differences among these action modalities, this article will focus on their potential confederation. It cites ten unifying elements that may construct an agenda characterized by the value of learners collectively reflecting on planned engagements that can not only expand but can create knowledge while at the same time serving to improve practice.
Finite element analysis of a quartz rotation sensor

A finite element study in support of the design of a quartz crystal resonator for use as a rotation sensor is presented. This work is the first three dimensional analysis of such a resonator. Rotation is sensed by measuring the coupling induced by Coriolis forces between two orthogonal shear modes. These shear modes are measured and excited through the piezoelectric effect. They consist of low-order shear motions coupled to high-order flexure. A highly refined mesh is required to accurately capture this behavior. The design is driven by the need to geometrically tune the sensor such that the two shear modes coincide in frequency. Finite element modeling proved to be indispensible in achieving this design goal. Experimental results from parts fabricated in accordance with the final design indicate that the measured and predicted modal frequencies agree with less than 1% error. The desired shear modes, which are greater than the 200th mode in the spectrum, are carefully classified using a straight-forward procedure which gives the effective piezoelectric coupling to specific electrode geometries. A description of the evolution of the finite element model is given along with various obstacles that were overcome during the course of the analysis. 9 refs., 9 figs.
The unpredictable deviousness of models

Computation models are central to algorithmic research. A model, designed to capture the essential features of a technology dispensing with irrelevant and burdensome details, is a judicious compromise between simplicity and fidelity (or reflectivity). This approach has unleashed an enormous amount of valuable algorithmic research over the years. However, the pursuit of simplicity may filter out details, once deemed irrelevant, which may later reassert their significance under either technological pressure or more careful scrutiny, in which case the inadequacy of the model cripples the validity of the derived results. Examples of this situation, drawn from computational geometry, numerical parallel computation, VLSI theory, and computational biology, will be reviewed and examined in detail.
Sand Catalyzed Oxidative Cleavage of Double Bonds

Abstract The discovery of a catalytic effect of sand on the activity of KMnO4/NaIO4 or KMnO4/NaClO oxidant system provides a convenient method for double bond cleavage under mild conditions. An oxidative rearrangement of α-bromostyrene to 2-bromoacetophenone was also observed.