cssi/SciSciGPT-SciSciNet huggingface dataset:
An approach to aflatoxins using type II photocyclization reactions

The type II photocyclization of 2,6-disubstituted acetophenones provides a direct synthetic route to a precursor to aflatoxin M2.
Semi-autonomous adaptive cruise control systems

The concept of a semi-autonomous adaptive cruise control (SAACC) system is developed, which enjoys significant advantages over present day adaptive cruise control (ACC) systems in terms of highway safety and traffic flow capacity. The semi-autonomous systems combine the deployment advantages of autonomous vehicles with the performance advantages of fully automated highway systems (AHSs) in which vehicles operate cooperatively as a platoon. Unlike platoon systems, the semi-autonomous systems are immediately deployable on present day highways, where both manually driven and adaptive cruise controlled vehicles can coexist. Our theoretical results show that the proposed system is able to maintain smaller time gaps safely, is string stable, and is guaranteed to have smaller actuator inputs than a standard autonomous ACC system. The simulation results indicate that more accurate and smoother tracking, smaller time gaps, smaller control efforts, and increased robustness to vehicle dynamics are achieved by semi-autonomous control.
LIGO/VIRGO Searches for Gravitational Radiation in Hypernovae

A torus around a stellar-mass Kerr black hole can emit about 10% of the spin energy of a black hole in gravitational radiation, which is potentially associated with a gamma-ray burst (GRB). Wide tori may develop buckling modes by the Papaloizou-Pringle instability and gravitational radiation-reaction forces in the Burke-Thorne approximation. Gravitational-wave experiments may discover these emissions in a fraction of nearby supernovae. This provides a test for Kerr black holes and for GRB inner engines by a comparison with the deredshifted durations of long GRBs.
Zoning Policy Changes and the Urban Fringe Land Market

This paper examines the effect of a zoning change on the land market in McHenry County, Illinois. One question addressed is whether zoning “follows the market.” It is found that, for agricultural land, zoning does tend to follow the market. In addition, the effect of land prices on land use is examined. The results here, however, are mixed. In the initial years after the zoning change, a high relative price of residential land increases the probability that a parcel will be zoned residential. However, several years later, a high relative price of residential land decreases the probability that a parcel is zoned residential. This result suggests that it may take some time for a zoning change to have a significant impact on the local land market.
Information-Based Trade

We study the possibility of trade for purely informational reasons. We depart from previous analyses (e.g. Grossman and Stiglitz (1980) [22] and Milgrom and Stokey (1982) [32]) by allowing the final payoff of the asset being traded to depend on an action taken by its eventual owner. We characterize conditions under which equilibria with trade exist.
Unobserved Ability, Efficiency Wages, and Interindustry Wage Differentials

Interindustry wage differentials in wage regressions estimated for individuals have been interpreted as evidence consistent with efficiency wage models. A principal competing explanation is that these differentials are generated by differences across workers in unobserved ability. This paper tests the unobserved ability hypothesis .by incorporating test scores into standard wage regressions as error-ridden indicators of unobserved ability. The results indicate that differences in unobserved ability explain relatively little of interindustry or interoccupation wage differentials.
Geometric constructions of nongeometric string theories

We advocate a framework for constructing perturbative closed string compactifications which do not have large-radius limits. The idea is to augment the class of vacua which can be described as fibrations by enlarging the monodromy group around the singular fibers to include perturbative stringy duality symmetries. As a controlled laboratory for testing this program, we study in detail six-dimensional (1,0) supersymmetric vacua arising from two-torus fibrations over a two-dimensional base. We also construct some examples of two-torus fibrations over four-dimensional bases, and comment on the extension to other fibrations.
Mapping and analysis of chromatin state dynamics in nine human cell types

Chromatin profiling has emerged as a powerful means of genome annotation and detection of regulatory activity. The approach is especially well suited to the characterization of non-coding portions of the genome, which critically contribute to cellular phenotypes yet remain largely uncharted. Here we map nine chromatin marks across nine cell types to systematically characterize regulatory elements, their cell-type specificities and their functional interactions. Focusing on cell-type-specific patterns of promoters and enhancers, we define multicell activity profiles for chromatin state, gene expression, regulatory motif enrichment and regulator expression. We use correlations between these profiles to link enhancers to putative target genes, and predict the cell-type-specific activators and repressors that modulate them. The resulting annotations and regulatory predictions have implications for the interpretation of genome-wide association studies. Top-scoring disease single nucleotide polymorphisms are frequently positioned within enhancer elements specifically active in relevant cell types, and in some cases affect a motif instance for a predicted regulator, thus suggesting a mechanism for the association. Our study presents a general framework for deciphering cis-regulatory connections and their roles in disease.
The Structural and Electrochemical Impact of Li and Fe Site Substitution in LiFePO4

The crystal structure and delithiation mechanism of Li-site substituted LiFePO4 have been revealed by investigation of supervalent V3+ substitution. The combined X-ray and neutron powder diffraction data analysis surprisingly shows that the substituting aliovalent vanadium ions occupy the Fe site while some of the Fe resides at the Li site, probably as sarcopside, which leads to an increase in the unit cell volume. Such substitution reduces the miscibility gap at room temperature and also significantly lowers the solid solution formation temperature in the two-phase region. The effect of the phase diagram modification results in improved kinetics, leading to better rate performance. Such substitution, however, significantly lowers the LiFePO4 capacity at moderate current densities.
Advanced Electron Microscopy of Metal–Support Interactions in Supported Metal Catalysts

Electron microscopy and its associated techniques have contributed significantly to the characterization of heterogeneous catalysts, especially supported metal catalysts, and can provide nano- or atomic-scale information on the structure, morphology, composition, and electronic state of the area of interest. With the recent advancement in aberration corrections to achieve an image resolution below 0.1 nm and the rapid development of in situ techniques, advanced electron microscopy is poised to probe fundamental questions of heterogeneous catalysis and catalysts. Understanding the nature of metal–support interactions becomes critical if we want to achieve the goal of designing and fabricating nanoarchitectured catalysts with desired performances. To reliably probe the fundamental mechanisms of charge transfer, which is the core of catalysis, between individual nanoscale components and under a realistic gas environment and temperature is still a formidable challenge. This Review discusses the recent contribution of advanced electron microscopy to the study of metal–support interactions, as well as the challenges and opportunities of applying aberration-corrected electron microscopy techniques to the investigation of atomic-scale structures of complex heterogeneous catalysts.
Privatisation in Developing Countries: A Review of the Evidence and the Policy Lessons

Privatisation is widely promoted as a means of improving economic performance in developing countries. However, the policy remains controversial and the relative roles of ownership and other structural changes, such as competition and regulation, in promoting economic performance remain uncertain. This article reviews the main empirical evidence on the impact of privatisation on economic performance in developing economies. The evidence suggests that if privatisation is to improve performance over the longer term, it needs to be complemented by policies that promote competition and effective state regulation, and that privatisation works best in developing countries when it is integrated into a broader process of structural reform.
Time Delay Extraction from Frequency Domain Data Using Causal Fourier Continuations for High-Speed Interconnects

We present a new method for time delay estimation using band limited frequency domain data representing the port responses of interconnect structures. The approach is based on the spectrally accurate method for causality characterization that employs SVD-based causal Fourier continuations, which was recently developed by the authors. The time delay extraction is constructed by incorporating a linearly varying phase factor to the system of equations that determines the Fourier coefficients. The method is capable of determining the time delay using data affected by noise or approximation errors that come from measurements or numerical simulations. It can also be employed when only a limited number of frequency responses is available. The technique can be extended to multi-port and mixed-mode networks. Several analytical and simulated examples are used to demonstrate the accuracy and strength of the proposed technique.
CEO turnover and outside succession A cross-sectional analysis

Abstract This study examines chief executive officer (CEO) turnover. It reports new evidence on factors that affect the likelihoods of voluntary and forced turnover, and for both of these turnover types, whether the new CEO is from inside the firm, from another firm in the industry, or from outside the industry. The evidence is consistent with arguments that poor CEOs are easier to identify and less costly to replace in industries that consist of similar firms than in heterogeneous industries. The likelihoods of forced turnover and of an intra-industry appointment increase with industry homogeneity.
A theoretical analysis of vertical flow equilibrium

The assumption of Vertical Equilibrium (VE) and of parallel flow conditions, in general, is often applied to the modeling of flow and displacement in natural porous media. However, the methodology for the development of the various models is rather intuitive, and no rigorous method is currently available. In this paper, we develop an asymptotic theory using as parameter the variable $$R_{{L}} = L/H\sqrt {k_{{V}} /k_{{H}} } $$ . It is rigorously shown that the VE model is obtained as the leading order term of an asymptotic expansion with respect to 1/R L 2 . Although this was numerically suspected, it is the first time that it is theoretically proved. Using this formulation, a series of special cases are subsequently obtained depending on the relative magnitude of gravity and capillary forces. In the absence of strong gravity effects, they generalize previous works by Zapata and Lake (1981), Yokoyama and Lake (1981) and Lake and Hirasaki (1981), on immiscible and miscible displacements. In the limit of gravity-segregated flow, we prove conditions for the fluids to be segregated and derive the Dupuit and Dietz (1953) approximations. Finally, we also discuss effects of capillarity and transverse dispersion.
3-D Elasticity-based Modeling of Anisotropic Piezocomposite Transducers for Guided Wave Structural Health Monitoring

Anisotropic piezocomposite transducers (APTs), such as macro fiber composites and active fiber composites, have great potential to be used as structurally integrated transducers for guided-wave (GW) structural health monitoring. Their main advantages over conventional monolithic piezoceramic wafer transducers are mechanical flexibility, curved surface conformability, power efficiency, their ability to excite focused GW fields, and their unidirectional sensing capability as a GW sensor. In this paper, models are developed to describe excitation of GW fields by APTs in isotropic structures. The configurations explored are plane Lamb-wave fields in beams with rectangular cross-section, axisymmetric GW fields in cylinders, and 3-D GW fields in plates. The dynamics of the substrate and transducer are assumed uncoupled. The actuator is modeled as causing shear traction at the edges of the actuator's active area along the fiber direction. The sensor is modeled as sensing the average extensional strain over the active area along the fiber direction. The work is unique in that the formulation is based on 3-D elasticity, and no reduced-order structural assumptions are used. This is crucial to model multimodal GW propagation, especially at high frequencies. A formulation is also proposed to model the behavior of APTs as GW sensors. Finally, results from experimental tests to examine the validity of the models are discussed and the possible sources of error are examined in detail.
Repairable Block Failure Resilient codes

In large scale distributed storage systems (DSS) deployed in cloud computing, correlated failures resulting in simultaneous failure (or, unavailability) of blocks of nodes are common. In such scenarios, the stored data or a content of a failed node can only be reconstructed from the available live nodes belonging to available blocks. To analyze the resilience of the system against such block failures, this work introduces the framework of Block Failure Resilient (BFR) codes, wherein the data (e.g., file in DSS) can be decoded by reading out from a same number of codeword symbols (nodes) from each available blocks of the underlying codeword. Further, repairable BFR codes are introduced, wherein any codeword symbol in a failed block can be repaired by contacting to remaining blocks in the system. Motivated from regenerating codes, file size bounds for repairable BFR codes are derived, trade-off between per node storage and repair bandwidth is analyzed, and BFR-MSR and BFR-MBR points are derived. Explicit codes achieving these two operating points for a wide set of parameters are constructed by utilizing combinatorial designs, wherein the codewords of the underlying outer codes are distributed to BFR codeword symbols according to projective planes.
Electromechanical Wave Green's Function Estimation from Ambient Electrical Grid Frequency Noise

Many electrical grid transients can be described by the propagation of electromechanical (EM) waves that couple oscillations of power flows over transmission lines and the inertia of synchronous generators. These EM waves can take several forms: large-scale standing waves forming inter-area modes, localized oscillations of single or multi-machine modes, or traveling waves that spread quasi-circularly from major grid disturbances. The propagation speed and damping of these EM waves are potentially a powerful tool for assessing grid stability, e.g. small signal or rotor angle stability, however, EM wave properties have been mostly extracted from post-event analysis of major grid disturbances. Using a small set of data from the FNET sensor network, we show how the spatially resolved Green's function for EM wave propagation can be extracted from ambient frequency noise without the need for a major disturbance. If applied to an entire interconnection, an EM-wave Green's function map will enable a model-independent method of predicting the propagation of grid disturbances and assessing stability.
Super orthogonal differential space-time trellis coding and decoding

In this paper, a differential space-time trellis-coded scheme, based on super orthogonal space-time trellis codes (SOSTTC), is proposed. Based on its trellis structure, a low-complexity suboptimal differential decoder using the per-survival processing technique (PSP) is developed. In slow fading channels, it can approach the performance of SOSTTC with coherent decoding. Furthermore, an adaptive receiver is presented for time-varying channels, in which no training data is needed. Simulation results show that our scheme can achieve a good performance in both slow fading and time-varying fading channels with a reasonable complexity.
Trade liberalization, factor market flexibility, and growth : the case of Morocco and Tunisia

In recent years there has been an increasing recognition of the importance of complementary policies in enhancing the benefits of a more open trade regime. This study focuses on the importance of factor market flexibility to trade reforms. Using the Global Trade Analysis Project (GTAP) model and database, the results show that the welfare impact of trade reform is contingent on the flexibility of factor markets, with higher welfare gains occurring where factor markets are more flexible, and vice-versa. Defining two extreme factor market scenarios over Morocco and Tunisia, the author finds that the welfare gains of trade reforms under conditions of flexible factor markets can be as much as six times the gains compared with a rigid factor market scenario. This is so because whereas trade reforms may improve the incentive structure for resource reallocation, the extent to which resources move from less efficient to more efficient sectors of an economy is dependent on the degree of flexibility of factor markets.
Prior Alliances with Targets and Acquisition Performance in Knowledge-Intensive Industries

An important focus of the research on mergers and acquisitions is the conditions under which acquisitions create value for the acquiring firm's shareholders. Given that the acquisition process is plagued by serious issues of information asymmetry, which are exacerbated in the context of knowledge acquisitions, we examine whether prior alliances with potential targets reduce the information asymmetry enough to create “partner-specific absorptive capacity” and yield superior stock returns on acquisition, compared with acquisitions not preceded by alliances. We test our hypotheses on a sample of high-technology acquisitions by U.S. firms during 1990--1998 using an event study methodology to assess abnormal stock returns. We find, unexpectedly, that no significant general effect emerges for acquisitions with prior alliances. However, international acquisitions following alliances show significantly better returns relative to both acquisitions without prior alliances and domestic acquisitions. Additionally, stronger forms of prior alliances lead to better acquisition performance than weaker forms of alliances. Together, the results broadly support our thesis that partner-specific absorptive capacity may be at work and suggest that under certain prior alliance conditions, acquisitions can indeed create value for acquirers.
2-Quinoxalinol Salen Copper Complexes for Oxidation of Aryl Methylenes

A copper(II) complex of the 2-quinoxalinol salen ligand (salquCu) 1 has been tested for use in catalysis. Here, an optimized method for oxidation of aryl methylenes and its potential applications are described. In organic solvents, the yields obtained are higher than with other commonly used catalytic methods. Because this methods does not require high heat or increased pressure, this presents an opportunity for more environmentally friendly or “green” chemistry in a single-phase system. Using this method, a key fragment of natural products Vitamin K1 and K2, 1,4-naphthoquinone, can be easily synthesized from 1,2,3,4-tetrahydronaphthalene in increased yield (65 %) as compared to established methods (30–40 % yield) that require higher temperatures and increased pressure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Probabilistic relational planning with first order decision diagrams

Dynamic programming algorithms have been successfully applied to propositional stochastic planning problems by using compact representations, in particular algebraic decision diagrams, to capture domain dynamics and value functions. Work on symbolic dynamic programming lifted these ideas to first order logic using several representation schemes. Recent work introduced a first order variant of decision diagrams (FODD) and developed a value iteration algorithm for this representation. This paper develops several improvements to the FODD algorithm that make the approach practical. These include, new reduction operators that decrease the size of the representation, several speedup techniques, and techniques for value approximation. Incorporating these, the paper presents a planning system, FODD-PLANNER, for solving relational stochastic planning problems. The system is evaluated on several domains, including problems from the recent international planning competition, and shows competitive performance with top ranking systems. This is the first demonstration of feasibility of this approach and it shows that abstraction through compact representation is a promising approach to stochastic planning.
Drug Discovery by Combinatorial Chemistry—the Development of a Novel Method for the Rapid Synthesis of Single Compounds

Through the advantages conferred in the speed of synthesis, combinatorial chemistry is making a significant impact on the process of drug discovery. The mix-and-split paradigm has been an effective method for the production of compound mixtures, although there is now a need for new, fast library approaches to generate well-characterised single compounds. Having already demonstrated the successful preparation and application of library mixtures, we have now developed a novel combinatorial method for the production of single compounds.
An Arbitrage-Free Approach to Quasi-Option Value☆☆☆

.In the presence of uncertainty and irreversibility, dynamic decision problems should not be solved using expected net present value analysis. The right to delay a decision can be w valuable. We show that the value of this right equals Arrow and Fisher’s Quart. J. Econom. . x 88, 312]319 1974 quasi-option value. In a discrete model we show how to derive quasi-option value using methods from finance. These methods yield the advantage that they permit avoidance of the common pitfall of improperly matching a riskless discount rate with a risky project. In our arbitrage-free model, use of the riskless rate is appropriate. Two main findings are presented. First, if the stochastic dynamic process underlying the problem is known, the w . xw Arrow and Fisher Quart. J. Econom. 88, 312]319 1974 and Henry Amer. Econom. Re¤. . x 64, 1006]1012 1974 result, that improper use of net present value too often leads to early development, is correct. Second, if the process is assessed incorrectly, their result can be incorrect in the sense that net present value methods may lead to the correct outcome while the dynamic rule does not. Q 1998 Academic Press
Stacks similar to the stack of perverse sheaves

We introduce, on a topological space X, a class of stacks of abelian categories we call "stacks of type P". This class of stacks includes the stack of perverse sheaves (of any perversity, constructible with respect to a fixed stratification) and is singled out by fairly innocuous axioms. We show that some basic structure theory for perverse sheaves holds for a general stack of type P: such a stack is locally equivalent to a MacPherson-Vilonen construction, and under certain connectedness conditions its category of global objects is equivalent to the category of modules over a finite-dimensional algebra. To prove these results we develop a rudimentary tilting formalism for stacks of type P—another sense in which these stacks are "similar to stacks of perverse sheaves".
The Food Stamp Program and Food Insufficiency

Food stamp participants have higher food insufficiency rates than eligible nonparticipants, even after controlling for other factors. Given the Food Stamp Program's prominent role in the alleviation of hunger, this is a counterintuitive result. We conjecture that these higher rates are due to adverse selection insofar as households more likely to be food insufficient are also more likely to receive food stamps. We establish a theoretical framework to address this adverse selection. Using a simultaneous equation model with two probits, we show that once one controls for this adverse selection, food stamp recipients have the same probability of food insufficiency as nonrecipients. Copyright 2001, Oxford University Press.
The fluvial history of Mars

River channels and valleys have been observed on several planetary bodies in addition to the Earth. Long sinuous valleys on Venus, our Moon and Jupiter's moon Io are clearly formed by lava, and branching valleys on Saturn's moon Titan may be forming today by rivers of methane. But by far the most dissected body in our Solar System apart from the Earth is Mars. Branching valleys that in plan resemble terrestrial river valleys are common throughout the most ancient landscapes preserved on the planet. Accompanying the valleys are the remains of other indicators of erosion and deposition, such as deltas, alluvial fans and lake beds. There is little reason to doubt that water was the erosive agent and that early in Mars' history, climatic conditions were very different from the present cold conditions and such that, at least episodically, water could flow across the surface. In addition to the branching valley networks, there are large flood features, termed outflow channels. These are similar to, but dwarf, the largest terrestrial flood channels. The consensus is that these channels were also cut by water although there are other possibilities. The outflow channels mostly postdate the valley networks, although most are still very ancient. They appear to have formed at a time when surface conditions were similar to those that prevail today. There is evidence that glacial activity has modified some of the water-worn valleys, particularly in the 30-50° latitude belts, and ice may also be implicated in the formation of geologically recent, seemingly water-worn gullies on steep slopes. Mars also has had a long volcanic history, and long, sinuous lava channels similar to those on the Moon and Venus are common on and around the large volcanoes. These will not, however, be discussed further; the emphasis here is on the effects of running water on the evolution of the surface.
The Cosmic Radio and Infrared Backgrounds Connection

We use the radio-infrared (IR) flux correlation between star-forming galaxies in the local universe to examine the connection between their cumulative contributions to the cosmic IR and radio backgrounds. The general expression relating the intensities of the two backgrounds is complicated and depends on details of the evolution of the galaxies' IR luminosity function with redshift. However, in the specific case in which the radio-IR flux correlation is linear, the relation between the intensity of the IR background and the brightness temperature of the radio background reduces to a simple analytical expression that at 178 MHz is ICIB (nW m-2 sr-1) = 2.7Tcrb (K), where the numerical coefficient was calculated for a radio spectral index of 0.7. This relation is insensitive to the star-formation history of the galaxies that produce the cosmic IR background (CIB). We use the observed CIB intensity to constrain the cosmic star formation history and the relation between the CIB and the cosmic radio background (CRB) to constrain the relative contribution of star-forming galaxies to the CRB. Current limits on the CIB intensity predict a 178 MHz brightness temperature of ~18 ± 9 K, about half of the 37 ± 8 K inferred for an isotropic radio component. This suggests that star-forming galaxies and active galactic nuclei (AGNs) contribute about equally to the CRB intensity at that frequency.
Cometary Refractory Grains: Interstellar and Nebular Sources

Comets are heterogeneous mixtures of interstellar and nebular materials. The degree of mixing of interstellar sources and nebular sources at different nuclear size scales holds the promise of revealing how cometary particles, cometesimals, and cometary nuclei accreted. We can ascribe cometary materials to interstellar and nebular sources and see how comets probe planet-forming process in our protoplanetary disk.
Cost-Benefit Analysis of the Aerocapture Mission Set

Calculations have been performed to qualify the cost and delivered mass advantages of aerocapture at all destinations in the solar system with significant atmospheres.
On the way or around the corner? Observed refueling choices of alternative-fuel drivers in Southern California

Abstract Limited refueling infrastructure is an oft-cited barrier to alternative fuel vehicle (AFV) adoption, but empirical data on AFV driver refueling behavior are rare. To address this need, we surveyed 259 drivers of compressed natural gas (CNG) vehicles in Southern California at five stations across the metropolitan area. The key survey questions concerned the stops immediately before and after refueling and the driver’s home location. Using GIS, we analyze the least travel-time routes and the station chosen to provide insight into what drivers consider to be their most convenient refueling location. Specifically, we focus on whether they select stations nearest to home or on routes that require the least deviation. When faced with a choice between the two—that is, when no station satisfies both criteria—we found that ten times as many CNG drivers selected the station most on their way between their origin and destination than chose the station closest to their home. This finding supports the notion that optimal location models for planning early AFV refueling infrastructures should maximize convenience by serving the routes that drivers use frequently rather than their home locations, and that locations near high-volume roads may be ideal candidates for early station sites.
Conditional Chow-Liu tree structures for modeling discrete-valued vector time series

We consider the problem of modeling discrete-valued vector time series data using extensions of Chow-Liu tree models to capture both dependencies across time and dependencies across variables. Conditional Chow-Liu tree models are introduced, as an extension to standard Chow-Liu trees, for modeling conditional rather than joint densities. We describe learning algorithms for such models and show how they can be used to learn parsimonious representations for the output distributions in hidden Markov models. These models are applied to the important problem of simulating and forecasting daily precipitation occurrence for networks of rain stations. To demonstrate the effectiveness of the models, we compare their performance versus a number of alternatives using historical precipitation data from Southwestern Australia and the Western United States. We illustrate how the structure and parameters of the models can be used to provide an improved meteorological interpretation of such data.
Imaging of the temporal bone

Classical descriptions of the temporal bone are based on its five embryologically distinct osseous components: the petrous, tympanic, mastoid, squamous, and styloid portions.
A general-equilibrium closed-form solution to the welfare costs of inflation

This article presents a closed-form solution to Lucas's (2000) general-equilibrium expression for the welfare costs of inflation. The formula applies when the money demand is bi-logarithmic. An analytical solution for the difference between Bailey's (1956) partial-equilibrium measure and Lucas's general-equilibrium measure is also provided. In Lucas's original work, only numerical solutions are offered to these questions.
Reduced Collocation Methods: Reduced Basis Methods in the Collocation Framework

In this paper, we present the first reduced basis method well-suited for the collocation framework. Two fundamentally different algorithms are presented: the so-called Least Squares Reduced Collocation Method (LSRCM) and Empirical Reduced Collocation Method (ERCM). This work provides a reduced basis strategy to practitioners who prefer a collocation, rather than Galerkin, approach. Furthermore, the empirical reduced collocation method eliminates a potentially costly online procedure that is needed for non-affine problems with Galerkin approach. Numerical results demonstrate the high efficiency and accuracy of the reduced collocation methods, which match or exceed that of the traditional reduced basis method in the Galerkin framework.
Polymer-layered silicate nanocomposites: Synthesis, properties and applications

Polymer nanocomposites, especially polymer-layered silicate (PLS) nanocomposites, represent a radical alternative to conventionally (macroscopically) filled polymers. Because of their nanometer-size dispersion, the nanocomposites exhibit markedly improved properties when compared with the pure polymers or conventional composites. These include increased modulus and strength, decreased gas permeability, increased solvent and heat resistance and decreased flammability. In addition to their potential applications, PLS nanocomposites are also unique model systems to study the structure and dynamics of polymers in confined environments. Using both delaminated and intercalated hybrids, the statics and dynamics of polymers confined over distances ranging from the radius of gyration of the polymer to the statistical segment length of the chains can be studied. © 1998 John Wiley & Sons, Ltd.
Rules, rogues, and risk assessors: Academic responses to Enron and other accounting scandals

Abstract The recent accounting scandals in the USA and the resulting regulation of the US profession via the Sarbanes–Oxley Act have led to the resurrection of an old debate: principles vs. rules. We argue that such a debate is jejune and serves as little more than a diversion from discussing more substantive issues raised by events like Enron and Andersen. Accounting is not confronted by a choice of principles to the exclusion of rules or vice versa. Principles underlie any set of rules, and any implementation of principles will inevitably involve adopting some rules. We take issue with various analyses of the accounting scandals that rely too exclusively on the principles of neo-classical economics. We conclude by identifying four major obstacles impeding meaningful academic and educational treatment of the maladies of which Enron is merely a symptom.
Computer Industry Executives: An Analysis of the New Barons Compensation

In this paper we study the compensation determinants for CEOs in the computer industry and compare these findings with a large samp le of firms from other manufacturing and service industries. We examine whether superior performance is rewarded by higher levels of compensation and find cash-based compensation, such as salary and bonus, is influenced by performance. Depending on the gr owth prospects of the company, pay is tied either to accounting measures of performance or to stock return. In contrast, stock-based compensation, such as options and restricted stock awards, is not reflective of performance but depends upon the firm's growth. Two other interesting findings are that the prevalent use of stock-based compensation in the computer industry does not appear to be the result of computer firms being "cash starved." In addition, stock-based compensation does not appear to lead to larger executive stock ownership, as is widely believed.
The Symbolic Management of Strategic Change: Sensegiving Via Framing and Decoupling

This study develops a symbolic management perspective on strategic change to predict and test the antecedents and consequences of how firms frame strategic change. Using data from a sample of conte...
Identification and characterization of Rhodopseudomonas palustris TIE-1 hopanoid biosynthesis mutants.

Hopanes preserved in both modern and ancient sediments are recognized as the molecular fossils of bacteriohopanepolyols, pentacyclic hopanoid lipids. Based on the phylogenetic distribution of hopanoid production by extant bacteria, hopanes have been used as indicators of specific bacterial groups and/or their metabolisms. However, our ability to interpret them ultimately depends on understanding the physiological roles of hopanoids in modern bacteria. Toward this end, we set out to identify genes required for hopanoid biosynthesis in the anoxygenic phototroph Rhodopseudomonas palustris TIE-1 to enable selective control of hopanoid production. We attempted to delete 17 genes within a putative hopanoid biosynthetic gene cluster to determine their role, if any, in hopanoid biosynthesis. Two genes, hpnH and hpnG, are required to produce both bacteriohopanetetrol and aminobacteriohopanetriol, whereas a third gene, hpnO, is required only for aminobacteriohopanetriol production. None of the genes in this cluster are required to exclusively synthesize bacteriohopanetetrol, indicating that at least one other hopanoid biosynthesis gene is located elsewhere on the chromosome. Physiological studies with the different deletion mutants demonstrated that unmethylated and C_30 hopanoids are sufficient to maintain cytoplasmic but not outer membrane integrity. These results imply that hopanoid modifications, including methylation of the A-ring and the addition of a polar head group, may have biologic functions beyond playing a role in membrane permeability.
Equilibrium Returns Policies in the Presence of Supplier Competition

The pioneering Pasternack returns-policy model analyzed channel coordination with a single supplier catering to a retailer facing stochastic demand for a perishable product with a fixed price, and the model showed that giving partial returns of unsold stock to the retailer is the optimal policy for the entire supply chain. The result thus begs the question as to why manufacturers of perishable commodities widely accept full returns of unsold stock as the norm. We model the environment as one where two capacity-constrained manufacturers compete for shelf space with the same retailer, and we show that a complete-credit returns policy is in fact the only possible equilibrium of the game. Our results obviate the need for knowing the exact functional form of the demand distribution in order to compute the returns credit, as Pasternack's results would require. From a retailer's standpoint, we establish a simple procurement strategy and show that it is optimal. The same game with price-only contracting has a pure-strategy equilibrium when the supplier capacities are below a threshold value and a mixed-strategy equilibrium when the supplier capacities cross this threshold but are still so limited that no single supplier can with certainty supply all the quantity demanded.
Nondiversification Traps in Catastrophe Insurance Markets

We develop a model for markets for catastrophic risk. The model explains why insurance providers may choose not to offer insurance for catastrophic risks and not to participate in reinsurance markets, even though there is a large enough market capacity to reach full risk sharing through diversification in a reinsurance market. This is a “nondiversification trap.” We show that nondiversification traps may arise when risk distributions have heavy left tails and insurance providers have limited liability. When they are present, there may be a coordination role for a centralized agency to ensure that risk sharing takes place.
NUMERICAL KUBO FORMULA STUDY OF FRICTIONAL DRAG IN THE INTEGER QUANTUM HALL REGIME

We study interlayer frictional drag between two-dimensional electron systems in the strong magnetic field limit by evaluating the weak-coupling Kubo formula for interlayer drag numerically. The key quantity in this theory is the disorder averaged "triangle function", a product of three Greens functions of electrons that represents the dc current response of electrons in one layer to charge fluctuations in a remote current-carrying layer. We find that the disorder averaged triangle functions are proportional to the momentum transfer $\vec{q}$ at small $|\vec{q}|$ and that they change sign under a ν→1-ν particle-hole transformations, vanishing for half-filled Landau levels.
The Extended Relativity Theory in Clifford Phase Spaces and Modifications of Gravity at the Planck/Hubble Scales

We extend the construction of Born’s Reciprocal Phase Space Relativity to the case of Clifford Spaces which involve the use of polyvectors and a lower/upper length scale. The generalized polyvector-valued velocity and acceleration/force boosts in Clifford Phase Spaces is presented and we find an explicit Clifford algebraic realization of the velocity and acceleration/force boosts in ordinary phase space. Finally, we provide a Clifford Phase-Space Gravitational Theory based in gauging the generalization of the Quaplectic group and invoking Born’s reciprocity principle between coordinates and momenta (maximal speed of light velocity and maximal force). The generalized gravitational vacuum field equations are explicitly displayed. We conclude with a brief discussion on the role of higher-order Finsler geometry in the construction of extended relativity theories with an upper and lower bound to the higher order accelerations (associated with the higher order tangent and cotangent spaces).
Multi-Timescale Nonlinear Robust Control for a Miniature Helicopter

A new nonlinear control approach, which is applied to a miniature aerobatic helicopter through a multi-timescale structure, is proposed. Because of the highly nonlinear, unstable, and underactuated nature of a miniature helicopter, it is a challenge to design an autonomous flight control system that is capable of operating in the full flight envelope. To deal with unstable internal dynamics, the translational, rotational, and flapping dynamics of the helicopter (eleven degrees of freedom) are organized into a three-timescale, nonlinear model. The concepts of dynamic inversion and sliding manifold are combined together such that 1) the controller proposed is robust with respect to functional and parametric uncertainties, and 2) the settling time in faster modes is guaranteed to be less than the fixed step size of slower modes. A time-varying feedback gain, derived according to global stability and sliding manifold variations, is proved to be uniquely solvable based on the Perron-Frobenius Theorem. Partial uncertainties are explicitly taken into account in the nonlinear robust control design, and Monte Carlo simulations are used for validations under other sensor noises, model uncertainties, and a Federal Aviation Administration suggested gust condition.
Aberration Correction in Electron Microscopy

Spherical and chromatic aberrations limit the resolution of conventional electron microscopes. Both defects are unavoidable in the case of static rotationally symmetric electromagnetic fields (Scherzer’s theorem). To compensate for these aberrations, multipole correctors or electron mirrors are required. The correction of the resolution-limiting aberrations is demonstrated for the hexapole corrector, the quadrupole-octopole corrector and the tetrode mirror. Electron mirrors require a magnetic beam separator, which must be free of second-order aberrations. The multipole correctors are highly symmetric telescopic systems compensating for the defects of the round lenses. The hexapole corrector has the simplest structure yet eliminates only third-order spherical aberration and coma, whereas the mirror and the quadrupole-octopole (QO) corrector are able to correct the chromatic aberration as well. The QO corrector eliminates chromatic aberration by means of crossed electric and magnetic quadrupoles and the third-order spherical aberration by octopoles. At present, aberration-corrected electron microscopes obtain a resolution limit of about 1 Angstroem.
Option Pricing and the Martingale Restriction

In the absence of frictions, the value of the underlying asset implied by option prices must equal its actual market value. With frictions, however, this requirement need not hold. Using S&P 100 index options data, I find that the implied cost of the index is significantly higher in the options market than in the stock market, and is directly related to measures of transaction costs and liquidity. I show that the Black-Scholes model has strong bid-ask spread, trading volume, and open interest biases. Option pricing models that relax the martingale restriction perform significantly better. Article published by Oxford University Press on behalf of the Society for Financial Studies in its journal, The Review of Financial Studies.
A question-answering system for high school algebra word problems

The aim of the research reported here was to discover methods for building computer programs which can understand and communicate with people in a non-trivial subset of English. A computer program understands a subset of English if it accepts input sentences which are members of this subset, and answers questions based on information contained in the input. We describe in this paper a semantic theory of discourse, and utilize a first approximation to the analytical portion of this theory in the STUDENT question-answering system, a program which understands a subset of English in the sense defined above.
Automated Remote Sensing with Near Infrared Reflectance Spectra: Carbonate Recognition

Reflectance spectroscopy is a standard tool for studying the mineral composition of rock and soil samples and for remote sensing of terrestrial and extraterrestrial surfaces. We describe research on automated methods of mineral identification from reflectance spectra and give evidence that a simple algorithm, adapted from a well-known search procedure for Bayes nets, identifies the most frequently occurring classes of carbonates with reliability equal to or greater than that of human experts. We compare the reliability of the procedure to the reliability of several other automated methods adapted to the same purpose. Evidence is given that the procedure can be applied to some other mineral classes as well. Since the procedure is fast with low memory requirements, it is suitable for on-board scientific analysis by orbiters or surface rovers.
Global tunability of one-dimensional SISO systems

It is shown by example that with a suitably defined certainty equivalence controller Sigma /sub R/, it is possible to make a closed-loop parameterized system Sigma tunable on its entire parameter space P, even though P may contain points at which the parameterized Sigma /sub D/, upon which Sigma /sub R/'s definition is based, is not stabilizable. The implications of this discovery are briefly discussed. >
COMPLETE POSITIVITY OF THE MAP FROM A BASIS TO ITS DUAL BASIS

The dual of a matrix ordered space has a natural matrix ordering that makes the dual space matrix ordered as well. The purpose of these notes is to give a condition that describes when the linear map taking a basis of Mn to its dual basis is a complete order isomorphism. We exhibit “natural” orthonormal bases for Mn such that this map is an order isomorphism, but not a complete order isomorphism. Included among such bases is the Pauli basis. Our results generalize the Choi matrix by giving conditions under which the role of the standard basis {Eij} can be replaced by other bases.
Metal and mixed-metal coordination polymers synthesized with pyrazine-2-carboxylate

This Dalton Perspective summarizes the rich structural diversity in coordination polymers that utilize pyrazine-2-carboxylate (pca) as the linking ligand. Pyrazine-2-carboxylate has two donor groups in the form of ring nitrogens and carboxylato oxygens. This dual functionality imparts this ligand with unique and reliable networking abilities described herein. Preceding the structural details of pca based coordination polymers is a brief examination of the separate components (organic and inorganic) and the syntheses of these hybrid materials.