cssi/SciSciGPT-SciSciNet huggingface dataset:
Ambiguity Aversion: Implications for the Uncovered Interest Rate Parity Puzzle

Empirically, high-interest-rate currencies tend to appreciate in the future relative to low-interest-rate currencies instead of depreciating as uncovered interest rate parity (UIP) states. The explanation for the UIP puzzle that I pursue in this paper is that the agents’ beliefs are systematically distorted. This perspective receives some support from an extended empirical literature using survey data. I construct a model of exchange rate determination in which ambiguity-averse agents need to solve a ltering problem to form forecasts but face signals about the time-varying hidden state that are of uncertain precision. In the presence of such uncertainty, ambiguityaverse agents take a worst-case evaluation of this precision and respond stronger to bad news than to good news about the payos
Hölder continuity for a drift-diffusion equation with pressure

We address the persistence of Holder continuity for weak solutions of the linear drift-diffusion equation with nonlocal pressure ut + bru − 4 u = r p, ru = 0 on (0,1 ) � R n , with n � 2. The drift velocity b is assumed to be at the critical regularity level, with respe ct to the natural scaling of the equations. The proof draws on Campanato's characterization of Holder spaces, and uses a maximum-principle-type argument by which we control the growth in time of certain local averages of u. We provide an estimate that does not depend on any local smallness condition on the vector field b, but only on scale invariant quantities.
Ray‐based synthesis of bistatic ground‐penetrating radar profiles

An algorithm has been developed to numerically synthesize 2-D bistatic (common‐offset), ground‐penetrating radar (GPR) profiles using the principles of geometrical ray theory. By assuming nondispersive propagation, kinematic properties of electromagnetic waves are simulated by ray tracing. Dynamic properties are simulated by computing transmitter and receiver directivities, reflection and transmission coefficients, geometrical spreading, and attenuation coefficients. The main limitations are that wave effects, such as diffractions, and offline (3-D) effects are not included. The algorithm is applied to iterative modeling of multioffset, multifrequency GPR data acquired over an outcrop of fractured Austin Chalk in Dallas County in northeast Texas. Modeling is able to simulate realistically the main time and amplitude behaviors observed in GPR reflections at 50, 100, and 200 MHz at each of 1, 3, and 5 meter antenna separations from a single model. Detailed modeling produces quantitative estimates of the spa...
Switching between consumer technologies

Consumer technologies have become pervasive and ubiquitous in modern societies. These technologies have moved from being luxuries to necessities for average consumers. Moreover, they have become more affordable, are easily accessible, and have significant value-propositions. Many of these technologies, e.g. Web browsers, are available on the Internet as shareware or freeware. Today, it has become an increasingly simple task for the average consumer to find, acquire, set up and use these technologies. Consequently, there is little in the way that prevents a consumer from abandoning these technologies once they are adopted, or switching over to competitive offerings. The focus of this article is to seek an understanding of what factors lead a consumer to abandon one product offering for another. Scholars in marketing and consumer behavior have identified several factors that influence consumer switching in general, as illustrated in Figure 1. However, examining switching behavior between technology substitutes, especially in the case of consumer technologies, is salient for several reasons. First, the technology marketplace is extremely competitive. For most consumer needs, there is an abundance of technology choices and technology providers have to fight fiercely to introduce their products in an already saturated, and highly contested, marketplace. For example, in today's mobile technology marketplace a consumer is offered choices from a wide assortment of products and services from existing technology providers, hence making it difficult for a new provider to carve out a niche. Second, most consumer technologies are relatively easy to acquire, try out, and even abandon. For instance, today, through portals such as CNET.com a consumer can find and download several dozen options of software products for any given task. These technologies are all available at little or no expense to the consumer and hence there is low if any switching cost. Third, there is often low differentiation among various technology options. For instance, consider the differences between Internet Explorer (IE) and Firefox, both products offer very similar functionality, have similar user-interfaces, and may not be clearly differentiated by a novice user. Hence, the decision to switch from an incumbent technology solution to a substitute becomes even more interesting. Why would one switch if the two products are highly similar, and there are no obvious differences. Finally, user switching between technology products is also interesting to study because it represents a form of post-adoption behavior that is generally unexplored in the Information Systems literature. While there is an abundance of studies on technology adoption,12 only recently have researchers started to examine post-adoption issues.7 Among the studies that have examined post-adoption behavior, we believe that we are one of the first to study the switching behavior that is associated with the abandoning of one technology product in favor of a substitute.
ON THE ASYMPTOTIC POWER OF THE VARIANCE RATIO TEST

The variance-ratio (VR) test statistic, which is based on k-period differences of the data, is commonly used in empirical finance and economics to test the random walk hypothesis. We obtain the asymptotic power function of the VR test statistic when the differencing period k is increasing with the sample size n such that k/n -o 8 > 0. We show that the test is inconsistent against a variety of meanreverting alternatives, confirm the result in simulations, and then characterize the functional form of the asymptotic power in terms of 8 and these alternatives.
Sulfur, Chlorine, and Argon in Planetary Nebulae. IIA. Observations of a Southern Sample

In this paper we present fully reduced and dereddened emission line strengths for a sample of 45 southern type II planetary nebulae (PNs).The spectrophotometry for these PNs covers an extended optical/near-IR range from 3600 to 9600 A. This PN study and subsequent analysis (presented in a companion paper), together with a similar treatment for a northern PN sample, is aimed at addressing the lack of homogeneous, consistently observed, reduced, and analyzed data sets that include the near-IR [S III] lines at 9069 and 9532 A. The use of type II objects only is intended to select disk nebulae that are uncontaminated by nucleosynthetic products of the progenitor star. Extending spectra redward to include the strong [S III] lines enables us to look for consistency between S+2 abundances inferred from these lines and from the more accessible, albeit weaker, [S III] line at λ6312.
Synthesis and Characterization of Pyrazolyl-Functionalized Imidazolium-Based Ionic Liquids and Hemilabile (Carbene)palladium(II) Complex Catalyzed Heck Reaction

Neat reactions of 1-(pyrazolylmethyl)imidazole with an excess of alkyl or polyfluoroalkyl halides at 100 °C followed by subsequent metathetical reactions with LiN(SO2CF3)2 or KPF6 at 25 °C gave rise to a series of monoquaternary salts 3a–3k. These salts can be also prepared through treatment of 1-alkylimidazole with 1-(chloromethyl)pyrazole hydrochloride in the presence of base, followed by anion exchange with LiN(SO2CF3)2 or KPF6. Their phase-transition temperature, thermal stability, density and solubility in common solvents have been investigated. Most of the bis(trifluoromethanesulfon)amide salts are room-temperature ionic liquids. The effect of anions and of alkyl substituents bonded to the imidazolium cation on the physicochemical properties was examined. Using 3-butyl-1-(pyrazolylmethyl)imidazolium chloride (2d), the precursor of 3-butyl-1-(pyrazolylmethyl)imidazolium bis(trifluoromethanesulfon)amide (3d), as a reactant, a hemilabile (N-heterocyclic carbene)palladium(II) complex 4 was synthesized through a (carbene)silver(I) transfer reagent. It was characterized by single-crystal X-ray diffraction analysis. The catalytic activity and recyclability of 4 in 3d were preliminarily evaluated by consecutive Heck reactions using different substrates. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Ultrafast Cleavage and Deprotection of Oligonucleotides Synthesis and Use of CAc Derivatives

Abstract We have investigated the use of alkylamines as fast cleavage and deprotection reagents for the solid phase synthesis of oligonucleotides and found methylamine/ammonium hydroxide (or methylamine) as an efficient reagent. The transamination side product formed with the commonly used dCbz has been eliminated by the use of dCAc phosphoramidite. This system has successfully been used in the synthesis of oligonucleotides and oligonucleoside phosphorothioates. DMT dCAc hydrogen phosphonate and DMT ribo CAc-2′-O Me phosphoramidite also have been prepared and used in the synthesis of oligonucleotides.
Disorder-enhanced phase coherence in trapped bosons on optical lattices

The consequences of disorder on interacting bosons trapped in one-dimensional optical lattices are investigated by quantum Monte Carlo simulations. A numerical analysis of the momentum distribution function, the stiffness and the compressibility reveals a unique response to small to moderate strengths of potential disorder. If there is a Mott plateau at the centre of the trap in the clean limit, phase coherence increases as a result of disorder. The localization effects due to correlation and disorder compete against each other, resulting in a partial delocalization of the particles in the Mott region, which in turn leads to increased phase coherence. In the absence of a Mott plateau, this effect is absent. A detailed analysis of the uniform system without a trap shows that the disordered states participate in a Bose glass phase.
Rudder Control Strategies and Force/Feel System Designs in Transport Aircraft

An analytical investigation of rudder control strategies in transport aircraft is undertaken. The study was motivated by an airline crash in which rudder usage by the pilot might have been a contributing factor. A detailed mathematical model of the human pilot is employed in a computer simulation to examine the closed-loop nature of rudder control strategies. Emphasis is placed on pilot-induced oscillation tendencies. A task suitable for pilot-in-the-loop flight-simulator evaluation of rudder control systems is proposed. A comparison of the pedal force/feel characteristics of three transport aircraft and a military helicopter is provided. The adverse effect that highly nonlinear pedal force/feel system characteristics can have on pilot/vehicle response predictability is demonstrated. A linearity index is defined to quantify the linear force/displacement characteristics of any force/feel system. Nomenclature A(−) =g ain factors in vehicle transfer functions ayps = lateral acceleration at pilot’s station, g
A critical assessment of the Burning Index in Los Angeles County, California

The Burning Index (BI) is commonly used as a predictor of wildfire activity. An examination of data on the BI and wildfires in Los Angeles County, California, from January 1976 to December 2000 reveals that although the BI is positively associated with wildfire occurrence, its predictive value is quite limited. Wind speed alone has a higher correlation with burn area than BI, for instance, and a simple alternative point process model using wind speed, relative humidity, precipitation and temperature well outperforms the BI in terms of predictive power. The BI is generally far too high in winter and too low in fall, and may exaggerate the impact of individual variables such as wind speed or temperature during times when other variables, such as precipitation or relative humidity, render the environment ill suited for wildfires.
An integrated Bayesian approach to layer extraction from image sequences

This paper describes a Bayesian approach for modeling 3D scenes as collection of approximately planar layers that are arbitrarily positioned and oriented in the scene. In contrast to much of the previous work on layer-based motion modeling, which computes layered descriptions of 2D image motion, our work leads to a 3D description of the scene. There are two contributions within the paper. The first is to formulate the prior assumptions about the layers and scene within a Bayesian decision making framework which is used to automatically determine the number of layers and the assignment of individual pixels to layers. The second is algorithmic. In order to achieve the optimization, a Bayesian version of RANSAC is developed with which to initialize the segmentation. Then, a generalized expectation maximization method is used to find the MAP solution.
Design for Diagnosability Guidelines

In this paper, we will define some of the terminology, provide a model for the diagnostic process, and highlight areas of diagnostic complications. We will apply the diagnostic complications in a Venn diagram to get a better illustration and possibly create a basis for diagnosability metrics in future work. With the tools at hand, we will finally tackle the design issues by hypothesizing on various causes of each diagnostic complication and providing some (though not exhaustive) DFD guidelines.
Instruction-level distributed processing

Shifts in hardware and software technology will soon force designers to look at microarchitectures that process instruction streams in a highly distributed fashion.
The Empirical Saddlepoint Likelihood Estimator Applied to Two-Step GMM

The empirical saddlepoint likelihood (ESPL) estimator is introduced. The ESPL provides improvement over one-step GMM estimators by including additional terms to automatically reduce higher order bias. The first order sampling properties are shown to be equivalent to efficient two-step GMM. New tests are introduced for hypothesis on the model's parameters. The higher order bias is calculated and situations of practical interest are noted where this bias will be smaller than for currently available estimators. As an application, the ESPL is used to investigate an overidentified moment model. It is shown how the model's parameters can be estimated with both the ESPL and a conditional ESPL (CESPL), conditional on the overidentifying restrictions being satisfied. This application leads to several new tests for overidentifying restrictions. Simulations demonstrate that ESPL and CESPL have smaller bias than currently available one-step GMM estimators. The simulations also show new tests for overidentifying restrictions that have performance comparable to or better than currently available tests. The computations needed to calculate the ESPL estimator are comparable to those needed for a one-step GMM estimator.
Jump linear quadratic Gaussian control in continuous time

The optimal quadratic control of continuous-time linear systems that possess randomly jumping parameters which can be described by finite-state Markov processes is addressed. The systems are also subject to Gaussian input and measurement noise. The optimal solution for the jump linear-quadratic-Gaussian (JLQC) problem is given. This solution is based on a separation theorem. The optimal state estimator is sample-path dependent. If the plant parameters are constant in each value of the underlying jumping process, then the controller portion of the compensator converges to a time-invariant control law. However, the filter portion of the optimal infinite time horizon JLQC compensator is not time invariant. Thus, a suboptimal filter which does converge to a steady-state solution (under certain conditions) is derived, and a time-invariant compensator is obtained. >
Neural-network-based parasitic modeling and extraction verification for RF/millimeter-wave integrated circuit design

This paper reports an interconnect modeling approach for RF and millimeter-wave integrated circuits (ICs) using neural network models and a novel parasitic extraction verification procedure using automatically generated test structures. The effects of the parasitics in RF/millimeter-wave ICs are investigated with special focus on the parasitic inductances, since they are not evaluated by most of the commercially available extraction tools. State-of-the-art silicon-based multilayer RF process parameters are utilized to extract the resistive, the capacitive, and the inductive components of the layout interconnects. Neural network models are developed using electromagnetic (EM) simulation results of a set of passive interconnect structures. In addition, an automated layout generation methodology is used for the verification of the parasitic extraction methodologies. The proposed verification approach is demonstrated using automatically generated passive test structures and ring oscillators. The effects of parasitics are also investigated in voltage-controlled oscillators (VCOs) and amplifiers for millimeter-wave applications, and the neural models are verified using 30-GHz VCO measurement results. Hence, we present a complete modeling report of layout interconnect parasitics in RF/millimeter-wave integrated circuits as well as a novel verification procedure to validate non-EM analytical or neural models
Neural network adaptive digital image screen halftoning (DISH) based on wavelet transform preprocessing

Artificial neural network (ANN) can be used to process the digital image screen halftoning (DISH), designed to be adaptive to the local variation of image intensity based on the wavelet transform (WT) preprocessing of the local gradient at each pixel. Our preliminary digital simulation results have shown an improved multiresolution visual effect of the bi-level representation of a gray-scale image. An interesting device concept is to build a fast "WT chip" of order (N) with a smart "neurochip" for DISH applications, in order to achieve an nonuniformly enhanced dot matrix printing.
Figure–figure interaction between bodies having arbitrary shapes and mass distributions: a power series expansion approach

We derive an expression for the mutual gravitational force and torque of two bodies having arbitrary shapes and mass distributions, as an expansion in power series of their products of inertia and of the relative coordinates of their centres of mass. The absolute convergence of all the power series developed is rigorously demonstrated. The absence of transcendental functions makes this formalism suitable for fast numerical applications. The products of inertia used here are directly related to the spherical harmonics coefficients, and we provide a detailed analysis of this relationship.
Multi stage three-dimensional sweeping and annealing of disc galaxies in clusters

We present new three-dimensional, hydrodynamic simulations of the ram pressure stripping of disc galaxies via interaction with a hot intracluster medium (ICM). The simulations were carried with the smoothed-particle hydrodynamics, adaptive mesh ‘HYDRA’ code (SPH-AP 3 M), with model galaxies consisting of gas and stellar disc components and dark haloes. The simulations also include radiative cooling, which is important for keeping the warm, diffuse gas of moderate density from being unrealistically heated by the ICM. We examine the role that wind velocity, density and galaxy tilt play in gas stripping. We include cases with lower ram pressures than other recent studies. In accord with previous studies, we find that low column density gas is promptly removed from the outer disc. However, we also find that not all of the gas stripped from the disc escapes immediately from the halo, some of material can linger for times of order 10 8 yr. We use a simple analytic model to demonstrate that gas elements in the ICM wind feel an effective potential with a minimum displaced downstream from the halo centre. The onset of the ICM wind has a profound effect on the disc gas that is not immediately stripped. This remnant disc is displaced relative to the halo centre and compressed. This can trigger gravitational instability and the formation of numerous flocculent spirals. These waves transport angular momentum outward, resulting in further compression of the inner disc and the formation of a prominent gas ring. This ‘annealing’ process makes the inner disc, which contains much of the total gas mass, resistant to further stripping, but presumably susceptible to global starbursts. Spirals in the outer disc stretch, shear and are eventually stripped on timescales of a few times 10 8 yr, after which time, mass and angular momentum loss effectly cease. For inclined galaxies, these effects are considerably modified over the same time-scale. The amount of mass loss is reduced. In addition, we find that a higher galaxy tilt couples the wind and the rotating disc, and produces a higher degree of angular momentum removal. Temperature and line-of-sight velocity maps from several of the simulations are presented for comparison with observation. When the mass loss and annealing processes go to completion, we find that the total amount of mass lost from a fixed target galaxy is well-fitted by a simple power-law function of a dimensionless parameter that combines the ram pressure and internal properties of the galaxy. Ramifications for the cluster galaxy evolution are discussed.
The Cost of Security: Foreign Policy Concessions and Military Alliances

It is well recognized that military alliances can provide their members with important security benefits. However, less attention has been paid to the policy concessions states must grant others to enter into military alliances. To study this aspect of alliances, I develop a three-actor bargaining model of alliance formation that endogenizes both external threat and policy concessions. Specifically, a target state bargains with a potential defender over the concessions it must make to ally and then responds to a potential challenger. The model suggests that what is important for policy concessions in alliances is not just the power of the threatened state but its power relative to its challenger and how an alliance will change the distribution of power. I test implications of this model using data on promised policy concessions formalized in alliance treaties and find strong support for the hypotheses. More specifically, I find that states are willing to make more concessions in exchange for an alliance w...
Simplicial complexes of triangular Ferrers boards

We study the simplicial complex that arises from non-attacking rook placements on a subclass of Ferrers boards that have a i rows of length i where a i >0 and i?n for some positive integer n. In particular, we will investigate enumerative properties of their facets, their homotopy type, and homology.
Secondary Metabolites from Andrographis paniculata

Two new flavonoid glycosides, 5-hydroxy-7,8-dimethoxy (2R)-flavanone-5-O-beta-D-glucopyranoside (1) and 5-hydroxy-7,8,2',5'-tetramethoxy-flavone-5-O-beta-D-glucopyranoside (2), and a new diterpenoid, andrographic acid (3), along with andrographidine A (4) were isolated from Andrographis paniculata, and their structures were determined on the basis of physicochemical and spectroscopic analysis. Compound 3 was evaluated for cytotoxicity to KB cells along with andrographolide, isoandrographolide, neoandrographolide and 14-deoxy-11,12-didehydroandrographolide obtained from A. paniculata in the present study. Cytotoxicity was observed for andrographolide and isoandrographolide with ED50 values of 6.5 and 5.1 microg/ml, respectively.
Complex Matrix Remodeling and Durotaxis Can Emerge From Simple Rules for Cell-Matrix Interaction in Agent-Based Models

Using a top-down approach, an agent-based model was developed within NetLogo where cells and extracellular matrix (ECM) fibers were composed of multiple agents to create deformable structures capable of exerting, reacting to, and transmitting mechanical force. At the beginning of the simulation, long fibers were randomly distributed and cross linked. Throughout the simulation, imposed rules allowed cells to exert traction forces by extending pseudopodia, binding to fibers and pulling them towards the cell. Simulated cells remodeled the fibrous matrix to change both the density and alignment of fibers and migrated within the matrix in ways that are consistent with previous experimental work. For example, cells compacted the matrix in their pericellular regions much more than the average compaction experienced for the entire matrix (696% versus 21%). Between pairs of cells, the matrix density increased (by 92%) and the fibers became more aligned (anisotropy index increased from 0.45 to 0.68) in the direction parallel to a line connecting the two cells, consistent with the “lines of tension” observed in experiments by others. Cells migrated towards one another at an average rate of ∼0.5 cell diameters per 10,000 arbitrary units (AU); faster migration occurred in simulations where the fiber density in the intercellular area was greater. To explore the potential contribution of matrix stiffness gradients in the observed migration (i.e., durotaxis), the model was altered to contain a regular lattice of fibers possessing a stiffness gradient and just a single cell. In these simulations cells migrated preferentially in the direction of increasing stiffness at a rate of ∼2 cell diameter per 10,000 AU. This work demonstrates that matrix remodeling and durotaxis, both complex phenomena, might be emergent behaviors based on just a few rules that control how a cell can interact with a fibrous ECM.
An invariant of finitary codes with finite expected square root coding length

Let p and q be probability vectors with the same entropy h. Denote by B(p) the Bernoulli shift indexed by Z with marginal distribution p. Suppose that ' is a measure preserving homomorphism from B(p) to B(q). We prove that if the coding length of ' has a finite 1/2 moment, then � 2 = � 2 , where � 2 p = P i pi(−logpi − h)
Growth of triglycine sulfate (TGS) crystals by solution technique

The growth of crystals from solution is greatly influenced by buoyancy driven convection. In a low-g environment, convection is greatly suppressed and diffusion becomes the predominant mechanism for thermal and mass transport. An experiment to grow TGS crystals by solution technique during the orbital Spacelab III mission has been designed. Crystals are grown by a new and unique technique of extracting heat from the crystal through a sting. The cooling at the sting tip is responsible for the desired supersaturation near the growing crystal. Calculations indicate that the cooled sting technique for solution crystal growth is necessary in low-g to maintain a maximum growth rate of 1 mm/day. Results of groundbased work in support of the flight experiment are discussed.
Dielectric surface flashover in vacuum at 100 K

Cryogenic components in high power electrical systems and in power electronics gain more and more importance. The behavior of insulators for cryogenic conditions, however, is virtually unknown. In a fast coaxial setup, dielectric test sample and electrodes in vacuum are cooled to <100 K and flashover is characterized using fast electrical and optical diagnostics. Three consecutive development stages for flashover in self-breakdown mode with a gap distance of 0.5 cm can be distinguished: (1) a fast current rise to mA amplitudes within /spl sim/2 ns, probably associated with field emission, followed by, (2) a slow current rise to /spl sim/5 to 10 A amplitude with duration of 40 ns to 1 /spl mu/s, associated with secondary emission avalanche saturation, and (3) a transition to a rapid gaseous ionization above the sample caused by electron induced outgassing, leading to impedance-limited current amplitudes of /spl les/300 A. Phase (1) shows a higher final current at lower temperature, which is probably due to a higher initial velocity of the secondary electrons, the duration of phase (2) is a decreasing function of breakdown voltage and only slightly dependent on temperature, which points to a weak temperature dependence of the outgassing process. Flashover potentials show a slight increase at lower temperature.
On the Theoretical Uncertainties in the Muon Anomalous Magnetic Moment

I present a fairly detailed discussion of various contributions to the anomalous magnetic moment of the muon aμ. I try to give an unbiased evaluation of the validity of the SM prediction for this quantity and to point out some delicate issues involved in its calculation. I conclude that the theory uncertainties in the SM prediction for the muon anomalous magnetic moment are underestimated and a great deal of work will be required to reduce these uncertainties to the level required by experiment.
Expectation, Conditional Expectation and Martingales in Local Fields

We investigate a possible definition of expectation and conditional expectation for random variables with values in a local field such as the $p$-adic numbers. We define the expectation by analogy with the observation that for real-valued random variables in $L^2$ the expected value is the orthogonal projection onto the constants. Previous work has shown that the local field version of $L^\infty$ is the appropriate counterpart of $L^2$, and so the expected value of a local field-valued random variable is defined to be its ``projection'' in $L^\infty$ onto the constants. Unlike the real case, the resulting projection is not typically a single constant, but rather a ball in the metric on the local field. However, many properties of this expectation operation and the corresponding conditional expectation mirror those familiar from the real-valued case; for example, conditional expectation is, in a suitable sense, a contraction on $L^\infty$ and the tower property holds. We also define the corresponding notion of martingale, show that several standard examples of martingales (for example, sums or products of suitable independent random variables or ``harmonic'' functions composed with Markov chains) have local field analogues, and obtain versions of the optional sampling and martingale convergence theorems.
A nonhydrolyzable analogue of phosphotyrosine, and related aryloxymethano- and aryloxyethano-phosphonic acids as motifs for inhibition of phosphatases

Abstract Nonhydrolyzable analogues of both stereoisomers of phosphotyrosine, and a series of related aryloxy (or thio) methyl and aryloxy (or thio) ethyl phosphonic acids of the general formula RX–(CH 2 ) n –PO 3 H 2 (where X = O or S and n = 1 or 2), have been tested as nonhydrolyzable mimetics of phosphatase substrates. These compounds were tested against a panel of phosphatases (two alkaline phosphatases, a protein–tyrosine phosphatase, and two serine/threonine phosphatases) with different active site motifs. The compounds exhibit competitive inhibition toward all enzymes tested, with the best inhibition expressed toward the Ser/Thr phosphatases. The stereoisomers of the phosphotyrosine analogues exhibited an unexpected difference in their inhibitory properties toward the protein–tyrosine phosphatase from Yersinia . The K i for the d isomer is 33-fold lower than that of the l isomer, and is more than an order of magnitude lower than the reported K m of the substrate l -phosphotyrosine.
Videoconferencing as Access to Spoken French

This article analyzes a classroom interaction taking place between language learners in the U.S. and France via international videoconferencing. The videoconferencing event is described in its technical and discursive dimensions; its pedagogical value is evaluated in terms of the American learners' putative Zone of Proximal Development (ZPD). Much of the language use that took place during the conference was beyond these learners' capability, due in part to heightened language classroom anxiety, and in part to differences between the variety of French learned in American schools and the French spoken by educated native speakers (NSs). A return to the learners' ZPD was achieved by using the videotaped record of the conference to provide access to a corpus of the spoken language as it is used in contemporary France. The aim of this exercise was observation and awareness of the morphosyntactic and discourse difficulties experienced by American second language learners interacting with NSs of French.
Prediction of Icing Effects on the Coupled Dynamic Response of Light Airplanes

Most methods for the preliminary safety and performance evaluation of airplane dynamical response, stability characteristics, and climb performance in icing conditions require relatively sophisticated methods, based on detailed empirical data and existing flight data. This paper extends a pitch axis 3-degree-of-freedom methodology to the fully coupled, 6-degree-of-freedom case. It evaluates various levels of icing severity and addresses distributed icing with unequal ice distribution between wing halves on the coupled pitch, roll, and yaw responses. The important aspect of dynamic response sensitivity to pilot control input with the autopilot disabled is also highlighted. Using only basic mass properties, configuration, propulsion data, and known icing data from a similar configuration, icing effects are applied to the 6-degree-of-freedom dynamics of a nonreal-time simulation model of a different, but similar, light airplane. Results presented in the paper for a series of simulated climb maneuvers and cruise disturbances with equal or unequal ice levels between wing halves show that the methodology captures the basic effects of ice accretion on the coupled pitch, roll, and yaw responses and the sensitivity of the dynamic response to pilot control inputs.
The Mukaiyama-Michael Reaction of N-Acyl-2,3-dihydro-4-pyridones: Regio- and Stereoselective Synthesis of cis-2,6-Disubstituted 1,2,5,6-Tetrahydropyridines

A convenient regio- and stereoselective preparation of 1,2,5,6-tetrahydropyridines of the type 1 has been developed, starting from readily available N-acyl-2,3-dihydro-4-pyridones 2.
Progress toward the total synthesis of frondosin C.

A straightforward approach toward the total synthesis of frondosin C is described. This strategy involves a key one-pot, microwave-assisted 5-exo cyclization−Claisen rearrangement sequence that was used for the expedient assembly of the frondosic C scaffold. Subsequent manipulation of the tetracyclic core allowed the synthesis of an advanced intermediate bearing the characteristic diene moiety in the B ring.
Polymer crystal–melt interfaces and nucleation in polyethylene

Kinetic barriers cause polymers to crystallize incompletely, into nanoscale lamellae interleaved with amorphous regions. As a result, crystalline polymers are full of crystal–melt interfaces, which dominate their physical properties. The longstanding theoretical challenge to understand these interfaces has new relevance, because of accumulating evidence that polymer crystals often nucleate via a metastable, partially ordered “rotator” phase. To test this idea requires a theory of the bulk and interfacial free energies of the critical nucleus. We present a new approach to the crystal–melt interface, which represents the amorphous region as a grafted brush of loops in a self-consistent pressure field. We combine this theory with estimates of bulk free energy differences, to calculate nucleation barriers and rates via rotator versus crystal nuclei for polyethylene. We find rotator-phase nucleation is indeed favored throughout the temperature range where nucleation is observed. Our methods can be extended to other polymers.
Design Method for Constant Power Consumption of Differential Logic Circuits

Side channel attacks are a major security concern for smart cards and other embedded devices. They analyze the variations of the power consumption to find the secret key of the encryption algorithm implemented within the security IC. To address this issue, logic gates that have a constant power dissipation independent of the input signals are used in security ICs. The paper presents a design methodology to create fully connected differential pull down networks. Fully connected differential pull down networks are transistor networks that, for any complementary input combination, connect all the internal nodes of the network to one of the external nodes of the network. They are memoryless and, for that reason, have a constant load capacitance and power consumption. This type of network is used in specialized logic gates to guarantee a constant contribution of the internal nodes into the total power consumption of the logic gate.
RABIT: a new framework for runtime emulation and binary translation

Binary translation has been widely used as object code migration across different architectures. Most current works are targeted towards running an existing (old architecture) binary version of a complex application on a newer architecture and so availability of resources is not a problem. In this paper we propose a technique called RABIT for emulating a newer architecture's binary on an older one. RABIT will allow the consumers to emulate the applications developed for newer hardware on their older machines by incurring some performance trade-offs. This way the needy consumers can take advantage of the newer software features on their existing machines before they decide to upgrade them to later models. In situations where the newer hardware is in place, our technique can be used to run applications redundantly on the older machine for dependability analysis. It also provides the CPU architects with an instruction-level simulator to test the design and stability of a new CPU before the new hardware is actually in place. RABIT's design consists of a translator, an interpreter and a set of operating system services. To deal with the less amount of resources like registers in the older architecture as compared to the newer ones, we present a new register allocation algorithm. The feasibility of the technique is established by simulating RABIT for its performance.
Start-to-end simulation for the LCLS X-ray FEL

X-ray FELs, such as the LCLS and TESLA FEL, require electron beams with large peak current and very small emittance. The X-ray peak power, temporal and spectral properties, depend significantly on details of the electron beam phase space distribution. The electron beam distribution is determined by many effects, as the emission process at the gun photo-cathode, bunch compression, acceleration and wakefields within the undulator. Although analytical results can give an estimate of the expected performance, the complexity of the electron beam generation, acceleration and compression can only be evaluated using a numerical simulation of all these processes, a start-to-end simulation. In this presentation we discuss the LCLS X-Ray FEL performance estimated by a start-to-end simulation, and we compare the results with those obtained using a simpler model.
Sense-level subjectivity in a multilingual setting

Recent research on English word sense subjectivity has shown that the subjective aspect of an entity is a characteristic that is better delineated at the sense level, instead of the traditional word level. In this paper, we seek to explore whether senses aligned across languages exhibit this trait consistently, and if this is the case, we investigate how this property can be leveraged in an automatic fashion. We first conduct a manual annotation study to gauge whether the subjectivity trait of a sense can be robustly transferred across language boundaries. An automatic framework is then introduced that is able to predict subjectivity labeling for unseen senses using either cross-lingual or multilingual training enhanced with bootstrapping. We show that the multilingual model consistently outperforms the cross-lingual one, with an accuracy of over 73% across all iterations.
Total synthesis and revised structure of biyouyanagin A

Japan as a folk medicine for the treatment of female disorders. This compound exhibited significant and selective inhibitory activity against HIV replication in H9 lymphocytes (EC50= 0.798 mgmL ) compared with noninfected H9 lymphocytes (EC50> 25 mgmL ), which amounts to a therapeutic index (TI) of greater than 31.3. Furthermore, biyouyanagin A strongly inhibited lipopolysaccharide (LPS)-induced cytokine production (at 10 mgmL , IL-10= 0.03; IL-12= 0.02; tumor necrosis factor a (TNF a)= 0.48). In view of the potential of biyouyanagin A as a biological tool and a drug-discovery lead, and to clarify the remaining structural ambiguity (the stereochemistry at the C24 position), we set out to synthesize the two epimers 1a and 1b (Figure 1). Herein we report the total synthesis of both the (24S) and (24R) epimers of biyouyanagin A in their enantiomerically pure form, and the full structural elucidation of the natural product, which required not only assignment of the R configuration at the C24 position, but also revision of the stereochemistry at the C17 and C18 positions (2a and 2b, Figure 1). In our quest to synthesize biyouyanagin A, we decided to employ the rather apparent, but unprecedented [2+2] photocycloaddition reaction that involved the two required components, diene 3a (ent-7-epizingiberene) or 3b (ent-zingiberene) and enone 4, as shown retrosynthetically in Scheme 1a. Proposed as a biosynthetic pathway, this route had the advantage of optimum convergency, but left the stereochemical outcome of the [2+2] cycloaddition open.
Tests of international CAPM with time-varying covariances

We perform maximum-likelihood estimation of a model of international asset pricing based on CAPM. We test the restrictions imposed by CAPM against a more general asset pricing model. The ‘betas’ in our CAPM vary over time as the supplies of assets change and as the conditional covariances or returns on those assets change. We let the covariances change over time as a function of macroeconomic data, and an alternative model allows the covariances to follow a multivariate ARCH process. We also can identify a modified CAPM model with measurement error. We find that the estimated CAPM performs much better when variances are not constant over time. Nonetheless, CAPM is rejected in favour of the lessrestricted model of asset pricing.
High Resolution Genome Wide Binding Event Finding and Motif Discovery Reveals Transcription Factor Spatial Binding Constraints

An essential component of genome function is the syntax of genomic regulatory elements that determine how diverse transcription factors interact to orchestrate a program of regulatory control. A precise characterization of in vivo spacing constraints between key transcription factors would reveal key aspects of this genomic regulatory language. To discover novel transcription factor spatial binding constraints in vivo, we developed a new integrative computational method, genome wide event finding and motif discovery (GEM). GEM resolves ChIP data into explanatory motifs and binding events at high spatial resolution by linking binding event discovery and motif discovery with positional priors in the context of a generative probabilistic model of ChIP data and genome sequence. GEM analysis of 63 transcription factors in 214 ENCODE human ChIP-Seq experiments recovers more known factor motifs than other contemporary methods, and discovers six new motifs for factors with unknown binding specificity. GEM's adaptive learning of binding-event read distributions allows it to further improve upon previous methods for processing ChIP-Seq and ChIP-exo data to yield unsurpassed spatial resolution and discovery of closely spaced binding events of the same factor. In a systematic analysis of in vivo sequence-specific transcription factor binding using GEM, we have found hundreds of spatial binding constraints between factors. GEM found 37 examples of factor binding constraints in mouse ES cells, including strong distance-specific constraints between Klf4 and other key regulatory factors. In human ENCODE data, GEM found 390 examples of spatially constrained pair-wise binding, including such novel pairs as c-Fos:c-Jun/USF1, CTCF/Egr1, and HNF4A/FOXA1. The discovery of new factor-factor spatial constraints in ChIP data is significant because it proposes testable models for regulatory factor interactions that will help elucidate genome function and the implementation of combinatorial control.
Anisotropy in Fracking: A Percolation Model for Observed Microseismicity

Hydraulic fracturing (fracking), using high pressures and a low viscosity fluid, allow the extraction of large quantiles of oil and gas from very low permeability shale formations. The initial production of oil and gas at depth leads to high pressures and an extensive distribution of natural fractures which reduce the pressures. With time these fractures heal, sealing the remaining oil and gas in place. High volume fracking opens the healed fractures allowing the oil and gas to flow to horizontal production wells. We model the injection process using invasion percolation. We use a 2D square lattice of bonds to model the sealed natural fractures. The bonds are assigned random strengths and the fluid, injected at a point, opens the weakest bond adjacent to the growing cluster of opened bonds. Our model exhibits burst dynamics in which the clusters extend rapidly into regions with weak bonds. We associate these bursts with the microseismic activity generated by fracking injections. A principal object of this paper is to study the role of anisotropic stress distributions. Bonds in the y-direction are assigned higher random strengths than bonds in the x-direction. We illustrate the spatial distribution of clusters and the spatial distribution of bursts (small earthquakes) for several degrees of anisotropy. The results are compared with observed distributions of microseismicity in a fracking injection. Both our bursts and the observed microseismicity satisfy Gutenberg–Richter frequency-size statistics.
C–H insertions in oxidative gold catalysis: synthesis of polycyclic 2H-pyran-3(6H)-ones via a relay strategy

An expedient synthesis of bicyclic/polycyclic 2H-pyran-3(6H)-ones is realized in a cascade cyclization triggered by oxidative gold catalysis and terminated by streamlining C–H insertions. In this reaction, an α-oxo gold carbene intermediate, initially formed upon gold-catalyzed oxidation of alkynes, could be trapped by a tethered C–C triple bond, thereby resulting in the formation of a putative vinyl cation intermediate. This intermediate of high electrophilicity is proposed to be responsible for intramolecular C–H insertions, the mostly concerted nature of which is established by the reactions of chiral substrates. The reaction provides a rapid approach to the construction of functionalized polycyclic systems from easily accessible bispropargyl ethers and with minimal structural prefunctionalization.
Calculation of light scattering from a spherical particle on a surface by the multipole expansion method

The multipole expansion method for calculating light scattering from a spherical particle on or near a smooth surface is reviewed and presented with special attention to symmetry for reduction of the computational effort. Formulas for the scattering amplitude and the differential scattering cross section are presented. In addition, useful new formulas are derived for the absorption and extinction cross sections. The theory is exact in the limiting case in which the substrate is a perfect conductor, but an approximation is needed to handle problems with dielectric substrates. As a test of the approximation, a series of calculations for particles on dielectric substrates is carried out. The results of these tests are presented and compared with previously published calculations for the same problems.