cssi/SciSciGPT-SciSciNet huggingface dataset:
Online actor-critic algorithm to solve the continuous-time infinite horizon optimal control problem

In this paper we discuss an online algorithm based on policy iteration for learning the continuous-time (CT) optimal control solution with infinite horizon cost for nonlinear systems with known dynamics. That is, the algorithm learns online in real-time the solution to the optimal control design HJ equation. This method finds in real-time suitable approximations of both the optimal cost and the optimal control policy, while also guaranteeing closed-loop stability. We present an online adaptive algorithm implemented as an actor/critic structure which involves simultaneous continuous-time adaptation of both actor and critic neural networks. We call this 'synchronous' policy iteration. A persistence of excitation condition is shown to guarantee convergence of the critic to the actual optimal value function. Novel tuning algorithms are given for both critic and actor networks, with extra nonstandard terms in the actor tuning law being required to guarantee closed-loop dynamical stability. The convergence to the optimal controller is proven, and the stability of the system is also guaranteed. Simulation examples show the effectiveness of the new algorithm.
Parametric multiple sequence alignment and phylogeny construction

Abstract Bounds are given on the size of the parameter-space decomposition induced by multiple sequence alignment problems where phylogenetic information may be given or inferred. It is shown that many of the usual formulations of these problems fall within the same integer parametric framework, implying that the number of distinct optima obtained as the parameters are varied across their ranges is polynomially bounded in the length and number of sequences.
A hierarchy of deterministic top-down tree transformations

The classDTT DR (resp.DTT) is the family of all deterministic top-down tree transductions with deterministic top-down look-ahead (resp. no look-ahead). In this paper we prove that the two hierarchies (DTT DR ) n and (DTT DR ) n oDTT are proper and that they “shuffle perfectly” in the sense that (DTT DR ) n is properly contained in (DTT DR ) n oDTT and (DTT DR ) n oDTT is properly contained in (DTT DR ) n+1 for alln ≥ 0. Using these results we show that the problem of determining the correct inclusion relationship between two arbitrary compositions of tree transformation classes from the set {DTA, DTT, DTT DR ,DTT R } can be decided in linear time.
Dual-fuel propulsion in single-stage Advanced Manned Launch System Vehicle

As part of the United States Advanced Manned Launch System study to determine a follow-on, or complement, to the Space Shuttle, a reusable single-stage-to-orbit concept utilizing dual-fuel rocket propulsion has been examined. Several dual-fuel propulsion concepts were investigated. These include: a separate-engine concept combining Russian RD-170 kerosene-fueled engines with space shuttle main engine-derivative engines: the kerosene- and hydrogen-fueled Russian RD-701 engine; and a dual-fuel, dual-expander engine. Analysis to determine vehicle weight and size characteristics was performed using conceptual-level design techniques. A response-surface methodology for multidisciplinary design was utilized to optimize the dual-fuel vehicles with respect to several important propulsion-system and vehicle design parameters, in order to achieve minimum empty weight. The tools and methods employed in the analysis process are also summarized. In comparison with a reference hydrogen- fueled single-stage vehicle, results showed that the dual-fuel vehicles were from 10 to 30% lower in empty weight for the same payload capability, with the dual-expander engine types showing the greatest potential.
Quasirandom arithmetic permutations

Abstract In [J.N. Cooper, Quasirandom permutations, 2002, to appear], the author introduced quasirandom permutations, permutations of Z n which map intervals to sets with low discrepancy. Here we show that several natural number-theoretic permutations are quasirandom, some very strongly so. Quasirandomness is established via discrete Fourier analysis and the Erdős–Turan inequality, as well as by other means. We apply our results on Sos permutations to make progress on a number of questions relating to the sequence of fractional parts of multiples of an irrational. Several intriguing open problems are presented throughout the discussion.
UV Excess Measures of Accretion onto Young Very Low Mass Stars and Brown Dwarfs

Low-resolution spectra from 3000 to 9000 A of young low-mass stars and brown dwarfs were obtained with LRIS on Keck I. The excess UV and optical emission arising in the Balmer and Paschen continua yields mass accretion rates ranging from 2 × 10^(−12) to 10^−8 M☉ yr^−1. These results are compared with HST STIS spectra of roughly solar-mass accretors with accretion rates that range from 2 × 10^(−10) to 5 × 10^−8 M☉ yr^−1. The weak photospheric emission from M dwarfs at <4000 A leads to a higher contrast between the accretion and photospheric emission relative to higher mass counterparts. The mass accretion rates measured here are systematically ~4-7 times larger than those from Hα emission line profiles, with a difference that is consistent with but unlikely to be explained by the uncertainty in both methods. The accretion luminosity correlates well with many line luminosities, including high Balmer and many He I lines. Correlations of the accretion rate with Hα 10% width and line fluxes show a large amount of scatter. Our results and previous accretion rate measurements suggest that M ∝ M^(1.87 ± 0.26) for accretors in the Taurus molecular cloud.
Implications of X-ray Line Variations for 4U1822-371

4U 1822–371 is one of the prototype accretion disk coronal sources with an orbital period of about 5.6 hr. The binary is viewed almost edge-on at a high inclination angle of 83°, which makes it a unique candidate to study binary orbital and accretion disk dynamics in high powered X-ray sources. We observed the X-ray source in 4U 1822–371 with the Chandra High Energy Transmission Grating Spectrometer for almost nine binary orbits. X-ray eclipse times provide an update of the orbital ephemeris. We find that our result follows the quadratic function implied by previous observations; however, it suggests a flatter trend. From the orbital line dynamics, we confirm the previous suggestion that recombination emission is located at the impact bulge of the accretion stream. Our observations show that the recombining plasma is confined to this region, and prove that it has to be a very thin layer on top of the accretion disk. Fe XXVI emission is detected at all phases and likely originates from the hot central corona which has optical depth 1. The implied ionization parameters from both regions strongly suggest that the illuminating source is obscured with respect to the observer and is orders of magnitude brighter than what is actually observed. This is independently confirmed by the best fit of a flat power law with a high-energy cutoff and partial covering absorption with a covering fraction of about 50%. We discuss the implications of our findings with respect to the photoionized line emission and the spectral continuum on basic properties of the X-ray source.
Measuring M Dwarf Winds with DAZ White Dwarfs

Hydrogen atmosphere white dwarfs with metal lines, so-called DAZs, show evidence for ongoing accretion of material onto their surfaces. Some DAZs are known to have unresolved M dwarf companions, which could account for the observed accretion through a stellar wind. I combine observed Ca abundances of the DAZs with information on the orbital separation of their M dwarf companions to infer the mass-loss rate of the M dwarfs. I find that for three of the six known DAZs with M dwarf companions, a stellar wind can plausibly explain the observed accretion on the white dwarfs assuming Bondi-Hoyle accretion of solar abundance stellar winds on the order of 10-14 to 10-16 M☉ yr-1. The rest of the sample have companions with orbits 1 AU and require companion mass-loss rates of >10-11 M☉ yr-1. I conclude that there must be an alternative explanation for accretion of material onto DAZs with widely separated companions. The inferred winds for two of the close binaries are orders of magnitude smaller than typically assumed for the angular momentum loss of red dwarf-white dwarf pairs due to magnetic braking from a stellar wind and may seriously affect predictions for the formation rate of CVs with low-mass companions.
An experimental study of solidification of binary mixtures with double-diffusive convection in the liquid

An experimental study is reported of solidification of ammonium chloride-water solutions inside a rectangular enclosure. The phase-change and convection processes are studied through shadowgraph and flow visualization as well as temperature and concentration measurements. A number of different initial and boundary conditions are utilized in the experiments in order to obtain a representative data base of the system behavior. It is found that the solidification process induces a variety of double-diffusive convection phenomena in the liquid, including layers, plumes, and stable stratifications. The convection processes influence considerably the local solidification rates and can cause remelting in parts of the system. It is emphasized that many of the physical phenomena identified through the present experiments are expected to be of considerable importance in actual casting processes involving metallic alloys. Consequently, careful consideration must be given to these phenomena when developing more reali...
The control networks of the satellites of Uranus

Abstract Control networks of the five large satellites of Uranus have been established photogrammetrically from pictures taken by the Voyager 2 spacecraft. The control networks cover the illuminated southern hemisphere of each satellite. Coordinates are listed for 103 points on Miranda, 52 points on Ariel, 43 points on Umbriel, 46 points on Titania, and 34 points on Oberon; some points are identified on the U.S. Geological Survey maps of these satellites. Miranda is ellipsoidal in shape with radii of 241, 235 and 232 km. Mean radii are 579 km for Ariel, 586 km for Umbriel, 790 km for Titania, and 762 km for Oberon.
Physical Properties of Trans-Neptunian Object (20000) Varuna

We present new time-resolved photometric observations of the bright trans-Neptunian object (20000) Varuna and use them to study the rotation period, shape, and color. In observations from 2001 February and April, we find a best-fit two-peaked light curve with period 6.3442 ± 0.0002 hr. The peak-to-peak photometric range in the R band is 0.42 ± 0.02 mag. We find no rotational variation in colors over the 0.45 μm ≤ λ ≤ 0.85 μm wavelength range. From the short, double-peaked period and large amplitude, we suggest that Varuna is an elongated, body, perhaps close in shape to one of the Jacobi ellipsoids. If so, the ratio of the axes projected into the plane of the sky is 1.5:1 and the density is near 1000 kg m-3. Varuna may be a rotationally distorted rubble pile, with a weak internal constitution due to fracturing by past impacts. The high specific angular momentum implied by our observations and recent detections of binary trans-Neptunian objects both point to an early, intense collisional epoch in which large trans-Neptunian objects were ~100 times more abundant than now. In order to maintain a cosmochemically plausible rock : ice mass ratio of ~0.5, Varuna must be internally porous.
Time-periodic control of a multi-blade helicopter

Abstract : The flap-lag equations of motion of an isolated rotor blade and those for a rigid helicopter containing four blades free to flap and lag are derived. Control techniques are developed which stabilize both systems for a variety of flight conditions. Floquet theory is used to investigate the stability of a rotor blade's flap-lag motion. A modal control technique, based on Floquet theory, is used to eliminate the blade's instabilities using collective and cyclic pitch control mechanisms. The technique shifts the unstable roots to desired locations while leaving the other roots unaltered. The control, developed for a single design point, is shown to significantly reduce or eliminate regions of flap-lag instabilities for a variety of off-design conditions. Both scalar and vector control are successfully used to stabilize the blade's motion. Coupling the flap-lag equations of motion of four rotor blades to a rigid airframe alters the flap, lg, and airframes roots. The airframe roots are stabilized using a combination of the body's pitch attitude and pitch rate feedback to the main rotor's longitudinal cyclic pitch. The modal control technique is used to eliminate multiple blade instabilities by first controlling a pair of unstable roots at a specific design point. The resulting closed loop system is a new linear system which periodic coefficients. Another modal controller is designed for this new system to shift a second pair of unstable roots to desired locations. This process is repeated until all instabilities are eliminated. Numerical inaccuracies, however, become noticeable when modal control is used more than once.
Asymmetric Effects of Interest Rate Changes on Stock Prices

This study examines the stock price adjustment process around announcements of changes in the federal funds rate target in the 1990s using an asymmetric autoregressive exponential GARCH model (ASAR-EGARCH). We find that target change announcements convey new information to the stock market. Risk aversion increases before the announcement of a rate change, and especially before the announcement of a joint target and discount rate change. The volatility estimates suggest that such joint rate changes send a clearer signal to the stock market about monetary policy objectives relative to unilateral target changes. Our findings are consistent with overreaction in the wake of bad news (rate hikes), and point to a shift in volatility from before to after the rate change announcement since the adoption of the immediate disclosure policy of the Federal Open Market Committee in February 1994.
Experimental and theoretical investigations in two-dimensional transonic flow.

Experimental and theoretical results are presented from a study of the flow over a family of transonically scaled circular-arc bodies mounted in a solid-wall wind tunnel. Data are presented for Reynolds numbers between 30,000 and 3,600,000, based on chord. The high Reynolds number results are compared with computations based on inviscid theory, and are used to investigate transonic similarity and the behavior of the flow near choking. The results at low Reynolds number are used to demonstrate the effect of viscosity on the overall flowfield, and comparisons are made with existing laminar viscous/inviscid interaction theory.
Extension of Levins' Loop Analysis to transient and periodic disturbances

Abstract Levins' Loop Analysis was developed for investigating the behavior of distributed, interconnected systems, in which the interactions are not well enough known to allow complete quantitative modelling; this situation arises in many ecological communities. All that is assumed in the model structure may be the presence or absence and the signs of the interactions between the subsystems. The analysis focuses on the question of the qualitative stability, in the small, of the equilibrium points of the system, as well as on the possible first-order shifts in these equilibrium points due to the influence of constantly acting disturbances. The loop method is extended in this discussion to the qualitative analysis of the transient and long-term tracking behavior of stable systems experiencing time-dependent and periodic disturbances.
Room temperature stable 3-lithiothiophene: a facile synthesis of 3-functional thiophenes

Abstract 3-Functionalized thiophenes were readily prepared by reacting electrophiles with 3-lithiothiophene at room temperature. 3-Lithiothiophene was found to be stable in hexane at room temperature.
Stabilizing Rabi oscillations in a superconducting qubit using quantum feedback

Real-time quantum feedback based on weak measurement of the quantum state is used to stabilize the oscillation phase of a driven quantum bit. By performing weak measurements of a quantum state, it is possible to slow the rate of collapse of its wavefunction, so that information about the quantum state can be gradually acquired. Such information can be used to continuously track and steer the quantum state using feedback. This paper reports quantum feedback control of a superconducting quantum bit (qubit) coupled to a microwave cavity. The qubit undergoes coherent oscillations that can be made to speed up, slow down or persist indefinitely. This ability to actively suppress decoherence could find many applications in quantum error correction, quantum-state stabilization and purification, entanglement generation and adaptive measurements. The act of measurement bridges the quantum and classical worlds by projecting a superposition of possible states into a single (probabilistic) outcome. The timescale of this ‘instantaneous’ process can be stretched using weak measurements1,2, such that it takes the form of a gradual random walk towards a final state. Remarkably, the interim measurement record is sufficient to continuously track and steer the quantum state using feedback3,4,5,6,7,8. Here we implement quantum feedback control in a solid-state system, namely a superconducting quantum bit (qubit) coupled to a microwave cavity9. A weak measurement of the qubit is implemented by probing the cavity with microwave photons, maintaining its average occupation at less than one photon. These photons are then directed to a high-bandwidth, quantum-noise-limited amplifier10,11, which allows real-time monitoring of the state of the cavity (and, hence, that of the qubit) with high fidelity. We demonstrate quantum feedback control by inhibiting the decay of Rabi oscillations, allowing them to persist indefinitely12. Such an ability permits the active suppression of decoherence and enables a method of quantum error correction based on weak continuous measurements13,14. Other applications include quantum state stabilization4,7,15, entanglement generation using measurement16, state purification17 and adaptive measurements18,19.
Selective reduction of α,β-unsaturated esters in the presence of olefins

Abstract Several α,β-unsaturated esters containing also isolated olefins or other functionalities subject to saturation were selectively reduced to the corresponding saturated esters by magnesium in methanol.
Synthesis of a photoaffinity analogue of phosphatidylinositol 3,4-bisphosphate, an effector in the phosphoinositide 3-kinase signaling pathway

A Ferrier rearrangement strategy starting from α-d-glucose gave a protected inositol, which after coupling to a chiral diacylglycerol phosphoramidite, provided a tritium-labeled, benzophenone-containing derivative of P-l-(O-aminopropyl) linked dipalmitoyl PtdIns(3,4)P2.
A multi-channel CRC register

The Cyclic Redundancy Check (CRC) is extremely efficient and well suited for error detection in transmission, retrieval or storage of variable length records of binary data. The cyclic check is capable of detecting nearly all patterns of error with almost negligible amount of redundancy. For example, a 16-digit (2 bytes) CRC character will detect all error-bursts of length 16 or less and better than 99.99 percent of all other error-bursts in binary records of any length. For average record length of 1000 bytes this amounts to less than 0.2 percent redundancy. Peterson and Brown's paper is an excellent exposition on the subject of error detection with cyclic codes.
Structural basis for the polysialylation of the neural cell adhesion molecule.

Polysialic acid is a unique glycan polymer composed of long chains of α2, 8-linked sialic acid residues; it is found on a small subset of mammalian proteins. The neural cell adhesion molecule, NCAM, is the most abundant polysialylated protein in mammalian cells. The presence of polysialic acid on NCAM has been demonstrated to decrease cell adhesion, and it is critical for a variety of processes including brain development, synaptic plasticity, axon guidance and pathfinding, neurite outgrowth, and general cell migration. Polysialic acid is also expressed on the surface of several highly metastatic cancers and has been implicated in cancer cell growth and invasiveness. This review will focus on the protein specificity of the polysialylation of NCAM by summarizing the current information on the sequence and structural requirements for NCAM recognition, and polysialylation by the polysialyltransferases, ST8Sia IV/PST and ST8Sia II/STX.
Empirical managerial accounting research: are we just describing management consulting practice?

This short commentary responds to several issues raised in Zimmerman (2001). We address Zimmerman's criticisms that managerial accounting studies are purely descriptive, conducted without an underlying theory, and unguided by research hypotheses. We also discuss our views regarding the importance of practice-oriented research for understanding managerial accounting choices and for testing economic and non-economic theories. Finally, we highlight some of the new directions in the finance literature, and their relevance for managerial accounting research.
A constant update time finger search tree

Levcopolous and Overmars [12] describe a search tree in which the time to insert or delete a key is O(1) once the position of the key to be inserted or deleted was known. Their data structure does not support fingers, pointers to points of high access or update activity in the set such that access and update operations in the vicinity of a finger are particularly efficient [3, 8, 10, 11, 15]. Levcopolous and Overmars leave as an open question whether a data structure can be designed which allowed updates in constant time and supports fingers. We answer the question in the affirmative by giving an algorithm in the RAM with logarithmic word size model [1].
Step-frequency radar with compressive sampling (SFR-CS)

This paper proposes a novel radar system, namely step-frequency with compressive sampling (SFR-CS), that achieves high target range and speed resolution using significantly smaller bandwidth than traditional step-frequency radar. This bandwidth reduction is accomplished by employing compressive sampling ideas and exploiting the sparseness of targets in the range-speed space.
Fluoride dose-response of human and bovine enamel artificial caries lesions under pH-cycling conditions

This laboratory study aimed to (a) compare the fluoride dose-response of different caries lesions created in human and bovine enamel (HE/BE) under pH-cycling conditions and (b) investigate the suitability of Knoop and Vickers surface microhardness (K-SMH/V-SMH) in comparison to transverse microradiography (TMR) to investigate lesion de- and remineralization. Caries lesions were formed using three different protocols (Carbopol, hydroxyethylcellulose-HEC, methylcellulose-MeC) and assigned to 24 groups using V-SMH, based on a 2 (enamel types) × 3 (lesion types) × 4 (fluoride concentrations used during pH-cycling-simulating 0/250/1100/2800 ppm F as sodium fluoride dentifrices) factorial design. Changes in mineral content and structural integrity of lesions were determined before and after pH-cycling. Data were analyzed using three-way ANOVA. BE was more prone to demineralization than HE. Both enamel types showed similar responses to fluoride with BE showing more remineralization (as change in integrated mineral loss and lesion depth reduction), although differences between tissues were already present at lesion baseline. Carbopol and MeC lesions responded well to fluoride, whereas HEC lesions were almost inert. K- and V-SMH correlated well with each other and with the integrated mineral loss data, although better correlations were found for HE than for BE and for MeC than for Carbopol lesions. Hardness data for HEC lesions correlated only with surface zone mineral density data. BE is a suitable surrogate for HE under pH-cycling conditions. The in vitro modeling of dental caries is complex and requires knowledge of lesion behavior, analytical techniques, and employed hard tissues.
Ti(o-i-pr)4 mediated lactamizations

Abstract Ti(O-i-Pr)4 promotes the formation of 5- and 6-membered lactams from primary and secondary ω-amino acids, giving the lactams in good yield (75–93%).
7Be breakup on heavy and light targets

We present all-order quantum mechanical calculations of 7 Be breakup on heavy ( 208 Pb) and light ( 12 C) targets. We examine the issues concerning the extraction of the astrophysical S -factor S 34 (0) from the breakup data. We discuss the peripherality of the breakup reactions and the interplay between Coulomb and nuclear breakup.
Economical nitrogen-sulfur fluids.

The National Fertilizer & Environmental Research Center (NFERC) has developed and begun introduction of a new family of nitrogen—sulfur (NS) suspensions with several advantages. The new NS suspensions have a substantial economic advantage over ammonium thiosulfate-based solutions and they are considerably higher in grade and more versatile than ammonium sulfate-based solutions currently on the market. In some areas, the NS suspensions are less expensive sources of nitrogen alone than UAN solutions, urea, or ammonium nitrate. High-quality, long-storing NS suspensions can be produced from the lowest quality, wet by-product ammonium sulfate (AS) fines. These new products provide an excellent means for long-term storage, handling, and application of by-product AS fines, which are inexpensive but do not store, handle, or apply well as a solid. In August of 1989, NFERC produced 500 tons of 25-0-0-10S N-S suspension, stored the material through winter, and introduced the product during the spring 1990 season through several dealers in the Southeast.
Lipid in Renal Clear Cell Carcinoma: Detection on Opposed-Phase Gradient-Echo MR Images

PURPOSE: To determine if comparison of in-phase and opposed-phase gradient-echo magnetic resonance (MR) images enables detection of lipid in renal clear cell carcinoma. MATERIALS AND METHODS: A retrospective search of MR and pathologic records identified 43 patients with biopsy-proved renal masses who underwent in-phase and opposed-phase MR imaging. Thirty-three patients had renal cell carcinoma (27 with clear cell carcinoma), and 10 patients had other renal tumors. With MR images, a region-of-interest measurement of signal intensity of the renal mass was divided by that of reference tissue. In each patient, a ratio of these region-of-interest measurements on the opposed-phase images to those on the in-phase images was calculated and termed the opposed-phase/in-phase signal intensity ratio (OIR). RESULTS: The mean OIR of clear cell carcinomas was significantly different from that of other renal masses (P < .0002); in 16 (59%) of 27 patients with clear cell carcinoma, the OIR was less than 2 standard devia...
CALISTO: a cryogenic far-infrared/submillimeter observatory

We present a design for a cryogenically cooled large aperture telescope for far-infrared astronomy in the wavength range 30 μm to 300 μm. The Cryogenic Aperture Large Infrared Space Telescope Observatory, or CALISTO, is based on an off-axis Gregorian telesocope having a 4 m by 6 m primary reflector. This can be launched using an Atlas V 511, with the only optical deployment required being a simple hinged rotation of the secondary reflector. The off-axis design, which includes a cold stop, offers exceptionally good performance in terms of high efficiency and minimum coupling of radiation incident from angles far off the direction of maximum response. This means that strong astronomical sources, such as the Milky Way and zodiacal dust in the plane of the solar system, add very little to the background. The entire optical system is cooled to 4 K to make its emission less than even this low level of astronomical emission. Assuming that detector technology can be improved to the point where detector noise is less than that of the astronomical background, we anticipate unprecedented low values of system noise equivalent power, in the vicinity of 10-19 WHz-0.5, through CALISTO's operating range. This will enable a variety of new astronomical investigations ranging from studies of objects in the outer solar system to tracing the evolution of galaxies in the universe throughout cosmic time.
Axisymmetric bending oscillations of stellar disks

Self-gravitating stellar disks with random motion support both exponentially growing and, in some cases, purely oscillatory axisymmetric bending modes, unlike their cold disk counterparts. A razor-thin disk with even a very small degree of random motion in the plane is both unstable and possesses a discrete spectrum of neutral modes, irrespective of the sharpness of the edge. Random motion normal to the disk plane is stabilizing but at the same time allows bending waves to couple to the internal vibrations of the particles, which causes the formerly neutral modes to decay through Landau damping. Focusing first on instabilities, I here determine the degree of random motion normal to the plane needed to suppress global, axisymmetric, bending instabilities in a family of self-gravitating disks. As found previously, bending instabilities are suppressed only when the thickness exceeds that expected from a naive local criterion when the degree of pressure support within the disk plane is comparable to, or exceeds, the support from rotation. Nevertheless, a modest disk thickness would seem to be adequate for the bending stability of most disk galaxies, except perhaps near their centers. The discretization of the neutral spectrum in a zero-thickness disk is due to the existence of a turning point for bending waves in a warm disk, which is absent when the disk is cold. When the disk is given a finite thickness, the discrete neutral modes generally become strongly damped through wave-particle interactions. It is surprising therefore that I find some simulations of warm, stable disks can support (quasi-)neutral, large-scale, bending modes that decay very slowly, if at all.
Learnability and Definability in Trees and Similar Structures

We prove upper bounds for combinatorial parameters of finite relational structures, related to the complexity of learning a definable set. We show that monadic second-order (MSO) formulas with parameters have bounded Vapnik–Chervonenkis dimension over structures of bounded clique-width, and first-order formulas with parameters have bounded Vapnik–Chervonenkis dimension over structures of bounded local clique-width (this includes planar graphs). We also show that MSO formulas of a fixed size have bounded strong consistency dimension over MSO formulas of a fixed larger size, for labeled trees. These bounds imply positive learnability results for the PAC and equivalence query learnability of a definable set over these structures. The proofs are based on bounds for related definability problems for tree automata.
Oligopoly price discrimination and resale price maintenance

Oligopoly price discrimination in the retail market prevents a manufacturer from inducing optimal retail margins through any wholesale price. This motivates the manufacturer to impose resale price maintenance. In a model of third-degree price discrimination by rival retailers, a retail price ceiling (or floor) enables the manufacturer to restore the first best. Imposing a fixed retail price is generally not optimal because the manufacturer wants to eliminate price discrimination based on consumers’ abilities to switch retailers, not based on consumers’ valuations. Under resale price maintenance, welfare may either increase or decrease, and it may increase even when total output is reduced.
A user-oriented time-shared online system

An existing system and planned additions within the Data Processing Laboratory of the Brain Research Institute at UCLA is described. The system represents an attempt to provide research workers of the Institute with the ability to interact directly with a highly sophisticated digital computing complex in the most direct and simple fashion possible. It is anticipated that, with the accumulation of experience using the present system, significant advances will be possible in the system design through determination of interface parameters between the biological scientist and the digital computer.
Alkoxydienes via Copper-Promoted Couplings: Utilizing an Alkyne Effect

Simple alkenes and alkynes, with 3-hexyne in particular, are found to be important π ligands for oxidative copper-based coupling (modern Ullmann) reactions. This enabled syntheses of various alkoxydienes with removable protecting groups that are valuable substrates for Diels−Alder reactions from alcohols and vinyl boronate esters. In addition to demonstrating that 3-hexyne is a ligand for copper in both stoichiometric and catalytic reactions, the reaction atmosphere was found to play a critical role.
A Concept for the Intrinsic Dielectric Strength of Electrical Insulation Materials

There are analytical solutions of Laplace's Field equation which can be used to calculate the maximum potential gradient EMAX on an electrode surface as a function of voltage difference V, separation t, and radius R. Such solutions can be series-expanded and, after combining the first two terms of the series algebraically, they yield the general expression V/t= EMAXan (t+a)-n, where (V/t)= VA is the average voltage across the separation t, and a is a term involving radius of curvature only. If K is defined as EMAXan , then the expression becomes VA=K(t+a)-n which is strikingly similar to the expression VA= K(t)-n, an historically observed data correlation between VA and t, if a is ignored. The experimental observation that VA decreases with increasing t has been interpreted as a material property. However, the similarity with the series expression suggests that, at constant EMAX, this is a manifestation of the thickness-dependence of the spatial distribution of the electric field. If true, then voltage breakdown of an insulation material is occurring whenever a critical but constant value of the potential gradient EMAX is reached or exceeded on an electrode surface. It is suggested that this critical value of EMAX may be the intrinsic dielectric strength of an insulation material, herein designated as S.
The Application of Virtual Simulations Using Second Life in a Foreign Language Classroom

The purpose of this paper is to investigate the effects of virtual simulation-based language learning in a foreign language class in Korea. Total 35 1st-year university students in Korea participated in this research to figure out the effect of simulations. A virtual English learning community, ‘Cypris Chat’ in Second Life was selected as a learning tool. For the data collection, a survey questionnaire was distributed and analy z ed quantitatively. The result shows that the majority of the students had a positive attitude toward using a virtual simulation in English learning and had better understanding in learning English by experiencing an authentic practice. The first section of this paper provides a general overview of simulations in educational settings through an insightful literature review of the current research in the area. The review includes a comprehensive outlook on simulations, an example of successful classroom integration and some of the considerations researchers have found for their implementation. The latter section addresses the research method, results and conclusions.
Unilateral Regulation of the Internet: A Modest Defence

This article analyses the conflicts-of-law problems that supposedly arise from the fact that every nation can unilaterally regulate every Internet transaction. It argues that the threat of multiple national regulation of Internet transactions is significantly exaggerated. It then examines a more serious problem: the spillover effects from unilateral national regulation. These spillovers do not affect the legitimacy of unilateral regulation, but they might argue for public and private harmonization strategies to eliminate the spillovers. Unfortunately, the prospects for such harmonization are generally dim in many contexts. This means that unilateral national regulation will continue to be a primary vehicle of Internet regulation -- a prospect that is not nearly as destructive of the Internet's future as conventional wisdom suggests.
Numerical Study of Flexible Flapping Wing Propulsion

In this study, a strong-coupling approach is applied to simulate highly flexible flapping wings interacting with fluid flows. Here, the fluid motion, solid motion, and their interaction are solved together by a single set of equations of motion on a fixed Eulerian mesh, with the elastic stress being solved on a Lagrangian mesh and projected back to the Eulerian mesh. To provide necessary flapping mechanism, control cells are implemented in solid area (i.e., the wing) as "skeleton." The moving trajectory of the skeleton is therefore prescribed by a conventional direct-forcing type of immersed boundary method, while the rest of the wing moves passively through elasticity and fluid-structure interaction. This combined algorithm is then used to study the propulsion characteristics of flexible flapping wings with different elastic moduli and at different flapping frequencies and amplitudes. A two-dimensional NACA0012 airfoil is chosen as a model wing, and it is under active plunging defined by control cells and corresponding passive pitching motion. With different input parameters, very different wake structures can be observed. As a result, the coupled plunging-pitching motion can be either drag-producing or thrust-producing. Finally, passive pitching angle θ and nominal angle of attack α for flexible wings are defined to characterize the flapping motion. It is found that θ needs to be greater than 0.26 and α needs to be greater than 0.3 to generate thrust instead of drag for the flapping motion within the current parametric matrix.
Bottom-quark fragmentation in top-quark decay

Abstract We study the fragmentation of the b quark in top decay in NLO QCD, within the framework of perturbative fragmentation, which allows one to resum large logarithms ∼ log(mt2/mb2). We show the b-energy distribution, which we compare with the exact O (α S ) result for a massive b quark. We use data from e+e− machines in order to describe the b-quark hadronization and make predictions for the energy spectrum of b-flavoured hadrons in top decay. We also investigate the effect of NLL soft-gluon resummation in the initial condition of the perturbative fragmentation function on parton- and hadron-level energy distributions.
Longitudinal Control of Automotive Vehicles in Close-Formation Platoons

This paper explains many of the technical considerations in the design of automatic longitudinal control systems by employing a general nonlinear simulation model to develop quantitative results. The effects on control system performance of external forces, process and measurement noise, and sampling and quantization of measurements are shown. The importance of acceleration and jerk limits is demonstrated, and examples are used to illustrate how the control system must be designed to accommodate variations in the severity of the maneuvers it is expected to execute, as well as variations in propulsion system dynamics.
Localization and gluing of orbifold amplitudes: The Gromov-Witten orbifold vertex

We define a formalism for computing open orbifold GW invariants of [C^3/G] where G is any finite abelian group. We prove that this formalism and a suitable gluing algorithm can be used to compute GW invariants in all genera of any toric CY orbifold of dimension 3. We conjecture a correspondence with the DT orbifold vertex of Bryan-Cadman-Young.
Parallel triangle counting in massive streaming graphs

The number of triangles in a graph is a fundamental metric widely used in social network analysis, link classification and recommendation, and more. In these applications, modern graphs of interest tend to both large and dynamic. This paper presents the design and implementation of a fast parallel algorithm for estimating the number of triangles in a massive undirected graph whose edges arrive as a stream. Our algorithm is designed for shared-memory multicore machines and can make efficient use of parallelism and the memory hierarchy. We provide theoretical guarantees on performance and accuracy, and our experiments on real-world datasets show accurate results and substantial speedups compared to an optimized sequential implementation.
Combinatorics and invariant differential operators on multiplicity free spaces

We study the generalization of shifted Jack polynomials to arbitrary multiplicity free spaces. In a previous paper (math.RT/0006004) we showed that these polynomials are eigenfunctions for commuting difference operators. Our central result now is the "transposition formula", a generalization of Okounkov's binomial theorem (q-alg/9608021) for shifted Jack polynomials. From this formula, we derive an interpolation formula, an evaluation formula, a scalar product, a binomial theorem, and properties of the algebra generated by the multiplication and difference operators.
D-branes and fat black holes

Abstract The application of D-brane methods to large black holes whose Schwarzschild radius is larger than the compactification scale is problematic. Callan and Maldacena have suggested that despite apparent problems of strong interactions when the number of branes becomes large, the open string degrees of freedom may remain very dilute due to the growth of the horizon area which they claim grows more rapidly than the average number of open strings. Such a picture of a dilute weakly coupled string system conflicts with the picture of a dense string soup that saturates the bound of one string per Planck area. A more careful analysis shows that Callan and Maldacena were not fully consistent in their estimates. In the form that their model was studied it can not be used to extrapolate to large mass without being in conflict with the Hawking-Bekenstein entropy formula. A somewhat modified model can reproduce the correct entropy formula. In this “improved model” the number of string bits on the horizon scales like the entropy in agreement with earlier speculations of Susskind.
Molecular diversity approach to the synthesis of peptide-derived ruthenium complexes and their evaluation as oxidation catalysts

Abstract This paper reports the synthesis of a small library of peptide-derived ruthenium complexes as potential oxidation catalysts. Evaluation of the solid-supported complexes identified several potentially promising epoxidation catalysts. Liberation of the promising catalysts from the solid-support resulted in catalysts with improved activity.
Structure and Reactivity of “Unusual” N-Heterocyclic Carbene (NHC) Palladium Complexes Synthesized from Imidazolium Salts

The reaction between palladium acetate and IMES.HCl leads to the formation of a novel palladium complex. The X-ray crystal structure analysis reveals that the palladium is C(2) bound to one NHC ligand (the normal binding mode), whereas the second ligand is attached through the C(5) carbon of the second imidazolium. The metalation site on the imidazolium salt is strongly influenced by the presence of base. Furthermore, the binding mode of the NHC to Pd is shown to substantially affect the catalytic behavior of the palladium complexes in cross-coupling reactions.
Transferred Intent: An Inquiry Into the Nature of Criminal Culpability

This article critically examines the criminal law doctrine of transferred intent. It concludes that doctrine cannot be squared with the criminal law's commitment to punishing for harms culpably caused.
Chemo- and site-selective derivatizations of natural products enabling biological studies.

Covering: 2006 to July 2013 Bioactive natural products and derivatives remain an enduring starting point for the discovery of new cellular targets for disease intervention and lead compounds for the development of new therapeutic agents. The former goal is accomplished through the synthesis of bioactive cellular probes from natural products, enabling insights into the mechanism of action of these natural products by classical affinity chromatography or more recent proteome profiling methods. However, the direct and selective modification of native natural products for these purposes remains a challenge due to the structural complexity and the wide functional group diversity found in these natural substances. The lack of selective synthetic methods available to directly manipulate unprotected complex small molecules, in particular to perform structure–activity relationship studies and prepare appropriate cellular probes, has recently begun to be addressed, benefitting from the broader emerging area of chemoselective synthetic methodology. Thus, new reagents, catalysts and reaction processes are enabling both chemo- and site-selective modifications of complex, native natural products. In this review, we describe selected recent examples of these functionalization strategies in this emerging area.
Observation of optically pumped intersubband emission from quantum wells

AbstractWe report the first observation of optically pumped spontaneous emission from intersubband transitions by elec- trons in an n-type GaAs/A1GaAs coupled-quantum-well structure. Electrons were pumped from the first to fourth con- duction subbands with a CW CO2 laser operating at a photon energy of 133 meV. The transition from the fourth to the third subbands occurred at an energy of 17 meV and had a full width at half-maximum of 3 meV. 1. IntroductionThere is growing interest in new optical devices based on confined states in quantum wells. Intersubband transi-tions are of special interest because they can be designed to occur over most of the far- and mid-infrared spectrum.17Our research is aimed at determining whether the quantum-well intersubband transitions can be used as a source ofcoherent radiation in the far-infrared. Electrically pumped spontaneous emission from transitions between conductionsubbands in isolated quantum wells has been observed by Helm et al. by electrically heating the electrons in a widequantum well.1'2 We describe here the first observation of spontaneous intersubband emission from carriers in a
On reconfiguration of disks in the plane and related problems

We revisit two natural reconfiguration models for systems of disjoint objects in the plane: translation and sliding. Consider a set of n pairwise interior-disjoint objects in the plane that need to be brought from a given start (initial) configuration S into a desired goal (target) configuration T, without causing collisions. In the translation model, in one move an object is translated along a fixed direction to another position in the plane. In the sliding model, one move is sliding an object to another location in the plane by means of a continuous rigid motion (that could involve rotations). We obtain various combinatorial and computational results for these two models:(I)For systems of n congruent unlabeled disks in the translation model, Abellanas et al. showed that 2n-1 moves always suffice and @?8n/5@? moves are sometimes necessary for transforming the start configuration into the target configuration. Here we further improve the lower bound to @?5n/3@?-1, and thereby give a partial answer to one of their open problems. (II)We show that the reconfiguration problem with congruent disks in the translation model is NP-hard, in both the labeled and unlabeled variants. This answers another open problem of Abellanas et al. (III)We also show that the reconfiguration problem with congruent disks in the sliding model is NP-hard, in both the labeled and unlabeled variants. (IV)For the reconfiguration with translations of n arbitrary labeled convex bodies in the plane, 2n moves are always sufficient and sometimes necessary.