cssi/SciSciGPT-SciSciNet huggingface dataset:
Parametric Control of Conservative Mechanical Systems

Parametric excitation is used to control the vibration of a conservative mechanical system. The excitation is varied according to a quadratic, state feedback, control law. If the system has distinct eigenvalues and a full rank, diagonalizable, parametric control matrix, then the control law is asymptotically stabilizing. To eliminate the required full state sensing, an observer is designed to estimate the states from the minimum number of linear measurements. There always exists an observer if the system is linearly observable and the control is bounded. An example demonstrates the method.
Amsterdam and London as financial centers in the eighteenth century

In the seventeenth century, Amsterdam and London developed distinctive innovations in finance through both banks and markets that facilitated the growth of trade in each city. In the eighteenth century, a symbiotic relation developed that led to bank-oriented finance in Amsterdam cooperating with market-oriented finance in London. The relationship that emerged allowed each to rise to unprecedented dominance in Europe, while the respective financial innovations in each city provided the means for the continued expansion of European trade, both within Europe and with the rest of the world. The increasing strains of war finance for the competing European powers over the course of the eighteenth century stimulated fresh financial innovations in each city that initially reinforced the symbiosis of the two centers. The external shocks arising from revolutionary movements in America and France, however, interrupted the relationship long enough to leave London as the supreme financial center.
Thyroid disease associated with cowden syndrome: A meta‐analysis

Background We investigated the pathology and surgical management of thyroid disease in patients with Cowden syndrome (CS). Methods A query of the PubMed database between 2001 and January 2010 was performed using the terms “cowden syndrome OR cowden's syndrome OR cowden disease OR cowden's disease.” Original articles, reviews, case reports, and case series were included. Articles were excluded if they were not written in English, did not present case/cases of CS, or did not include patient information to qualify for a diagnosis of CS. Ninety-five articles met the inclusion and exclusion criteria. A total of 181 cases were analyzed. Results Of the 181 patients, 99 female (54.7%) and 77 male patients (42.5%) had sex reported. The age at presentation ranged from 3 days to 78 years. Ninety-six patients (96/181, 53.0%) were reported to have thyroid disease. Surgical management of thyroid disease was performed in 80.2% (77/96) of patients with thyroid disease, with total thyroidectomy being the most common operation reported (23/77, 29.9%). Thyroid pathology reported with CS patients included goiter (39/96, 40.6%), adenoma (24/96, 25%), unknown/unspecified pathology (8/96, 8.3%), follicular carcinoma (7/96, 7.3%), thyroiditis (7/96, 7.3%), papillary carcinoma (6/96, 6.3%), cancer (unknown type) (3/96, 3.1%), medullary carcinoma (1/96, 1%), and hyperthyroidism (1/96, 1%). Conclusion Careful monitoring of thyroid disease in CS patients is imperative. © 2012 Wiley Periodicals, Inc. Head Neck, 2013
Nanowires and nanostructures that grow like polymer molecules.

Unique properties (e.g., rubber elasticity, viscoelasticity, folding, reptation) determine the utility of polymer molecules and derive from their morphology (i.e., one-dimensional connectivity and large aspect ratios) and flexibility. Crystals do not display similar properties because they have smaller aspect ratios, they are rigid, and they are often too large and heavy to be colloidally stable. We argue, with the support of recent experimental studies, that these limitations are not fundamental and that they might be overcome by growth processes that mimic polymerization. Furthermore, we (i) discuss the similarities between crystallization and polymerization, (ii) critically review the existing experimental evidence of polymer-like growth kinetic and behavior in crystals and nanostructures, and (iii) propose heuristic guidelines for the synthesis of “polymer-like” crystals and assemblies. Understanding these anisotropic materials at the boundary between molecules and solids will determine whether we can confer the unique properties of polymer molecules to crystals, expanding them with topology, dynamics, and information and not just tuning them with size.
EVIDENCE OF MANAGERIAL TIMING: THE CASE OF EXCHANGE LISTINGS

Before an exchange listing, stock performance is exceptionally high. Earlier research reports that post-listing performance is poor. I document that the post-listing performance of most firms that list on either the American Stock Exchange or the New York Stock Exchange differs little from that of similar stocks that do not list. However, listing stocks that experience the highest pre-listing performance underperform their control stocks after listing. This finding supports the hypothesis that managers can time exchange listings around a peak in stock performance.
A financial model of foreign exchange exposure

The paper describes a model of foreign exchange exposure. This is defined as the sensitivity of a specific investment's value in reference currency to changes in exchange rate forecasts. This sensitivity may result because some share of the investment cash flows are denominated in foreign currency. Alternatively, a share of cash flows denominated in reference currency which are affected by future exchange rates can also generate sensitivity.
Controlling the False-Discovery Rate in Astrophysical Data Analysis

The false-discovery rate (FDR) is a new statistical procedure to control the number of mistakes made when performing multiple hypothesis tests, i.e., when comparing many data against a given model hypothesis. The key advantage of FDR is that it allows one to a priori control the average fraction of false rejections made (when comparing with the null hypothesis) over the total number of rejections performed. We compare FDR with the standard procedure of rejecting all tests that do not match the null hypothesis above some arbitrarily chosen confidence limit, e.g., 2 σ, or at the 95% confidence level. We find a similar rate of correct detections, but with significantly fewer false detections. Moreover, the FDR procedure is quick and easy to compute and can be trivially adapted to work with correlated data. The purpose of this paper is to introduce the FDR procedure to the astrophysics community. We illustrate the power of FDR through several astronomical examples, including the detection of features against a smooth one-dimensional function, e.g., seeing the "baryon wiggles" in a power spectrum of matter fluctuations, and source pixel detection in imaging data. In this era of large data sets and high-precision measurements, FDR provides the means to adaptively control a scientifically meaningful quantity—the fraction of false discoveries over total discoveries.
Mixing of a Generalized Newtonian Fluid in a Cavity

Mixing of a generalized Newtonian fluid in a corotating discontinuous cavity flow is studied. The flow period and the rheological coefficients are used as parameters. Using geometrical construction of periodic orbits and bifurcation analysis we find mixing windows in the parameter space. A system within a mixing window is capable of producing uniform mixtures. Some bifurcation values have also been determined. A system whose parameters are in the neighborhood of these values will mostly not produce a uniform mixture. The main conclusion is that shear thinning degrades mixing in the cavity flow.
An efficient entry to furo[2,3-d]pyrimidines via inverse electron demand Diels―Alder reactions of 2-aminofurans with 1,3,5-triazines

Furo[2,3-d]pyrimidines were readily prepared via an inverse electron demand Diels–Alder (IDA) reaction between 2-aminofurans and 1,3,5-triazines. 2-Aminofurans proved to be productive dienophiles leading to the IDA product in moderate to good yields. This study further expanded the scope of 1,3,5-triazine IDA reactions with five-membered aromatic heterocycles as dienophiles.
Impact Theory of the Noble-Gas-Broadened HCl Vibration-Rotation Lines

The widths and shifts of the noble-gas-broadened HCl (0-1) and (0-2) band vibration-rotation lines are calculated using an impact theory similar to Anderson's. To obtain agreement with the experimentally observed shifts, Anderson's approach is modified in that the imaginary parts of the optical cross sections are calculated in greater detail. The cross sections are evaluated in a representation which allows further understanding of the physical processes active in impact broadening. It is shown that many broadening and shifting characteristics can be explained upon taking into account the eccentricity of the HCl molecule, in which the centers of charge and mass do not coincide. Substantial agreement with experiment is reached, although several features of the observed shapes and shifts---particularly the variation in width with perturber species---remain unexplained.
Labile dissolved organic carbon supply limits hyporheic denitrification

[1] We used an in situ steady state 15N-labeled nitrate (15NO3−) and acetate (AcO−) well-to-wells injection experiment to determine how the availability of labile dissolved organic carbon (DOC) as AcO−influences microbial denitrification in the hyporheic zone of an upland (third-order) agricultural stream. The experimental wells receiving conservative (Cl− and Br) and reactive (15NO3−) solute tracers had hyporheic median residence times of 7.0 to 13.1 h, nominal flowpath lengths of 0.7 to 3.7 m, and hypoxic conditions (<1.5 mg O2 L−1). All receiving wells demonstrated 15N2 production during ambient conditions, indicating that the hyporheic zone was an environment with active denitrification. The subsequent addition of AcO− stimulated more denitrification as evidenced by significant δ15N2 increases by factors of 2.7 to 26.1 in receiving wells and significant decreases of NO3− and DO in the two wells most hydrologically connected to the injection. The rate of nitrate removal in the hyporheic zone increased from 218 kg ha−1 yr−1 to 521 kg ha−1 yr−1 under elevated AcO− conditions. In all receiving wells, increases of bromide and 15N2 occurred without concurrent increases in AcO−, indicating that 100% of AcO− was retained or lost in the hyporheic zone. These results support the hypothesis that denitrification in anaerobic portions of the hyporheic zone is limited by labile DOC supply.
A div-curl-grad formulation for compressible buoyant flows solved by the least-squares finite element method

Abstract The present paper reports the development of the least-squares finite-element method for simulating compressible buoyant flows at low Mach numbers. We propose a div-curl-grad formulation with unknowns including vorticity, velocity, heat fluxes, temperature and pressure variation. The formulation is proved to be elliptic such that permissible boundary conditions become self-evident for a well posed flow problem. In contrast to conventional approaches, the present method evades the predicament of the ‘singularity’ problem of low-speed flows and no special treatment or artificial boundary condition is needed. Moreover, the assembled coefficient matrix is symmetric and positive-definite; its inversion is implemented by an element-by-element jacobi conjugate gradient method. As a numerical example, we calculate two-dimensional compressible buoyant flows inside a square enclosure at various Rayleigh numbers. For Rayleigh number one million, four secondary vortices were found embedded in the primary vortex. Due to significant temperature variations, the fluid flows are highly compressible in the interior. Along the walls, however, the flows are incompressible. The Nusselt number-Rayleigh number correlation deduced from the numerical result compared favorably with previously reported data.
Amidation of esters assisted by Mg(OCH3)2 or CaCl2

Abstract Magnesium methoxide (Mg(OCH3)2) and calcium chloride have been shown to facilitate the direct aminolysis of esters by ammonia to primary amides. Methyl, ethyl, isopropyl, and tert-butyl esters were converted to the corresponding carboxamides in good yields. Reactions have been run on a larger scale and without the safety liability inherent in the use of magnesium nitride (Mg3N2). Ammonium chloride and amine hydrochlorides have been used successfully in the place of ammonia with magnesium methoxide.
Effect of tether flexibility on the tethered Shuttle subsatellite stability and control

This paper investigates the effect of tether flexibility on the (in-plane) stability regions as a function of tether tension control parameters during stationkeeping. It is found that the size of the stability regions for the flexible tether is reduced considerably as compared with that for the rigid massive tether for some control parameters. An alternate optimal control law, which includes additional feedback of the first vibrational mode and its rate, is introduced; the results of stationkeeping simulations show that the transient responses of both the in-plane swing angle and vibrations are improved as compared with previously developed control laws. For retrieval a typical nonlinear control law, which includes the nonlinear feedback of the tether length, in-plane and out-of-plane swing angles and their rates, is developed. Simulation results show that the amplitudes of the in-plane and out-of-plane swing angles could be reduced significantly; also, it is demonstrated that the amplitudes of the tether vibrational modes should be considered for the selection of the control gains.
Bis(imidazolylidene)s as modular building blocks for monomeric and macromolecular organometallic materials

The synthetic and structural progression surrounding N-heterocyclic carbenes has given rise to great functional and architectural diversity in organometallic chemistry, catalysis, and materials science. The development of new, modular scaffolds for bridging transition metals is essential in order to expand the boundaries of these scientific areas. This Frontier article summarizes recent advances in the synthesis and study of ditopic ligands displaying two linearly opposed carbene moieties and emphasizes their versatility in the preparation of new organometallic and macromolecular materials. The conclusion previews their utility in conjugated organic/inorganic hybrid materials with potential applications in the emerging fields of molecular- and nanoelectronics.
Ionospheric absorption investigations at Hawaii and Johnston Island

Abstract Measurements of ionospheric absorption by the cosmic noise monitoring method show that, at certain tropical latitudes, an irregular component of absorption is often present in the evening hours. If the variable absorption is present at one observing site (Johnston Island), then variations are also likely to be present at another station about 1325km away (Hawaii). The individual variations of absorption as a function of time are not correlated at the two stations, however, suggesting that the scale of the patches causing the absorption must be less than about 1000 km. An attempt is made to find a correspondence between hourly averages of the apparent absorption with other ionospheric parameters. Both a nighttime and daytime absorption are observed. A greater nighttime component appears at Johnston Island than at Hawaii, implying the existence of a latitude dependence. Correlation with spread F or with sporadic E on the basis of ionosonde data from Maui was not found, although a correlation is apparent between cosmic noise absorption and ionosonde minimum reflection frequency during geomagnetically quiet periods. There is good correlation between average hourly values of the absorption and F2 critical frequency, f°F2. This latter observation is explainable by the shielding effect of the F region.
The Mass Function of Active Black Holes in the Local Universe

We present the first measurement of the BH mass function for broad-line active galaxies in the local universe. Using the ~8500 broad-line active galaxies from SDSS DR4, we construct a broad-line luminosity function that agrees very well with the local soft X-ray luminosity function. Using standard virial relations, we then convert observed broad-line luminosities and widths into BH masses. A mass function constructed in this way has the unique capability to probe the mass region <106 M☉, which, while insignificant in terms of total BH mass density, nevertheless may place important constraints on the mass distribution of seed BHs in the early universe. The characteristic local active BH has a mass of ~107 M☉ radiating at 10% of the Eddington rate. The active fraction is a strong function of BH mass; at both higher and lower masses the active mass function falls more steeply than one would infer from the distribution of bulge luminosity. The deficit of local massive radiating BHs is a well-known phenomenon, while we present the first robust measurement of a decline in the space density of active BHs at low mass.
An impulse-response function for a vector autoregression with multivariate GARCH-in-mean

Abstract This paper derives an analytical expression for an impulse-response function for a vector autoregression with multivariate GARCH errors, where the vector of conditional means is a function of the conditional variances. We also provide the appropriate interpretation of an impulse-response function for such models and suggest interesting empirical issues that can be addressed within this framework.
High Power Electronics and flexible AC Transmission System

During the last decade, higher energy costs, the difficulty in building new power plants and improved converter technology provided an increased Market for HVDC transmission. However, HVDC, due to the high cost of converters, will play a limited role in the overall ac power system. The author discusses the potential of thyristors in ac power systems. The concept of a thyristor-assisted ac power system, called Flexible AC Transmission System is introduced and discussed.
A method for testing the spectral responsivity of infrared cameras using tunable lasers

We are developing a technique for accurately measuring spectral responsivity functions of infrared cameras using tunable lasers. We present preliminary results for uniform scenes where tunable infrared lasers illuminate an integrating sphere, diffusing the light to fill the imaging system optics. A commercial camera based on a liquid nitrogen-cooled InSb focal plane array was tested in the 1.4 micrometer to 4.7 micrometer spectral range using a continuously-tunable periodically-poled lithium niobate (PPLN) optical parametric oscillator. Another commercial camera based on an uncooled microbolometer array was tested using a discrete-tunable CO2 laser in the 9 micrometer to 11 micrometer spectral range. Results from these tests show that signal-to-noise ratio, uniformity, stability, and other characteristics are favorable for use of this technique in the characterization of infrared imaging systems. We also propose a generalization of this technique, to include scenes with arbitrary, controlled spatial content such as bar patterns or even pictures, by illuminating a commercially-available digital micromirror device (DMD). Dependence on irradiance level, exposure time, and polarization can also be measured. This technique has an inherent advantage over thermal-emitter based methods in that it measures absolute spectral responsivity directly without requiring knowledge of the spectral emissivity or temperature of the source.
SPECTRAL EVOLUTION OF ANOMALOUS COSMIC RAYS AT VOYAGER 1 BEYOND THE TERMINATION SHOCK

When the Voyager 1 spacecraft crossed the termination shock (TS) on 2004 December 16, the energy spectra of anomalous cosmic rays (ACRs) could not have been produced by steady-state diffusive shock acceleration. However, over the next few years, in the declining phase of the solar cycle, the spectra began to evolve into the expected power-law profile. Observations at the shock led to a broad range of alternative theories for ACR acceleration. In spite of that, in this work we show that the observations could be explained by assuming ACRs are accelerated at the TS. In this paper, we propose that the solar cycle had an important effect on the unrolling of the spectra in the heliosheath. To investigate the spectral evolution of ACRs, a magnetohydrodynamic background model with stationary solar-wind inner boundary conditions was used to model the transport of helium and oxygen ions. We used a backward-in-time stochastic integration technique where phase-space trajectories are integrated until the so-called “injection energy” is reached. Our simulation results were compared with Voyager 1 observations using three different diffusion models. It is shown that the spectral evolution of ACRs in the heliosheath at Voyager 1 could be explained by an increase in the source strength and an enhancement in diffusion as a result of a decrease of the turbulent correlation length in the declining phase of the solar cycle. At the same time, drift effects seem to have had a smaller effect on the evolution of the spectra.
Conditional independence in sample selection models

Abstract In most sample selection models, the conditional mean function for regression error terms is independent of the regressors conditional on the selection-propensity score. Conditioning on the selection-propensity score therefore controls selection bias, a fact that underlies much of the literature on semi-parametric selection models. This note provides a general formulation of the conditional-independence properties that make it possible to control selection bias using the selection-propensity score.
Heat Transfer in the Forced Laminar Wall Jet

The mean and fluctuating characteristics of a plane, unsteady, laminar, wall jet were investigated experimentally for a constant wall-temperature boundary condition. Temperature and streamwise velocity profiles, including the downstream development of the thermal and hydrodynamic boundary layer thicknesses, were obtained through simultaneous hot and cold wire measurements in air. Even at relatively low temperature differences, heating or cooling of a floor surface sufficiently altered the mean velocity profile in the inner, near-wall region to produce significant effects on the jet stability. Selective forcing of the flow at the most amplified frequencies produced profound effects on the temperature and velocity fields and hence the time-averaged heat transfer and shear stress. Large amplitude excitation of the flow ( up to 2 percent of the velocity measured at the jet exit plane) at a high frequency resulted in a reduction in the maximum skin friction by as much as 65 percent, with an increase in the maximum wall heat flux as high as 45 percent. The skin friction and wall heat flux were much less susceptible to low-frequency excitation.
Design and implementation of CLASS: A Cross-Layer ASSociation scheme for wireless mesh networks

This paper focuses on the design and implementation of CLASS, a Cross-Layer Association scheme for IEEE 802.11-based multi-hop wireless mesh networks. The widely-used association strategy in traditional IEEE 802.11 wireless LANs allows a Mobile Station (MS) to scan wireless access links and then associate with the Access Point (AP) that has the best Received Signal Strength Indication (RSSI) value. Unlike traditional wireless LANs, IEEE 802.11-based wireless mesh networks consist of a multi-hop wireless backhaul. As such, the performance experienced by an MS after association with a specific Mesh Access Point (MAP) depends heavily on the conditions of both the access link (e.g., traffic load of associated stations, the frame error rate between an MS and an MAP) and the mesh backhaul (e.g., end-to-end latency and asymmetric uplink/downlink transportation costs). That is, selecting the MAP that yields the ''best'' performance depends on several factors and cannot be determined solely on the RSSI of the MS-MAP access link. CLASS uses an end-to-end airtime cost metric to determine the MAP to which an MS should associate. The airtime cost metric is based on the IEEE 802.11s, and comprises the access link airtime cost and the backhaul airtime cost. The proposed association scheme considers the frame error rate for various packet sizes, the available bandwidth on the access link after the association of the new MS, and the asymmetric uplink and downlink transportation costs on the backhaul. All experimental results are based on actual Linux-base testbed implementation. We also implement a general Cross-Layer Service Middleware (CLSM) module that is used to monitor network conditions and gather relevant metrics and factor values. Experimental results show that the proposed association scheme is able to identify the MAP which yields the highest end-to-end network performance for the mobile stations after their associations.
Toward Global Democracy: Thoughts in Response to the Rising Tide of Nation-to-Nation Interdependencies

1. Jurgen Habermas, L’Etat-Nation Europeen: Passe et Avenir de la Souverainete et de la Citoyennete, in L’Integration Republicaine: Essais de Theorie Politique 95, 115 (Rainer Rochlitz trans., 2000). *Visiting Scholar, Harvard Law School, (2003–2004). I would like to thank Jose Correa (President of Doublevision) who provided me with many outstanding comments about this article. I would also like to thank my mentors Craig Scott (Dean and Associate Professor, Osgoode Hall Law School, Toronto, Ontario) who has assisted with revisions and provided challenging comments while remaining very enthusiastic about my ideas, and who is persistently encouraging me to pursue my ideas and Professor Richard Janda for his constant support of all my projects, always providing suggestions and great advice about my ideas. I wish to further thank Professors Janet Halley, Jerry Kang, David Kennedy (Director of the European Community Law Center), Henry Steiner (Director of the Human Rights Center), Franck Vogel (Director of the Islamic Law Center), all of Harvard Law School, as well as anonymous reviewers, for their continuous encouragement and confidence. I would also like to thank Professor Stephen Toope, who is the Director of the Trudeau Foundation and formerly Dean of McGill University, and Professor David Lametti, Director of the Comparative Law Institute of McGill University, who have believed in me, constantly pointing out that my research is not only relevant, but important at this point in international history. An earlier version of this article was presented at a graduate seminar at Osgoode Hall Law School. I wish to thank participants at those sessions for their valuable comments, in particular Adam Vasey. I would also like to thank Obiora Okafor and Professor Liora Salter of Osgoode Hall Law School, for their comments and encouragement on an earlier version of this text, and their ongoing interest in my work in international democracy. I would like to thank Juan Castro, Visiting Scholar, Harvard Law School (2003), who, at the end of my research, and in spite of his admiration of the theory elaborated herein, enthusiastically provided a substantive critique of my ideas, which has reoriented my thoughts. Research support was generously provided by Osgoode’s Hallett Scholarship and Harvard Law School (in the latter part of my research). Finally, I would like to thank Harvard Law School for allowing me to present related ideas in the Colloquium Seminar in December 2003.
Benchmarking Monte Carlo Codes for Criticality Safety Using Subcritical Measurements

Monte Carlo codes that are used for criticality safety evaluations are typically validated using critical experiments in which the neutron multiplication factor is unity. However, the conditions for most fissile material operations do not coincide to those of the critical experiments. This paper demonstrates that Monte Carlo methods and nuclear data can be validated using subcritical measurements whose conditions may coincide more closely to actual configurations of fissile material.
Catalytic, Nucleophilic Allylation of Aldehydes with Allyl Acetate

A new catalytic allylation of aldehydes has been developed that employs allyl acetate as the allylating reagent. Under catalysis by ruthenium trichloride (3 mol %) in the presence of carbon monoxide (30 psi), water (1.5 equiv), and triethylamine (0.1 equiv), a wide range of aromatic, olefinic, and aliphatic aldehydes are efficiently allylated under mild conditions (70 degrees C, 24-48 h). The stoichiometric byproducts of this reaction are carbon dioxide and acetic acid.
Reversible Tuning of Silver Quantum Dot Monolayers Through the Metal-Insulator Transition

The linear and nonlinear (χ(2)) optical responses of Langmuir monolayers of organically functionalized silver quantum dots were measured as a continuous function of interparticle separation under near-ambient conditions. As the distance between metal surfaces was decreased from 12 to ∼5 angstroms, both quantum and classical effects were observed in the optical signals. When the separation was less than 5 angstroms, the optical second-harmonic generation (SHG) response exhibited a sharp discontinuity, and the linear reflectance and absorbance began to resemble those of a thin metallic film, indicating that an insulator-to-metal transition occurred. This transition was reversible.
Environmental and High Strain Rate Effects on Composites for Engine Applications.

The Lewis Research Center is conducting a series of programs intended to investigate and develop the application of composite materials to structural components for turbojet engines. A significant part of that effort is directed to establishing resistance, defect growth, and strain rate characteristics of composite materials over the wide range of environmental and load conditions found in commercial turbojet engine operations. Both analytical and experimental efforts are involved.
Trifluoroacetic anhydride-catalyzed oxidation of isonitriles by DMSO: a rapid, convenient synthesis of isocyanates.

A smooth and efficient oxidation of isonitriles to isocyanates by sulfoxides is catalyzed by trifluoroacetic anhydride. With use of DMSO as the oxidant and 5 mol·% TFAA (dichloromethane, −60 to 0 °C), the process is complete in a few minutes, forming dimethyl sulfide as the only byproduct. The newly formed isocyanates may be used directly or isolated in high purity by solvent evaporation.
From Planck to GUT via dimensional transmutation

Abstract Consider a gauge singlet superfield S coupled to a pair of adjoint fields in a SUSY-GUT. If the tree-level vacuum is flat in S , the vev 〈 S 〉 which defines the GUT scale will be determined via dimensional transmutation at a scale M where the soft-breaking (mass) 2 vanishes as a result of running from M P = (8πG N ) − 1 2 . Because of the large number of adjoint fields N A coupled to S , one finds that M can be generically close to M GUT = 2 × 10 16 GeV: M≃M p exp −16π 2 log ( 3 2 ) (N A + 4)λ 2 , where λ is a Yukawa ∼ 0.7. This work examines the symmetries and dynamical constraints required in a SUSY-GUT in order that the desired flatness in S is achieved, and that this flatness may survive in a supergravity framework.
BRST operators for higher-spin algebras

Abstract In this paper, we construct non-critical BRST operators for matter and Liouville systems whose currents generate two different W algebras. At the classical level, we construct the BRST operators for W 2,s m ⊗ W 2,s′ l . The construction is possible for s = s ′ or s ≥ s ′ + 2. We also obtain the BRST operator for W 2,4 m ⊗ W 4 l at the classical level. We use free scalar realisations for the matter currents in the above constructions. At the full quantum level, we obtain the BRST operators for W 2,s m ⊗ W 2 l with s = 4,5,6, where W 2 denotes the Virasoro algebra. For the first and last cases, the BRST operators are expressed in terms of abstract matter and Liouville currents. As a by-product, we obtain the W 2,4 algebra at c = −24 and the W 2,6 algebra at c = −2 and −286 3 , at which values the algebras were previously believed not to exist.
Liquid-crystal point-diffraction interferometer

A new point-diffraction interferometer has been developed with a liquid-crystal filter that permits arbitrary phase shifts to be introduced between the object and reference beams. A microsphere embedded within the liquid-crystal layer provides a locally generated reference beam. We phase shift the object beam by varying a voltage across the liquid crystals, thereby altering the refractive index of the birefringent nematic liquid crystals.
Behavioral simulations in MapReduce

In many scientific domains, researchers are turning to large-scale behavioral simulations to better understand real-world phenomena. While there has been a great deal of work on simulation tools from the high-performance computing community, behavioral simulations remain challenging to program and automatically scale in parallel environments. In this paper we present BRACE (Big Red Agent-based Computation Engine), which extends the MapReduce framework to process these simulations efficiently across a cluster. We can leverage spatial locality to treat behavioral simulations as iterated spatial joins and greatly reduce the communication between nodes. In our experiments we achieve nearly linear scale-up on several realistic simulations.Though processing behavioral simulations in parallel as iterated spatial joins can be very efficient, it can be much simpler for the domain scientists to program the behavior of a single agent. Furthermore, many simulations include a considerable amount of complex computation and message passing between agents, which makes it important to optimize the performance of a single node and the communication across nodes. To address both of these challenges, BRACE includes a high-level language called BRASIL (the Big Red Agent SImulation Language). BRASIL has object-oriented features for programming simulations, but can be compiled to a dataflow representation for automatic parallelization and optimization. We show that by using various optimization techniques, we can achieve both scalability and single-node performance similar to that of a hand-coded simulation.
Technique for Efficient Evaluation of SRAM Timing Failure

This brief presents a technique to evaluate the timing variation of static random access memory (SRAM). Specifically, a method called loop flattening, which reduces the evaluation of the timing statistics in the complex highly structured circuit to that of a single chain of component circuits, is justified. Then, to very quickly evaluate the timing delay of a single chain, a statistical method based on importance sampling augmented with targeted high-dimensional spherical sampling can be employed. The overall methodology has shown 650× or greater speedup over the nominal Monte Carlo approach with 10.5% accuracy in probability. Examples based on both the large-signal and small-signal SRAM read path are discussed, and a detailed comparison with state-of-the-art accelerated statistical simulation techniques is given.
Acid-catalyzed reactions of a strained ring nazarov substrate

Abstract The synthesis and acid-catalyzed rearrangements of cross-conjugated cyclobutylidene ketone 1 are described. With strong Bronsted acids it gave a mixture of 5,7-dimethyltetralin 10 and 2-cyclohexenyl-1-methyl-3-phenylbenzene 11 , the former by an initial retroaldol reaction and the latter by a series of tautomerizations and electrocyclic reactions following cation induced four-membered ring cleavage. Iodotrimethylsilane converted 1 to 11 in excellent yield. Tin (IV) chloride converted 1 to a kinetically controlled mixture of Nazarov rearrangement products 2 , 3 and 4 . This mixture was stable under the reaction conditions, but treatment with toluene sulfonic acid converted 2 completely to 3 . Even under more severe conditions, however, 4 could not be induced to isomerize.
A toy black hole S-matrix in the D1-D5 CFT

To model the process of absorption and emission of quanta by an extremal D1-D5 black hole in the dual CFT, we consider transitions between different Ramond vacua via absorption and emission of chiral primaries. We compute the probabilities to reach different CFT states starting with a special Ramond vacuum, using techniques of the orbifold CFT. It is found that the processes involving the change of angular momentum by k units are suppressed as ~ 1/N k .
A Reduced Efficiency of Terrestrial Planet Formation following Giant Planet Migration

Substantial orbital migration of massive planets may occur in most extrasolar planetary systems. Since migration is likely to occur after a significant fraction of the dust has been locked up into planetesimals, ubiquitous migration could reduce the probability of forming terrestrial planets at radii of the order of 1 AU. Using a simple time dependent model for the evolution of gas and solids in the disk, I show that replenishment of solid material in the inner disk, following the inward passage of a giant planet, is generally inefficient. Unless the timescale for diffusion of dust is much shorter than the viscous timescale, or planetesimal formation is surprisingly slow, the surface density of planetesimals at 1 AU will typically be depleted by 1-2 orders of magnitude following giant planet migration. Conceivably, terrestrial planets may exist only in a modest fraction of systems where a single generation of massive planets formed and did not migrate significantly.
Electronic transport in mesoscopic systems

1. Preliminary concepts 2. Conductance from transmission 3. Transmission function, S-matrix and Green's functions 4. Quantum Hall effect 5. Localisation and fluctuations 6. Double-barrier tunnelling 7. Optical analogies 8. Non-equilibrium Green's function formalism.
THEORY OF SOLAR MERIDIONAL CIRCULATION AT HIGH LATITUDES

We build a hydrodynamic model for computing and understanding the Sun's large-scale high-latitude flows, including Coriolis forces, turbulent diffusion of momentum, and gyroscopic pumping. Side boundaries of the spherical "polar cap," our computational domain, are located at latitudes ≥ 60°. Implementing observed low-latitude flows as side boundary conditions, we solve the flow equations for a Cartesian analog of the polar cap. The key parameter that determines whether there are nodes in the high-latitude meridional flow is = 2ΩnπH 2/ν, where Ω is the interior rotation rate, n is the radial wavenumber of the meridional flow, H is the depth of the convection zone, and ν is the turbulent viscosity. The smaller the (larger turbulent viscosity), the fewer the number of nodes in high latitudes. For all latitudes within the polar cap, we find three nodes for ν = 1012 cm2 s–1, two for 1013, and one or none for 1015 or higher. For ν near 1014 our model exhibits "node merging": as the meridional flow speed is increased, two nodes cancel each other, leaving no nodes. On the other hand, for fixed flow speed at the boundary, as ν is increased the poleward-most node migrates to the pole and disappears, ultimately for high enough ν leaving no nodes. These results suggest that primary poleward surface meridional flow can extend from 60° to the pole either by node merging or by node migration and disappearance.
Application of cyano ylide methodology to the synthesis of cyclotheonamides E2 and E3

Abstract A total synthesis of cyclotheonamides E 2 and E 3 is reported. A key step in the synthesis involves the formation of the α-keto amide linkage by application of the cyano ylide activation of a carboxyl group as developed in our earlier syntheses of cyclic peptide protease inhibitors.
The Universality of the Quantum Fourier Transform in Forming the Basis of Quantum Computing Algorithms

Abstract The quantum Fourier transform (QFT) is a powerful tool in quantum computing. The main ingredients of QFT are formed by the Walsh–Hadamard transform H and phase shifts P (·), both of which are 2×2 unitary matrices as operators on the two-dimensional 1-qubit space. In this paper, we show that H and P (·) suffice to generate the unitary group U (2) and, consequently, through controlled- U operations and their concatenations, the entire unitary group U (2 n ) on n qubits can be generated. Since any quantum computing algorithm in an n -qubit quantum computer is based on operations by matrices in U (2 n ), in this sense we have the universality of the QFT.
A 2k kernel for the cluster editing problem

The cluster editing problem is a decision problem that, for a graph G and a parameter k, determines if one can apply at most k edge insertion/deletion operations on G so that the resulting graph becomes a union of disjoint cliques. The problem has attracted much attention because of its applications in a variety of areas. In this paper, we present a polynomial-time kernelization algorithm for the problem that produces a kernel of size bounded by 2k. More precisely, we develop an O(mn)-time algorithm that, on a graph G of n vertices and m edges and a parameter k, produces a graph G^' and a parameter k^' such that k^'=
Measurement of isothermal pressure of lattice gas by random walk

Abstract We present a computational random walk method of measuring the isothermal pressure of the lattice gas with and without the excluded volume interaction. The method is based on the discretization of the exact thermodynamic relation for the pressure. The simulation results are in excellent agreement with the theoretical predictions.
Mass Flux Sensing via Tunable Diode Laser Absorption of Water Vapor

A high-speed mass flux sensor based on diode laser absorption of water vapor is designed, constructed and tested in a low-speed wind tunnel at Stanford and a supersonic ground test facility at NASA Langley. Water vapor absorption is monitored, capitalizing on the presence of its large mole fraction in combustion-driven facilities and the availability of fiber-coupled diode lasers that access the 2ν1, 2ν3, and ν1+ν3 absorption bands near 1.4 microns. Mass flux is determined from the product of velocity and density measured using a pair of absorption transitions: velocity is obtained from the relative Doppler shift of the absorption line centers for beams directed upstream and downstream in the flow. Temperature is determined from the ratio of absorption signals and coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios. The optimization of the modulation for 1f-normalized WMS-2f (WMS-2f/1f) signals for velocity sensing is presented for the first time. Criteria to select the absorption transitions are presented and the spectroscopic parameters of the needed database are determined with laboratory measurements. Using this database, the measurement of temperature is validated against thermocouple measurements in a heated cell. The velocity measurements are validated at low velocity to ±0.5 m/s in a high-uniformity wind tunnel. Finally, the measurements of temperature and velocity are demonstrated in supersonic flows in the direct-coupled supersonic combustion test facility (DCSCTF) at NASA Langley.
An ultraviolet Fe II image of SN 1885 in M31

Ultraviolet imaging of the remnant of supernova (SN) 1885 in M31 with the Hubble Space Telescope using the F255W filter on the WFPC2 reveals a dark spot of Fe II absorption at the remnant's known position in the bulge of M31. The diameter of the absorbing spot, ~05, is consistent with the 070 ± 005 diameter measured in the higher quality WFPC2 Ca II absorption image previously reported by us. The flux in the spot is 0.76 ± 0.21 lower than that in adjacent regions; that is, three-quarters of the bulge starlight is being absorbed by supernova remnant (SNR) 1885. The depth of absorption is consistent with the amount 0.67 ± 0.04 expected on the basis of a model fit to the previously obtained near-UV Faint Object Spectrograph (FOS) spectrum. The observed depth of Fe II absorption suggests that Fe II is fully saturated, with an iron mass consistent with the range MFe = 0.1-1.0 M☉ previously inferred from the near-UV spectrum. Besides Fe, ion species Mg I, Mg II, and Mn I probably make some contribution to the absorption from the SN 1885 remnant in the F255W image.
Barrier coverage with wireless sensors

When a sensor network is deployed to detect objects penetrating a protected region, it is not necessary to have every point in the deployment region covered by a sensor. It is enough if the penetrating objects are detected at some point in their trajectory. If a sensor network guarantees that every penetrating object will be detected by at least k distinct sensors before it crosses the barrier of wireless sensors, we say the network provides k-barrier coverage. In this paper, we develop theoretical foundations for k-barrier coverage. We propose efficient algorithms using which one can quickly determine, after deploying the sensors, whether the deployment region is k-barrier covered. Next, we establish the optimal deployment pattern to achieve k-barrier coverage when deploying sensors deterministically. Finally, we consider barrier coverage with high probability when sensors are deployed randomly. The major challenge, when dealing with probabilistic barrier coverage, is to derive critical conditions using which one can compute the minimum number of sensors needed to ensure barrier coverage with high probability. Deriving critical conditions for k-barrier coverage is, however, still an open problem. We derive critical conditions for a weaker notion of barrier coverage, called weak k-barrier coverage.
Parton distribution functions

Abstract Parton distribution functions give the probability to find partons (quarks and gluons) in a hadron as a function of the fraction η of the proton's momentum carried by the parton. They are conventionally defined in terms of matrix elements of certain operators. They are determined from experimental results on short distance scattering of the partons. Integrals of these functions weighted with ηn are calculable using lattice QCD. Some simple models for their behavior have implications that could also be tested in lattice QCD.
The Minimum Equivalent DNF Problem and Shortest Implicants

We prove that the Minimum Equivalent DNF problem is ?P2-complete, resolving a conjecture due to Stockmeyer. We also consider the complexity and approximability of a related optimization problem in the second level of the polynomial hierarchy, that of finding shortest implicants of a Boolean function. We show that when the input is given as a DNF, this problem is complete for a complexity class above coNP utilizing O(log2n)-limited nondeterminism. When the input is given as a formula or circuit, the problem is ?P2-complete, and ?P2-hard to approximate within factors of n1/2?? and n1??, respectively.
Condensed-matter physics: Wien route to monopoles

Determining the magnetic charge of monopoles in a crystalline host seemed a mountain too high for physicists to climb. An experiment based on Wien's theory of electrolytes has now measured its value.
The virtual tourism environment. Utilisation of information technology to enhance strategic travel marketing

This paper provides a descriptive overview of the use of the Internet and applications of World Wide Web technology in the travel and tourism industry at a moment in time†. Emphasis is placed on informing tourism practitioners and academics about present developments in Web technologies and current applications within the travel and tourism strategic planning and marketing process. Several examples of travel-related Web sites are provided that illustrate applications within the industry. Additionally, the authors explore future opportunities and industry trends relating to the adoption of electronic information technologies into the next decade.