cssi/SciSciGPT-SciSciNet huggingface dataset:
Topological Ramsey spaces and metrically Baire sets

We characterize a class of topological Ramsey spaces such that each element R of the class induces a collection { R k } k < ω of projected spaces which have the property that every Baire set is Ramsey. Every projected space R k is a subspace of the corresponding space of length-k approximation sequences with the Tychonoff, equivalently metric, topology. This answers a question of S. Todorcevic and generalizes some results of Carlson, Carlson-Simpson, Promel-Voigt, and Voigt. We also present a new family of topological Ramsey spaces contained in the aforementioned class which generalize the spaces of ascending parameter words of Carlson-Simpson and Promel-Voigt and the spaces FIN m ∞ ] , 0 < m < ω , of block sequences defined by Todorcevic.
The patterns of job expansions in the USA: a comparison of the 1960s and 1990s

This paper examines the quality of jobs generated during periods of job expansion from the 1960s through to the 1990s in the USA. The central results of the study are: first, the long 1990s economic boom produced a pattern of asymmetrically polarized job expansion: very strong expansion of jobs in the top tier of the employment structure combined with very limited growth in the middle. Secondly, while job growth at the top was strong in the 1990s, the overall pattern of job expansion was much less favorable for the labor force as a whole than in earlier expansions. Thirdly, there has been a dramatic change in the racial and gender patterns of job expansion since the 1960s: gender differences in job expansion were very sharp in the 1960s and quite muted in the 1990s, while the racially polarized character of job expansion has increased, especially at the bottom of the employment structure. Finally, immigration, especially of Hispanics, is deeply connected to the employment expansion in the bottom tiers of the employment structure. Underlying these descriptive patterns are dramatic changes in the sectoral patterns of job expansion in the 1990s compared with the 1960s: the much slower growth of middle-level jobs in the 1990s is rooted in the decline of manufacturing; the stronger growth of bottom-end jobs is rooted in accelerated growth of retail trade and personal services in the 1990s; and the very strong growth of high-end jobs is rooted in high tech sectors.
Testing for Cointegration in the Presence of Moving Average Errors

This study explores performance of the Johansen cointegration statistics on data containing negative moving average (NMA) errors. Monte Carlo experiments demonstrate that the asymptotic distributions of the statistics are sensitive to NMA parameters, and that using the standard 5% asymptotic critical values results in severe underestimation of the actual test sizes. We demonstrate that problems associated with NMA errors do not decrease as sample size increases; instead, they become more severe. Further we examine evidence that many U.S. commodity prices are characterized by NMA errors. Pretesting data is recommended before using standard asymptotic critical values for Johansen’s cointegration tests.
Why share in peer-to-peer networks?

Prior theory and empirical work emphasize the enormous free-riding problem facing peer-to-peer (P2P) sharing networks. Nonetheless, many P2P networks thrive. We explore two possible explanations that do not rely on altruism or explicit mechanisms imposed on the network: direct and indirect private incentives for the provision of public goods. The direct incentive is a traffic redistribution effect that advantages the sharing peer. We find this incentive is likely insufficient to motivate equilibrium content sharing in large networks. We then approach P2P networks as a graph-theoretic problem and present sufficient conditions for sharing and free-riding to co-exist due to indirect incentives we call generalized reciprocity.
Comments on the IIA NS5-brane

We study N coincident IIA NS5-branes at large N using supergravity. We show that the absorption cross section for gravitons in this background does not vanish at zero string coupling for energies larger than ms/√N (ms is the string scale). Using a holographic description of the intrinsic theory of the IIA NS5-branes, we find an expression for the two point function of the stress energy tensor, and comment on its structure.
Viscous/inviscid interactions of the forebody flowfield of an airbreathing hypersonic vehicle

A hypersonic cruisemissile, which can be launched from conventional aircraft or from surface-based assets and whichcan cruiseataMachnumberof8,requiresatleasttwopropulsionsystems:arocket-basedpropulsionsystem and a supersonic combustion ramjet system. The inlet to the airbreathing propulsion system will be closed during that portionofthee ightpoweredby therocket-basedpropulsion system. Asa result,a shock-wave/boundary-layer interaction will result when the supersonic e ow on the forebody encounters the compression ramp formed by the closed inlet. To investigate the e owe eld for this interaction, surface-pressure measurements and e ow-visualization photographs have been obtained during an experimental program conducted in the Tri-Sonic Wind Tunnel at the U.S. Air Force Academy. Data were obtained at a freestream Mach number of 4.28 and at a freestream Reynolds number (based on the model length ) of 12 79 10 6 over an angle-of-attack range from 7 3 to +7 3 deg. The data are compared with computations made with version 3 of the General Aerodynamic Simulation Program. The three-dimensional viscous/inviscid interaction that occurs nearthe compression ramp contains transverse vortices and streamwise vortices, with pressures in the reattachment region being approximately an order of magnitude larger than those for the undisturbed e ow upstream of the interaction.
Connectivity-based segmentation of human amygdala nuclei using probabilistic tractography

The amygdala plays an important role in emotional and social functions, and amygdala dysfunction has been associated with multiple neuropsychiatric disorders, including autism, anxiety, and depression. Although the amygdala is composed of multiple anatomically and functionally distinct nuclei, typical structural magnetic resonance imaging (MRI) sequences are unable to discern them. Thus, functional MRI (fMRI) studies typically average the BOLD response over the entire structure, which reveals some aspects of amygdala function as a whole but does not distinguish the separate roles of specific nuclei in humans. We developed a method to segment the human amygdala into its four major nuclei using only diffusion-weighted imaging and connectivity patterns derived mainly from animal studies. We refer to this new method as Tractography-based Segmentation, or TractSeg. The segmentations derived from TractSeg were topographically similar to their corresponding amygdaloid nuclei, and were validated against a high-resolution scan in which the nucleic boundaries were visible. In addition, nuclei topography was consistent across subjects. TractSeg relies on short scan acquisitions and widely accessible software packages, making it attractive for use in healthy populations to explore normal amygdala nucleus function, as well as in clinical and pediatric populations. Finally, it paves the way for implementing this method in other anatomical regions which are also composed of functional subunits that are difficult to distinguish with standard structural MRI.
Random Geometric Complexes

We study the expected topological properties of Cech and Vietoris–Rips complexes built on random points in ℝd . We find higher-dimensional analogues of known results for connectivity and component counts for random geometric graphs. However, higher homology H k is not monotone when k>0. In particular, for every k>0, we exhibit two thresholds, one where homology passes from vanishing to nonvanishing, and another where it passes back to vanishing. We give asymptotic formulas for the expectation of the Betti numbers in the sparser regimes, and bounds in the denser regimes.
Signal estimation from modified short-time Fourier transform

In this paper, we present an algorithm to estimate a signal from its modified short-time Fourier transform (STFT). This algorithm is computationally simple and is obtained by minimizing the mean squared error between the STFT of the estimated signal and the modified STFT. Using this algorithm, we also develop an iterative algorithm to estimate a signal from its modified STFT magnitude. The iterative algorithm is shown to decrease, in each iteration, the mean squared error between the STFT magnitude of the estimated signal and the modified STFT magnitude. The major computation involved in the iterative algorithm is the discrete Fourier transform (DFT) computation, and the algorithm appears to be real-time implementable with current hardware technology. The algorithm developed in this paper has been applied to the time-scale modification of speech. The resulting system generates very high-quality speech, and appears to be better in performance than any existing method.
Precomputing strategy for Hamiltonian Monte Carlo method based on regularity in parameter space

Markov Chain Monte Carlo (MCMC) algorithms play an important role in statistical inference problems dealing with intractable probability distributions. Recently, many MCMC algorithms such as Hamiltonian Monte Carlo (HMC) and Riemannian Manifold HMC have been proposed to provide distant proposals with high acceptance rate. These algorithms, however, tend to be computationally intensive which could limit their usefulness, especially for big data problems due to repetitive evaluations of functions and statistical quantities that depend on the data. This issue occurs in many statistic computing problems. In this paper, we propose a novel strategy that exploits smoothness (regularity) in parameter space to improve computational efficiency of MCMC algorithms. When evaluation of functions or statistical quantities are needed at a point in parameter space, interpolation from precomputed values or previous computed values is used. More specifically, we focus on HMC algorithms that use geometric information for faster exploration of probability distributions. Our proposed method is based on precomputing the required geometric information on a set of grids before running sampling algorithm and approximating the geometric information for the current location of the sampler using the precomputed information at nearby grids at each iteration of HMC. Sparse grid interpolation method is used for high dimensional problems. Tests on computational examples are shown to illustrate the advantages of our method.
Generating Small Numbers by Tunneling in Multi-Throat Compactifications

A generic F-theory compactification containing many D3 branes develops multiple brane throats. The interaction of observers residing inside different throats involves tunneling suppression and, as a result, is very weak. This suggests a new mechanism for generating small numbers in Nature. One application is to the hierarchy problem: large supersymmetry breaking near the unification scale inside a shallow throat causes TeV-scale SUSY-breaking inside the standard-model throat. Another application, inspired by nuclear-decay, is in designing naturally long-lived particles: a cold dark matter particle residing near the standard model brane decays to an approximate CFT-state of a longer throat within a Hubble time. This suggests that most of the mass of the universe today could consist of CFT-matter and may soften structure formation at sub-galactic scales. The tunneling calculation demonstrates that the coupling between two throats is dominated by higher dimensional modes and consequently is much larger than a naive application of holography might suggest.
Inequities in Enforcement? Environmental Justice and Government Performance.

This paper examines whether state governments perform systematically less environmental enforcement of facilities in communities with higher minority and low-income populations. Although this is an important claim made by environmental justice advocates, it has received little attention in the scholarly literature. Specifically, I analyze state regulatory enforcement of three U.S. pollution control laws—the Clean Air Act, the Clean Water Act, and the Resource Conservation and Recovery Act—over the period 1985–2000. To test for disparities in enforcement, I estimate a series of count models and find strong evidence across each of the three environmental laws that states perform less enforcement in poor counties, but little evidence of race-based inequities. © 2009 by the Association for Public Policy Analysis and Management.
Successive Refinement of Vector Sources Under Individual Distortion Criteria

The successive refinement problem is extended to vector sources where individual distortion constraints are posed on each vector component. For vector Gaussian sources with squared-error distortion, a single-letter rate-distortion characterization is inherited from the previously studied Gaussian multiple descriptions problem with covariance distortion constraints. Though this characterization is amenable to well-known numerical convex optimization techniques, an analytical solution is difficult to obtain in full generality even for 2-D sources. In this work, the special case of successive refinability is addressed analytically. Specifically, vector Gaussian sources are shown to be not successively refinable everywhere unlike scalar Gaussian sources. It is also shown that, for 2-D Gaussian sources, the rate loss at the second stage can be as high as 0.5 b/sample in a ?degenerate? scenario corresponding to what is known as sequential coding of correlated sources. Finally, analysis of 2-D binary symmetric sources with Hamming distortion reveals that the behavior of these sources with respect to successive refinability exhibits remarkable similarity to their 2-D Gaussian counterparts.
Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, and the Impact on Fuel Economy

This paper considers modeling and energy management control problems for an automotive powertrain augmented with an ultracapacitor and an induction motor. The ultracapacitor-supplied motor assists the engine during periods of high power demand. The ultracapacitor may be recharged via regeneration during braking and by the engine during periods of low power demand. A reduced-order model and a detailed simulation model of the powertrain are created for control design and evaluation of fuel economy, respectively. A heuristic rule-based controller is used for testing the impact of different component combinations on fuel economy. After a suitable combination of engine, motor, and ultracapacitor sizes has been determined, a model predictive control strategy is created for power management which achieves better fuel economy than the rule-based approach. Various component sizing and control strategies tested consistently indicate a potential for 5% to 15% improvement in fuel economy in city driving with the proposed mild hybrid powertrain. This order of improvement to fuel economy was confirmed by deterministic dynamic programming which finds the best possible fuel economy.
Right ventricular performance and left ventricular assist device filling

Abstract Background . Right ventricular (RV) function is believed to be an important determinant of left ventricular assist device (LVAD) filling. This study was designed to demonstrate this relation in patients. Methods . To demonstrate the interaction between RV ejection and LVAD filling, 10 patients (mean age, 49 ± 13 years) supported with an LVAD were studied. Right ventricular pressure–area loops from cross-sectional area using transesophageal echocardiographic automated border detection and high-fidelity RV pressure were recorded simultaneously with LVAD volume during intraoperative inferior vena cava occlusion. Beat-by-beat RV ejection phase indices were calculated: stroke area, peak ejection rate, and stroke work. The LVAD filling rate was calculated as the first derivative of the volume, and the peak filling rate and the mean filling rate during RV systole were determined for each cardiac cycle. Results . Right ventricular stroke area, peak ejection rate, and stroke work were closely correlated with LVAD peak filling rate ( r = 0.87 ± 0.09, r = 0.83 ± 0.09, and r = 0.85 ± 0.10, respectively). Also, baseline LVAD mean filling rate correlated with RV stroke work ( r = 0.77) and LVAD peak filling rate with RV peak ejection rate for the group ( r = 0.75). Conclusions . These correlations demonstrate predictable associations of RV ejection with LVAD filling. (Ann Thorac Surg 1997;63:1044–9)
Mild Conversion of β-Diketones and β-Ketoesters to Carboxylic Acids

A mild protocol for the conversion of β-ketoesters and β-diketones to carboxylic acids with use of CAN in CH3CN is described. The method is compatible with a number of functional groups, and can generate carboxylic acids under neutral conditions at room temperature. The reaction is fast and general, providing an alternative method to the commonly used malonic ester acid preparation. Initial mechanistic studies show that initial oxidation of the enol form of the β-dicarbonyl initiates the reaction. The presence of nitrate as an oxidant ligand or as an additive is critical for success of the reaction.
Spatial economic analysis of early detection and rapid response strategies for an invasive species

Economic impacts from invasive species, conveyed as expected damages to assets from invasion and expected costs of successful prevention and/or removal, may vary significantly across spatially differentiated landscapes. We develop a spatial–dynamic model for optimal early detection and rapid response (EDRR) policies, commonly exploited in the management of potential invaders around the world, and apply it to the case of the Brown treesnake (Boiga irregularis) in Oahu, Hawaii. EDRR consists of search activities beyond the ports of entry, where search (and potentially removal) efforts are targeted toward areas where credible evidence suggests the presence of an invader. EDRR costs are a spatially dependent variable related to the ease or difficulty of searching an area, while damages are assumed to be a population-dependent variable. A myopic strategy in which search only occurs when and where current expected net returns are positive is attractive to managers, and, we find, significantly lowers present value losses (by $270 m over 30 years). We find further that in the tradeoff between search costs and damages avoided, early and aggressive measures that search some high priority areas beyond points of entry even when current costs of search exceed current damages can save the island more ($295 m over 30 years). Extensive or non-targeted search is not advised however.
Space-Time Coding Over Fading Channels With Stable Noise

This paper addresses the performance of space-time coding over fading channels with impulsive noise, which is known to accurately capture network interference. We use symmetric alpha stable noise distribution and adopt two models that assume dependent and independent noise components across receive antennas. We derive the pairwise error probability (PEP) of orthogonal space-time block codes (STBCs) with a benchmark genie-aided receiver (GAR) or the minimum distance receiver (MDR), which is optimal in the Gaussian case. For general space-time codes, we propose a maximum-likelihood (ML) receiver and its approximation at high signal-to-noise ratio (SNR). The resulting asymptotically optimal receiver (AOR) does not depend on noise parameters and is computationally simple. Monte Carlo simulations are used to supplement our analytical results and compare the performance of the receivers.
Fuzzy ARTMAP and back-propagation neural networks based quantitative structure-property relationships (QSPRs) for octanol-water partition coefficient of organic compounds.

Quantitative structure−property relationships (QSPRs) for estimating the logarithm octanol/water partition coefficients, logKow, at 25 °C were developed based on fuzzy ARTMAP and back-propagation neural networks using a heterogeneous set of 442 organic compounds. The set of molecular descriptors were derived from molecular connectivity indices and quantum chemical descriptors calculated from PM3 semiempirical MO-theory. Quantum chemical input descriptors include average polarizability, dipole moments, exchange energy, total electrostatic interaction energy, total two-center energy, and ionization potential. The fuzzy ARTMAP/QSPR performed, for a logKow range of −1.6 to 7.9, with average absolute errors of 0.03 and 0.14 logKow for the overall data and test sets, respectively. The optimal 12−11−1 back-propagation/QSPR model, for the same range of logKow, exhibited larger average absolute errors of 0.23 and 0.27 logKow for the test and validation data sets, respectively, over the same range of logKow values....
Advertising and aggregate consumption: an analysis of causality

This paper is concerned with testing for causation, using the Granger definition, in a bivariate time-series context. It is argued that a sound and natural approach to such tests must rely primarily on the out-of-sample forecasting performance of models relating the original (non-prewhitened) series of interest. A specific technique of this sort is presented and employed to investigate the relation between aggregate advertising and aggregate consumption spending. The null hypothesis that advertising does not cause consumption cannot be rejected, but some evidence suggesting that consumption may cause advertising is presented.
Distribution-free confidence intervals

Summary A general approach for converting a certain class of nonparametric tests into confidence intervals for suitably defined parameters is discussed. The class of tests comprises but is not limited to lineair rank tests for the one-sample, two-sample, and linear regression problems.
Enantio-, Diastereo-, and Regioselective Iridium-Catalyzed Asymmetric Allylic Alkylation of Acyclic β-Ketoesters

The first regio-, diastereo-, and enantioselective allylic alkylation of acyclic β-ketoesters to form vicinal tertiary and all-carbon quaternary stereocenters is reported. Critical to the successful development of this method was the employment of iridium catalysis in concert with N-aryl-phosphoramidite ligands. Broad functional group tolerance is observed at the keto-, ester-, and α-positions of the nucleophile. Various transformations demonstrating the utility of this method for rapidly accessing complex enantioenriched compounds are reported.
Ages for illustrative field stars using gyrochronology: viability, limitations and errors

We here develop an improved way of using a rotating star as a clock, set it using the Sun, and demonstrate that it keeps time well. This technique, called gyrochronology, derives ages for low-mass main-sequence stars using only their rotation periods and colors. The technique is developed here and used to derive ages for illustrative groups of nearby field stars with measured rotation periods. We first demonstrate the reality of the interface sequence, the unifying feature of the rotational observations of cluster and field stars that makes the technique possible, and extend it beyond the proposal of Skumanich by specifying the mass dependence of rotation for these stars. We delineate which stars it cannot currently be used on. We then calibrate the age dependence using the Sun. The errors are propagated to understand their dependence on color and period. Representative age errors associated with the technique are estimated at ~15% (plus possible systematic errors) for late F, G, K, and early M stars. Gyro ages for the Mount Wilson stars are shown to be in good agreement with chromospheric ages for all but the bluest stars, and probably superior. Gyro ages are then calculated for each of the active main-sequence field stars studied by Strassmeier and collaborators. These are shown to have a median age of 365 Myr. The sample of single field stars assembled by Pizzolato and collaborators is then assessed and shown to have gyro ages ranging from under 100 Myr to several Gyr, with a median age of 1.2 Gyr. Finally, we demonstrate that the individual components of the three wide binaries ξ Boo AB, 61 Cyg AB, and α Cen AB yield substantially the same gyro ages.
Identification, development, synthesis and evaluation of boron-containing nucleosides for neutron capture therapy

Abstract The development of boron compounds with the capacity for selectively targeting tumor cells would offer the potential for specifically destroying such cells using the capture reaction of the nonradioactive 10 B nuclide and thermal neutrons. The key problem is the development of compounds with the ability to discriminate between tumor cells and contiguous normal cells and to concentrate in the former at suitable concentration levels. One category of agents that has been explored is boron-containing nucleosides. Such recent structures have been biochemically converted in vitro to their corresponding nucleotides by the action of human thymidine kinase. These studies have attempted to correlate a compound’s physiochemical properties with its biochemical attributes. Since only a fraction of cells are undergoing replication at any one time, requiring the need for nucleic acid precursors, such boron compounds must be only one component of a cocktail of agents that are targeting malignant cells. This presentation is selective, focusing on those boron-containing nucleosides that have been designed for studies with kinases.
From String Nets to Nonabelions

We discuss Hilbert spaces spanned by the set of string nets, i.e. trivalent graphs, on a lattice. We suggest some routes by which such a Hilbert space could be the low-energy subspace of a model of quantum spins on a lattice with short-ranged interactions. We then explain conditions which a Hamiltonian acting on this string net Hilbert space must satisfy in order for the system to be in the DFib (Doubled Fibonacci) topological phase, that is, be described at low energy by an SO(3)3 × SO(3)3 doubled Chern-Simons theory, with the appropriate non-abelian statistics governing the braiding of the low-lying quasiparticle excitations (nonabelions). Using the string net wavefunction, we describe the properties of this phase. Our discussion is informed by mappings of string net wavefunctions to the chromatic polynomial and the Potts model.
Checks and Choices: The House Bank Scandal's Impact on Voters in 1992

Analysis of the 1992 American National Election Study (ANES) data indicates that the House bank scandal reduced the vote for House incumbents by approximately five percentage points. The scandal mainly affected the small subset of voters who were most offended by bank overdrafts and who did not assume that their representative had a clean record. Fortunately for members who had written bad checks, voters who knew about the transgression were least disposed to be outraged by it, while the voters most disposed to outrage were also most inclined to believe the guilty were innocent. The explanation for these curious patterns is that voters who faced the option of condemning an incumbent they otherwise appreciated or dismissing the offense as inconsequential often chose the latter course. The damage was also moderated by partisanship; voters of the incumbent's party showed a strong tendency to err in the incumbent's favor in assessing involvement in the scandal. The classical theory of cognitive dissonance rea...
A water soluble tin hydride reagent

Abstract A water soluble tin hydride has been synthesized carrying three methoxyethoxypropyl groups. It reduces various alkyl halides in water, or in organic solvents.
Chemistry of 8‐Chloroberberine

Abstract 8‐Chloroberberine (V), obtained by treatment of oxyber‐berine (I) with phosphorus oxychloride, is a reactive intermediate. Treatment with ammonia, methylamine, n ‐propylamine, aniline, and p ‐toluidine furnished the 8‐berberinylidene derivatives IV and VII‐X. Reaction of V with malononitrile, ethyl acetoacetate, and ethyl malonate anions yielded the 8‐berberinylidene derivatives XII‐XIV. Acid hydrolysis of XIV gave 8‐berberinylacetic acid (XV) whose reduction provided 8‐canadinylacetic acid (XVI). Grignard reagents react readily with V. Methylmagnesium iodide, ethylmagnesium iodide, and benzylmagnesium iodide led to 8, 8‐dimethyldihydroberberine (XVII), 8, 8‐dithyldihydroberberine (XIX), and the benzyl derivative XX, respectively. Sodium borohydride reduction of XX gave rise to 8‐benzylcanadinc (XXI).
An algorithm for pre- and post-irradiation fade in the Thermo 8802 LiF:Mg,Ti thermoluminescent dosimeter.

The diminished response of thermoluminescent phosphors over time is a well-documented challenge to thermoluminescent dosimetry. Wide ranges in fading rates for various phosphor types have been reported, making it necessary for many external dosimetry programs to perform individual studies on thermoluminescent fade. Sandia National Laboratories currently uses the Thermo 8802 LiF:Mg,Ti thermoluminescent dosimeter (TLD) in its personnel external dosimetry program. Doses received in the field are calculated by applying a fade algorithm published by the manufacturer to TLD readings. Since the algorithm was established by characterizing the diminished response of a TLD similar to the 8802, Sandia chose to model its fade study after the analysis done by Thermo. As a result, the parameters of each experiment were comparable, and data from the two studies were compared to determine whether or not the current algorithm should be modified specifically for use at Sandia. Cards were irradiated using an internal 9 0 Sr/ 9 0 Y source, and pre- and post-irradiation fading rates were monitored over a period of 18 wk. While significant fading was demonstrated, results closely matched those found in the original Thermo study.
IDENTIFICATION OF TIME-VARYING FUZZY SYSTEMS

This paper discusses the identification of time-varying fuzzy systems. A square-root type recursive algorithm with variable forgetting factor is presented to estimate the parameters of systems. Numerical examples are provided to illustrate the performance of the identification algorithm. An interesting discovery of this paper is that, for a linear system, a fuzzy model may have a frequency response close to that of a conventional model, say, a difference equation model, although the orders of two models may be different.
ELECTRODE FUNCTION (PH RESPONSE) OF THE SODA‐SILICA GLASSES*

A scries of Na2O-SiO2 glasses was studied for durability, hygroscopicity, glass-electrode function, and apparent response to [Na +]. These glasses showed three distinct regions of durability characteristics at pH 4.6: (1) below 81% of SiO2, where the glass was carried into solution; (2) between 81 and 89.5% of SiO2, where differential solution of the constituents of the glass left a swollen silica-rich layer; and (3) a region in which greatly reduced attack was indicated. Glass electrodes of low silica content having poor chemical durability and high hygroscopicity exhibited large voltage departures approaching the values of a “punctured” mercury-filled electrode and a calomel half cell. The apparent response to [Na+] ranged from 9 to 339 mv. per pNa for the glasses of 82.6 and 56.6% of SiO2, respectively.
Design of optomechanical cavities and waveguides on a simultaneous bandgap phononic-photonic crystal slab

In this paper we study and design quasi-2D optomechanical crystals, waveguides, and resonant cavities formed from patterned slabs. Two-dimensional periodicity allows for in-plane pseudo-bandgaps in frequency where resonant optical and mechanical excitations localized to the slab are forbidden. By tailoring the unit cell geometry, we show that it is possible to have a slab crystal with simultaneous optical and mechanical pseudo-bandgaps, and for which optical waveguiding is not compromised. We then use these crystals to design optomechanical cavities in which strongly interacting, co-localized photonic-phononic resonances occur. A resonant cavity structure formed by perturbing a “linear defect” waveguide of optical and acoustic waves in a silicon optomechanical crystal slab is shown to support an optical resonance at wavelength λ0 ≈ 1.5 µm and a mechanical resonance of frequency ωm/2π ≈ 9.5 GHz. These resonances, due to the simultaneous pseudo-bandgap of the waveguide structure, are simulated to have optical and mechanical radiation-limited Q-factors greater than 107. The optomechanical coupling of the optical and acoustic resonances in this cavity due to radiation pressure is also studied, with a quantum conversion rate, corresponding to the scattering rate of a single cavity photon via a single cavity phonon, calculated to be g/2π = 292 kHz.
A logical analysis of banks' financial strength ratings

We evaluate the creditworthiness of banks using statistical, as well as combinatorics-, optimization-, and logic-based methodologies. We reverse-engineer the Fitch risk ratings of banks using ordered logistic regression, support vector machine, and Logical Analysis of Data (LAD). The LAD ratings are shown to be the most accurate and most successfully cross-validated. The study shows that the LAD rating approach is (i) objective, (ii) transparent, and (iii) generalizable. It can be used to build internal rating systems that (iv) have varying levels of granularity, and (v) are Basel compliant, allowing for their use in the decisions pertaining to the determination of the amount of regulatory capital.
Tragedy in the Gulf: A Call for a New Engineering Ethic

The question that the present work addresses is how might we move the engineering profession towards a more encompassing engineering ethic and do it in a way which the practitioners might be receptive to such new ideas? Put another way, how might we develop a new engineering ethic, which focuses more upon the results as evidence by its adoption across the myriad of disciplines rather than the purity or elegance of the argument? The present work seeks to offer one approach that might work borrowing from our developing view of complex systems theory. One important characteristic of a complex system — and we shall consider others — is that a system is composed of interconnected parts that as a whole exhibit one or more properties. Stated another way, the behavior among the possible properties may not be obvious from the properties of the individual parts. The proposed new ethic also integrates new ideas from quantum mechanics as well as eco-philosophy.
Dyson's Constant in the Asymptotics of the Fredholm Determinant of the Sine Kernel

We prove that the asymptotics of the Fredholm determinant of I−K α, where K α is the integral operator with the sine kernel on the interval [0, α], are given by This formula was conjectured by Dyson. The proof for the first and second order asymptotics was given by Widom, and higher order asymptotics have also been determined. In this paper we identify the constant (or third order) term, which has been an outstanding problem for a long time.
Optimal freeway ramp control without origin-destination information

Abstract This paper develops an analytical framework for ramp metering, under which various ramp control strategies can be viewed as ramifications of the same most-efficient control logic with different threshold values, control methods, and equity considerations. The most-efficient control logic only meters the entrance ramps nearest critical freeway mainline sections so as to eliminate freeway internal queues, which is derived from a new formulation of the optimal ramp control problem. Instead of assuming the availability of real-time origin–destination information, the new formulation takes advantages of the stability and predictability of off-ramp exit percentages. Those properties of the off-ramp exit percentages are supported by empirical data, and allow us to formulate the optimal ramp control problem as a linear program whose input variables are all directly measurable by detectors in real-time. The solution is also tested on a real-world freeway section in a microscopic traffic simulator for demonstration. Time-dependent origin–destination tables and off-ramp exit percentages are compared as two alternative ways to represent the true real-time demand patterns that are important to freeway ramp metering.
Solar wind driving of magnetospheric ULF waves: Field line resonances driven by dynamic pressure fluctuations

[1] Several observational studies suggest that solar wind dynamic pressure fluctuations can drive magnetospheric ultralow‐frequency (ULF) waves on the dayside. To investigate this causal relationship, we present results from Lyon‐Fedder‐Mobarry (LFM) global, three‐dimensional magnetohydrodynamic (MHD) simulations of the solar wind–magnetosphere interaction. These simulations are driven with synthetic solar wind input conditions where idealized ULF dynamic pressure fluctuations are embedded in the upstream solar wind. In three of the simulations, a monochromatic, sinusoidal ULF oscillation is introduced into the solar wind dynamic pressure time series. In the fourth simulation, a continuum of ULF fluctuations over the 0–50 mHz frequency band is introduced into the solar wind dynamic pressure time series. In this numerical experiment, the idealized solar wind input conditions allow us to study only the effect of a fluctuating solar wind dynamic pressure, while holding all of the other solar wind driving parameters constant. We show that the monochromatic solar wind dynamic pressure fluctuations drive toroidal mode field line resonances (FLRs) on the dayside at locations where the upstream driving frequency matches a local field line eigenfrequency. In addition, we show that the continuum of upstream solar wind dynamic pressure fluctuations drives a continuous spectrum of toroidal mode FLRs on the dayside. The characteristics of the simulated FLRs agree well with FLR observations, including a phase reversal radially across a peak in wave power, a change in the sense of polarization across the noon meridian, and a net flux of energy into the ionosphere.
Stability and Noise in Biochemical Switches

Many processes in biology, from the regulation of gene expression in bacteria to memory in the brain, involve switches constructed from networks of biochemical reactions. Crucial molecules are present in small numbers, raising questions about noise and stability. Analysis of noise in simple reaction schemes indicates that switches stable for years and switchable in milliseconds can be built from fewer than one hundred molecules. Prospects for direct tests of this prediction, as well as implications, are discussed.
Semi-automatic tuning of PID gains for atomic force microscopes

The control of a typical commercial Atomic Force Microscope (AFM) is through some variant on a Proportional, Integral, Derivative (PID) controller. Typically, the gains are hand tuned so as to keep the bandwidth of the system far below the first resonant frequency of the actuator. This paper shows a straightforward method of selecting PID gains from the actuator model so as to allow considerably higher bandwidths. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Water-tolerant unstabilized carbanion equivalents: Bismuth(III) chloride-aluminum promoted alkylations of immonium cations to amines in aqueous Media

Abstract In the presence of bismuth(III) chloride-metallic aluminum, alkyl as well as allyl halides react with N-(alkylamino)benzotriazoles at 20°C in THF-water to give the corresponding homoalkylated amines in high yields.
WU-CRISPR: characteristics of functional guide RNAs for the CRISPR/Cas9 system

The CRISPR/Cas9 system has been rapidly adopted for genome editing. However, one major issue with this system is the lack of robust bioinformatics tools for design of single guide RNA (sgRNA), which determines the efficacy and specificity of genome editing. To address this pressing need, we analyze CRISPR RNA-seq data and identify many novel features that are characteristic of highly potent sgRNAs. These features are used to develop a bioinformatics tool for genome-wide design of sgRNAs with improved efficiency. These sgRNAs as well as the design tool are freely accessible via a web server, WU-CRISPR (http://crispr.wustl.edu).
Combinatorial conditions that imply word-hyperbolicity for 3-manifolds

Abstract Thurston conjectured that a closed triangulated 3-manifold in which every edge has degree 5 or 6, and no two edges of degree 5 lie in a common 2-cell, has word-hyperbolic fundamental group. We establish Thurston's conjecture by proving that such a manifold admits a piecewise Euclidean metric of non-positive curvature and the universal cover contains no isometrically embedded flat planes. The proof involves a mixture of computer computation and techniques from small cancellation theory.
Induction of first-order decision lists: results on learning the past tense of English verbs

This paper presents a method for inducing logic programs from examples that learns a new class of concepts called first-order decision lists, defined as ordered lists of clauses each ending in a cut. The method, called Foidl, is based on Foil (Quinlan, 1990) but employs intensional background knowledge and avoids the need for explicit negative examples. It is particularly useful for problems that involve rules with specific exceptions, such as learning the past-tense of English verbs, a task widely studied in the context of the symbolic/connectionist debate. Foidl is able to learn concise, accurate programs for this problem from significantly fewer examples than previous methods (both connectionist and symbolic).
A novel route to fully substituted 1H-pyrazoles

A novel one-step synthesis route to fully substituted pyrazol-4-ols is reported. This simple yet nonobvious method for the construction of pyrazol-4-ols by the condensation−fragmentation−cyclization−extrusion reactions of thietanones with 1,2,4,5-tetrazines is reported. All of the elements of the thietanone except its sulfur are incorporated in these novel products.
Mixed finite element approximation of the vector Laplacian with Dirichlet boundary conditions

We consider the finite element solution of the vector Laplace equation on a domain in two dimensions. For various choices of boundary conditions, it is known that a mixed finite element method, in which the rotation of the solution is introduced as a second unknown, is advantageous, and appropriate choices of mixed finite element spaces lead to a stable, optimally convergent discretization. However, the theory that leads to these conclusions does not apply to the case of Dirichlet boundary conditions, in which both components of the solution vanish on the boundary. We show, by computational example, that indeed such mixed finite elements do not perform optimally in this case, and we analyze the suboptimal convergence that does occur. As we indicate, these results have implications for the solution of the biharmonic equation and of the Stokes equations using a mixed formulation involving the vorticity.
List distinguishing parameters of trees

A coloring of the vertices of a graph G is said to be distinguishing provided no nontrivial automorphism of G preserves all of the vertex colors. The distinguishing number of G, D(G), is the minimum number of colors in a distinguishing coloring of G. The distinguishing chromatic number of G, @g"D(G), is the minimum number of colors in a distinguishing coloring of G that is also a proper coloring. Recently the notion of a distinguishing coloring was extended to that of a list distinguishing coloring. Given an assignment L={L(v)}"v"@?"V"("G") of lists of available colors to the vertices of G, we say that G is (properly) L-distinguishable if there is a (proper) distinguishing coloring f of G such that f(v)@?L(v) for all v. The list distinguishing number of G, D"@?(G), is the minimum integer k such that G is L-distinguishable for any list assignment L with |L(v)|=k for all v. Similarly, the list distinguishing chromatic number of G, denoted @g"D"""@?(G) is the minimum integer k such that G is properly L-distinguishable for any list assignment L with |L(v)|=k for all v. In this paper, we study these distinguishing parameters for trees, and in particular extend an enumerative technique of Cheng to show that for any tree T, D"@?(T)=D(T), @g"D(T)[email protected]"D"""@?(T), and @g"D(T)@?D(T)+1.
BAYESIAN ESTIMATION OF ASYMMETRIC JUMP-DIFFUSION PROCESSES

The hypothesis that asset returns are normally distributed has been widely rejected. The literature has shown that empirical asset returns are highly skewed and leptokurtic. The affine jump-diffusion (AJD) model improves upon the normal specification by adding a jump component to the price process. Two important extensions proposed by Ramezani and Zeng (1998) and Kou (2002) further improve the AJD specification by having two jump components in the price process, resulting in the asymmetric affine jump-diffusion (AAJD) specification. The AAJD specification allows the probability distribution of the returns to be asymmetrical. That is, the tails of the distribution are allowed to have different shapes and densities. The empirical literature on the "leverage effect" shows that the impact of innovations in prices on volatility is asymmetric: declines in stock prices are accompanied by larger increases in volatility than the reverse. The asymmetry in AAJD specification indirectly accounts for the leverage effect and is therefore more consistent with the empirical distributions of asset returns. As a result, the AAJD specification has been widely adopted in the portfolio choice, option pricing, and other branches of the literature. However, because of their complexity, empirical estimation of the AAJD models has received little attention to date. The primary objective of this paper is to contribute to the econometric methods for estimating the parameters of the AAJD models. Specifically, we develop a Bayesian estimation technique. We provide a comparison of the estimated parameters under the Bayesian and maximum likelihood estimation (MLE) methodologies using the S&P 500, the NASDAQ, and selected individual stocks. Focusing on the most recent spectacular market bust (2007–2009) and boom (2009–2010) periods, we examine how the parameter estimates differ under distinctly different economic conditions.
Optimum diversity combiner based multiuser detection for time-dispersive Rician fading CDMA channels

Multiuser detection for asynchronous code division multiple access (CDMA) data transmission over the time-dispersive two-path Rician fading channel is considered. The multiuser maximum likelihood sequence detector (MLSD) is derived, and an equivalence of the fading channel to an asynchronous Gaussian intersymbol interference (AGISI) CDMA channel is established. However, the MLSD is found to be implementationally infeasible and this motivates the derivation of the optimum linear detector with near/far resistance as the performance criterion. The optimally near/far resistant linear time-invariant K-user detector is shown to consist of a cascade of a 2 K input/K output linear multiuser diversity combining filter followed by a K input/K output decorrelator that is designed for the equivalent AGISI/CDMA channel. This detector solves the near/far problem and also supports significantly higher bandwidth efficiencies for CDMA communication over the fading channel than does the conventional near/far limited single-user diversity combiner. The performance penalties incurred by multiuser detectors designed for the Gaussian channel when used over the Rician fading channel are also analytically characterized. It is shown that these penalties can be significant, making the case for the use of multiuser detectors optimized for this fading channel, particularly the optimum linear detector due to its relative implementational simplicity. >