cssi/SciSciGPT-SciSciNet huggingface dataset:
Vassiliev invariants of virtual Legendrian knots

We introduce a theory of virtual Legendrian knots. A virtual Legendrian knot is a cooriented wavefront on an oriented surface up to Legendrian isotopy of its lift to the unit cotangent bundle and stabilization and destablization of the surface away from the wavefront. We show that the groups of Vassiliev invariants of virtual Legendrian knots and of virtual framed knots are isomorphic. In particular, Vassiliev invariants cannot be used to distinguish virtual Legendrian knots that are isotopic as virtual framed knots and have equal virtual Maslov numbers.
Recent developments in the chemistry, biology and medicine of the epothilones.

The epothilones have occupied center stage on the scenes of total synthesis, chemical biology and medicine for the last five years, no doubt because of their intriguing mode of action and unusually high potency against tumor cells, including multidrug-resistant cell lines. This article highlights the most recent advances within this exciting field. Thus, an overview of recent synthetic endeavors culminating in a new generation of total syntheses and analogues, some with higher potencies than the naturally occurring substances, will be given, and the chemical biology, in particular the current understanding of structure–activity relationships of the epothilones, will also be discussed in light of the latest biological results. In addition, the recently elucidated biosynthetic machinery of the natural epothilone-producing myxobacterium Sorangium cellulosum, as it is now understood, will be described. Finally, some preclinical and clinical studies will be summarized.
THE PENDULUM WEAVES ALL KNOTS AND LINKS

The behavior of a dissipative chaotic dynamical system is determined by the skeleton of its strange attractor, which consists of an uncountably infinite set of unstable periodic orbits. Each orbit is a topological knot, and the set is an infinite link. The types of knots and links supported by the system may be determined by collapsing the attractor along its local stable manifolds to form a template, a branched two manifold with boundary that supports the same set of knots and links as the original attractor. We show that the strange attractor of a chaotic, vertically forced physical pendulum can be collapsed to a template that supports all knots and links. Thus, one of the simplest and most well known dynamical systems is capable of the most complex behavior possible.
Return times of polynomials as meta-Fibonacci numbers

We consider generalized closest return times of a complex polynomial of degree at least two. Most previous studies on this subject have focused on the properties of polynomials with particular return times, especially the Fibonacci numbers. We study the general form of these closest return times. The main result of this paper is that these closest return times are metaFibonacci numbers. In particular, this result applies to the return times of a principal nest of a polynomial. Furthermore, we show that an analogous result holds in a tree with dynamics that is associated with a polynomial.
Clustered OFDM with adaptive antenna arrays for interference suppression

We investigate clustered orthogonal frequency-division multiplexing (OFDM) with adaptive antenna arrays for interference suppression. To calculate weights for interference suppression, instantaneous correlations of the received signals and channel responses corresponding to the desired signals have to be estimated. However, due to smaller size of each cluster for clustered OFDM than for classical OFDM, the discrete Fourier transform (DFT)-based estimator has large leakage and results in severe performance degradation. Therefore, a polynomial-based parameter estimator is proposed to combat the severe leakage of the DFT based estimator. We study the impact of the polynomial order and window size on the estimation error. An approximately optimal window size for the polynomial-based estimator is obtained and an adaptive algorithm for the optimal window size is developed. With the adaptive algorithm, the polynomial-based estimator has no leakage and does not require channel statistics. Simulation results show that the developed algorithm improves the performance significantly.
The Atmosphere of Titan

Review of the currently available knowledge on Titan's atmosphere, based on the report of the 1973 Titan Atmosphere Workshop. The atmosphere composition, clouds, haze, and thermal structure are discussed, along with the photochemistry, escape, and recycling of the atmosphere.
Lattice Boltzmann method on irregular meshes

A finite-volume scheme for the lattice Boltzmann method (FVLBM) is described. The scheme uses a finite-volume formulation based on triangular elements in two dimensions and is implemented assuming that velocity space is isotropically discretized at each node in position space. The accuracy of the finite-volume scheme is numerically demonstrated by comparing the computed macroscopic velocity field with the exact solution of the Navier-Stokes equations for the flow of an incompressible fluid between two relatively rotating cylinders. The FVLBM scheme is applicable to irregular two-dimensional regions which contain both exterior and interior boundaries of arbitrary shape. Thus, the range of applicability of systems to which the FVLBM may be applied is seen to be significantly extended.
Plasma ionization enhancement by laser line radiation

The possibility of increasing the degree of ionization in a plasma, by use of incident laser wavelengths matched to specific atomic transitions, is theoretically investigated. Such electron production occurs via a multistep process involving laser excitation of neutral atoms to electronic levels near the continuum and subsequent ionization of these atoms through collisions with thermalized plasma electrons. Detailed calculations for atomic oxygen, nitrogen, carbon, and cesium indicate that present state-of-the-art pulsed lasers are capable of raising 10 to 10 cm~ electron densities by a factor of two. Use of laser-diode and lasershock tube combinations for diagnostic studies of recombination processes is discussed briefly.
Nuclear Waste Repository Characterization: A Spatial Estimation/Identification Approach

In this paper we consider the application of spatial estimation techniques to groundwater aquifer and geological borehole data. We investigate the adequacy of these techniques to reliably develop contour maps from various data sets. The estimator is developed theoretically in a simplified fashion using vector-matrix calculus. The practice of spatial estimation is discussed and the estimator is then applied to a groundwater aquifer system and a deep geological formation. It is shown that the various statistical models must first be identified from the data and evaluated before reasonable results can be expected.
Adaptive Mesh Refinement for Supersonic Molecular Cloud Turbulence

We present the results of three-dimensional numerical simulations of supersonic isotropic Euler turbulence with adaptive mesh refinement (AMR) and effective grid resolution up to 10243 zones. Our experiments describe nonmagnetized, driven turbulent flows with an isothermal equation of state. Mesh refinement on shocks and shear is implemented to resolve dynamically important structures and calibrated to match the turbulence statistics obtained from the equivalent uniform-grid simulations. We demonstrate that as soon as the integral and dissipation scales are sufficiently separated, further increasing the resolution does not require mesh refinement all over the computational domain. The volume of finer subgrids in our AMR simulations scales with linear resolution approximately as N-1. Turbulence statistics derived from our AMR simulations and simulations performed on uniform grids agree surprisingly well, even though only a fraction of the volume is covered by AMR subgrids. We show that subdimensional nested "Mach cones" and U-shaped shocklets dominate the dynamics in supersonic turbulent flows. Based on these results, we discuss the fractal dimension of dissipative structures, their signature in the statistical properties of supersonic turbulence, and their role in overall flow dynamics.
Simultaneous measurements of temperature and density in air flows using UV laser spectroscopy

The simultaneous measurement of temperature and density using laser-induced fluorescence of oxygen in combination with Q-branch Raman scattering of nitrogen and oxygen is demonstrated in a low-speed air flow. The lowest density and temperature measured in the experiment correspond to the freestream values at Mach 5 in the Ames 3.5-Foot Hypersonic Wind Tunnel for stagnation conditions of 100 atm and 1000 K. The experimental results demonstrate the viability of the optical technique for measurements that support the study of compressible turbulence and the validation of numerical codes in supersonic and hypersonic wind tunnel flows.
Convenient preparation of 1-(indol-3-yl)-2,2,2-trifluoroethylamines via Friedel–Crafts reaction of α-trifluoroacetaldehyde hemiaminal

Abstract Electrophilic substitution of indole with trifluoroacetaldehyde hemiaminals 1a–f, prepared from primary amines and trifluoroacetaldehyde ethyl hemiacetal (TFAE), proceeds readily in the presence of Lewis acids. Formation of N-alkyl 1-(indol-3-yl)-2,2,2-trifluoroethylamines (2) is preferred in the presence of BF3, but yield of 2,2,2-trifluoroethyl alcohol (3) markedly increases when ZnI2 is used. A stereochemistry study clearly showed that ethylamines 2e and 2f are produced with high diastereoselective excess when the optically active hemiaminals 1e and 1f are used.
Metamouse: multiple mice for legacy applications

Traditional Single Display Groupware (SDG) solutions have been used to create software for developing regions. SDG allows for greater utilization of the limited infrastructure available in such areas. This technology is particularly appropriate in classrooms where groups of children often use educational software on a single computer. However, SDG has faced several challenges working with legacy applications. Our technology, called metamouse, takes a step toward an integrated multi-user application by allowing users to collaborate within unmodified legacy educational software.
Opposition politics and international crises: : a formal model

Democratic foreign policy choices are a function of expected international outcomes and the preferences, power, and information of domestic actors. Studies of domestic political competition and international crisis bargaining have argued that an opposition's policy positions send credible signals of the government's intentions to adversarial target states. This paper contends that while opposition behavior may send informative signals, it can also directly constrain the policy options of the government. We relax previous assumptions that the opposition cannot directly prevent war or influence the outcomes of war (Schultz 2001). Instead, we assume that the opposition controls some political resources and attempts to influence the government's policy decisions in a way that advances its own partisan interests. To empirically demonstrate the theoretical differences in our model in comparison with previous domestic opposition models, we examine the case of the Quasi-War of 1798 between the United States and France.
Locating PHEV Exchange Stations in V2G

Plug-in hybrid electric vehicles (PHEVs) are an environmentally friendly technology that is expected to rapidly penetrate the transportation system. Renewable energy sources such as wind and solar have received considerable attention as clean power options for future generation expansion. However, these sources are intermittent and increase the uncertainty in the ability to generate power. The deployment of PHEVs in a vehicle-to-grid (V2G) system provide a potential mechanism for reducing the variability of renewable energy sources. For example, PHEV supporting infrastructures like battery exchange stations that provide battery service to PHEV customers could be used as storage devices to stabilize the grid when renewable energy production is fluctuating. In this paper, we study how to best site these stations in terms of how they can support both the transportation system and the power grid. To model this problem we develop a two-stage stochastic program to optimally locate the stations prior to the realization of battery demands, loads, and generation capacity of renewable power sources. We develop two test cases to study the benefits and the performance of these systems.
Oral corticosteroids in the treatment of ocular myasthenia gravis.

Eight patients with ocular myasthenia gravis unresponsive to anticholines-terase medications were treated with alternate-day prednisone. Seven of the eight showed significant and sustained improvement. The patients exhibited few side effects of steroid therapy, and none manifested neurologic deterioration after institution of the therapy. Since anticholines-terase medications fail to benefit most patients with ocular myasthenia and since these agents reportedly have long-term undesirable effects on the neuromuscular junction, oral prednisone is proposed as an alternative therapy for ocular myasthenia.
Financial flows, financial crises, and global imbalances

Abstract In this lecture I document the proliferation of gross international asset and liability positions and discuss some consequences for individual countries’ external adjustment processes and for global financial stability. In light of the rapid growth of gross global financial flows and the serious risks associated with them, one might wonder about the continuing relevance of the net financial flow measured by the current account balance. I argue that global current account imbalances remain an essential target for policy scrutiny, for financial as well as macroeconomic reasons. Nonetheless, it is critically important for policymakers to monitor as well the rapidly evolving structure of global gross assets and liabilities.
An Extreme Ultraviolet Explorer Atlas of Seyfert Galaxy Light Curves: Search for Periodicity

The Deep Survey instrument on the Extreme Ultraviolet Explorer (EUVE) satellite obtained long, nearly continuous soft X-ray light curves of 5-33 days duration for 14 Seyfert galaxies and quasars. We present a uniform reduction of these data, which account for a total of 231 days of observation. Several of these light curves are well suited to a search for periodicity or quasi-periodic oscillations in the range of hours to days that might be expected from dynamical processes in the inner accretion disk around ~108 M☉ black holes. Light curves and periodograms of the three longest observations show features that could be transient periods: 0.89 days in RX J0437.4-4711, 2.08 days in Ton S180, and 5.8 days in 1H 0419-577. The statistical significance of these signals is estimated using the method of Timmer & Konig, which carefully takes into account the red-noise properties of Seyfert light curves. The result is that the signals in RX J0437.4-4711 and Ton S180 exceed 95% confidence with respect to red noise, while 1H 0419-577 is only 64% significant. These period values appear unrelated to the length of the observation, which is similar in the three cases, but they do scale roughly as the luminosity of the object, which would be expected in a dynamical scenario if luminosity scales with black hole mass.
Weak chaos in a quantum Kepler problem

Abstract Transition from regular to chaotic dynamics in a crystal made of singular scatterers U(r) = λ¦r¦ −σ can be reached by varying either σ or λ. We map the problem to a localization problem, and find that in all space dimensions the transition occurs at σ = 1, i.e., Coulomb potential has marginal singularity. We study the critical line σ = 1 by means of a renormalization group technique, and describe universality classes of this new transition. An RG equation is written in the basis of states localized in momentum space. The RG flow evolves the distribution of coupling parameters to a universal stationary distribution. Analytic properties of the RG equation are similar to that of Boltzmann kinetic equation: the RG dynamics has integrals of motion and obeys an H -theorem. The RG results for σ = 1 are used to derive scaling laws for transport and to calculate critical exponents.
A superweak solution of the Strong CP Problem

Abstract A non-axion solution to the Strong CP Problem is proposed that works even in the context of gravity-mediated supersymmetry breaking. Both ϵ′/ϵ and indirect CP violation in the B− B are predicted to be unobservably small. μ→eγ is predicted to arise, typically, with branching ration 3×10−12. A new source of dark matter is also predicted in the model.
Alternating permutations and symmetric functions

We use the theory of symmetric functions to enumerate various classes of alternating permutations w of {1,2,...,n}. These classes include the following: (1) both w and w^-^1 are alternating, (2) w has certain special shapes, such as (m-1,m-2,...,1), under the RSK algorithm, (3) w has a specified cycle type, and (4) w has a specified number of fixed points. We also enumerate alternating permutations of a multiset. Most of our formulas are umbral expressions where after expanding the expression in powers of a variable E, E^k is interpreted as the Euler number E"k. As a small corollary, we obtain a combinatorial interpretation of the coefficients of an asymptotic expansion appearing in Ramanujan's ''Lost'' Notebook.
Soft X-ray emission from electron-beam-heated solar flares

Using time-dependent numerical simulations and Solar Maximum Mission observations of a solar flare on 1985 January 23, a study is conducted of the ability of an electron-beam-heating model to reproduce the rise phase of a flare as observed in soft X-ray lines of Ca XIX. The electron beam is parameterized by a peak flux, a low-energy cutoff, and a spectral index, and has a time dependence similar to the observed hard X-ray burst. For a spectral index of 6, only models with a low-energy cutoff of 20 keV reproduce the observed peak emission in the Ca XIX line complex. All models with a low-energy cutoff of 15 keV produce too much emission, while all models with a 25-keV cutoff too little emission. None of the models reproduces the temporal behavior of the soft X-ray emission. The electron-beam-heated component is theorized to only represent a small fraction of the energy released in the impulsive phase of this flare.
Manifolds of Fixed Points and Duality in Supersymmetric Gauge Theories

There are many physically interesting superconformal gauge theories in four dimensions. In this talk I discuss a common phenomenon in these theories: the existence of continuous families of infrared fixed points. Well-known examples include finite N = 4 and N = 2 supersymmetric theories; many finite N '= 1 examples are known also. These theories are a subset of a much larger class, whose existence can easily be established and understood using the algebraic methods explained here. A relation between the N = 1 duality of Seiberg and duality in finite N = 2 theories is found using this approach, giving further evidence for the former. This talk is based on work with R. Leigh. l)
X-Ray Signatures of Evolving Radio Galaxies

We present a simple model for an evolving radio galaxy as it expands into the hot, X-ray-emitting interstellar medium (ISM) of its host galaxy or similarly into the hot intracluster medium (ICM) of its host cluster. We solve the governing equations numerically on a grid of model parameters in order to present simple analytical tools for X-ray observations of the shocked shell that is pushed out by the cocoon and the associated cavity in the cluster emission. We apply these tools to the well-known example of Perseus A to show that its time-averaged kinetic luminosity probably exceeds 1046 ergs s-1, much larger than the estimated current power. We show how future observations can be used to extract useful source parameters such as the average kinetic power and the source age, and discuss detectability of sources at various stages of their lives.
Smoking, self-selection and absenteeism

Abstract How much, if any, does smoking contribute to absenteeism? Separate samples of employed men and women are drawn from the 1986 wave of the Panel Study of Income Dynamics (PSID) to answer this question. The 1986 wave is the most recent one with information on smoking. In the first analysis, single equation Tobit regressions are run explaining the absence rate. Independent variables include a binary smoking variable together with others for age, race, marital status, and so on. In the single equation models, smoking appeared to raise absence rates by 42 and 232 percent for women and men, respectively. In the second analysis, decomposition techniques, which also adjust for smoking and employment hazard rates, are applied to four separate samples of smokers, non-smokers, men, and women. The decomposition techniques lowered these differentials. Smoking appears to make a moderate contribution to absenteeism for men, but only a slight contribution for women. The decomposition suggests that it is the observed and unobserved personal characteristics of female smokers that account for most of the simple positive correlations between absenteeism and smoking among women found in the single equation models.
The work of the international competition policy advisory committee to the attorney general and the assistant attorney general for antitrust

This article is a brief summary of the activities and issues under consideration by the International Competition Policy Advisory Committee (ICPAC) to the Attorney General and Assistant Attorney General for Antitrust, US Department of Justice. It describes the outreach efforts to date of the ICPAC and the analytical issues being reviewed by ICPAC members with respect to multijurisdictional mergers, trade and competition policy interface issues and enforcement cooperation between US and foreign authorities. Copyright 1999 by Oxford University Press.
DESIGN OF WRAPPER FOR SELF-MANAGEMENT OF COTS COMPONENTS

This paper describes an approach to the design of a wrapper for self-managing COTS (commercial off-the-shelf) components. Each wrapper for COTS components encapsulates the properties of self-management — detection, reconfiguration, and repair. A COTS component deals with the application perspectives, whereas the wrapper handles the self-management perspectives, separately from the application perspectives. Each wrapper for self-managing COTS components is structured into several objects in support of detection, reconfiguration, and repair of the anomalous COTS components. The approach suggested in this paper is applied to the distributed elevator system consisting of multiple COTS components.
The Long-Run Behavior of Consumption and Wealth Dynamics in Complete Financial Market with Heterogeneous Investors

A type of complete financial market with finite and countable heterogeneous investors, that is, investors equipped with heterogeneous elasticities of intertemporal substitution, heterogeneous time discount rates, and also heterogeneous beliefs, is constructed and two main results are established. First, long-run behaviors, specifically golden rules or modified golden rules, about consumption path and wealth accumulation are investigated under uncertainty and in the sense of uniform topology. Second, inefficacy of temporary taxation policies, which are chosen to be consumption tax and wealth tax, is confirmed in the current financial market.
Cohort size and schooling choice.

We develop a perfect-foresight overlapping generations model to investigate the effects of cohort size on schooling decisions and cohort-specific welfare measures. A set of sufficient conditions are presented which ensure the existence of an unique sequence of human capital rental rates and schooling choices for any sequence of cohort sizes. We calibrate the partial equilibrium model using data on schooling investments and aggregate wages over the period 1920 through 1980, and use the parameters to assess the magnitude of lifetime cohort wealth and schooling elasticities computed with respect to the entire cohort size sequence. We find that the equilibrium response of schooling to perturbations in the cohort size sequence is small, so that the adverse effects of increases in the size of own and neighboring cohorts on cohort wealth are not significantly migrated by adjustments in schooling investments within our modelling framework.
Computational Techniques for Closed–loop Reservoir Modeling with Application to a Realistic Reservoir

Abstract Real-time model-based reservoir management requires efficient computational techniques for optimizing reservoir performance under uncertainty. A variety of algorithms addressing various aspects of this “closed-loop” methodology have been presented by various investigators, but substantial effort is still needed to make the entire process robust and efficient. In our recent work, we introduced an approximate feasible direction optimization algorithm for treating nonlinear path constraints (which are constraints such as maximum liquid production rate, which must be satisfied at every time step) and a new parameterization based on kernel principal component analysis (KPCA) for multipoint geostatistical models. The KPCA representation allows for the use of a gradient-based history-matching procedure that is able to maintain a higher degree of geological realism in the history-matched model. In this article, we combine these procedures with our general adjoint-based optimization technique to provide a...
Atrial Fibrillation and Sinus Node Dysfunction in Human Ankyrin-B Syndrome: A Computational Analysis

Ankyrin-B is a multifunctional adapter protein responsible for localization and stabilization of select ion channels, transporters, and signaling molecules in excitable cells including cardiomyocytes. Ankyrin-B dysfunction has been linked with highly penetrant sinoatrial node (SAN) dysfunction and increased susceptibility to atrial fibrillation. While previous studies have identified a role for abnormal ion homeostasis in ventricular arrhythmias, the molecular mechanisms responsible for atrial arrhythmias and SAN dysfunction in human patients with ankyrin-B syndrome are unclear. Here, we develop a computational model of ankyrin-B dysfunction in atrial and SAN cells and tissue to determine the mechanism for increased susceptibility to atrial fibrillation and SAN dysfunction in human patients with ankyrin-B syndrome. Our simulations predict that defective membrane targeting of the voltage-gated L-type Ca2+ channel Cav1.3 leads to action potential shortening that reduces the critical atrial tissue mass needed to sustain reentrant activation. In parallel, increased fibrosis results in conduction slowing that further increases the susceptibility to sustained reentry in the setting of ankyrin-B dysfunction. In SAN cells, loss of Cav1.3 slows spontaneous pacemaking activity, while defects in Na+/Ca2+ exchanger and Na+/K+ ATPase increase variability in SAN cell firing. Finally, simulations of the intact SAN reveal a shift in primary pacemaker site, SAN exit block, and even SAN failure in ankyrin-B-deficient tissue.These studies identify the mechanism for increased susceptibility to atrial fibrillation and SAN dysfunction in human disease. Importantly, ankyrin-B dysfunction involves changes at both the cell and tissue level that favor the common manifestation of atrial arrhythmias and SAN dysfunction.
State reproductive policies and adolescent pregnancy resolution: The case of parental involvement laws

State laws regulating abortion have increased markedly in the wake of recent Supreme Court decisions. We test whether laws that require minors to notify or obtain consent from a parent before receiving an abortion affect the likelihood that a pregnancy will be terminated. We use individual data on births and abortions from three southern states, South Carolina, Tennessee, and Virginia. We find that South Carolina's parent consent statute is associated with a decline of 10 percentage points in the probability of abortion among non-black minors of 16 years of age. We find no effect for any other age or racial group and conclude that the impact of parental involvement laws on the pregnancy resolution of minors is not large.
Homotopy type of the boolean complex of a Coxeter system

In any Coxeter group, the set of elements whose principal order ideals are boolean forms a simplicial poset under the Bruhat order. This simplicial poset defines a cell complex, called the boolean complex. In this paper it is shown that, for any Coxeter system of rank n, the boolean complex is homotopy equivalent to a wedge of (n−1)-dimensional spheres. The number of such spheres can be computed recursively from the unlabeled Coxeter graph, and defines a new graph invariant called the boolean number. Specific calculations of the boolean number are given for all finite and affine irreducible Coxeter systems, as well as for systems with graphs that are disconnected, complete, or stars. One implication of these results is that the boolean complex is contractible if and only if a generator of the Coxeter system is in the center of the group.
Psychology in the Schools, School Psychology Review, School Psychology Quarterly and Journal of Educational and Psychological Consultation editors collaborate to chart school psychology's past, present, and “futures”

(2004). Psychology in the Schools, School Psychology Review, School Psychology Quarterly, and Journal of Educational and Psychological Consultation Editors Collaborate to Chart School Psychology's Past, Present, and “Futures”. School Psychology Review: Vol. 33, Special Issue Proceedings of the Multisite Conference on the Future of School Psychology, pp. 3-6.
Microscopic calculation of in-medium nucleon-nucleon cross sections.

We derive in-medium nucleon-nucleon (NN) cross sections in a microscopic model. Our calculations are based upon the Bonn NN potential and the Dirac-Brueckner approach for nuclear matter. We consider energies up to 300 MeV (in the laboratory frame) and densities up to twice nuclear matter density. Our results deviate substantially from cross section parametrizations that are commonly used in the nuclear medium.
Onsager relations and hydrodynamic balance equations in 2D quantum wells

Abstract We clarify the role of heat flux in the hydrodynamic balance equations in 2D quantum wells, facilitating the formulation of an Onsager relation within the framework of this theory. We find that the Onsager relation is satisfied within the framework of the 2D hydrodynamic balance equation transport theory at sufficiently high density. The condition of high density is consonant with the requirement of strong electron-electron interactions for the validity of our balance equation formulation.
Conjugate addition of a primary carbon radical to α,β-unsaturated carboxylic acids

Abstract Triethylborane in the presence of trace oxygen was employed simultaneously as a radical initiator and carboxyl protecting group to promote the conjugate radical addition of 2-phenethyl iodide to α,β-unsaturated carboxylic acids in good yields.
Bayesian and non-Bayesian methods for combining models and forecasts with applications to forecasting international growth rates

Abstract Bayesian methods for combining models and their forecasts are developed and applied using various time series models which yield forecasts of output growth rates for eighteen countries, 1974–87. Optimal Bayesian combining procedures involve use of posterior odds for alternative models which are derived and computed for several fixed parameter vs. time-varying parameter models. These odds shed light on the parameter constancy issue and are also used in predictive tests to decide whether or not combine forecasts of alternative models since, as indicated in the paper, it is not always optimal to combine forecasts. Finally, various Bayesian pooling techniques and non-Bayesian forecast combining techniques are described and their performance in forecasting one-year-ahead output growth rates of eighteen countries, 1974–87, is reported.
Intelligent physiologic modeling: an application of knowledge based systems technology to medical education.

Abstract This article describes the design and implementation of a knowledge-based physiologic modeling system (KBPMS) and a preliminary evaluation of its use as a learning resource within the context of an experimental medical curriculum — the Harvard New Pathway. KBPMS possesses combined numeric and qualitative simulation capabilities and can provide explanations of its knowledge and behavior. It has been implemented on a microcomputer with a user interface incorporating interactive graphics. The preliminary evaluation of KBPMS is based on anecdotal data which suggests that the system might have pedagogic potential. Much work remains to be done in enhancing and further evaluating KBPMS.
Association between reduced plasma 25-hydroxy vitamin D and increased risk of cancer in patients with inflammatory bowel diseases

Background & Aims Vitamin D deficiency is common among patients with inflammatory bowel diseases (IBD) (Crohn's disease or ulcerative colitis). The effects of low plasma 25-hydroxy vitamin D (25[OH]D) on outcomes other than bone health are understudied in patients with IBD. We examined the association between plasma level of 25(OH)D and risk of cancers in patients with IBD. Methods From a multi-institutional cohort of patients with IBD, we identified those with at least 1 measurement of plasma 25(OH)D. The primary outcome was development of any cancer. We examined the association between plasma 25(OH)D and risk of specific subtypes of cancer, adjusting for potential confounders in a multivariate regression model. Results We analyzed data from 2809 patients with IBD and a median plasma level of 25(OH)D of 26 ng/mL. Nearly one-third had deficient levels of vitamin D ( Conclusions In a large multi-institutional IBD cohort, a low plasma level of 25(OH)D was associated with an increased risk of cancer, especially colorectal cancer.
Real-time network security monitoring, assessment and optimization

Abstract Network security analysis and optimization forms the core of the advanced application software in modern power system energy management systems. Recent progress in network security analysis and optimization is reviewed in this paper. Topics include state estimation, observability analysis, bad data processing, topology error detection, parameter error estimation, external network modelling, contingency selection, optimal power flow, corrective rescheduling and constrained economic dispatch. Issues concerning modelling, assumptions and limitations, solution methods, computational efficiency, solution accuracy and applications are addressed. Future trends in research are also discussed.
Interactive learning with a “society of models”

Digital library access is driven by features, but the relevance of a feature for a query is not always obvious. This paper describes an approach for integrating a large number of context-dependent features into a semi-automated tool. Instead of requiring universal similarity measures or manual selection of relevant features, the approach provides a learning algorithm for selecting and combining groupings of the data, where groupings can be induced by highly specialized features. The selection process is guided by positive and negative examples from the user. The inherent combinatorics of using multiple features is reduced by a multistage grouping generation, weighting, and collection process. The stages closest to the user are trained fastest and slowly propagate their adaptations back to earlier stages, improving overall performance.
Soliton Energetics in Extended Peierls-Hubbard Models: A Quantum Monte Carlo Study

Abstract Using quantum Monte Carlo techniques, we study the effects of on-site (U) and nearest-neighbor (V) Hubbard interactions on the energetics of solitons in coupled electron-phonon (Peierls) models of quasi-one-dimensional materials.
The membrane environment can promote or suppress bistability in cell signaling networks.

Many key biochemical reactions that mediate signal transduction in cells occur at the cell membrane, yet how the 2-dimensional membrane environment influences the collective behavior of signaling networks is poorly understood. We study models of two topologically different signaling pathways that exhibit bistability, examining the effects of reduced protein mobility and increased concentration at the membrane, as well as effects due to differences in spatiotemporal correlations between the membrane environment and 3-dimensional cytoplasm. The two model networks represent the distributive enzymatic modification of a protein at multiple sites and the positive feedback-mediated activation of a protein. In both cases we find that confining proteins to a membrane-like environment can markedly alter the emergent dynamics. For the distributive protein modification network, increased concentration promotes bistability through enhanced protein-protein binding, while lower mobility and membrane-enhanced spatiotemporal correlations suppress bistability. For the positive feedback-mediated activation network, confinement to a membrane environment enhances protein activation, which can induce bistability or stabilize a monostable, active state. Importantly, the influence of the membrane environment on signaling dynamics can be qualitatively different for signaling modules with different network topologies.
Nonlinear System Modeling, Optimal Cam Design, and Advanced System Control for an Electromechanical Engine Valve Drive

A cam-based shear force-actuated electromechanical valve drive system offering variable valve timing in internal combustion engines was previously proposed and demonstrated. To transform this concept into a competitive commercial product, several major challenges need to addressed, including the reduction of power consumption, transition time, and size. As shown in this paper, by using nonlinear system modeling, optimizing cam design, and exploring different control strategies, the power consumption has been reduced from 140 to 49 W (65%), the transition time has been decreased from 3.3 to 2.7 ms (18%), and the actuator torque requirement has been cut from 1.33 to 0.30 N·m (77%).
Directed methallylations as a synthetic route to 1,3-polyols.

Abstract The directed methallylation of β-hydroxyaldehydes and ketones with methallyboronic acid is examined. The reaction proceeds with good to excellent selectivity with ketones.
Fuzzy models, modular networks, and hybrid learning

Abstract This paper proposes a new approach that can integrate fuzzy logic and neural networks in a “natural” manner. Unlike most existing fuzzy-neural models which usually make use of the structure of feedforward multilayer networks, the proposed model takes advantage of the structure of a kind of modular networks. We show that fuzzy models have a direct correspondence with the modular networks. Based on this correspondence, we develop an efficient hybrid learning scheme which combines an unsupervised learning algorithm (fuzzy-c-means algorithm) and a supervised algorithm (LMS algorithm). The utility of the proposed approach is illustrated using the well-known Zimmermann and Zysno data [36].
The relative importance of terrestrial versus marine sediment sources to the Nueces-Corpus Christi Estuary, Texas: An isotopic approach

Determining sources of sediment to coastal systems is an important and complex problem that figures prominently in a myriad of geological, geomorphological, geochemical, and biological processes. Lithogenic (226Ra,228Ra,228Th,230Th,232Th) and fallout (137Cs,210Pb) isotopes were employed in conjunction with sedimentological methods to determine rates of sedimentation in the Nueces Delta and Nueces-Corpus Christi Estuary and to assess the relative importance of marine versus terrestrial sediment sources to the estuary. Similarity of lithogenic isotope ratios in surface sediments throughout the system precluded a numeric approach to discerning the importance of each of the two large scale sediment sources (terrestrial and marine). A stepwise, graphical examination of discrete lithogenic isotope activity concentrations shows more promise. Terrestrial, marine, and bay sediment means for226Ra versus232Th,226Ra versus230Th, and228Ra versus232Th show that terrestrial and marine sediment sources have different signatures, despite having similar grain size distributions (sands), and that sediment deposited in Nueces and Corpus Christi Bays are indistinguishable from the terrestrial component. Supporting evidence is provided by thorium isotopes,230Th versus232Th,228Th versus232Th, and228Th versus230Th. Nueces Delta sedimentation (0.09–0.53 g cm−2 yr−1) shows a subtle gradient, with rates generally lower in the west and progressively higher moving east, likely reflecting contrasts in land use and topography. Nueces Bay cores differ from those in Corpus Christi Bay in that sands comprise a larger percentage of their composition, and they are mixed over greater depth, most likely due to geographic and physiographic effects. Sediment accumulation rates consistently decrease over the first 20 km from the Nueces River and become constant after that, implying that the river is the most significant source of sediment to the estuary. The interpretation of sediment supply to this estuary as dominated by terrestrial inputs is based on three complimentary sets of data: sediment grain size distributions, discrete lithogenic isotope data (Ra versus Th and Th versus Th), and sediment accumulation rates for both Nueces and Corpus Christi Bays.
Geography, poverty and conflict in Nepal:

We conduct an empirical analysis of the geographic, economic, and social factors that contributed to the spread of civil war in Nepal over the period 1996—2006. This within-country analysis complements existing cross-country studies on the same subject. Using a detailed dataset to track civil war casualties across space and over time, several patterns are documented. Conflict-related deaths are significantly higher in poorer districts and in geographical locations that favor insurgents, such as mountains and forests; a 10 percentage point increase in poverty is associated with 25—27 additional conflict-related deaths. This result is similar to that documented in cross-country studies. In addition, the relationship with poverty and geography is similar for deaths caused by the insurgents and deaths caused by the state. Furthermore, poorer districts are likely to be drawn into the insurgency earlier, consistent with the theory that a lower cost of recruiting rebels is an important factor in starting conflict. On the other hand, geographic factors are not significantly associated with such onset, suggesting that they instead contribute to the intensity of violence only after conflict has started. Finally, in contrast to some cross-country analyses, ethnic and caste polarization, land inequality, and political participation are not significantly associated with violence.
Spherical oscillation patterns

Spherical harmonics are an integral part of the study of stellar pulsations. To gain an understanding of how the star is affected by non-radial pulsations, the radial part of the oscillation is plotted, with an assumed sinusoidal time variation. The amplitude of the motion is arbitrarily set at 20% of the radius.
The roles of Na+ and K+ in pyridoxal phosphate enzyme catalysis

Abstract The group I monovalent cations Na+ and K+ and ammonium ion are important effectors of catalytic activity for a wide variety of enzymes. Until recently, little was known about the mechanism of action of these effectors. However, in the past year, X-ray structures of three metal-ion-activated pyridoxal phosphate (PLP)-requiring enzymes have been solved. This information together with solution studies of these and related enzymes have provided new insights into the relationship between structure and function for monovalent cation-activated enzymes. By drawing on the extensive literature concerning the complexes formed between macrocyclic multidentate chelators and group I metal ions, this review examines the relationships between the properties of the metal ions, chelator affinity and binding specificity. This information is integrated with the structural information on the metal ion sites of monovalentmetal-ion-activated PLP enzymes and mechanistic hypotheses for the metal-ion-mediated interconversion of inactive and active forms of this class of enzymes. The available X-ray structures show in each case the active site(s) and the metal ion binding site(s) at distinctly separate loci. Consequently, in these systems the metal ion cofactor is properly classified as an allosteric effector that does not participate directly in bonding interactions with the reacting substrate. It is concluded that, under most physiological conditions, these effector sites are saturated, and binding of the metal ion is a permanent feature of catalysis. Given these constraints, two types of mechanism are considered to explain the effects of monovalent metal ions on catalytic activity: (1) mechanisms involving the metal ion in a static structural role wherein binding activates the enzyme by simply stabilizing the catalytically active conformation of the protein and (2) mechanisms where the metal ion plays a dynamic role in which binding selectively assists one or more of the protein conformational transitions essential for complementarity between enzyme site and the structure of an activated complex.
Space division switches based on semiconductor optical amplifiers

Multiple space-division switches based on semiconductor optical amplifiers (SOAs) can be cascaded to obtain larger switching fabrics. The authors present a general analysis of optical switching fabrics using SOAs, considering noise and saturation effects associated with amplified spontaneous emission. They find that the SOA saturation output power limits the number of switches which can be cascaded. For example, a saturation output power of 100 mW limits the size of switching fabrics to 100 64*64 switches or 200 8*8 switches if distributed gain matrix-vector multiplier (MVM) switches or Benes switches are employed. The corresponding limit for lumped gain MVM fabrics is 10 64*64 or 100 8*8. The Benes switch may be more suitable for large switch size (N>16) because it requires fewer SOAs. >
Weak lensing of the high redshift SNIa sample

The current sample of high-redshift Type Ia supernovae (SNeIa), which combines results from two teams, the High-z Supernova Search Team and the Supernova Cosmology Project, is analysed for the effects of weak lensing. After correcting supernovae (SN) magnitudes for cosmological distances, assuming recently published, homogeneous distance and error estimates, we find that brighter SNe are preferentially found behind regions (5-15 arcmin radius) that are overdense in foreground, z ∼ 0.1 galaxies. This is consistent with the interpretation that SN fluxes are magnified by foreground galaxy excess and demagnified by foreground galaxy deficit, compared with a smooth universe case. The difference between most magnified and most demagnified SNe is approximately 0.3-0.4 mag. The effect is significant at the >99 per cent level. Simple modelling reveals that the slope of the relation between supernova magnitude and foreground galaxy density depends on the amount and distribution of matter along the line of sight to the sources, but does not depend on the specifics of the galaxy biasing scheme.