cssi/SciSciGPT-SciSciNet huggingface dataset:
Van Hove Jahn-Teller effect and high-Tc superconductivity

Abstract A new model is introduced, in which the structural instabilities associated with the van Hove singularities are reinterpreted in terms of band Jahn-Teller (JT) effects. This allows a model of the low-temperature phases of La2 − χBaχCuO4 in terms of static (the low-T tetragonal) or dynamic (the orthorhombic) JT phases. A solitonic model of the dynamic JT phase is presented.
α-Lithioamine synthetic equivalents from dipole-stabilized carbanions: The t-Boc group as an activator for α′-lithiation of carbamates

Abstract The t -Boc group activates the α′-lithiation of piperidinyl and related carbamates to give lithium reagents which add to electrophiles to provide α′-elaborated carbamates.
The coherent-constructible correspondence and Fourier-Mukai transforms

As evidence for his conjecture in birational log geometry, Kawamata constructed a family of derived equivalences between toric orbifolds. In a previous paper, the authors showed that the derived category of a toric orbifold is naturally identified with a category of polyhedrally-constructible sheaves on ℝ n . In this paper we investigate and reprove some of Kawamata’s results from this perspective.
Asymmetric Co(II)-Catalyzed Cyclopropanation with Succinimidyl Diazoacetate: General Synthesis of Chiral Cyclopropyl Carboxamides

[Co(P1)] is an effective catalyst for asymmetric cyclopropanation with succinimidyl diazoacetate. The Co(II)-catalyzed reaction is suitable for various olefins, providing the desired cyclopropane succinimidyl esters in high yields and excellent diastereo- and enantioselectivity. The resulting enantioenriched cyclopropane succinimidyl esters can serve as convenient synthons for the general synthesis of optically active cyclopropyl carboxamides.
Fatigue criterion to system design, life and reliability

A generalized methodology to structural life prediction, design, and reliability based upon a fatigue criterion is advanced. The life prediction methodology is based in part on work of Weibull and Lundberg and Palmgren. The approach incorporates the computed life of elemental stress volumes of a complex machine element to predict system life. The results of coupon fatigue testing can be incorporated into the analysis allowing for life prediction and component or structural renewal rates with reasonable statistical certainty.
A Practical SCR Model for Computer Aided Analysis of AC Resonant Charging Circuits

The SPICE2 SCR MODEL by C. Hu and W. Ki [1] is modified to better simulate the SCR turnoff transient while maintaining the practicality of using only data sheet specifications to determine model parameters. The modified SCR model is used to do SPICE2 simulation of ac resonant charging circuits for pulse power applications.
Yangian in the twistor string

We study symmetries of the quantized open twistor string. In addition to global PSL(4|4) symmetry, we find non-local conserved currents. The associated non-local charges lead to Ward identities which show that these charges annihilate the string gluon tree amplitudes, and have the same form as symmetries of amplitudes in \( \mathcal{N} = 4 \) super conformal Yang Mills theory. We describe how states of the open twistor string form a realization of the PSL(4|4) Yangian superalgebra.
Screening Enhancement of Thermonuclear Reactions in High Density Stars

The screening function for zero separation for two reacting nuclei in a strongly coupled OCP plasma is obtained using new very accurate Monte Carlo OCP fluid simulation data by two methods. The first method obtains H(0), the screening function at x = 0, from the difference of free energies before and after the reaction. The second method is direct fitting of the Widom expansion in powers of x2 to the MC data for the pair distribution function, g(x). The two methods agree to 0.2%.
A formula for the *-core of an ideal

Expanding on the work of Fouli and Vassilev \cite{FV}, we determine a formula for the *-$\rm{core}$ of an ideal in two different settings: (1) in a Cohen--Macaulay local ring of characteristic $p>0$, perfect residue field and test ideal of depth at least two, where the ideal has a minimal *-reduction that is a parameter ideal and (2) in a normal local domain of characteristic $p>0$, perfect residue field and $\m$-primary test ideal, where the ideal is a sufficiently high Frobenius power of an ideal. We also exhibit some examples where our formula fails if our hypotheses are not met.
Pipe flow measurements of a transparent non-Newtonian slurry

An experimental description of the flow structure of non-newtonian slurries in the laminar, transitional, and full turbulent pipe flow regimes is the primary objective of this research. Experiments were conducted in a large-scale pipe slurry flow facility with an inside pipe diameter of 51 mm. The transparent slurry formulated for these experiments exhibited a yield-power-law behavior from cup viscometer measurements. The velocity profile for laminar flow from laser Doppler velocimeter (LDV) measurements had a central plug flow region, and it was in agreement with theory. The range of the transition region was narrower than that for a Newtonian fluid. The mean velocity profile for turbulent flow was close to a 1/7 power-law velocity profile. The rms longitudinal velocity profile was also similar to a classical turbulent pipe flow experiment for a Newtonian fluid; however, the rms tangential velocity profile was significantly different.
Random load fluctuations and collapse probability of a power system operating near codimension 1 saddle-node bifurcation

For a power system operating in the vicinity of the power transfer limit of its transmission system, effect of stochastic fluctuations of power loads can become critical as a sufficiently strong such fluctuation may activate voltage instability and lead to a large scale collapse of the system. Considering the effect of these stochastic fluctuations near a codimension 1 saddle-node bifurcation, we explicitly calculate the autocorrelation function of the state vector and show how its behavior explains the phenomenon of critical slowing-down often observed for power systems on the threshold of blackout. We also estimate the collapse probability/mean clearing time for the power system and construct a new indicator function signaling the proximity to a large scale collapse. The new indicator function is easy to estimate in real time using data from PMU and SCADA information about power load fluctuations on the nodes of the grid. We discuss control strategies leading to the minimization of the collapse probability.
The Era of Massive Population III Stars: Cosmological Implications and Self-Termination

The birth and death of the first generation of stars have important implications for the thermal state and chemical properties of the intergalactic medium (IGM) in the early universe. Sometime after recombination, the neutral chemically pristine gas was reionized by ultraviolet photons emitted from the first stars but was also enriched with heavy elements when these stars ended their lives as energetic supernovae. Using the results from previous high-resolution cosmological simulations of early structure formation that include radiative transfer, we show that a significant volume fraction of the IGM can be metal polluted, as well as ionized, by massive Population III stars formed in small-mass (~106-107 M?) halos early on. If most of the early generation stars die as pair-instability supernovae with energies up to ~1053 ergs, the volume-averaged mean metallicity will quickly reach Z ~ 10-4 Z? by a redshift of ~15-20, possibly causing a transition to the formation of a stellar population that is dominated by low-mass stars. In this scenario, the early chemical enrichment history should closely trace the reionization history of the IGM, and the end of the Population III era is marked by the completion of reionization and preenrichment by z ~ 15. We conclude that, while the preenrichment may partially account for the metallicity floor in high-redshift Ly? clouds, it does not significantly affect the elemental abundance in the intracluster medium.
Infrared Observations of AR Ursae Majoris: Modeling the Ellipsoidal Variations

We have obtained time-series infrared photometry for the highly magnetic cataclysmic variable AR UMa. Our J- and K-band observations occurred during a low state, and they show a distinctive double-humped structure. Using detailed models for the expected ellipsoidal variations in the infrared caused by the nonspherical secondary star, we find that the most likely value for the system inclination is 70°. We also model low-state V-band photometry and find that its observed double-humped structure is caused not by ellipsoidal variations, to which it has been ascribed, but by beamed cyclotron radiation. We use this result to estimate the magnetic field strength of the active southern accretion region (B 190 MG) and its magnetic longitude (ψS ~ 330°).
Variety Evasive Sets

We give an explicit construction of a large subset $${S \subset \mathbb{F}^n}$$ S ? F n , where $${\mathbb{F}}$$ F is a finite field, that has small intersection with any affine variety of fixed dimension and bounded degree. Our construction generalizes a recent result of Dvir and Lovett (STOC 2012) who considered varieties of degree one (that is, affine subspaces).
Trapped modes for periodic structures in waveguides

The Laplace operator is considered for waveguides perturbed by a periodic structure consisting of N congruent obstacles spanning the waveguide. Neumann boundary conditions are imposed on the periodic structure, and either Neumann or Dirichlet conditions on the guide walls. It is proven that there are at least N (resp. N-1) trapped modes in the Neumann case (resp. Dirichlet case) under fairly general hypotheses, including the special case where the obstacles consist of line segments placed parallel to the waveguide walls. Copyright © 2004 John Wiley & Sons, Ltd.
Distributed source coding without Slepian-Wolf compression

Slepian-Wolf (SW) coding, which is concerned with separate near-lossless compression of correlated sources (with joint decoding), forms the basis of distributed source coding (DSC) and can be used to exploit the correlation among quantized sources in lossy DSC problems such as Wyner-Ziv (WZ) coding and multiterminal (MT) source coding. However, SW coding is in general lossy, especially at short block length, and practical implementation is not nearly as well understood as entropy coding. This paper studies distributed source coding without SW coding. We employ entropy coding (after quantization if necessary) at each encoder while relying on joint estimation at the decoder to exploit the source correlation. We start from the simple lossless case before giving single-letter characterizations of the rate-distortion function for WZ coding without SW compression, and achievable rate region for MT source coding without SW compression. Examples on the binary symmetric and quadratic Gaussian cases are given.
Advances in Inequality Measurement and Usefulness of Statistical Inference

Assessment of inequality measurement is the focus for this survey. All measures of inequality must be evaluated based on a set of desirable properties. More importantly, the usefulness of statistical inference for measures of inequality needs examination.
Numerical Simulation of Three-Dimensional Tuft Corona and Electrohydrodynamics

The importance of high-voltage and low-current operation in the wire-duct precipitator has focused attention on collecting high-resistivity dust. The local current density of individual tufts is considerably higher even at a low average current level and therefore could contribute to both the formation of back corona in the collected-dust layer and the generation of the secondary flow. Numerical simulation for three-dimensional tuft corona is, successfully solved. The electrical characteristics of the tuft corona is investigated and the structure and role of the three-dimensional secondary flow and electrohydrodynamics in relation to transport of the fine particles is described.
Evaluation of disk-level workloads at different time-scales

In this paper, we characterize three different sets of disk-level traces collected from enterprise systems. The data sets differ in the granularity of the recorded information and are called accordingly the Millisecond, the Hour, and the Lifetime traces. We analyze the disk-level utilization, the availability of idleness, the dynamics of the read and write traffic, over time and across an entire drive family. Our evaluation confirms that disk drives operate in moderate utilization and experience long stretches of idleness. The workload arriving at the disk is bursty across all time scales evaluated. Also, there is variability across drives of the same family, with a portion of them fully utilizing the available disk bandwidth for hours at a time.
Noteworthy observations accompanying synthesis of the apoptolidin disaccharide

A stereoselective synthesis of the apoptolidin disaccharide is reported. The key chemistry features a new transformation utilizing a highly selective tetramethylalkoxyalanate[V]-directedsyn-methylation of a vinylogous ester, isolation of a hydrate of a 2-keto sugar, an eco-friendly radical cleavage of a bromomethyl group, and an efficient preparation of a fluorodisaccharidevia the use of XtalFluor-E.
Economic evaluation of solar-only and hybrid power towers using molten-salt technology

Abstract Several hybrid and solar-only configurations for molten-salt power towers were evaluated with a simple economic model, appropriate for screening analysis. The solar-specific aspects of these plants were highlighted. In general, hybrid power towers were shown to be economically superior to solar-only plants with the same field size. Furthermore, the power-booster hybrid approach was generally preferred over the fuel-saver hybrid approach. Using today's power tower technology, economic viability for the solar power-boost occurs at fuel costs in the neighborhood of $8.90 to $15/MW h ($2.60 to $4.40/MBtu, low heating value) depending on whether coal-based or gas-turbine-based technology is being offset. These fuel prices exist today in certain areas of the world (e.g. India). The cost of CO 2 avoidance was also calculated for solar cases in which the fossil fuel cost was too low for solar to be economically viable. The avoidance costs are competitive with other proposed methods of removing CO 2 from fossil-fired power plants and appear to be within the range of interest (
On Primitive Ideals in Polynomial Rings over Nil Rings

Let R be a nil ring. We prove that primitive ideals in the polynomial ring R[x] in one indeterminate over R are of the form I[x] for some ideals I of R.
User interface in the 1990's

Abstract The process control industry is highly competitive. Most systems have similar features. However, a major factor to consider in the selection process is the user interface. This is where the user, operator, engineer, production control engineer, scheduler, etc., obtains the information he/she needs to effectively operate the plant in a safe and efficient manner. In discussing the scope of the user interface, three major areas will be reviewed: the functional areas of the production process and how the user interface fits into that domain in terms of functional scope, the user trends in terms of emerging operational trends and their impact on functional requirements, and the user interface concepts including control room operations, control room layout, non-control room operations, and solution management.
Mortality as an indicator of economic success and failure.

Quality of life depends on various physical and social conditions such as the epidemiological environment in which a person lives. The availability of health care and the nature of medical insurance--public as well as private--are among the important influences on life and death. So are other social services including basic education and the orderliness of urban living and the access to modern medical knowledge in rural communities. The statistics on mortality draw our attention to all these policy issues. Mortality information can throw light also on the nature of social inequalities including gender bias and racial disparities. (EXCERPT)
Direct numerical simulations of turbulent Ekman layers with increasing static stability: modifications to the bulk structure and second-order statistics

Direct numerical simulations of stably stratified Ekman layers are conducted to study the effect of increasing static stability on turbulence dynamics and modelling in wall-bounded flows at three moderate Reynolds numbers. The flow field is analysed by examining the mean profiles of wind speed, potential temperature and momentum flux, as well as streamwise velocity and temperature spectra. The maximum stabilizing buoyancy flux that a flow can sustain while remaining fully turbulent is found to depend on the Reynolds number. The flows with the highest Reynolds number display a relatively well-developed inertial range and logarithmic layer, and are found to bear similarities to much higher-Reynolds-number flows like the ones encountered in the atmospheric boundary layer. In particular, the near-wall mean profiles follow the Monin–Obukhov similarity theory. However, several flow features, such as the critical Richardson number and the stress–strain alignment, are found to maintain significant dependence on the Reynolds number. The budgets of turbulence kinetic energy (TKE), vertical velocity variance, momentum and buoyancy fluxes, and temperature variance are analysed. The results indicate that the effect of stability on turbulence is first directly manifested in the vertical velocity variance budget, and results in damping of vertical motions. This then leads to a reduction in the downward transport of horizontal momentum components towards the surface, and consequently to a decrease in the shear production term in the TKE budget: changes in the vertical profile of TKE shear production with increasing Richardson number are significant and have a larger impact on TKE than direct buoyancy destruction. The reduction in vertical velocity variance also results in significant drops in the production terms in the momentum flux, buoyancy flux and temperature variance budgets. Various assumptions and parameters related to low-order turbulence closures are investigated. The results suggest that the vertical velocity variance is a more appropriate parameter than the full TKE on which to base eddy-diffusivity and viscosity models.
Mechanical response of beams of a nonlinear viscoelastic material

A constitutive equation for nonlinear viscoelasticity is used to model the mechanical response of solid polymers such as polycarbonate. The nonlinearity arises from a reduced time which causes stress relaxation to accelerate with increasing strain. The constitutive equation can account for the occurrence of yield in a homogeneous uniaxial constant strain rate test. The constitutive equation is used in a study of the pure bending of beams. It is assumed that the classical assumption of beam theory is valid, i.e., plane sections remains plane. At each fixed time, the strains vary linearly through the depth of the beam. At a fixed material element the strain varies in time with the curvature. This spatial variation of the strains combined with the nonlinear dependence of the reduced time on strain leads to a significantly different response from that given by traditional beam theory. The implications of this for the bending moment history, stress distributions, and other factors that relate to beam design are discussed.
Detection of turbulent boundary-layer separation using fluctuating wall pressure signals

A technique for detecting intermittent, shock-induced, turbulent, boundary-layer separation has been developed and tested in a Mach 5 blowdown tunnel. The interactions were generated by «semi-infinite» circular cylinders. The method employs two miniature pressure transducers oriented streamwise and installed flush with the test surface. Through cross correlations of the conditionally sampled signals of the two transducers under the moving shock
Laser measurements and stochastic simulations of turbulent reacting flows

these diagnostic techniques.12 In the second part, three different approaches to the modeling of turbulent reacting flows are discussed. These include the moment, the probability density function, and the vortex dynamics approaches. Model predictions of some portions of the experimental results described in the first part of the paper are discussed, as are predictions of other chemically reacting flows documented in the literature. Most of these comparisons between modeling predictions and experimental measurements have not been previously published.
Formation and utility of azasilacyclopentadienes derived from silacyclopropenes and nitriles

The copper-catalyzed insertions of nitriles into the Si−C bonds of silacyclopropenes provide azasilacyclopentadienes, which can be converted to allylic amines after reduction and protodesilylation. The enamine functionality of azasilacyclopentadienes also participates in 1,4-addition reactions and undergoes a hydroboration and oxidation sequence to form an allylic 1,2-amino alcohol.
Nonlinear combining of laser beams

We propose to combine multiple laser beams into a single diffraction-limited beam by beam self-focusing (collapse) in a Kerr medium. Beams with total power above critical are first combined in the near field and then propagated in the optical fiber/waveguide with Kerr nonlinearity. Random fluctuations during propagation eventually trigger a strong self-focusing event and produce a diffraction-limited beam carrying the critical power.
Photoisomerization dynamics of stilbenes in polar solvents

Abstract Recent studies of rite photoisomerization kinetics of trans-stilbene and substituted stilbenes in polar solvents are discussed. The experimental studies and their comparison with reaction rate theories are reviewed. Recent theoretical development of stochastic models of reaction in more than one dimension is discussed and compared with the experimental findings at a semiquantitative level. The qualitative characteristics of the reactive process are, discussed.
Heat transfer from a negatively buoyant wall jet

Abstract An experimental investigation has been carried out on the heat transfer characteristics of a turbulent, negatively buoyant, two-dimensional wall jet. The heat transfer to the surface from the jet, the discharge temperature of which is taken as greater than the surface temperature, is measured as a function of distance along the isothermal surface for several values of wall, jet and ambient temperatures. It is found that the total heat transfer rate to the isothermal vertical surface decreases with an increase in the mixed convection parameter. The effect of the surface temperature excess on the downward penetration of the jet and on the heat transfer rate is also investigated. Relevant correlating equations are derived.
Analysis of Three-Dimensional Turbomachinery Flows on C-Type Grids Using an Implicit Euler Solver

A 3-D Euler analysis for turbomachinery flows on a C-type grid is presented. The analysis is based on the Beam and Warming implicit algorithm for solution of the unsteady Euler equations and is derived from the ARC3D code developed by Pulliam at NASA Ames Research Center. Modifications made to convert this code from external flow applications to internal turbomachinery flows are given in detail. These changes include the addition of inflow, outflow, and periodic boundary point calculation procedures. Also presented are the C-grid construction procedures. Finally, results of code experimental verification studies for 3-D compressor cascade and rotor flows are presented.Copyright © 1989 by ASME
Robust observer for uncertain linear quantum systems

In the theory of quantum dynamical filtering, one of the biggest issues is that the underlying system dynamics represented by a quantum stochastic differential equation must be known exactly in order that the corresponding filter provides an optimal performance; however, this assumption is in general unrealistic. Therefore, in this paper we consider a class of linear quantum systems subject to time-varying norm-bounded parametric uncertainty and then propose a robust observer such that the variance of the estimation error is guaranteed to be within a certain bound. Although the proposed observer is different from the optimal filter in the sense of the least mean square error, it is demonstrated in a typical quantum control problem that the observer is fairly robust against a parametric uncertainty even when the other estimators, the optimal Kalman filter and the risk-sensitive observer, fail in the estimation due to the uncertain perturbation.
Bevacizumab and albumin-bound paclitaxel treatment in metastatic breast cancer.

Abstract Background Miller et al demonstrated that the combination of bevacizumab and paclitaxel has significant activity in metastatic breast cancer (MBC). Because albumin-bound paclitaxel has been shown to have less toxicity, a better tumor delivery, and possibly better response for MBC, we combined it with bevacizumab to treat women with MBC. Patients and Methods This is a retrospective analysis. Billing records from March 2005 through December 2006 were reviewed to identify all patients treated with a combination of albumin-bound paclitaxel/bevacizumab. A total of 40 women were identified. They received a minimum of 2 courses. Patients with measurable disease were monitored for response using Response Evaluation Criteria in Solid Tumors. Women with bone-only disease were monitored with positron emission tomography (PET)/computed tomography/magnetic resonance imaging and tumor markers. All response data were confirmed by independent review. Results Of 33 women with measurable disease, 16 had objective responses to the albumin-bound paclitaxel/bevacizumab regimen (3 complete responses and 13 partial responses) for an overall response rate (ORR) of 48.5%. Median time to progression for responders was 128 days. Another 5 women had stable disease (SD) with a median duration of 135 days. Of 7 patients with bone-only disease, 2 had almost complete resolution of PET activity and 4 had SD (median, 148 days). Toxicity was acceptable with fatigue, neuropathy, pain, and hypertension being the most common complaints. Conclusion In our limited series of women with advanced, heavily pretreated MBC treated with albumin-bound paclitaxel/bevacizumab, we saw a 48.5% ORR. The regimen was well tolerated. Randomized studies are needed to confirm efficacy and safety of this combination in treating breast cancer.
Measuring material cycling in industrial systems

Abstract As the negative environmental implications of a modern industrial economy have begun to be recognized, a growing comprehension of the key role of material flows in industrial systems has developed. To this end, several indices characterizing material cycling have been developed. Current indices of material cycling for industrial systems, however, do not effectively measure cycling due to the lack of consideration of both direct and indirect flows in a system. A physical flow modeling approach from ecology, input–output flow analysis, is used in this study to develop cycling indices to address the limited scope of existing measures. The input–output cycling metrics measure the percent of both direct and indirect flows in a system or in a particular process that are cycled. Including the effects of indirect flows is particularly important because their role (relative to direct flows) grows as cycling increases. The input–output cycling indices are compared to traditional industrial cycling metrics in this paper with a set of hypothetical cases. From these comparisons, the input–output cycling metrics are shown to measure cycling of both direct and indirect flows in complex systems while traditional metrics are shown to only account for direct flows.
Optimized conditions for the formation of buried insulating layers in Si by high dose implantation of oxygen

Results are presented detailing the dependence of the residual damage on substrate temperature and dose for high dose implantation of oxygen in Si. It has been previously demonstrated that a buried oxide layer can be formed by this method. However, the usefulness of this silicon on insulator (SOI) structure has been limited by the considerable damage which accumulates in the crystal overlayer during irradiation. Much of the damage remains even after high temperature annealing. It is shown that the quality of the crystalline layer depends critically on the implant conditions. The preservation of the crystal quality of this layer by implanting at high temperatures to prevent defect clustering competes with the adverse effects caused by rapid diffusion of oxygen into this region. This leads to a rather narrow range of temperature over which optimization occurs. Rutherford backscattering/channeling spectroscopy and cross-sectional, transmission electron microscopy were used for analyzing the samples and for understanding the phenomena of formation of buried insulating layers.
Multiple frequency sounding of a Jovian cloud

A thermal asymmetry displayed in Pioneer 10 45-micron IR radiometric data between the rising and setting limbs of the Jovian South Equatorial Belt (SEB) between -5.0 and -7.0 deg latitude is examined. A high correlation is found between the longitudinal asymmetry of the SEB at 45 microns and the appearance of Jupiter in 5-micron radiation. It is shown that there was a cooler 'obscuring' cloud within the SEB latitude region which correlates highly with the location of relatively reduced intensities at 45 microns. The cloud-top temperature is estimated on the basis of simultaneous 5- and 45-micron observations
Solution-phase counterion effects in supramolecular and mechanostereochemical systems

The self-assembly of molecular components into complex superstructures involves the subtle interplay of various noncovalent forces. Charged species are often utilised in self-assembly processes as a result of the favorable π–π, cation–π, electrostatic, and hydrogen bonding interactions that form between these species. Although the counterions associated with these charged species can exert significant effects on the synthesis, stability, and operation of superstructures in solution, rarely are the counterions considered, leading to misinterpretations and misunderstandings of the studied systems. In this tutorial review, we discuss a variety of solution-phase counterion effects, from the fundamental origins to innovative ways in which these effects are exploited for useful functions.
Revealing Nonlinear Dynamics Phenomena in Mooring Due to Slowly-Varying Drift

The effects of slowly-varying wave drift forces on the nonlinear dynamics of mooring systems have been studied extensively in the past 30 years. It has been concluded that slowly-varying wave drift may resonate with mooring system natural frequencies. In recent work, we have shown that this resonance phenomenon is only one of several possible nonlinear dynamic interactions between slowly-varying wave drifts and mooring systems. We were able to reveal new phenomena, based on the design methodology developed at the University, of Michigan for autonomous mooring systems, and treating slowly-varying wave drift as an external time-varying force in systematic simulations. This methodology involves exhaustive search regarding the nonautonomous excitation, however, and approximations in defining response bifurcations. In this paper, a new approach is developed, based on the harmonic balance method, where the response to the slowly-varying wave drift spectrum is modeled by limit cycles of frequency estimated from a limited number of simulations. Thus, it becomes possible to rewrite the nonautonomous system as autonomous and reveal stability properties of the nonautonomous response. Catastrophe sets of the symmetric principal equilibrium, serving as design charts, define regions in the design space where the trajectories of the mooring system are asymptotically stable, limit cycles, or nonperiodic. This methodology reveals and proves that mooring systems subjected to slowly-varying wave drift exhibit many nonlinear phenomena, which lead to motions with amplitudes two to three orders of magnitude larger than those resulting from linear resonance. A turret mooring system (TMS) is used to demonstrate the harmonic balance methodology developed. The produced catastrophe sets are then compared with numerical results obtained from systematic simulations of the TMS dynamics.
Forward reasoning and dependency-directed backtracking in a system for computer-aided circuit analysis

Abstract We present a rule-based system for computer-aided circuit analysis. The set of rules, called EL, is written in a rule language called ARS. Rules are implemented by ARS as pattern-directed invocation demons monitoring an associative data base. Deductions are performed in an antecedent manner, giving EL's analysis a catch-as-catch-can flavour suggestive of the behavior of expert circuit analyzers. We call this style of circuit analysis propagation of constraints. The system threads deduced facts with justifications which mention the antecedent facts and the rule used. These justifications may be examined by the user to gain insight into the operation of the set of rules as they apply to a problem. The same justifications are used by the system to determine the currently active data-base context for reasoning in hypothetical situations. They are also used by the system in the analysis of failures to reduce the search space. This leads to effective control of combinatorial search which we call dependency-directed backtracking.
Water adsorption and dissociation on BeO (001) and (100) surfaces

Abstract Plateaus in water adsorption isotherms on hydroxylated BeO surfaces suggest significant differences between the hydroxylated (1 0 0) and (0 0 1) surface structures and reactivities. Density functional theory structures and energies clarify these differences. Using relaxed surface energies, a Wulff construction yields a prism crystal shape exposing long (1 0 0) sides and much smaller (0 0 1) faces. This is consistent with the BeO prisms observed when beryllium metal is oxidized. A water oxygen atom binds to a single surface beryllium ion in the preferred adsorption geometry on either surface. The water oxygen/beryllium bonding is stronger on the surface with greater beryllium atom exposure, namely the less-stable (0 0 1) surface. Water/beryllium coordination facilitates water dissociation. On the (0 0 1) surface, the dissociation products are a hydroxide bridging two beryllium ions and a metal-coordinated hydride with some surface charge depletion. On the (1 0 0) surface, water dissociates into a hydroxide ligating a Be atom and a proton coordinated to a surface oxygen but the lowest energy water state on the (1 0 0) surface is the undissociated metal-coordinated water. The (1 0 0) fully hydroxylated surface structure has a hydrogen bonding network which facilitates rapid proton shuffling within the network. The corresponding (0 0 1) hydroxylated surface is fairly open and lacks internal hydrogen bonding. This supports previous experimental interpretations of the step in water adsorption isotherms. Further, when the (1 0 0) surface is heated to 1000 K, hydroxides and protons associate and water desorbs. The more open (0 0 1) hydroxylated surface is stable at 1000 K. This is consistent with the experimental disappearance of the isotherm step when heating to 973 K.
Elastic scattering of deuterons from complex nuclei at high energies

Abstract The high energy elastic scattering of deuterons from complex nuclei is considered in terms of the impulse approximation for the deuteron. The results derived from either a many-body or a quasi two-body approach are identical to second order if simultaneous scattering via nuclear excited states is neglected. At high energies, the correction to the impulse approximation for the deuteron caused by simultaneous deuteron-nucleon scattering is smaller by a factor 1/ N than the effect of simultaneous deuteron-nucleus scattering, where N is the number of target nucleons. Deutron-nucleus scattering amplitudes are expressed in terms of nucleon-nucleus scattering amplitudes obtained from optical model potentials which yield optimum fits to the angular distributions and the reaction cross sections of nucleon-nucleus scatterings at half the deuteron incident energy. It is seen that simultaneous scattering strongly affects both the differential cross sections and the polarizations and greatly improves the results of the first order calculations. The theory gives a good agreement with experiment for energies above 156 MeV although the agreement becomes poor for lower energies.
Synthesis of exo and endo-brevicomin via the rhodium acetate catalyzed cycloaddition reaction of 1-diazo-2,5-hexanedione

Abstract Treatment of 1-diazo-2,5-hexanedione with rhodium (II) acetate in the presence of various aldehydes affords the 6,8-dioxabicyclo[3.2.1]octane ring system in high yield.
CORRELATION FUNCTIONS FROM TWO-DIMENSIONAL STRING WARD IDENTITIES

We rederive the w∞ Ward identities, starting from the existence of trivial linearized gauge invariances, and using the method of canceled propagators in the operator formalism. Recursion relations for certain classes of correlation functions are derived, and these correlation functions are calculated exactly. We clarify the relation of these results with another derivation of the Ward identities, which relies directly on charge conservation. We also emphasize the importance of the kinematics of canceled propagators in ensuring that the Ward identities are non-trivial. Finally, we sketch an extension of Ward identities to open strings.
Gas Flow Tightly Coupled to Elastoplastic Geomechanics for Tight- and Shale-Gas Reservoirs: Material Failure and Enhanced Permeability

We investigate coupled flow and geomechanics in gas production from extremely low permeability reservoirs such as tight and shale gas reservoirs, using dynamic porosity and permeability during numerical simulation. In particular, we take the intrinsic permeability as a step function of the status of material failure, and the permeability is updated every time step. We consider gas reservoirs with the vertical and horizontal primary fractures, employing the single and dynamic double porosity (dual continuum) models. We modify the multiple porosity constitutive relations for modeling the double porous continua for flow and geomechanics. The numerical results indicate that production of gas causes redistribution of the effective stress fields, increasing the effective shear stress and resulting in plasticity. Shear failure occurs not only near the fracture tips but also away from the primary fractures, which indicates generation of secondary fractures. These secondary fractures increase the permeability significantly, and change the flow pattern, which in turn causes a change in distribution of geomechanical variables. From various numerical tests, we find that shear failure is enhanced by a large pressure drop at the production well, high Biot's coefficient, low frictional and dilation angles. Smaller spacing between the horizontal wells also contributes to faster secondarymore » fracturing. When the dynamic double porosity model is used, we observe a faster evolution of the enhanced permeability areas than that obtained from the single porosity model, mainly due to a higher permeability of the fractures in the double porosity model. These complicated physics for stress sensitive reservoirs cannot properly be captured by the uncoupled or flow-only simulation, and thus tightly coupled flow and geomechanical models are highly recommended to accurately describe the reservoir behavior during gas production in tight and shale gas reservoirs and to smartly design production scenarios.« less
Aspects of N = 1 String Dynamics

We review several topics of interest in the study of 4d N=1 supersymmetric compactifications of the heterotic string. After a brief introduction to the construction of such models, our focus is on the novel physics which occurs at singularities in the moduli space of vacua. Among the phenomena we discuss are nonperturbative superpotentials, dynamical generation of poles in various low-energy couplings, and phase transitions which change the net number of chiral generations.
Prognostic significance of endometrial extension from primary carcinoma of the uterine cervix

This is a retrospective analysis of 302 patients with histologically confirmed primary carcinoma of the cervix on whom a dilatation and curettage was performed during the initial workup. The prognostic significance of endometrial extension of this tumor was investigated. Four different types of specimens were identified: 1) endometrial extension of cervical carcinoma; 2) cervical carcinoma in the curettings only; 3) a mixture of normal endometrium and epidermoid carcinoma in the curettings; 4) no cervical carcinoma noted (negative D & C). The patients were staged according to the FIGO classification. Patients with Stage I carcinoma and positive D & Cs showed significantly lower 3- and 5-year survival rates (50–60%), as opposed to those with negative D & C (approximately 80–85%). In Stage II, the endometrial extension of the cervical carcinoma decreased the 3-year survival rates to 50–56%, in contrast to 73% with negative D & C. At 5-years, the survival rates were 45% with positive D & C, in contrast to approximately 70% in those with negative D & Cs. Patients with Stage I cervical carcinoma and positive curettings showed a 20% incidence of distant metastasis, in comparison to only 4.5% in the patients with negative D & C (p ≦ .05). Patients with Stage II cervical tumors and positive D & C had a 21% incidence of distant metastasis, in contrast to 10.7% in those with negative D & C. It is strongly recommended that a dilatation and curettage be routinely obtained in the evaluation of patients with cervical carcinoma. The plan of treatment should be modified; whenever possible, packing of the endometrial cavity with Heyman capsules should be performed. The indication for hysterectomy following irradiation, the value of which has been demonstrated on patients with Stage II carcinoma of the endometrium or in carcinoma of the cervix with barrel-shaped configuration, needs further evaluation on patients with endometrial extension of cervical carcinoma, because of the high incidence of distant metastasis.
Coding and Decoding for the Dynamic Decode and Forward Relay Protocol

We study the dynamic decode-and-forward (DDF) protocol for a single half-duplex relay, single-antenna channel with quasi-static fading. The DDF protocol is well known and has been analyzed in terms of the diversity-multiplexing tradeoff (DMT) in the infinite block length limit. We characterize the finite block length DMT and give new explicit code constructions. The finite block length analysis illuminates a few key aspects that have been neglected in the previous literature: 1) we show that one dominating cause of degradation with respect to the infinite block length regime is the event of decoding error at the relay; 2) we explicitly take into account the fact that the destination does not generally know a priori the relay decision time at which the relay switches from listening to transmit mode. Both of the above problems can be tackled by a careful design of the decoding algorithm. In particular, we introduce a decision rejection criterion at the relay based on Forney's decision rule (a variant of the Neyman-Pearson rule), such that the relay triggers transmission only when its decision is reliable. Also, we show that a receiver based on the generalized likelihood ratio test (GLRT) rule that jointly decodes the relay decision time and the information message achieves the optimal DMT. Our results show that no cyclic redundancy check (CRC) for error detection or additional protocol overhead to communicate the decision time are needed for DDF. Finally, we investigate the use of minimum mean-squared error generalized decision feedback equalizer (MMSE-GDFE) lattice decoding at both the relay and the destination, and show that it provides near-optimal performance at moderate complexity.
Direct evidence for magnetic reconnection in the solar wind near 1 AU

[1] We have obtained direct evidence for local magnetic reconnection in the solar wind using solar wind plasma and magnetic field data obtained by the Advanced Composition Explorer (ACE). The prime evidence consists of accelerated ion flow observed within magnetic field reversal regions in the solar wind. Here we report such observations obtained in the interior of an interplanetary coronal mass ejection (ICME) or at the interface between two ICMEs on 23 November 1997 at a time when the magnetic field was stronger than usual. The observed plasma acceleration was consistent with the Walen relationship, which relates changes in flow velocity to density-weighted changes in the magnetic field vector. Pairs of proton beams having comparable densities and counterstreaming relative to one another along the magnetic field at a speed of ∼1.4VA, where VA was the local Alfven speed, were observed near the center of the accelerated flow event. We infer from the observations that quasi-stationary reconnection occurred sunward of the spacecraft and that the accelerated flow occurred within a Petschek-type reconnection exhaust region bounded by Alfven waves and having a cross section width of ∼4 × 105 km as it swept over ACE. The counterstreaming ion beams resulted from solar wind plasma entering the exhaust region from opposite directions along the reconnected magnetic field lines. We have identified a limited number (five) of other accelerated flow events in the ACE data that are remarkably similar to the 23 November 1997 event. All such events identified occurred at thin current sheets associated with moderate to large changes in magnetic field orientation (98°–162°) in plasmas characterized by low proton beta (0.01–0.15) and high Alfven speed (51–204 km/s). They also were all associated with ICMEs.
SWIFT X-RAY TELESCOPE MONITORING OF FERMI-LAT GAMMA-RAY SOURCES OF INTEREST

We describe a long-term Swift monitoring program of Fermi gamma-ray sources, particularly the 23 gamma-ray ''sources of interest''.We present a systematic analysis of the Swift X-Ray Telescope light curves and hardness ratios of these sources, and we calculate excess variability. We present data for the time interval of 2004 December 22 through 2012 August 31. We describe the analysis methods used to produce these data products, and we discuss the availability of these data in an online repository, which continues to grow from more data on these sources and from a growing list of additional sources. This database should be of use to the broad astronomical community for long-term studies of the variability of these objects and for inclusion in multiwavelength studies.
Multiple Slot Laminar Film Cooling

An analytical investigation is presented showing the effect of film cooling using single and double slots. The analysis considers the tangential injection of a gas of the same molecular weight as the main flow into a laminar boundary layer. Results in terms of heat transfer to the wall are presented for different slot heights, and injection velocities for both single and double slot configurations. The results indicate that the double slot is a more effective means of film cooling than the single slot.