cssi/SciSciGPT-SciSciNet huggingface dataset:
Stable adaptive fuzzy control of nonlinear systems

A direct adaptive fuzzy controller that does not require an accurate mathematical model of the system under control, is capable of incorporating fuzzy if-then control rules directly into the controllers, and guarantees the global stability of the resulting closed-loop system in the sense that all signals involved are uniformly bounded is developed. The specific formula for the bounds is provided, so that controller designers can determine the bounds based on their requirements. The direct adaptive fuzzy controller is used to regulate an unstable system to the origin and to control the Duffing chaotic system to track a trajectory. The simulation results show that the controller worked without using any fuzzy control rules, and that after fuzzy control rules were incorporated the adaptation speed became much faster. It is shown explicitly how the supervisory control forces the state to remain within the constraint set and how the adaptive fuzzy controller learns to regain control. >
System-wide energy minimization for real-time tasks: Lower bound and approximation

We present a dynamic voltage scaling (DVS) technique that minimizes system-wide energy consumption for both periodic and sporadic tasks. It is known that a system consists of processors and a number of other components. Energy-aware processors can be run in different speed levels; components like memory and I/O subsystems and network interface cards can be in a standby state when they are active, but idle. Processor energy optimization solutions are not necessarily efficient from the perspective of systems. Current system-wide energy optimization studies are often limited to periodic tasks with heuristics in getting approximated solutions. In this paper, we develop an exact dynamic programming algorithm for periodic tasks on processors with practical discrete speed levels. The algorithm determines the lower bound of energy expenditure in pseudopolynomial time. An approximation algorithm is proposed to provide performance guarantee with a given bound in polynomial running time. Because of their time efficiency, both the optimization and approximation algorithms can be adapted for online scheduling of sporadic tasks with irregular task releases. We prove that system-wide energy optimization for sporadic tasks is NP-hard in the strong sense. We develop (pseudo-) polynomial-time solutions by exploiting its inherent properties.
Highly Stereoselective Formal [3 + 3] Cycloaddition of Enals and Azomethine Imines Catalyzed by N-Heterocyclic Carbenes

N-Heterocyclic carbenes derived from N-mesityl benzimidazolium salts are effective catalysts for generating homoenolate species from α,β-unsaturated aldehydes. The nucleophilic intermediate adds to azomethine imines, and the resulting activated carbonyl unit undergoes an intramolecular acylation event. This formal [3 + 3] cycloaddition between α,β-unsaturated aldehydes and azomethine imines catalyzed by NHC has been developed to give substituted pyridazinones in good to excellent yields with high diastereoselectivity (>20:1). The NHC-catalyzed reaction accommodates aromatic and alkyl α,β-unsaturated aldehydes and various aromatic azomethine imines. The pyridazinones can undergo selective six-membered ring opening upon addition of alcohols or amines to give esters and amides.
SEARCH FOR NEW PARTICLES IN CDF

Preliminary results on searches for new particles beyond the Standard Model are presented. The data were taken by the CDF collaboration at the Fermilab {bar p}p collider at a center of mass energy of 1.8 TeV. Limits on the masses of the gluino and squark in a minimal supersymmetric theory are given. The 90% confidence level asymptotic lower mass limits on each are 150 GeV/c{sup 2}. A special data run was taken to search for the diffractively produced sextet quark state {eta}{sub 6}. An {eta}{sub 6} with a mass larger than 20 GeV/c{sup 2} is excluded at the 95% confidence level. Limits are also set on the pair-production of massive stable charged particles. Unit-charged particles belonging to spin {1/2} color triplets with masses between 50 and 139 GeV/c{sup 2} are ruled out at the 95% confidence level as are charge 2/3 particles with masses between 50 and 116 GeV/c{sup 2} and charge 4/3 particles with masses between 50 and 140 GeV/c{sup 2}. 5 refs., 3 figs.
Three-Dimensional Navier–Stokes Computation of Turbine Nozzle Flow With Advanced Turbulence Models

A three-dimensional Navier-Stokes procedure has been used to compute the three-dimensional viscous flow through the turbine nozzle passage of a single-stage turbine. A low-Reynolds-number k- e model and a zonal k-e/ARSM (algebraic Reynolds stress model) are utilized for turbulence closure. The algebraic Reynolds stress model is used only in the endwall region to represent the anisotropy of turbulence. A four-stage Runge-Kutta scheme is used for time integration of both the mean-flow and the turbulence transport equations. For the turbine nozzle flow, comprehensive comparisons between the predictions and the experimental data obtained at Penn State show that most features of the vortex-dominated endwall flow, as well as nozzle wake structure, have been captured well by the numerical procedure. An assessment of the performance of the turbulence models has been carried out. The two models are found to provide similar predictions for the mean flow parameters, although slight improvement in the prediction of some secondary flow quantities has been obtained by the ARSM model.
The continuity of the Aumann-Shapley price mechanism☆

Abstract In this paper we show, under quite weak assumptions on the cost function, that the Aumann-Shapley price mechanism is continuous with respect to the quantities consumed. The proof uses the theory of non-atomic games.
Yang-Mills and supersymmetry covariance must coexist

Abstract Supersymmetry and Yang–Mills type gauge invariance are two of the essential properties of most, and possibly the most important models in fundamental physics. Supersymmetry is nearly trivial to prove in the (traditionally gauge-noncovariant) superfield formalism, whereas the gauge-covariant formalism makes gauge invariance manifest. In 3+1 dimensions, the transformation from one into the other is elementary and essentially unique. By contrast, this transformation turns out to be impossible in the most general ( 1+1 )-dimensional case. In fact, only the (manifestly) gauge- and supersymmetry-covariant formalism guarantees both universal gauge-invariance and supersymmetry.
Morphological decomposition of 2-D binary shapes into conditionally maximal convex polygons

Mathematical morphology is an approach to image analysis based on the geometric concept of shape and size. Naturally, it provides a very effective tool for shape analysis. In this paper we present a morphological shape segmentation algorithm that decomposes a 2-D (two-dimensional) binary shape into a collection of restricted convex polygons. We use simple morphological operations to extract shape information from different skeleton subsets to form a group of conditionally maximal convex polygonal shape components. Then a set of more meaningful and natural convex polygonal components are constructed from these maximal components. The resulting algorithm is very simple and the decomposition is always unique. The components produced have well-defined mathematical characterizations and they seem to be in good agreement with the nature structures of the given shapes. The shape segments produced can be used to construct structural shape description and for other shape analysis purposes.
Sloshing dynamics-modulated fluid angular momentum and moment fluctuations driven by orbital gravity gradient and jitter accelerations in microgravity

The dynamical behavior of spacecraft propellant affected by the asymmetric combined gravity gradient and jitter acceleration are studied. In particular the effect of surface tension on partially-filled rotating fluids applicable to a full-scale Gravity Probe-B Spacecraft dewar tank has been investigated. Three different cases of orbital accelerations: (a) gravity gradient-dominated, (b) equally weighted between gravity gradients and jitter, and (c) gravity jitter-dominated accelerations are considered. Fluctuations of angular momentum, fluid moment and bubble mass center caused by slosh wave excitations driven by gravity gradient and jitter accelerations are also investigated.
Distributed Channel Synthesis

Two familiar notions of correlation are rediscovered as the extreme operating points for distributed synthesis of a discrete memoryless channel, in which a stochastic channel output is generated based on a compressed description of the channel input. Wyner's common information is the minimum description rate needed. However, when common randomness independent of the input is available, the necessary description rate reduces to Shannon's mutual information. This paper characterizes the optimal tradeoff between the amount of common randomness used and the required rate of description. We also include a number of related derivations, including the effect of limited local randomness, rate requirements for secrecy, applications to game theory, and new insights into common information duality. Our proof makes use of a soft covering lemma, known in the literature for its role in quantifying the resolvability of a channel. The direct proof (achievability) constructs a feasible joint distribution over all parts of the system using a soft covering, from which the behavior of the encoder and decoder is inferred, with no explicit reference to joint typicality or binning. Of auxiliary interest, this paper also generalizes and strengthens this soft covering tool.
Analytical chemistry--feeding the environmental revolution?

There can be no question in anyone's mind that our ability to analyze the structure and composition of materials in all media has grown in amazingly exponential ways in the last several decades. Our detection limits have gone from micrograms to the subpicogram level. A millimeter-sized sample presented a challenge in 1950; but today we look at submicron units, in fact, at single atoms resolved in analytical electron microscopes in an almost routine manner. Analysis time has changed from hours or sometimes even days for a complete qualitative and quantitative analysis on a sample to modern capabilities which include real-time spectroscopy on in situ experiments which give us data on molecular dynamics in the femtosecond time regime. Trace analysis, the detection and determination of impossibly tiny quantities of elements and molecules in increasingly complex matrices, is readily accomplished today. These are exactly the types of samples usually involved in environmental analysis. Yet, there is a tendency among some groups to view analytical advances as a negative factor in environmental studies because the ability to measure extremely small quantities can focus regulators on placing restrictions on materials not previously detectable. If so, that is a rare instance where increased knowledge can be considered a setback.
Electromagnetic Measurement of Lightning Strikes to Aircraft

Recent in-flight direct-strike lightning research, using an NASA F-1068 aircraft, is reviewed. The instrumentation system which records the rates of change of electric and magnetic flow density at several locations on the aircraft and rate of change of strike current to the boom is described. The measurement parameters are: rate of change of electric flux density over a range of 50 amperes per square meter, rate of change of magnetic flux density over a range of 20,000 tesla per second, and rate of change of strike current over a range of 100 kilo-amperes per microsecond. The isolated and shielded instrumentation system employs high-sample-rate digital transient recorders with augmented memory capacity and a wideband analog recorder for data acquisition and recording. The data obtained during the 1980 flight test program are presented and the data significance is discussed.
Cosmology from Supernova Magnification Maps

High-z Type Ia supernovae are expected to be gravitationally lensed by the foreground distribution of large-scale structure. The resulting magnification of supernovae is statistically measurable, and the angular correlation of the magnification pattern directly probes the integrated mass density along the line of sight. Measurements of the cosmic magnification of supernovae therefore complement measurements of galaxy shear in providing a direct measure of the clustering of the dark matter. As the surface density of supernovae is typically much smaller than that of sheared galaxies, the two-point correlation function of lensed Type Ia supernovae suffers from significantly increased shot noise. Nevertheless, we find that the magnification map of a large sample of supernovae provides an important cosmological tool. For example, a search over 20 deg2 over 5 years leading to a sample of ~10,000 supernovae would measure the angular power spectrum of cosmic magnification with a cumulative signal-to-noise ratio of ~20. This detection can be further improved once the supernova distance measurements are cross-correlated with measurements of the foreground galaxy distribution. The magnification maps made using supernovae can be used for important cross-checks with traditional lensing shear statistics obtained in the same fields and can help to control systematics.
Direct-to-consumer advertising and consumer welfare

The welfare implications of direct-to-consumer advertising (DTCA) have garnered considerable attention and are complicated since the consumer delegates some decision-making authority to the physician, who is exposed to advertising as well. In this paper, I develop and estimate a structural model that explains the demand side behavior in the market for prescription drugs. I then use the estimated parameters of the model to compute the impact on consumer welfare that results from changes in demand for cholesterol-reducing drugs due to increased expenditure in DTCA. The results of the policy analysis indicate increased levels of consumer welfare due to presence of DTCA in comparison to the absence of DTCA. The results also support the argument that DTCA helps bring under-diagnosed patients to the physicians' offices. Furthermore, the results of the estimation support the informative role of DTCA on the decision to seek care, and both informative and persuasive roles of physician advertising on the choice of the drug.
Orbital Ordering in Transition-Metal Compounds: I. The 120-Degree Model

We study the classical version of the 120∘-model. This is an attractive nearest-neighbor system in three dimensions with XY (rotor) spins and interaction such that only a particular projection of the spins gets coupled in each coordinate direction. Although the Hamiltonian has only discrete symmetries, it turns out that every constant field is a ground state. Employing a combination of spin-wave and contour arguments we establish the existence of long-range order at low temperatures. This suggests a mechanism for a type of ordering in certain models of transition-metal compounds where the very existence of long-range order has heretofore been a matter of some controversy.
Supersymmetric inflationary cosmology

Abstract We discuss a supersymmetric inflationary cosmological scenario in which inflation takes place after GUT breaking but before SUSY breaking. The framework is within N = 1 supergravity with the inflation and SUSY breaking sectors hidden from one another. We present a specific one-parameter inflation sector coupled with F-type SUSY breaking, with more than sufficient entropy release. Adequate baryon asymmetry is produced by an out-of-equilibrium decay mechanism in spite of a low reheat temperature. The condition that the gravitino abundance should not affect nucleosynthesis fixes the single parameter and the resultant density flucctuation to be of O(10 −4 ). If gravitinos are stable their resulting abundance is sufficient to account for the dark matter.
On a Theorem of Burde and de Rham

We generalize a theorem of Burde and de Rham characterizing the zeros of the Alexander polynomial. Given a representation of a knot group π, we define an extension $\tilde{\pi}$ of π, the Crowell group. For any GLNℂ representation of π, the zeros of the associated twisted Alexander polynomial correspond to representations of $\tilde{\pi}$ into the group of dilations of ℂN.
Cosmic ray anisotropy analysis with a full-sky observatory

Abstract A cosmic ray observatory with full-sky coverage can exploit standard anisotropy analysis methods that do not work if part of the celestial sphere is never seen. In particular, the distribution of arrival directions can be fully characterized by a list of spherical harmonic coefficients. The dipole vector and quadrupole tensor are of special interest, but the full set of harmonic coefficients constitutes the anisotropy fingerprint that may be needed to reveal the identity of the cosmic ray sources. The angular power spectrum is a coordinate-independent synopsis of that fingerprint. The true cosmic ray anisotropy can be measured despite non-uniformity in celestial exposure, provided the observatory is not blind to any region of the sky. This paper quantitatively examines how the accuracy of anisotropy measurement depends on the number of arrival directions in a data set.
Motions of hard X-ray sources during an asymmetric eruption

Filament eruptions and hard X-ray (HXR) source motions are commonly observed in solar flares, which provide critical information on the coronal magnetic reconnection. This Letter reports an event on 2005 January 15, in which we found an asymmetric filament eruption and a subsequent coronal mass ejection together with complicated motions of HXR sources during the GOES-class X2.6 flare. The HXR sources initially converge to the magnetic polarity inversion line (PIL), and then move in directions either parallel or perpendicular to the PIL depending on the local field configuration. We distinguish the evolution of the HXR source motion in four phases and associate each of them with distinct regions of coronal magnetic fields as reconstructed using a nonlinear force-free field extrapolation. It is found that the magnetic reconnection proceeds along the PIL toward the regions where the overlying field decreases with height more rapidly. It is also found that not only the perpendicular but the parallel motion of the HXR sources correlates well with the HXR light curve. These results are discussed in favor of the torus instability as an important factor in the eruptive process.
The engineer-scientist and an information retrieval system

During the last few years a veritable explosion of study, effort and accomplishment by business, government, and university organizations has taken place in the realm of information retrieval and dissemination. Theoretical problems have been explored, new equipment and techniques have been developed, and a number of successful operating systems have been implemented.
A Study of the Impact of Public School Spending on Postsecondary Educational Attainment Using Statewide School District Refinancing in Kansas.

Abstract This paper uses a policy change involving statewide school district refinancing in Kansas during the early 1990s to identify the relationship between per-pupil expenditure and the probability that a student will progress to higher education. Kansas’s school district refinancing was intended to equalize per-pupil expenditure conditional on a measure of cost developed by the state. This equalization process resulted in a change in spending that, although not completely exogenous, is understood well enough that an unbiased estimate of the effect of spending on students’ post-secondary destinations can be made. Since additional years of education are known to increase lifetime earnings, a simple cost-benefit analysis of a hypothetical spending increase is considered.
Uniqueness Results for Ill-Posed Characteristic Problems in Curved Space-Times

We prove two uniqueness theorems concerning linear wave equations; the first theorem is in Minkowski space-times, while the second is in the domain of outer communication of a Kerr black hole. Both theorems concern ill-posed Cauchy problems on bifurcate, characteristic hypersurfaces. In the case of the Kerr space-time, the hypersurface is precisely the event horizon of the black hole. The uniqueness theorem in this case, based on two Carleman estimates, is intimately connected to our strategy to prove uniqueness of the Kerr black holes among smooth, stationary solutions of the Einstein-vacuum equations, as formulated in [14].
Oxygen ion conductivity in new oxygen deficient phases with scheelite related structures

Abstract Phases of the type Bi1−2xA2xVO4−x have been prepared up to x≈0.25 with A = Ca, Sr, and Cd. The monoclinic distortion of the ideal tetragonal scheelite structure disappears with increasing x. Single crystal X-ray diffraction studies were conducted for samples with A = Ca and Cd. Impedance measurements show conductivity values analogous to those observed for stabilized zirconia.
Friction, wear, and lubrication of hydrogels as synthetic articular cartilage

Abstract In recent years, synthetic hydrogels have been studied not only as possible replacements for articular cartilage but as platforms for growing cartilage in a damaged joint. In the present study, the tribological behavior of synthesized poly(2-hydroxyethyl)methacrylate (polyHEMA) hydrogels was investigated in a four-factor, two-level designed experiment using a device developed for biotribology research. The contact geometry consisted of a 6-mm diameter stainless steel ball on flat polyHEMA disks. The variables in the designed experiment were (a) applied load, (b) lubrication, (c) hydrogel crosslink density, and (d) degree of hydrogel hydration. Linear oscillating sliding contact tests were conducted for 30 min for each test. The results showed several significant main effects and first-order interactions. Increasing the applied load from 6 to 20 N increased average hydrogel wear by 125%. Increased crosslink density reduced wear by over 60%. And increased hydration resulted in an increase of 130% in wear. The coefficient of friction ranged from a low value of 0.02 to a high of 1.7 while linear wear varied by a factor of over 60. Interactions between (a) hydration and lubrication and (b) hydration and crosslinking on wear were highly significant. The single most important finding from this study was that, as expected, there was no correlation between friction — which is commonly reported in the literature on hydrogels — and wear. Most of the data fell into two groups, namely low wear/low friction and high wear/low friction. These results may be useful in the tribological design of hydrogels for both low wear and low friction.
Magnetotunneling from accumulation layers in AlxGa1−xAs capacitors

Observations of magnetic freeze-out, sequential single-phonon emission, and the effect of Landau levels on tunneling from accumulation layers in n−-GaAs-undoped AlxGa1−xAs-n+ GaAs capacitors are reviewed.
Recent Applications of Acyclic (Diene)iron Complexes and (Dienyl)iron Cations in Organic Synthesis

Complexation of (tricarbonyl)iron to an acyclic diene serves to protect the ligand against oxidation, reduction, and cycloaddition reactions, whereas the steric bulk of this adjunct serves to direct the approaches of reagents to unsaturated groups attached to the diene onto the face opposite to iron. Furthermore, the Fe(CO) 3 moiety can serve to stabilize carbocation centers adjacent to the diene (i.e. pentadienyliron cations). Recent applications of these reactivities to the synthesis of polyene-, cyclopropane-, cycloheptadiene-, and cyclohexenone-containing natural products or analogues are presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009).
Universality of Crystallographic Pinning

We study traveling waves for reaction diffusion equations on the spatially discrete domain \({\mathbb Z^2}\). The phenomenon of crystallographic pinning occurs when traveling waves become pinned in certain directions despite moving with non-zero wave speed in nearby directions. In [19] it was shown that crystallographic pinning occurs for all rational directions, so long as the nonlinearity is close to the sawtooth, which itself was considered in [6]. In this paper we show that crystallographic pinning holds in the horizontal and vertical directions for bistable nonlinearities which satisfy a specific computable generic condition. The proof is based on dynamical systems. In particular, it relies on an examination of the heteroclinic chains which occur as singular limits of wave profiles on the boundary of the pinning region.
Controlling Sexually Violent Predators: Continued Incarceration at What Cost?

Sexually violent predator (SVP) laws are inherently suspicious because they continue to incarcerate people not because of what they have done, but because of what they might do. I focus on three major criticisms of the laws. First, I use recent recidivism data to challenge the core motivation for the SVP laws—that sex offenders are monsters who cannot control themselves. Second, I situate the laws theoretically as examples of what Feeley and Simon call the “new penology. ” I argue that the SVP laws show the limited promise of the new penology— that we can use science to predict risk accurately—because the actuarial instruments used in SVP determinations make many mistakes. In making this argument, I focus particularly on the most commonly used such instrument, the Static-99. Finally, I argue that the Static-99 fails to meet the constitutional criteria laid out by the U.S. Supreme Court in Kansas v. Hendricks because it does not link an individual9s mental illness to his dangerousness.
Prime Ideals of q -Commutative Power Series Rings

We study the “q-commutative” power series ring R: = kq[[x1,...,xn]], defined by the relations xixj = qijxjxi, for mulitiplicatively antisymmetric scalars qij in a field k. Our results provide a detailed account of prime ideal structure for a class of noncommutative, complete, local, noetherian domains having arbitrarily high (but finite) Krull, global, and classical Krull dimension. In particular, we prove that the prime spectrum of R is normally separated and is finitely stratified by commutative noetherian spectra. Combining this normal separation with results of Chan, Wu, Yekutieli, and Zhang, we are able to conclude that R is catenary. Following the approach of Brown and Goodearl, we also show that links between prime ideals are provided by canonical automorphisms. Moreover, for sufficiently generic qij, we find that R has only finitely many prime ideals and is a UFD (in the sense of Chatters).
A fast track pattern recognition

Abstract An algorithm for fast track pattern recognition is presented. Its main features are an optimized data organization and a conformal mapping to speed up fitting procedures. The code is applied to a generic collider detector. Reconstruction time, track finding efficiencies, and momentum resolution are presented.
Cross-layer optimization for wireless video communication

With the rapid growth of wireless networks and increasing popularity of portable video devices, wireless video communication is poised to become the enabling technology for many multimedia applications over wireless networks. Real-time wireless video transmission typically has requirements on quality of service (QoS). However, wireless channels are unreliable and the channel capacities are time-varying, which may cause severe degradation to video presentation quality. In addition, for portable devices, video compression and wireless transmission are tightly coupled through the constraints on data rate, power, and delay. These issues make it particularly challenging to design an efficient real-time video compression and wireless transmission system on a portable device. In this paper, we take a cross-layer approach to this problem; our objective is to maximize the video quality under the constraints of resource and delay. Specifically, we minimize the end-to-end video distortion under the constraints of resource and delay, over the parameters in physical, link, and application (video) layers. This formulation is general and capable of capturing the fundamental aspects of the design of wireless video communication systems. Based on this formulation, we study how the resources could be intelligently allocated to maximize the video quality and analyze the performance limits of the wireless video communication system under resource constraints.
State Tax Changes and Quasi-Experimental Price Elasticities of U.S. Cigarette Demand: An Update

This paper uses 336 state tax changes across the U.S. spanning 42 years (1956–1997) to provide an updated look at the quasi-experimental price elasticities of cigarette demand. It also studies the sensitivity of these elasticity estimates to changes in the cigarette market over time as well as their sensitivity to border-effect purchases. Besides replicating earlier findings, the results show a downward trend in these elasticities over time and sensitivity to border effect purchases. Policy implications are discussed.
Analysis of Deployment and Inflation of Large Ribbon Parachutes

A method for predicting deployment and inflation of reefed ribbon parachutes is presented. The method is based on integration of axial and radial momentum equations developed in the paper. Axial and radial forces are assumed to be describable by drag and radial force coefficients. Computer solutions of the equations are compared to measured parachute loads and to parachute mouth and maximum diameters from tests of 23and 76-ft-diam conical ribbon parachutes. Comparison of load histories indicates that snatch loads depend to a large extent on deployment bag design and packing influences. Computed loads and parachute size histories for the inflation process compared favorably with flight data. The concept of a radial force coefficient appears to have considerable merit as a means of computing inflation for most types of parachutes.
Detector efficiency limits on quantum improvement

Although the National Institute of Standards and Technology has measured the intrinsic quantum efficiency of Si and InGaAs avalanche photo diode (APD) materials to be above 98% by building an efficient compound detector, commercially available devices have efficiencies ranging between 15 and 75%. This means bandwidth, dark current, cost, and other factors are more important than quantum efficiency for existing applications. For non-classical correlated photon applications, the system's correlated signal-to-noise ratio is proportional to (ηN) 1/2 /(1- η) 1/2 , rather than the classical signal-to-noise (ηN) 1/2 . Consequently, the detector design trade space must be re-evaluated. This paper systematically examines the generic detection process, lays out the considerations needed for designing detectors for non-classical applications, and identifies the ultimate physical limits on quantum efficiency.
The influence of solute segregation on the dislocation structure of small and large angle [001] twist boundaries in Fe-Sb alloys

In alloy systems where there is limited solubility in the solid solution solute atoms segregate to grain boundaries giving local compositions at the interface typically at the monolayer level. The practical consequence of such segregation in Fe-base alloys is frequently the embrittlement of the grain boundary region, making it susceptible to fracture at relatively low stresses. It is interesting to note that in polycrystalline Ni/sub 3/Al, which is intrinsically brittle, B segregation to grain boundaries and changes in stoichiometry, make the material ductile. It is of considerable importance to learn how the presence of solute changes the fracture resistance of grain boundaries. Briant and Messmer suggested that segregation causes a change in the nature of the electronic bonding at the interface, which is believed to influence its cohesive strength. Hart suggested that segregation causes a change in the structure of the boundary and in this manner controls its resistance to fracture. At present there is no experimental evidence concerning the bonding at grain boundaries in Fe-Te, and in Cu-Bi. Others have reported a characteristic grain boundary morphology in the presence of solute segregation, in the form of faceting. While both sets of observations lead to the suggestion that faceting resultsmore » from solute segregation, neither study examined the structure of the same boundary in both the clean and segregated states.« less
Exact Solutions to a Finite-difference Model of a Nonlinear Reaction-advection Equation: Implications for Numerical Analysis

This article gives exact solutions to a finite-difference model of a nonlinear reaction-advection equation. We show that this partial difference equation and the corresponding stationary and spatially independent difference equations derived from this model give the best representation of the original partial differential equation. The relevance of this work to the elimination of chaotic behavior in numerical solutions of differential equations is discussed.
Global regularity for the Maxwell-Klein-Gordon equation with small critical Sobolev norm in high dimensions

We show that in dimensions n ≥ 6 one has global regularity for the Maxwell-Klein-Gordon equations in the Coulomb gauge provided that the critical Sobolev norm of the initial data is sufficiently small. These results are analogous to those recently obtained for the high-dimensional wave map equation [17, 7, 14, 12] but unlike the wave map equation, the Coulomb gauge non-linearity cannot be iterated away directly. We shall use a different approach, proving Strichartz estimates for the covariant wave equation. This in turn will be achieved by use of Littlewood-Paley multipliers, and a global parametrix for the covariant wave equation constructed using a truncated, microlocalized Cronstrom gauge.
AN APL SHARED VARIABLE PROCESSOR IN A DISTRIBUTED REAL-TIME ENVIRONMENT

Abstract A hierarchical real-time computer system has been developed for laboratory automation purposes. It consists of microcomputers for data acquisition and control and a large mini for data processing. The control micros are connected to each other, the mini and an operator's terminal through a communication microprocessor. This latter is designed in accordance with the APL concept of Shared Variable Processor, taking into account the reliability and throughput considerations steming from the real-time and distributed nature of the system.
On the expressive power of database queries with intermediate types

Abstract The set-height of a complex object type is defined to be its level of nesting of the set construct. In a query of the complex object calculus which maps a database D to an output type T , an intermediate type is a type which is used by some variable of the query, but which is not present in D or T . For each k , i ⩾ 0 we define CALC k, i to be the family of calculus queries mapping from and to types with set-height ⩽ k and using intermediate types with set-height ⩽ i . In particular, CALC 0.0 is the classical relational calculus, and CALC 0.1 is equivalent to the family of second-order (relational) queries. Several results concerning these families of languages are obtained. A primary focus is on the families CALC 0, i , which map relations to relations. Upper and lower bounds in terms of hyper-exponential time and space on the complexity of these families are provided. The CALC 0, i hierarchy does not collapse with respect to expressive power. The union ∪ 0 ⩽ i CALC 0, i is exactly the family of elementary queries , i.e., queries with hyper-exponential complexity. The expressive power of queries from the complex object calculus interpreted using semantics based on the use of arbitrarily large finite or infinite set of invented values is studied. Under these semantics, the expressive power of the relational calculus is not increased, and the CALC 0, i hierarchy collapses at CALC 0.1 . In general, queries with these semantics may not be computable. We also consider an alternative semantics which yields a family of queries equivalent to the computable queries.
A far ultraviolet analysis of the stellar populations in six elliptical and s0 galaxies

We have analyzed the far-ultraviolet (FUV) spectra of six elliptical and S0 galaxies in order to characterize the stellar population that produces the ultraviolet flux in these galaxies. The spectra were obtained using the Hopkins Ultraviolet Telescope (HUT) during the Astro-2 mission aboard the Space Shuttle Endeavour in 1995 March and cover the spectral range from 820 to 1840 A with a resolution of 3 A. These data, together with the spectra of two galaxies observed with HUT on the Astro-1 mission, represent the only FUV spectra of early-type galaxies that extend to the Lyman limit at 912 A and therefore include the "turnover" in the spectral energy distribution below Lyα. Using an extensive new grid of LTE and non-LTE synthetic spectra that match the HUT resolution and cover the relevant parameter space of temperature and gravity, we have constructed synthetic spectral energy distributions by integrating over various predicted stellar evolutionary tracks for horizontal-branch stars and their progeny. When the computed models are compared with the HUT data, we find that models with supersolar metal abundances and helium best reproduce the flux across the entire HUT wavelength range, while those with subsolar Z and Y fit less well, partly because of a significant flux deficit shortward of 970 A in the models. High-Z models are preferred because the contribution from the later, hotter, post-HB evolutionary stages makes up a higher fraction of the sub-Lyα flux in these tracks. We find that AGB-Manque evolution is required in all of the fits to the HUT spectra, which suggests that all of the galaxies have some subdwarf B-star population. At any Z and Y, the model spectra that best match the HUT flux are dominated by stars evolving from a narrow range of envelope mass on the blue end of the horizontal branch. The Astro-1 and Astro-2 data are also the first with the resolution and signal-to-noise ratio needed to detect and measure absorption lines in the FUV spectra of elliptical galaxies, which allows a direct estimate of the abundances in the atmospheres of the stars that produce the UV flux. We find that most absorption features in the spectra are consistent with Z = 0.1 Z☉, significantly lower than the abundances implied by the best-fitting spectral energy distributions. However, given the strong observational and theoretical evidence for diffusion processes in the atmospheres of evolved stars, the observed atmospheric abundances may not reflect the interior abundances in the population producing the ultraviolet flux in elliptical galaxies.
BINOL-Salen-catalyzed highly enantioselective alkyne additions to aromatic aldehydes.

The BINOL−Salen compound (−)-1 can catalyze the addition of both aryl- and alkylalkynes to aromatic aldehydes at room temperature with high enantioselectivity (86−97% ee). The conditions for this catalytic process are both mild and simple. Unlike most other BINOL-based catalysts, using ligand (−)-1 not only avoids heating or cooling but also does not require the addition of Ti(OiPr)4.
Traceless Stereoinduction in the One-Pot Assembly of All Three Rings of Hexahydrodibenzopyrans

A one-pot method has been developed for the synthesis of all three rings of the hexahydrodibenzopyran ring system. This process involves a tandem sequence consisting of a benzannulation reaction of an alkenyl Fischer carbene complex and an alkyne followed by an elimination reaction that generates an o-quinone methide chromium tricarbonyl complex that is finally followed by an intramolecular heteroatom Diels−Alder cycloaddition. The stereoinduction for the overall process begins with the transfer of stereochemical information from the chiral center at the propargylic ether in the alkyne to the planar center of chirality in the in situ generated arene chromium tricarbonyl complexed intermediate and finally, after base-induced elimination to generate an o-quinone methide chromium tricarbonyl complexed intermediate, a transfer of chirality from the planar center of chirality in the o-quinone methide complex to the two new centers of chirality at positions 6a and 10a in the hexahydrodibenzopyran products upon ...
Cell transfer and monomial positivity

We give combinatorial proofs that certain families of differences of products of Schur functions are monomial-positive. We show in addition that such monomial-positivity is to be expected of a large class of generating functions with combinatorial definitions similar to Schur functions. These generating functions are defined on posets with labelled Hasse diagrams and include for example generating functions of Stanley's (P,?)-partitions.
Investigation of the Behavior of Ventilated Supercavities

A study has been carried out at the Saint Anthony Falls Laboratory (SAFL) to investigate various aspects of the flow physics of a supercavitating vehicle. For the experimental work presented here, artificial supercavitation behind a sharp-edged disk was investigated for various model configurations. Results regarding supercavity shape, closure, and ventilation requirements versus Froude number are presented. Conducting experiments in water tunnels introduces blockage effects that are not present in nature. As a result, effects related to flow choking are also discussed. Various methods for computing ventilated cavitation number, including direct measurement of pressure, Laser Doppler Velocimetry, and use of previous numerical results, were compared. Results obtained are similar in character to previous results from various authors, but differ significantly in measured values. Supercavitation parameters, especially the minimum obtainable cavitation number are strongly affected by tunnel blockage.Copyright © 2010 by ASME
Structural studies of Li5ReO6, Li4NpO5 and Li5NpO6 by neutron and X-ray powder diffraction

Abstract This paper reports on the preparation of Li 5 ReO 6 , Li 4 NpO 5 and Li 5 NpO 6 by solid-state reactions, the results of X-ray and neutron powder diffraction measurements on all three compounds, and the determination of the structures of Li 5 ReO 6 and Li 4 NpO 5 from the neutron data. The neutron powder diffraction refinement for Li 5 ReO 6 confirms a recent single-crystal X-ray diffraction study: monoclinic, space group C 2/ m . This structure is retained by Li 5 ReO 6 between 298 K and 10 K. The neutron powder diffraction refinement for Li 4 NpO 5 confirms earlier X-ray powder diffraction results: tetragonal, space group I 4/ m , a=6.698 A , c=4.415 A . The lithium and oxygen positional parameters of Li 4 NpO 5 have been refined: coordination about Np is an extended octahedron, with each Np ion surrounded equatorially by four oxygen ions at 2.00 A and axially by two oxygen ions at 2.21 A. Li 5 NpO 6 shows an X-ray powder pattern consistent with the original report, but the neutron diffraction data set could not be refined in terms of the originally proposed space group or any other plausible model structure.
Rotational nonequilibrium in CW chemical lasers

By including the spontaneous emission term in the radiative transfer equation, an explicit expression for the radiation term in the species equation is obtained in terms of the fluid variables. This formulation is used to study the role of rotational nonequilibrium in cw chemical lasers. It is shown that the phenomena of J shifting and the power being contained in the high J transitions are consequences of the rotational equilibrium assumption. When rotational nonequilibrium is allowed to occur, several J transitions within a given vibrational band lase simultaneously, most of the power is contained in those J transitions that are preferentially populated by the pumping reaction, and the power is decreased by 20%–30% from the rotational equilibrium value. Agreement between the predicted and observed lasing transitions in HF lasers is obtained.
Oscillations in light-triggered logic microfluidic circuit

Control of droplets in microfluidic environments has numerous applications ranging from analysis and sample preparation for biomaterials synthesis (Mann and Ozin Nature 382:313–318, 1996) and medical diagnostics (Pipper et al. Nat Med 13:1259–1263, 2007) to photonics (Schmidt and Hawkins Nat Photonics 5:598–604, 2011). Here we study the oscillations present in a microfluidic circuit capable of sorting curable droplets on demand by triggering the circuit with UV-light. Prior to this paper we showed that a simple circuit can self-sort particles and produce a binary output, sorted or rejected stream of particles, based on the hydrodynamic resistance induced by the particles as they flow through the microfluidic channels. We showed that the cross-linking of droplets can modulate the resistance, and demonstrated particle switching by sorting of otherwise identical droplets of uncured and cured photocurable solution immersed in mineral oil solution. Before arriving at the sorting circuit, droplets made of a photocurable solution were illuminated by a UV-light from a mercury lamp, curing them. By tuning the outlet pressures, the switching threshold could be tuned so that uncured droplets were rejected while cured droplets were switched (Raafat et al. μTAS Proc 1826–1828, 2010; Cartas-Ayala et al. Small 9:375–381, 2013). Here we use this system to study the oscillations in this circuit due to particle–particle interactions in the circuit. The circuit oscillation can be used as a counter with a light ON/OFF switch. The circuit behavior agrees well with theoretical predictions of droplet oscillations. Furthermore, the circuit oscillations can be switched on or off by UV-light illumination. This experiment demonstrates switching of particles based on deformability, illustrates the switching of particles by using light, and the possibility of creating new managing schemes for droplets by combining light control with droplet generation-rate control.
Regulation of the mTOR Complex 1 Pathway by Nutrients, Growth Factors, and Stress

The large serine/threonine protein kinase mTOR regulates cellular and organismal homeostasis by coordinating anabolic and catabolic processes with nutrient, energy, and oxygen availability and growth factor signaling. Cells and organisms experience a wide variety of insults that perturb the homeostatic systems governed by mTOR and therefore require appropriate stress responses to allow cells to continue to function. Stress can manifest from an excess or lack of upstream signals or as a result of genetic perturbations in upstream effectors of the pathway. mTOR nucleates two large protein complexes that are important nodes in the pathways that help buffer cells from stresses, and are implicated in the progression of stress-associated phenotypes and diseases, such as aging, tumorigenesis, and diabetes. This review focuses on the key components of the mTOR complex 1 pathway and on how various stresses impinge upon them.
Two-fold branched covers

Many three-dimensional manifolds are two-fold branched covers of the three-dimensional sphere. However, there are some that are not. This paper includes exposition about two-fold branched covers and includes many examples. It shows that there are three-dimensional homology spheres that do not two-fold branched cover any manifold, ones that only two-fold branched cover the three-dimensional sphere, ones that just two-fold branched cover a non-trivial manifold, and ones that two-fold branched cover both the sphere and non-trivial manifolds. When a manifold is surgery on a knot, the possible quotients via involutions generically correspond to quotients of the knot. There can, however, be a finite number of surgeries for which there are exceptional additional symmetries. The included proof of this result follows the proof of Thurston's Dehn surgery theorem. The paper also includes examples of such exceptional symmetries. Since the quotients follow the behavior of knots, a census of the behavior for knots with less than 11 crossings is included.