cssi/SciSciGPT-SciSciNet huggingface dataset:
Variations in Stellar Clustering with Environment: Dispersed Star Formation and the Origin of Faint Fuzzies

The observed increase in star formation efficiency with average cloud density, from several percent in whole giant molecular clouds to ~30% or more in cluster-forming cores, can be understood as the result of hierarchical cloud structure if there is a characteristic density at which individual stars become well defined. Also in this case, the efficiency of star formation increases with the dispersion of the density probability distribution function (PDF). Models with lognormal PDFs illustrate these effects. The difference between star formation in bound clusters and star formation in loose groupings is attributed to a difference in cloud pressure, with higher pressures forming more tightly bound clusters. This correlation accounts for the observed increase in the clustering fraction with star formation rate and with the observation of scaled OB associations in low-pressure environments. Faint fuzzie star clusters, which are bound but have low densities, can form in regions with high Mach numbers and low background tidal forces. The proposal by Burkert, Brodie & Larsen that faint fuzzies form at large radii in galactic collisional rings satisfies these constraints.
A composite adaptive output feedback tracking controller for robotic manipulators

This paper provides a solution to the composite adaptive output feedback tracking control problem for robotic manipulators. The proposed controller utilizes an update law that is a composite of a gradient update law driven by the link position tracking error and a least squares update law driven by the prediction error. In order to remove the controller's dependence on link velocity measurements, a linear filter and a new prediction error formulation are designed. The controller provides semi-global asymptotic link position tracking performance. Experimental results illustrate that the proposed controller provides improved link position tracking error transient performance and faster parameter estimate convergence in comparsion to the same controller using a gradient update law.
Geometric limits of knot complements, II: graphs determined by their complements

We prove that there are compact submanifolds of the 3-sphere whose interiors are not homeomorphic to any geometric limit of hyperbolic knot complements.
Voltage-Gated Sodium Channel in Grasshopper Mice Defends Against Bark Scorpion Toxin

Painful venoms are used to deter predators. Pain itself, however, can signal damage and thus serves an important adaptive function. Evolution to reduce general pain responses, although valuable for preying on venomous species, is rare, likely because it comes with the risk of reduced response to tissue damage. Bark scorpions capitalize on the protective pain pathway of predators by inflicting intensely painful stings. However, grasshopper mice regularly attack and consume bark scorpions, grooming only briefly when stung. Bark scorpion venom induces pain in many mammals (house mice, rats, humans) by activating the voltage-gated Na+ channel Nav1.7, but has no effect on Nav1.8. Grasshopper mice Nav1.8 has amino acid variants that bind bark scorpion toxins and inhibit Na+ currents, blocking action potential propagation and inducing analgesia. Thus, grasshopper mice have solved the predator-pain problem by using a toxin bound to a nontarget channel to block transmission of the pain signals the venom itself is initiating.
How to test for mass degenerate Higgs resonances

The Higgs-like signal observed at the LHC could be due to several mass degenerate resonances. We show that the number of resonances is related to the rank of a “production and decay” matrix, R if . Each entry in this matrix contains the observed rate in a particular production mode i and final state f. In the case of N non-interfering resonances, the rank of R is, at most, N. If interference plays a role, the maximum rank is generically N 2, or with a universal phase, N(N + 1)/2. As an illustration we use the present experimental data to constrain the rank of the corresponding matrix. We estimate the LHC reach of probing two and three resonances under various speculations on future measurements and uncertainties.
Henry George and Austrian Economics

HENRY GEORGE HAS been widely pigeonholed and dismissed as a single-taxer. Actually, he was a profound and original economist. He independently arrived at several of the most characteristic insights of the "Austrian" School, which is enjoying a revival nowadays. Yet George scorned the Austrians of his time, and their present-day successors show scant appreciation of his work. An apparent lapse in intellectual communication calls for repair.
Hard and soft acids and bases ― the evolution of a chemical concept

The present paper will deal mainly with the more recent developments of the concept of chemical hardness. However, a necessary summary of the early work will be given
MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. IV. The Parent Luminosity Function of Radio-Loud Blazars

We use a complete sample of active galactic nuclei (AGN) selected on the basis of relativistically beamed 15 GHz radio flux density (MOJAVE: Monitoring of Jets in AGN with VLBA Experiments) to derive the parent radio luminosity function (RLF) of bright radio-selected blazar cores. We use a maximum likelihood method to fit a beamed RLF to the observed data and thereby recover the parameters of the intrinsic (unbeamed) RLF. We analyze two subsamples of the MOJAVE sample: the first contains only objects of known FR II class, with a total of 103 sources, and the second subsample adds 24 objects of uncertain FR class for a total of 127 sources. Both subsamples exclude four known FR I radio galaxies and two gigahertz-peaked spectrum sources. We obtain good fits to both subsamples using a single power law intrinsic RLF and a pure density evolution function of the form zmexp{−1/2[(z − z0)/σ]2}. We find that a previously reported break in the observed MOJAVE RLF actually arises from using incomplete bins (because of the luminosity cutoff) across a steep and strongly evolving RLF, and does not reflect a break in the intrinsic RLF. The derived space density of the parent population of the FR II sources from the MOJAVE sample (with L15 GHz ≥ 1.3 × 1025 W Hz−1) is approximately 1.6 × 103 Gpc −3.
Hue Saturation and Lightness of Surface Colors with Chromatic Illumination

The visual mechanism of a normal observer is so constructed that objects keep nearly their daylight colors even when the illuminant departs markedly from average daylight. The processes by means of which the observer adapts to the illuminant or discounts most of the effect of a nondaylight illuminant are complicated; they are known to be partly retinal and partly cortical. By taking into account the various fragments of both qualitative and quantitative information to be found in the literature, relations have been formulated by means of which it is possible to compute approximately the hue, saturation, and lightness (tint, value) of a surface color from the tristimulus specifications of the light reflected from the surface and of the light reflected from the background against which it is viewed. Preliminary observations of 15 surfaces under each of 5 different illuminants have demonstrated the adequacy of the formulation and have led to an approximate evaluation of the constants appearing in it. More detailed and extensive observations have been carried out in the psychological laboratories of Bryn Mawr College. and these observations have resulted in an improved formulation.
Rapid impactor sample return (RISR) mission scenario

Abstract Due to the long lead time and great expense of traditional sample return mission plans to Mars or other astronomical bodies, there is a need for a new and innovative way to return materials, potentially at a lower cost. The Rapid Impactor Sample Return (RISR) mission is one such proposal. The general mission scenario involves a single pass of Mars, a Martian moon or an asteroid at high speeds (7 km/s), with the sample return vehicle skimming just 1 or 2 m above a high point (such as a top ridge on Olympus Mons on Mars) and releasing an impactor. The impactor strikes the ground, throwing up debris. The debris with roughly the same forward velocity will be captured by the sample return vehicle and returned to Earth. There is no delay or orbit in the vicinity of Mars or the asteroid: RISR is a one-pass mission. This paper discusses some of the details of the proposal. Calculations are presented that address the question of how much material can be recovered with this technique. There are concerns about the effect of Mars tenuous atmosphere. However, it will be noted that such issues do not occur for RISR style missions to Phobos, Deimos, or asteroids and Near Earth Objects (NEOs). Recent test results in the missile defense community (IFTs 6–8 in 2001, 2002) have scored direct hits at better than 1 m accuracy with closing velocities of 7.6 km/s, giving the belief that accuracy and sensing issues are developed to a point that the RISR mission scenario is feasible.
Polyfuran: a new synthetic approach and electronic properties

Polyfuran films have been synthesized by electropolymerization of terfuran and investigated as a function of film preparation conditions in both the doped and undoped state. These Films have been characterized by infrared spectroscopy, scanning electron microscopy, optical absorption, X-ray photoelectron spectroscopy, dc conductivity, and electron spin resonance measurements. The electrolyte anion (dopant) used for the preparation of these films heavily influences the π-conjugated system of the polymer backbone. Structural disorder and doping level depends on the nature of the electrolyte anion. CF 3 SO 3 - was found to be the best dopant and to cause the least structural disorder or furan ring opening
A genealogy of Pd-catalyzed cross-coupling

Abstract This paper describes (a) a very brief history leading to the birth of the Pd-catalyzed cross-coupling, (b) its birth in the mid-1970s, (c) the development of the Pd-catalyzed cross-coupling with organometals containing Zn, Al, Zr, and Mg (the ‘first-generation’ Pd-catalyzed cross-coupling) in the 1970s, (d) seeding of the Pd-catalyzed cross-coupling with organometals containing Sn, B, and Si (the ‘second-generation’ Pd-catalyzed cross-coupling) in the late-1970s, and (e) further developments in the author's group in the 1980s.
Do Doctors Practice Defensive Medicine

"Defensive medicine" is a potentially serious social problem: if fear of liability drives health care providers to administer treatments that do not have worthwhile medical benefits, then the current liability system may generate inefficiencies much larger than the costs of compensating malpractice claimants. To obtain direct empirical evidence on this question, we analyze the effects of malpractice liability reforms using data on all elderly Medicare beneficiaries treated for serious heart disease in 1984, 1987, and 1990. We find that malpractice reforms that directly reduce provider liability pressure lead to reductions of 5 to 9 percent in medical expenditures without substantial effects on mortality or medical complications. We conclude that liability reforms can reduce defensive medical practices.
Infection surveillance and antibiotic utilization in a community-based skilled nursing facility.

To survey the types of suspect infections, the antibiotic utilization and the patterns of antibiotic resistance among bacterial pathogens in a community Skilled Nursing Facility (SNF), we conducted a 20-month prospective observational surveillance program comprising all 585 patients admitted to a 149-bed private community SNF. Data were collected from medical charts, laboratory reports and nurses reports. Overall, 41% of the patients developed at least one presumptive nosocomial infection, and 54% of the patients received one or more antibiotic treatments. The overall presumptive nosocomial infection rate was 7.2 per 1000 patient days. The most common sites of presumptive nosocomial infection were the urinary tract (38%) and the respiratory tract (28%). The most common pathogens overall were E. coli (25%). Antibiotic groups used most frequently were the quinolones (22% of prescriptions). Thirty-nine percent of the Staphylococcus aureus isolates associated with suspected infections were resistant to methicillin, and of these 94% were also resistant to ciprofloxacin. Most of the resistant S. aureus isolates were from indwelling catheter-associated with UTIs. Infections associated with quinolone resistant strains of gramnegative bacilli were infrequent. No epidemiologic evidence of nosocomial clustering was apparent.
Mobius Energy of Graphs

In the present paper we introduce Mobius energy for the embedded graphs and formulate its main properties. This energy is invariant under the action of the group generated by all inversions in three-dimensional real space. We study critical configurations for the angles at vertices of degree less than five, and discuss the techniques of construction of symmetric toric embedded graphs with critical values of Mobius energy.
Hecke-Clifford Algebras and Spin Hecke Algebras I: The Classical Affine Type

Associated to the classical Weyl groups, we introduce the notion of degenerate spin affine Hecke algebras and affine Hecke-Clifford algebras. For these algebras, we establish the PBW properties, formulate the intertwiners and describe the centres. We further develop connections of these algebras with the usual degenerate (i.e., graded) affine Hecke algebras of Lusztig by introducing a notion of degenerate covering affine Hecke algebras.
Approximating separable nonlinear functions via mixed zero-one programs

We discuss two models from the literature that have been developed to formulate piecewise linear approximation of separable nonlinear functions by way of mixed-integer programs. We show that the most commonly proposed method is computationally inferior to a lesser known technique by comparing analytically the linear programming relaxations of the two formulations. A third way of formulating the problem, that shares the advantages of the better of the two known methods, is also proposed.
Natural language processing in an intelligent writing strategy tutoring system

The Writing Pal is an intelligent tutoring system that provides writing strategy training. A large part of its artificial intelligence resides in the natural language processing algorithms to assess essay quality and guide feedback to students. Because writing is often highly nuanced and subjective, the development of these algorithms must consider a broad array of linguistic, rhetorical, and contextual features. This study assesses the potential for computational indices to predict human ratings of essay quality. Past studies have demonstrated that linguistic indices related to lexical diversity, word frequency, and syntactic complexity are significant predictors of human judgments of essay quality but that indices of cohesion are not. The present study extends prior work by including a larger data sample and an expanded set of indices to assess new lexical, syntactic, cohesion, rhetorical, and reading ease indices. Three models were assessed. The model reported by McNamara, Crossley, and McCarthy (Written Communication 27:57-86, 2010) including three indices of lexical diversity, word frequency, and syntactic complexity accounted for only 6% of the variance in the larger data set. A regression model including the full set of indices examined in prior studies of writing predicted 38% of the variance in human scores of essay quality with 91% adjacent accuracy (i.e., within 1 point). A regression model that also included new indices related to rhetoric and cohesion predicted 44% of the variance with 94% adjacent accuracy. The new indices increased accuracy but, more importantly, afford the means to provide more meaningful feedback in the context of a writing tutoring system.
INELASTIC DIFFRACTION AT HEAVY ION COLLIDERS.

The heavy ion physics approach to global event characterization has led us to instrument the forward region in the PHENIX experiment at RHIC. In heavy ion collisions this coverage yields a measurement of the ''spectator'' energy and its distribution about the beam direction. This energy flow is the basis of event-by-event determination of the centrality and reaction plane which are key to analyzing particle production in heavy ion collisions. These same tools have also enabled a unique set of measurements on inelastic diffraction with proton, deuteron and gold ion beams in the PHENIX experiment. We present first new results on this topic and discuss briefly the opportunity for diffractive physics with Heavy Ion beams at the LHC.
Computational study of exciton generation in suspended carbon nanotube transistors.

Optical emission from carbon nanotube transistors (CNTFETs) has recently attracted significant attention due to its potential applications. In this paper, we use a self-consistent numerical solution of the Boltzmann transport equation in the presence of both phonon and exciton scattering to present a detailed study of the operation of a partially suspended CNTFET light emitter, which has been discussed in a recent experiment. We determine the energy distribution of hot carriers in the CNTFET and, as reported in the experiment, observe localized generation of excitons near the trench−substrate junction and an exponential increase in emission intensity with a linear increase in current versus gate voltage. We further provide detailed insight into device operation and propose optimization schemes for efficient exciton generation; a deeper trench increases the generation efficiency, and use of high-k substrate oxides could lead to even larger enhancements.
Data storage and delivery protocols to support interactive high-resolution image browsing on a PC-cluster-based image wall

We present a data storage retrieval and communications system capable of supporting high-resolution image browsing on an inexpensive PC cluster based Image-Wall system. The data is first partitioned and then strategically written both onto a single hard disk and then across multiple hard disks. After presenting the data allocation scheme, we present schemes for retrieving the data from the hard disks and neighboring renderers. The optimality of the storage and retrieval mechanisms is proved and analytical results are presented for an initial implementation.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Dual gauge programs, with applications to quadratic programming and the minimum-norm problem

A gauge functionf(·) is a nonnegative convex function that is positively homogeneous and satisfiesf(0)=0. Norms and pseudonorms are specific instances of a gauge function. This paper presents a gauge duality theory for a gauge program, which is the problem of minimizing the value of a gauge functionf(·) over a convex set. The gauge dual program is also a gauge program, unlike the standard Lagrange dual. We present sufficient conditions onf(·) that ensure the existence of optimal solutions to the gauge program and its dual, with no duality gap. These sufficient conditions are relatively weak and are easy to verify, and are independent of any qualifications on the constraints. The theory is applied to a class of convex quadratic programs, and to the minimuml p norm problem. The gauge dual program is shown to provide a smaller duality than the standard dual, in a certain sense discussed in the text.
Neutrino mass patterns and future double-beta decay experiments

The next generation of double-beta decay experiments have an excellent chance of providing data on the neutrino mass pattern. This presentation is a summary of what is currently known about the mass pattern and expectations from experiment. Uncertainties due to the precision in the oscillation parameters are not critical to the interpretation of a ββ (0 ν ) measurement in terms of the mass pattern. Even though there is reason for optimism, the matrix element uncertainty is still a concern. A selected, representative group of the future experiments is discussed.
D-terms and D-strings in open string models

We study the Fayet-Iliopoulos (FI) D-terms on D-branes in type-II Calabi-Yau backgrounds. We provide a simple worldsheet proof of the fact that, at tree level, these terms only couple to scalars in closed string hypermultiplets. At the one-loop level, the D-terms get corrections only if the gauge group has an anomalous spectrum, with the anomaly cancelled by a Green-Schwarz mechanism. We study the local type-IIA model of D6-branes at SU(3) angles and show that, as in field theory, the one-loop correction suffers from a quadratic divergence in the open string channel. By studying the closed string channel, we show that this divergence is related to a closed string tadpole, and is cancelled when the tadpole is cancelled. Next, we study the cosmic strings that arise in the supersymmetric phases of these systems in light of recent work of Dvali et al. In the type-IIA intersecting D6-brane examples, we identify the D-term strings as D4-branes ending on the D6-branes. Finally, we use = 1 dualities to relate these results to previous work on the FI D-term of heterotic strings.
Imaging performance analysis of adaptive optical telescopes using laser guide stars

The use of laser guide stars in conjunction with adaptive optical telescopes offers the possibility of nearly diffraction limited imaging performance from large, ground-based telescopes. In this paper we investigate the expected imaging performance of an adaptive telescope using laser guide stars created in the mesospheric sodium (Na) layer. A two to three meter class telescope is analyzed for the case of a single, on axis guide star at an altitude of 92 km (nominal height of the mesospheric Na layer). We assume the telescope pupil is annular with approximately 15 wave front sensor subapertures and mirror actuators spanning the pupil diameter. Imaging performance is quantified in terms of the pupil averaged rms wave front error, the optical transfer function, the point spread function, the Strehl ratio and finally the angular resolution. The performance analysis takes into account the degradation caused by the limitation of the wave front sensor as well as the deformable mirror. These limitations include the finite spacing and size of the wave front sensor subapertures and the spacing and influence function of the mirror actuators. The effects of anisoplanatism and shot noise are also included in the analysis. The results of the investigation indicate that a 3 meter adaptive telescope using a single Na guide star is capable of achieving a Strehl ratio of 0.57 and an angular resolution nearly matching that of diffraction limited performance (0.05 arcsec). This performance is achieved assuming ro equals 20 cm and a 5 watt laser is used to create the guide star. The effect of variations in seeing conditions and guide star brightness are also investigated.
Encore: Lightweight Measurement of Web Censorship with Cross-Origin Requests

Despite the pervasiveness of Internet censorship, we have scant data on its extent, mechanisms, and evolution. Measuring censorship is challenging: it requires continual measurement of reachability to many target sites from diverse vantage points. Amassing suitable vantage points for longitudinal measurement is difficult; existing systems have achieved only small, short-lived deployments. We observe, however, that most Internet users access content via Web browsers, and the very nature of Web site design allows browsers to make requests to domains with different origins than the main Web page. We present Encore, a system that harnesses cross-origin requests to measure Web filtering from a diverse set of vantage points without requiring users to install custom software, enabling longitudinal measurements from many vantage points. We explain how Encore induces Web clients to perform cross-origin requests that measure Web filtering, design a distributed platform for scheduling and collecting these measurements, show the feasibility of a global-scale deployment with a pilot study and an analysis of potentially censored Web content, identify several cases of filtering in six months of measurements, and discuss ethical concerns that would arise with widespread deployment.
Boundary conditions changing operators in non-conformal theories

Abstract Boundary conditions changing operators have played an important role in conformal field theory. Here, we study their equivalent in the case where a mass scale is introduced, in an integrable way, either in the bulk or at the boundary. More precisely, we propose an axiomatic approach to determine the general scalar products b 〈 θ 1 , … , θ m ‖ θ 1 ′, … , θ n ′〉 a , between asymptotic states in the Hilbert spaces with a and b boundary conditions respectively, and compute these scalar products explicitly in the case of the Ising and sinh-Gordon models with a mass and a boundary interaction. These quantities can be used to study statistical systems with inhomogeneous boundary conditions, and, more interestingly maybe, dynamical problems in quantum impurity problems. As an example, we obtain a series of new exact results for the transition probability in the double-well problem of dissipative quantum mechanics.
Output decision under demand uncertainty with stochastic production function: a contingent claims approach

This paper presents a contingent claims analysis of output decisions for the firm facing technological and demand uncertainty. The paper reveals that: i the optimal output level increases with the higher interest rate when the firm is subject to demand and technological uncertainty; ii the effect of demand volatility and production lead time on the optimal output level could be either positive or negative; iii the optimal project value decreases with the higher demand volatility; iv the optimal project value decreases with the longer production lead time when the firm is subject to demand uncertainty; and v the optimal project value decreases with the higher interest rate when the firm is subject to demand uncertainty; it increases with the higher interest rate, however, when the firm is subject to both demand and technological uncertainty. Some important managerial implications are discussed.
Salivary Gland Disorders

Patients with salivary gland disease present with certain objective and/or subjective signs. An accurate diagnosis for these patients requires a range of techniques that includes the organized integration of information derived from their history, clinical examination, imaging, serology, and histopathology. This article highlights the signs and symptoms of the salivary gland disorders seen in the Salivary Gland Center, and emphasizes the methodology used to achieve a definitive diagnosis and therapy.
Substituted hydrazulenones via cyclopropanone addition, cyclopropanol rearrangement, and a retroaldol/re-aldol sequence

Abstract 2-Substituted cycloheptanone enolates add to cyclopropanone to give adducts that undergo base-promoted rearrangement followed, in most cases, by a retroaldol/re-aldol sequence to give conjugated hydrazulenones that are substituted at a position γ to the carbonyl group.
Quantifying Depth and Complexity of Thinking and Knowledge

Qualitative approaches to cognitive rigor and depth and complexity are broadly represented by Webbâs Depth of Knowledge and Bloomâs Taxonomy. Quantitative approaches have been relatively scant, and some have been based on ancillary measures such as the thinking time expended to answer test items. In competitive chess and other games amenable to incremental search and expert evaluation of options, we show how depth and complexity can be quantified naturally. We synthesize our depth and complexity metrics for chess into measures of difficulty and discrimination, and analyze thousands of games played by humans and computers by these metrics. We show the extent to which human players of various skill levels evince shallow versus deep thinking, and how they cope with âdifficultâ versus âeasyâ move decisions. The goal is to transfer these measures and results to application areas such as multiple-choice testing that enjoy a close correspondence in form and item values to the problem of finding good moves in chess positions.
A fast planar partition algorithm, I

In this paper we give a fast randomized algorithm for finding a partition of the plane induced by a given set of line segments. The planar partition problem is interesting because it has important practical implications, especially in computer graphics, which indeed served as an inspiration for our investigation. Our algorithm is ideally suited for a practical use because: (i) it is extremely simple and robust, and (ii) despite this simplicity (or rather because of it) the algorithm is optimal; its expected running time is O(m+n log n), where n is the number of input segments and m is the number of points of intersection. The storage requirement is O(m + n). Though the algorithm itself is simple, the global evolution of the underlying partition is non-trivial, which makes the analysis of the algorithm theoretically interesting in its own right.
Experimental Analysis of an Ultrawideband Hybrid EBG/Ferrite Ground Plane

This paper presents an experimental analysis of the previously presented ultrawideband and low-profile hybrid electromagnetic-band-gap (EBG)/ferrite ground plane. The method implemented to fabricate the hybrid ground plane, the experimental measurement procedure, and the experimental results will be described. Measurements were performed in a transverse electromagnetic (TEM) cell that was specifically designed and characterized for these measurements. As will be shown, the experimental results of the reflectivity and phase analyses of the ultrawideband hybrid ground plane show good correlation with the simulated results.
Safety benefits of stability control systems for motorcoach buses

The potential safety benefits of electronic stability control (ESC) systems for motorcoach buses operating within the United States are analyzed. "Motorcoaches" are defined as flat-front, high-platform buses equipped for intercity or long-distance travel. In recent years, ESC has increasingly become available as standard or optional equipment on motorcoaches. However, national crash databases do not include information that can be used to identify ESC-equipped buses. Moreover, even if the buses could be identified, the number of cases in available crash data is not sufficient to evaluate the safety performance of the technology in its current stage of deployment, particularly given the low number of motorcoach crashes. In light of these limitations, all recent fatal motorcoach crashes were examined by using information from the accident reports, formal studies of the National Transportation Safety Board, and information in reconstruction reports to estimate the likelihood that the crash could have been pr...
Gel Systems for Controlling CO2 Mobility in Carbon Dioxide Miscible Flooding

Conformance control for carbon dioxide miscible flooding using gel has not been widely attempted. Laboratory research efforts at the University of Kansas have produced promising in-situ gelation techniques aimed at this application. Three in-situ gel systems were developed and tested in laboratory cores. Two systems are based on a new biopolymer, termed KUSP1, and the third gel system uses the reaction of sulfomethylated resorcinol and formaldehyde to form a gel. KUSP1 gel systems were studied using two different methods of inducing in-situ gelation. In the first method, gelation was accomplished by injecting CO2 at low pressure into the Berea sandstone core saturated by alkaline polymer solution. Permeability reduction to the brine and CO2 in the range of 80% was achieved. Stability of the gel was tested in the presence of supercritical CO2 . When supercritical CO2 was used to induce in-situ gelation, the same degree of permeability reduction was achieved. The gel remained stable after the injection of many pore volumes of supercritical CO2 . The second method of initiating in-situ gelation involved the use of an ester. Hydrolysis of the ester, monoethylphthalate, in the alkaline polymer solution caused the pH to drop to levels where in-situ gelation occurred. The permeability of the treated core to supercritical carbon dioxide was about 1 md which was equivalent to a permeability reduction of 95%–97% of the initial brine permeability. The third gel system, based on the reaction of sulfomethylated resorcinol and formaldehyde ~SMRF!, was gelled in situ and contacted with both brine and supercritical CO2 . Permeabilities to carbon dioxide on the order of 1 md or less were observed. This permeability is equivalent to a reduction of about 99% in the initial brine permeability. Reduced permeabilities were maintained after injecting many pore volumes of supercritical CO2 and brine.
The plutonium-silicon system

Abstract The principal characteristics of the plutonium-silicon system include five intermediate phases and three eutectics. The intermediate phases are nominally Pu5Si3 (ζ), Pu3Si2 (η), PuSi (θ), Pu3Si5 (ι) and PuSi2 (gc), which melt, respectively, at 1377, 1441, 1576, 1646 and 1638° C, all ± 10° C. Crystal structure data for the intermediate phases are given. The eutectics were found at 3.6 at % silicon and 590 ± 2° C, between e-plutonium and ζ; at 54.5 at % silicon and 1521 ± 10° C, between θ and ι; and at 83.6 at % silicon and 1232 ± 5° C, between χ and silicon. The solubility of silicon in δ and e-plutonium is discussed in detail.
Effective fine-grain synchronization for automatically parallelized programs using optimistic synchronization primitives

This article presents our experience using optimistic synchronization to implement fine-grain atomic operations in the context of a parallelizing compiler for irregular, object-based computations. Our experience shows that the synchronization requirements of these programs differ significantly from those of traditional parallel computations, which use loop nests to access dense matrices using affine access functions. In addition to coarse-grain barrier synchronization, our irregular computations require synchronization primitives that support efficient fine-grain atomic operations. The standard implementation mechanism for atomic operations uses mutual exclusion locks. But the overhead of acquiring and releasing locks can reduce the performance. Locks can also consume significant amounts of memory. Optimistic synchronization primitives such as loud-linked/store conditional are an attractive alternative. They require no additional memory and eliminate the use of heavyweight blocking synchronization constructs. We evaluate the effectiveness of optimistic synchronization by comparing experimental results from two versions of a parallelizing compiler for irregular, object-based computations. One version generates code that uses mutual exclusion locks to make operations execute atomically. The other version generates code that uses mutual exclusion locks to make operations execute atomically. The other version uses optimistic synchronization. We used this compiler to automatically parallelize three irregular, object-based benchmark applications of interest to the scientific and engineering computation community. The presented experimental results indicate that the use of optimistic synchronization in this context can significantly reduce the memory consumption and improve the overall performance.
Regioselective cationic reduction of 2-aryl-1-N-(ethoxycarbonyl)enamines to 2-arylethylamine carbamates

2-Aryl-1-N-carboalkoxyenamines (enamides) are selectively reduced to the corresponding 2-arylethylamine carbamates by Et3SiH in the presence of CF3COOH in excellent yields. The reduction proceeds by addition of hydride at C-1 and the rate-limiting step involves proton transfer from CF3COOH. This reduction is useful for preparation of isotopically labeled arylethylamines.
Electrocyclic ring closure of the enols of vinyl quinones. A 2H-chromene synthesis.

Thermolysis of enolizable vinyl quinones in polar, aprotic media provides 2H-chromenes. Experimental evidence supports a two-step mechanism in which enolization is followed by a thermal 6π-electrocyclic reaction of an intermediate quinone methide. Application of this method led to the total synthesis of the reputed structure of an Ageratum juvenile hormone. When enolizable vinyl quinones are the products of Stille coupling, the chromene annulation product is obtained directly.
Feedback linearization of transverse dynamics for periodic orbits in R 3 with points of transverse controllability loss

Research supported in part by NSF under grant PYI ECS-9396296, by AFOSR under grant AFOSR 94NM006, and by a grant from Hughes Aircraft Company.
El corso y la piratería ante la chancillería de Valladolid (1486-1490)

According a small number of Royal Executories (Reales Ejecutorias: documents to enforce a judgement) lying in the records of the Ancient Chancellery placed in Valladolid, we study an important activity of Castillan and, specially, Basque corsairs; frequently close to the piracy, in the Occident of the Mediterranean Sea; these activities were against the ships of Aragon. We know about these problems through the complaints presented before the Royal Justice, demanding an eviction
A nurse practitioner intervention to increase breast and cervical cancer screening for poor, elderly black women

Objective: To compare nurse practitioner (NP) and physician rates of breast and cervical cancer screening among poor, elderly black women. Design: A quasi-experimental design was used to compare pre- and postintervention annual screening rates. Rates were determined by medical record audits. Setting: Two urban public hospital primary care clinics served as the study sites. Patients: All women aged 65 years or more were eligible to participate. Interventions: Women were offered screening by a NP during a routine visit in the intervention site; a physician reminder system was used in the control site. Main results: Baseline annual screening rates were comparable in the two study sites. At the end of the study period, rates were significantly higher in the NP site, compared with the control. In the NP clinic, the annual rate of Pap tests increased to 56.9% from the baseline of 17.8%, and mammographies increased to 40% from 18.3%. In comparison, rates remained low in the control site, increasing only to 18.2% of women receiving Pap tests from a baseline of 11.8%, and remaining at 18% for mammography. Conclusions: Use of a NP to deliver same-day screening is an effective strategy to target poor, elderly black women for breast and cervical cancer screening. However, even with the substantial increases in rates obtained with the NP intervention, screening in this vulnerable population remains below nationally targeted levels.
Visualization of multidimensional data with collocated paired coordinates and general line coordinates

Often multidimensional data are visualized by splitting n-D data to a set of low dimensional data. While it is useful it destroys integrity of n-D data, and leads to a shallow understanding complex n-D data. To mitigate this challenge a difficult perceptual task of assembling low-dimensional visualized pieces to the whole n-D vectors must be solved. Another way is a lossy dimension reduction by mapping n-D vectors to 2-D vectors (e.g., Principal Component Analysis). Such 2-D vectors carry only a part of information from n-D vectors, without a way to restore n-D vectors exactly from it. An alternative way for deeper understanding of n-D data is visual representations in 2-D that fully preserve n-D data. Methods of Parallel and Radial coordinates are such methods. Developing new methods that preserve dimensions is a long standing and challenging task that we address by proposing Paired Coordinates that is a new type of n-D data visual representation and by generalizing Parallel and Radial coordinates as a General Line coordinates. The important novelty of the concept of the Paired Coordinates is that it uses a single 2-D plot to represent n-D data as an oriented graph based on the idea of collocation of pairs of attributes. The advantage of the General Line Coordinates and Paired Coordinates is in providing a common framework that includes Parallel and Radial coordinates and generating a large number of new visual representations of multidimensional data without lossy dimension reduction.
Omega meson cloud and the proton's light anti-quark distributions

Abstract We use the meson cloud model of the nucleon to calculate distribution functions for ( d − u ) and d / u in the proton. Including the effect of the omega meson cloud, with a coupling constant gω2/4π≈8, allows a reasonably good description of the data.
Interpenetrating Phase Composites

In this paper an assessment of the processing and properties of interpenetrating phase composites is presented. Such materials, defined as multiphase composites in which each phase is topologically interconnected throughout the microstructure, were the subject of a DOE Basic Energy Sciences sponsored workshop on research needs and opportunities held in July 1989 in Snowmass, Colorado. In place of a report representing the proceedings of the workshop, this paper provides a review of the field in its present, nascent state and identifies some of the critical scientific and technological issues posed by development of this class of material. The emphasis is on processing approaches and properties of interpenetrating phase composites. A list of the participants contributing to the workshop is given.
Influence of Gravity Driven Convection on the Directional Solidification of Bi/MnBi Eutectic Composites

The role of gravity on Bridgman-Stockbarger directional solidification of eutectic Bi/MnBi has been studied in reduced gravity aboard NASA soundinq rocket SPAR flight experiments and contrasted with normal gravity investigations. The directional solidification of eutectic Ri/MnBi results in a low volume fraction, faceted/nonfaceted aligned rod eutectic whose MnRi rod size, interrod spacing, thermal and magnetic properties are sensitive functions of solidification processing conditions. The morphology of the low-gravity samples showed striking differences compared with identically processed, normal gravity samples grown in the same apparatus. The MnBi rod diameter and interrod spacing distributions were significantly smaller, approximately 50%, for the low gravity samples compared with identically processed one gravity samples. Accompanying the smaller MnBi rod diameters observed in the flight samples, was an increase in permanent magnet properties which reached greater than 97% of the theoretical maximum. Gravitationally induced thermal instabilities in one-gravity which result in irregular interface movement and associated difficulty of the faceted MnRi phase to branch are suggested to explain the morphological differences between one and low gravity solidification.
Sparse equidistribution problems, period bounds and subconvexity

We introduce a "geometric" method to bound periods of automorphic forms. The key features of this method are the use of equidistribution results in place of mean value theorems, and the systematic use of mixing and the spectral gap. Applications are given to equidistribution of sparse subsets of horocycles and to equidistribution of CM points; to subconvexity of the triple product period in the level aspect over number fields, which implies subconvexity for certain standard and Rankin-Selberg L-functions; and to bounding Fourier coefficients of automorphic forms.
Page Replacement with Multi-Size Pages and Applications to Web Caching

Abstract. We consider the paging problem where the pages have varying size. This problem has applications to page replacement policies for caches containing World Wide Web documents. We consider two models for the cost of an algorithm on a request sequence. In the first (the FAULT model) the goal is to minimize the number of page faults. In the second (the BIT model) the goal is to minimize the total number of bits that have to be read into the cache. We show offline algorithms for both cost models that obtain approximation factors of O(log k) , where k is the ratio of the size of the cache to the size of the smallest page. We show randomized online algorithms for both cost models that are O(log 2 k) -competitive. In addition, if the input sequence is generated by a known distribution, we show an algorithm for the FAULT model whose expected cost is within a factor of O(log k) of any other online algorithm.
Delayed GeV-TeV Photons from Gamma-Ray Bursts Producing High-Energy Cosmic Rays

A scenario in which cosmic rays (CRs) above 1020 eV are produced by cosmological gamma-ray bursts (GRBs) is consistent with observations, provided that deflections by the intergalactic magnetic field (IGMF) delay and spread the arrival time of the CRs over ≥50 yr. The energy lost by the CRs as they propagate and interact with the microwave background is transformed by cascading into secondary GeV-TeV photons. We show that a significant fraction of these photons can arrive with delays much smaller than the CR delay if much of intergalactic space is occupied by large-scale magnetic "voids," regions of a size 5 Mpc and a field weaker than 10-15 G. Such voids might be expected, for example, in models where a weak primordial field is amplified in shocked, turbulent regions of the intergalactic medium during the formation of large-scale structure. For a field strength ~4 × 10-11 G in the high-field regions, the value required to account for observed galactic fields if the IGMF were frozen in the protogalactic plasma, the delay of CRs produced by a burst at a distance of 100 Mpc is ~100 yr, and the fluence of secondary photons above 10 GeV on hour-day timescales is I(>E) ~ 10-6 E cm-2. This fluence is close to the detection threshold of current high-energy gamma-ray experiments. Detection of the delayed flux would support the GRB-CR association and would also provide information on the IGMF structure.
Particle-Gas Dynamics with Athena: Method and Convergence

The Athena magnetohydrodynamics code has been extended to integrate the motion of particles coupled with the gas via aerodynamic drag in order to study the dynamics of gas and solids in protoplanetary disks (PPDs) and the formation of planetesimals. Our particle-gas hybrid scheme is based on a second-order predictor-corrector method. Careful treatment of the momentum feedback on the gas guarantees exact conservation. The hybrid scheme is stable and convergent in most regimes relevant to PPDs. We describe a semi-implicit integrator generalized from the leap-frog approach. In the absence of drag force, it preserves the geometric properties of a particle orbit. We also present a fully implicit integrator that is unconditionally stable for all regimes of particle-gas coupling. Using our hybrid code, we study the numerical convergence of the nonlinear saturated state of the streaming instability. We find that gas flow properties are well converged with modest grid resolution (128 cells per pressure length {eta}r for dimensionless stopping time {tau} {sub s} = 0.1) and an equal number of particles and grid cells. On the other hand, particle clumping properties converge only at higher resolutions, and finer resolution leads to stronger clumping before convergence is reached. Finally, we find that themore » measurement of particle transport properties resulted from the streaming instability may be subject to error of about {+-}20%.« less