cssi/SciSciGPT-SciSciNet huggingface dataset:
Metalated nitriles: internal 1,2-asymmetric induction.

Formula chem. Alkylations of conformationally constrained acyclic nitriles containing vicinal dimethyl groups and an adjacent phenyl group or trisubstituted alkene are exceptionally diastereoselective. Probing the alkylation stereoselectivity with a series of C- and N-metalated nitriles implicates a reactive conformation in which an sp 2 -hybridized substituent projects over the metalated nitrile to avoid allylic strain. Steric screening thereby directs the electrophilic attack to the face of the metalated nitrile opposite the projecting substituent. Excellent stereoselectively is maintained in a diverse range of alkylations that efficiently install quaternary centers, even with isopropyliodide in which a contiguous array of tertiary-quaternary-tertiary stereocenters is created! Screening the conformational requirements with a series of acyclic nitriles and esters reveals the key structural requirements for high selectivity while providing a robust, predictive model that accounts for comparable ester alkylations affording the opposite diastereomer! The intensive survey of metalated nitrile alkylations identifies the key structural features required for high 1,2-asymmetric induction, addresses the long-standing challenge of asymmetric alkylations with acylic metalated nitriles, and provides a versatile method for installing hindered quaternary centers with excellent stereocontrol.
The History and Morphology of Helium Reionization

A variety of observations now indicate that intergalactic helium was fully ionized by z ~ 3. The most recent measurements of the high-redshift quasar luminosity function imply that these sources had produced at least ~2.5 ionizing photons per helium atom by that time, consistent with a picture in which the known quasar population drives He II reionization. Here we describe the distribution of ionized and neutral helium gas during this era. Because the sources were rare and bright (with the photon budget dominated by quasars with luminosities L L), random fluctuations in the quasar population determined the morphology of ionized gas when the global ionized fraction i was small, with the typical radius Rc of a He III bubble ~15-20 comoving Mpc. Only when i 0.5 did the large-scale clustering of the quasars drive the characteristic size of ionized regions above this value. Still later, when i 0.75, most ionizing photons were consumed by dense, recombining systems before they reached the edge of their source's ionized surroundings, halting the bubble growth when Rc ~ 35-40 Mpc. These phases are qualitatively similar to those in hydrogen reionization, but the rarity of the sources makes the early stochastic phase much more important. Moreover, the well-known characteristics of the z = 3 intergalactic medium allow a much more robust description of the late phase in which recombinations dominate.
A simple, effective, new, palladium-catalyzed conversion of enol silanes to enones and enals

Abstract Enol silanes derived from aldehydes and ketones are readily converted to the corresponding α,β-unsaturated carbonyl compounds by 10% Pd(OAc) 2 in the presence of one atmosphere of oxygen in DMSO as the solvent.
CALCULATION OF MINIMUM MISCIBILITY PRESSURE

Abstract A method is described and tested for calculation of minimum miscibility pressure (MMP) that makes use of an analytical theory for one-dimensional, dispersion-free flow of multicomponent mixtures. The theory shows that in a displacement of an oil by a gas with nc components, the behavior of the displacement is controlled by a sequence of nc−1 key tie lines. Besides, the tie lines that extend through the initial oil and injection gas compositions, there are nc−3 tie lines, known as crossover tie lines, that can be found from a set of conditions that require the extensions of the appropriate tie lines to intersect each other. The MMP is calculated as the pressure at which one of the key tie lines becomes a tie line of zero length that is tangent to the critical locus. The numerical approach for solving the tie line intersection equations is described; slim tube test and compositional simulation data reported in the literature are used to show that the proposed approach can be used to calculate MMP accurately for displacements with an arbitrary number of components present.
STUDIES DIRECTED TOWARD THE TOTAL SYNTHESIS OF POLYCAVERNOSIDE A. ENANTIOSELECTIVE SYNTHESIS OF THE DISACCHARIDE COMPONENT

Abstract Adaptation of the Mukaiyama-Nicolaou protocol to the coupling of a monounprotected thioglycoside to a glycosyl fluoride is capable of delivering the unusual disaccharide present in the title toxin.
Electroclinic effect at the A-C phase change in a chiral smectic liquid crystal

When a smectic-$A$ phase is composed of chiral molecules, it exhibits an electroclinic effect, i.e., a direct coupling of molecular tilt to applied field. The pretransitional behavior of the electroclinic effect in the $A$ phase is used to study the critical behavior near the second-order, smectic-$A$---smectic-$C$ phase transition. This behavior is measured by monitoring the change in birefringence of a sample as the electroclinic effect causes a tilt of the molecules. A large pretransitional effect is measured, and constants describing the critical behavior are determined.
Self-force approach to synchrotron radiation

We analyze radiation reaction for synchrotron radiation by computing, via a multipole expansion, the near field and derive from it the Lorentz four-force, which we evaluate on the world-line of the charge. We find that the temporal component of the self four-force agrees with the radiated power, which one calculates in the radiation zone. This is the case for each mode in the multipole decomposition. We also find agreement with the Abraham–Lorentz–Dirac equation.
Clinical experience with CT colonography

Since the introduction of Computed Tomographic Colonography (CTC) in 1995, many advances in computer equipment and software have become available. Despite these advances, the promise of colon cancer prevention has not been realized. A colorectal screening tool that performs at a high level, is acceptable to patients, and can be performed safely and at low cost holds promise of saving lives in the future. Our institution has performed over two hundred seventy five clinical CTC examinations. These scans, which each entail a supine and a prone acquisition, only differ from our research protocol in the necessity of an expeditious interpretation. Patients arrive for their CTC examination early in the morning following a period of fasting and bowel preparation. If a CTC examination has a positive finding, the patient is scheduled for colonoscopic polypectomy that same morning. To facilitate this, the patients are required to continue fasting until the CTC examination has been interpreted. It is therefore necessary to process the CTC examination very quickly to minimize patient discomfort. A positive CTC result occurred in fifteen percent of examinations. Among these positive results, the specificity has been in excess of ninety five percent. Additionally, life threatening extra-colonic lesions were discovered in two percent of the screened population.
Specific binding of lacosamide to collapsin response mediator protein 2 (CRMP2) and direct impairment of its canonical function: implications for the therapeutic potential of lacosamide

The novel antiepileptic drug lacosamide (LCM; SPM927, Vimpat®) has been heralded as having a dual-mode of action through interactions with both the voltage-gated sodium channel and the neurite outgrowth-promoting collapsin response mediator protein 2 (CRMP2). Lacosamide’s ability to dampen neuronal excitability through the voltage-gated sodium channel likely underlies its efficacy in attenuating the symptoms of epilepsy (i.e., seizures). While the role of CRMP2 in epilepsy has not been well studied, given the proposed involvement of circuit reorganization in epileptogenesis, the ability of lacosamide to alter CRMP2 function may prove disease modifying. Recently, however, the validity of lacosamide’s interaction with CRMP2 has come under scrutiny. In this review, we address the contradictory reports concerning the binding of lacosamide to CRMP2 as well as the ability of lacosamide to directly impact CRMP2 function. Additionally, we address similarly the contradicting reports regarding the potential disease-modifying effect of lacosamide on the development and progression of epilepsy. As the vast majority of antiepileptic drugs influences only the symptoms of epilepsy, the ability to hinder disease progression would be a major breakthrough in efforts to cure or prevent this debilitating syndrome.
Viscous dissipation effect on solidification of a liquid onto a tube wall

The effect of viscous dissipation on solidification onto the inner surface of a straight circular tube of a liquid flowing laminarly with a specified volumetric rate is analytically determined. Steady conditions and a constant tube wall temperature below the solidification temperature of the liquid are assumed. Solutions for the thickness of the solidified shell and for the pressure drop are obtained. The pressure gradient versus volumetric flow rate curve exhibits a minimum, suggesting that it might be possible to design runners for injection molding machines to have a minimum pressure drop if the volumetric flow rate is specified.
Fuel-Optimal Periodic Control and Regulation in Constrained Hypersonic Flight

Acceleration-constrained hypersonice ight isexamined in thecontextofoptimalperiodiccontroland regulation. Fuel-optimalperiodictrajectoriesarefoundthatyieldan11%improvementoverthebeststaticcruisesolution,with a maximum vehicle acceleration of 5 g. These optimal periodic trajectories were implemented using a periodic regulator in feedback form, which minimized the second variation of the cost. This regulator was extended to account for a slowly varying system parameter (such as vehicle mass ) and was shown to perform strikingly well in the constrained hypersonic cruise problem.
Jordan-Brans-Dicke stochastic inflation

Abstract We study stochastic inflation in the presence of a dynamical gravitational constant. We describe the Arnowitt-Deser-Misner formalism for Jordan-Brans-Dicke theory of gravity with an inflaton field. The inflaton and dilaton scalar fields can be separated into course-grained background fields and quantum fluctuations. We compute the amplitude of the perturbations generated by those quantum fluctuations in JBD theory with an arbitrary potential for the inflaton field. The effect of the quantum fluctuations on the background fields is equivalent to a Brownian motion of the scalar fields, which can be described with the use of a Fokker-Planck diffusion equation. The probability to find a given value of the fields in the comoving frame can be written as a Gaussian distribution centered on their classical trajectory, with decreasing dispersion along both field directions. We also calculate the condition for the Universe to enter a self-regenerating inflationary phase. The probability distribution in the physical frame, which takes into account the expansion of the proper volume of the inflationary domains, will be concentrated at the Planck boundary and will move along it towards large values of the fields.
Topological orbifold models and quantum cohomology rings

We discuss the topological sigma model on an orbifold target space. We describe the moduli space of classical minima for computing correlation functions involving twisted operators, and show, through a detailed computation of an orbifold ofCP1 by the dihedral groupD4, how to compute the complete ring of observables. Through this procedure, we compute all the rings of dihedralCP1 orbifolds. We then considerCP2/D4, and show how the techniques of topologicalanti-topological fusion might be used to compute twist field correlation functions for nonabelian orbifolds.
Depth buffer compression for stochastic motion blur rasterization

Previous depth buffer compression schemes are tuned for compressing depths values generated when rasterizing static triangles. They provide generous bandwidth usage savings, and are of great importance to graphics processors. However, stochastic rasterization for motion blur and depth of field is becoming a reality even for real-time graphics, and previous depth buffer compression algorithms fail to compress such buffers due to the irregularity of the positions and depths of the rendered samples. Therefore, we present a new algorithm that targets compression of scenes rendered with stochastic motion blur rasterization. If possible, our algorithm fits a single time-dependent predictor function for all the samples in a tile. However, sometimes the depths are localized in more than one layer, and we therefore apply a clustering algorithm to split the tile of samples into two layers. One time-dependent predictor function is then created per layer. The residuals between the predictor and the actual depths are then stored as delta corrections. For scenes with moderate motion, our algorithm can compress down to 65% compared to 75% for the previously best algorithm for stochastic buffers.
4D structure from motion: a computational algorithm

A problem of long standing in vision research is the recovery of three-dimensional (3D) structure from two-dimensional (2D) images. Work on structure from motion has focused on the recovery of 3D structure from multiple views of feature points like the vertices of a cube. Recent work on the perception of four-dimensional (4D) structures has prompted us to determine the circumstances under which 4D structure can be recovered from multiple views of feature points projected onto 2D images. We present a computational algorithm to solve this problem under three assumptions: 1. the correspondence of each feature point over different views is pre-determined; 2. the 4D object undergoes a rigid motion, and 3. the projection from 4D space to 2D images is a orthographic (parallel) one. Four views of five points are required. The algorithm can be generalized to treat the recovery of nD structure from mD views (1≤m≤n). We give some results concerning the minimum number of points and views that are required to recover nD structure from mD views by this algorithm.
On certain geometric properties of the Yao---Yao graphs

We show that, for any constant $$\rho > 1$$ , there exists an integer constant $$k$$ such that the Yao---Yao graph with parameter $$k$$ defined on a civilized unit disk graph is a geometric spanner of stretch factor $$\rho $$ . This improves the results of Wang and Li in several aspects, as described in the paper. This partially answers an open problem posed by Demaine, Mitchell and O'Rourke about the spanner properties of Yao---Yao graphs. We also show that the Yao---Yao graph with parameter $$k=4$$ defined on the complete Euclidean graph is not plane.
Anticipation of Future Consumption: A Monetary Perspective

We adapt the monetary model (Sidrauski 1967) to study the hypothesis of anticipation of future consumption. We assume that anticipation of future consumption affects an agent’s instantaneous utility and that all effects of future consumption on current well-being are captured by the stock of future consumption. Monetary policy effectiveness is thereby reduced and a zero nominal lower interest rate (and thus the Friedman rule) is destabilizing. Given this, we can derive a “just stable” equilibrium nominal interest rate with matching definitions for inflation and monetary growth. We demonstrate that these implied lower bounds match their historical analogues well.
Vehicular Gas Turbine Periodic-Flow Heat Exchanger Solid and Fluid Temperature Distributions

Design, fabrication and operation experience with periodic-flow heat exchangers used in General Motors regenerative vehicular gas turbines has indicated that analysis techniques available in published reports are too restrictive for accurate performance and thermal-distortion calculations. The design usefulness of previously published anaylses is somewhat limited because fluid and metal-temperature distributions are not part of the calculated results. These distributions are required for primary seal matching and core and structural thermal-stress calculations. A nodal analysis has been accomplished at the General Motors Research Laboratories and a type of finite-difference solution obtained for the periodic-flow heat exchanger. This solution can be used to study the effects of longitudinal thermal conduction, variable heat-transfer coefficients, finite rotation, and provides temperature distributions as functions of time and space for transient as well as “steady state.” This has been checked both with available solutions for more simplified cases and some experimental measured results for periodic-flow heat exchangers designed and built as part of the General Motors vehicular regenerative gas-turbine program. A brief outline of the calculation procedures, program capabilities, and some calculated results are presented. This includes temperature distributions for periodic-flow heat exchanger parameters encountered in the vehicular regenerator application.© 1963 ASME
Why does the quark–gluon plasma at RHIC behave as a nearly ideal fluid?

Abstract This article gives a brief review in the following areas. (i) Collective flow phenomena in heavy ion collisions. The data from RHIC indicate robust collective flows, well described by hydrodynamics with the expected equation of state. The transport properties turned out to be unexpected, with very small viscosity. (ii) The physics of highly excited matter produced in heavy ion collisions at T c T T c , different from that of weakly coupled quark–gluon plasma because of the relatively strong coupling generating bound states of quasiparticles. (iii) Wider discussion of other “strongly coupled systems”, including strongly coupled supersymmetric theories studied via Maldacena duality, as well as recent progress as regards trapped atoms with very large scattering lengths.
On The Origin Of High Energy Correlations in Gamma-ray Bursts

I investigate the origin of the observed correlation between a gamma-ray burst's (GRB's) νF ν spectral peak E pk and its isotropic equivalent energy E iso through the use of a population synthesis code to model the prompt gamma-ray emission from GRBs. By using prescriptions for the distribution of prompt spectral parameters as well as the population's luminosity function and comoving rate density, I generate a simulated population of GRBs and examine how bursts of varying spectral properties and redshift would appear to a gamma-ray detector here on Earth. I find that a strong observed correlation can be produced between the source frame E pk and E iso for the detected population despite the existence of only a weak and broad correlation in the original simulated population. The energy dependance of a gamma-ray detector's flux-limited detection threshold acts to produce a correlation between the source frame E pk and E iso for low-luminosity GRBs, producing the left boundary of the observed correlation. Conversely, very luminous GRBs are found at higher redshifts than their low-luminosity counterparts due to the standard Malquest bias, causing bursts in the low E pk, high E iso regime to go undetected because their E pk values would be redshifted to energies at which most gamma-ray detectors become less sensitive. I argue that it is this previously unexamined effect which produces the right boundary of the observed correlation. Therefore, the origin of the observed correlation is a complex combination of the instrument's detection threshold, the intrinsic cutoff in the GRB luminosity function, and the broad range of redshifts over which GRBs are detected. Although the GRB model presented here is a very simplified representation of the complex nature of GRBs, these simulations serve to demonstrate how selection effects caused by a combination of instrumental sensitivity and the cosmological nature of an astrophysical population can act to produce an artificially strong correlation between observed properties.
Power spectrum estimators for large CMB datasets

Forthcoming high-resolution observations of the cosmic microwave background radiation will generate data sets many orders of magnitude larger than have been obtained to date. The size and complexity of such data sets present a very serious challenge to analyzing them with existing or anticipated computers. Here we present an investigation of the currently favored algorithm for obtaining the power spectrum from a sky-temperature map{emdash}the quadratic estimator. We show that, while improving on a direct evaluation of the likelihood function, current implementations still inherently scale as the equivalent of O(N{sub p}{sup 3}) in the number of pixels or worse, and demonstrate the critical importance of choosing the right implementation for a particular data set. {copyright} {ital 1998} {ital The American Physical Society}
Iridium-catalyzed kinetic asymmetric transformations of racemic allylic benzoates.

Versatile methods for iridium-catalyzed, kinetic asymmetric substitution of racemic, branched allylic esters are reported. These reactions occur with a variety of aliphatic, aryl, and heteroaryl allylic benzoates to form the corresponding allylic substitution products in high yields (74−96%) with good to excellent enantioselectivity (84−98% ee) with a scope that encompasses a range of anionic carbon and heteroatom nucleophiles. These kinetic asymmetric processes occur with distinct stereochemical courses for racemic aliphatic and aromatic allylic benzoates, and the high reactivity of branched allylic benzoates enables enantioselective allylic substitutions that are slow or poorly selective with linear allylic electrophiles.
A D-moduli problem?

Abstract We point out a generic problem in string-inspired supergravity models with an anomalous U (1) X . A large number of matter multiplets charged under U (1) X remain massless above the supersymmetry-breaking scale because of degeneracy of vacua solving the D-flatness conditions. A toy model is analyzed as an illustration of the mechanism; we find the surprising result that many scalars remain massless after supersymmetry-breaking in a hidden sector.
Energy conservation in new housing design

Publisher Summary This chapter discusses the potential implications of energy cost and availability for new housing design over the balance of the century. A primary incentive for increasing the thermal efficiency design of new housing at present is the increasing cost of energy. However, this is not the only factor stimulating energy consciousness in housing design. The more or less regular recurrence of brownouts in some large cities since 1970, the subsequent unavailability of natural gas to new residential customers in many parts of the country, and finally the Arab oil embargo of November 1973, all served to place in focus the vulnerability of the United States to an energy shortage and changing and uncertain patterns of future fuels availability. Existing housing and new construction data presented by the Federal Energy Administration (FEA) in its Project Independence Report show several important trends. The preceding analyses have demonstrated that rising energy prices and the potentials for increased energy conservation are powerful forces influencing change in housing design practices to follow the dictates of life-cycle performance optimization.
Long-term trends in radiation damage of Chandra x-ray CCDs

Soon after launch, the Advanced CCD Imaging Spectrometer (ACIS), one of the focal plane instruments on the Chandra X-ray Observatory, suffered radiation damage from exposure to soft protons during passages through the Earth's radiation belts. Current operations require ACIS to be protected during radiation belt passages to prevent this type of damage, but there remains a much slower and more gradual increase. We present the history of ACIS charge transfer inefficiency (CTI), and other measures of radiation damage, from January 2000 through June 2005. The rate of CTI increase is low, of order 1e-6 per year, with no indication of step-function increases due to specific solar events. Based on the time history and CCD location of the CTI increase, we speculate on the nature of the damaging particles.
An Approach to Reducing Annotation Costs for BioNLP

There is a broad range of BioNLP tasks for which active learning (AL) can significantly reduce annotation costs and a specific AL algorithm we have developed is particularly effective in reducing annotation costs for these tasks. We have previously developed an AL algorithm called ClosestInitPA that works best with tasks that have the following characteristics: redundancy in training material, burdensome annotation costs, Support Vector Machines (SVMs) work well for the task, and imbalanced datasets (i.e. when set up as a binary classification problem, one class is substantially rarer than the other). Many BioNLP tasks have these characteristics and thus our AL algorithm is a natural approach to apply to BioNLP tasks.
Copper-catalyzed arylation and alkenylation of polyfluoroarene C-H bonds.

An efficient, copper-catalyzed method for the arylation, alkenylation, and benzylation of polyfluoroarenes has been developed. Arenes containing two or more fluorine substituents on the aromatic ring can be efficiently functionalized. The best results are obtained by using a combination of copper iodide catalyst, phenanthroline ligand, aryl bromide or aryl iodide coupling partner, and DMF or DMF/xylene mixed solvent.
A contact process with mutations on a tree

Abstract Consider the following stochastic model for immune response. Each pathogen gives birth to a new pathogen at rate λ . When a new pathogen is born, it has the same type as its parent with probability 1 − r . With probability r , a mutation occurs, and the new pathogen has a different type from all previously observed pathogens. When a new type appears in the population, it survives for an exponential amount of time with mean 1, independently of all the other types. All pathogens of that type are killed simultaneously. Schinazi and Schweinsberg [R.B. Schinazi, J. Schweinsberg, Spatial and non-spatial stochastic models for immune response, Markov Process. Related Fields (2006) (in press)] have shown that this model on Z d behaves rather differently from its non-spatial version. In this paper, we show that this model on a homogeneous tree captures features from both the non-spatial version and the Z d version. We also obtain comparison results, between this model and the basic contact process on general graphs.
A NOTE ON COMPARING DEEP AND AGGREGATE HABIT FORMATION IN AN ESTIMATED NEW KEYNESIAN MODEL

Habit formation is a fixture of contemporary new Keynesian models. The vast majority assume that agents form habits strictly over consumption of an aggregate good, leaving open the question of whether it might be preferable to have them form habits over differentiated products insteadâ€“an arrangement known as deep habits. I answer this question by estimating a model that nests both habit concepts as special cases. Estimates reveal that the data favor a specification in which consumption habits are stronger at the product level than at the aggregate level. A mix of significance tests and simulation results indicate that including deep habits greatly improves model fit, most notably with regard to inflation dynamics.
Introducing EOR technology to independent operators

This paper describes how the authors stimulated application of permeability-modification techniques by independent oil operators through effective technology transfer. As of Spring 1987, they had worked with operators on 21 gelled-polymer field treatments. Three of the projects are described to illustrate the technology and the program.
Multiplexed and Programmable Regulation of Gene Networks with an Integrated RNA and CRISPR/Cas Toolkit in Human Cells

RNA-based regulation and CRISPR/Cas transcription factors (CRISPR-TFs) have the potential to be integrated for the tunable modulation of gene networks. A major limitation of this methodology is that guide RNAs (gRNAs) for CRISPR-TFs can only be expressed from RNA polymerase III promoters in human cells, limiting their use for conditional gene regulation. We present new strategies that enable expression of functional gRNAs from RNA polymerase II promoters and multiplexed production of proteins and gRNAs from a single transcript in human cells. We use multiple RNA regulatory strategies, including RNA-triple-helix structures, introns, microRNAs, and ribozymes, with Cas9-based CRISPR-TFs and Cas6/Csy4-based RNA processing. Using these tools, we efficiently modulate endogenous promoters and implement tunable synthetic circuits, including multistage cascades and RNA-dependent networks that can be rewired with Csy4 to achieve complex behaviors. This toolkit can be used for programming scalable gene circuits and perturbing endogenous networks for biology, therapeutic, and synthetic biology applications.
A New Band System in Nitrogen

I HAVE recently directed attention in a letter which has been sent to the Physical Review for publication to some new nitrogen bands. Three of these bands degrading to the violet and having wave lengths 2536, 2635 and 2740 A., have been found to increase in intensity as the pressure is lowered. This is true also of the new Appleyard-van der Ziel bands recently discussed by van der Ziel, and of the new system that is reported by me in the above-mentioned letter. The three bands have been identified as (0, 1), (0, 2) and (0, 3) bands of a new system, and their frequency differences agree well with those of the lower electronic state of the Appleyard-van der Ziel bands.
Stratospheric water vapor

We present a tutorial review of our understanding of stratospheric H2O and the processes controlling it. We attempt to synthesize a consistent global picture that requires rejection of a minimum of the conflicting observational data. As such, this synthesis is determined somewhat by the personal opinions and beliefs of the author. We note the paradoxes posed by currently available observational data and suggest ways they might be resolved. Resolution of the stratospheric H2O budget appears to require (1) either that the bulk of our current data provides unrepresentative and misleading latitudinal H2O gradients immediately downstream from the presumed tropical tropopause source of H2O or that there are unidentified polar stratospheric sinks for H2O; (2) that it also provides an unrepresentative vertical gradient in H2O immediately above the tropical tropopause source or that there is a stratospheric sink for H2O in this region; or (3) that there exist within the troposphere a mechanism different from or in addition to the tropical tropopause ‘cold trap’ for drying air to the mixing ratios found in the lower stratosphere. Satisfaction of conditions such as these are required to reconcile a rather large mass of puzzling observational data. Satisfaction of the third option would also permit tropospheric to stratospheric exchange through the mid-latitude tropopause gaps, a path suggested by minima in O3 profiles.
Statistical properties of the spectrum of the QCD Dirac operator at low energy

Abstract We analyze the statistical properties of the spectrum of the QCD Dirac operator at low energy in a finite box of volume L 4 by means of partially quenched Chiral Perturbation Theory, a low-energy effective field theory based on the symmetries of QCD. We derive the two-point spectral correlation function from the discontinuity of the chiral susceptibility. For eigenvalues much smaller than m c = F 2 / ΣL 2 , where F is the pion decay constant and Σ is the absolute value of the quark condensate, our result for the two-point correlation function coincides with the result previously obtained from chiral Random Matrix Theory (chRMT). The departure from the chRMT result above that scale is due to the contribution of the nonzero momentum modes. In terms of the variance of the number of eigenvalues in an interval containing n eigenvalues on average, it amounts to a crossover from a log n -behavior to a n 2 log n -behavior.
David R. Wones 1932–1984

On Thursday afternoon, October 25, 1984, Dr. David R. Wones, age 52, Professor at Virginia Polytechnic Institute and State University, Fellow of the American Geophysical Union and Secretary of the Volcanology, Geochemistry, and Petrology section 1961–1964, died in an automobile accident in Roanoke, Va. The ultimate cause of this accident is unknown. Dave gave of himself to mineralogy and petrology—in fact, to all of geology and to many colleagues—in a way few can match but that many have experienced and can appreciate.
Future directions in program transformations

As the emphasis of Programming Languages has evolved from computing on numbers to computing on programs, the area of program transformations has naturally gained in importance. This paper briefly surveys what transformational programming is about, and how to make progress in the field.
Two loop effective potential calculation of the lightest CP even Higgs boson mass in the MSSM

Abstract We calculate a two-loop effective potential to the order of O (λ t 2 α s ) in the MSSM. We then study the corresponding two-loop corrections to the CP -even Higgs-boson mass for arbitrary tan β and left-right top-squark mixings. We find that the lightest Higgs-boson mass is changed by at most a few GeV. We also show the improved scale dependence and compare to previous two-loop analyses.
Fractal growth processes

The methods of fractal geometry allow the classification of non-equilibrium growth processes according to their scaling properties. This classification and computer simulations give insight into a great variety of complex structures.
Effect of ion—electrode contact on the energetics of the heterogeneous electron transfer

Abstract Using molecular dynamics computer simulation technique we studied the effect of the ion—electrode contact on the energetics of electron transfer reactions. We observed that when the solvation shell of the ion undergoes large changes due to the ion transfer from the bulk to the interface, the energetics of the reaction at the interface differs substantially from the energetics of the reaction in bulk.
Distributed information systems

Distributed information systems represent an increasingly important trend to computer users. Distributed processing is a technique for implementing a single logical set of processing functions across a number of physical devices, so that each performs some part of the total processing required. Distributed processing is often accompanied by the formation of a distributed database. A distributed database exists when the data elements stored at multiple locations are interrelated, or if a process (program execution) at one location requires access to data stored at another location. Examples of how these techniques are being used are provided, with comments on the advantages and disadvantages of the distribution of processing and databases in the current state-of-the-art.
On scalable attack detection in the network

Current intrusion detection and prevention systems seek to detect a wide class of network intrusions (e.g., DoS attacks, worms, port scans) at network vantage points. Unfortunately, even today, many IDS systems we know of keep per-connection or per-flow state to detect malicious TCP flows. Thus, it is hardly surprising that these IDS systems have not scaled to multi-gigabit speeds. By contrast, both router lookups and fair queuing have scaled to high speeds using aggregation via prefix lookups or DiffServ. Thus, in this paper, we initiate research into the question as to whether one can detect attacks without keeping per-flow state. We will show that such aggregation, while making fast implementations possible, immediately causes two problems. First, aggregation can cause behavioral aliasing where, for example, good behaviors can aggregate to look like bad behaviors. Second, aggregated schemes are susceptible to spoofing by which the intruder sends attacks that have appropriate aggregate behavior. We examine a wide variety of DoS and scanning attacks and show that several categories (bandwidth based, claim-and-hold, port-scanning) can be scalably detected. In addition to existing approaches for scalable attack detection, we propose a novel data structure called partial completion filters (PCFs) that can detect claim-and-hold attacks scalably in the network. We analyze PCFs both analytically and using experiments on real network traces to demonstrate how we can tune PCFs to achieve extremely low false positive and false negative probabilities
Modeling the Very Small-Scale Clustering of Luminous Red Galaxies

We model the small-scale clustering of luminous red galaxies (LRGs) in the Sloan Digital Sky Survey. Specifically, we use the halo occupation distribution formalism to model the projected two-point correlation function of LRGs on scales well within the sizes of their host halos (0.016 h –1 Mpc ≤ r ≤ 0.42 h –1 Mpc). We start by varying P(N|M), the probability distribution that a dark matter halo of mass M contains N LRGs, and assuming that the radial distribution of satellite LRGs within halos traces the Navarro-Frenk-White (NFW) dark matter density profile. We find that varying P(N|M) alone is not sufficient to match the small-scale data. We next allow the concentration of satellite LRG galaxies to differ from that of dark matter and find that this is also not sufficient. Finally, we relax the assumption of an NFW profile and allow the inner slope of the density profile to vary. We find that this model provides a good fit to the data and the resulting value of the slope is –2.17 ± 0.12. The radial density profile of satellite LRGs within halos is thus not compatible with that of the underlying dark matter, but rather is closer to an isothermal distribution.
An Improved Method of Chlorinating 2-alkoxynicotinic Acids

Abstract A novel chlorination process for preparing 5-chloro-2-alkoxynicotinic acids has been developed using commercial 5.25% sodium hypochlorite (Clorox®) as a chlorinating agent.
The emerging forum for business policy scholars

Abstract This study is a follow-up on three others, published in Strategic Management Journal, 1987, 1989, and 1991. A sample of tenured business policy scholars, with significant track records in publishing, rated key management journals with respect to their appropriateness as outlets for scholarly research in the business policy field. The results of the survey are reported.
ASSESSING QUANTITATIVE RESULTS IN ACCRETION SIMULATIONS: FROM LOCAL TO GLOBAL

Discretized numerical simulations are a powerful tool for the investigation of nonlinear MHD turbulence in accretion disks. However, confidence in their quantitative predictions requires a demonstration that further refinement of the spatial grid scale would not result in any significant change. This has yet to be accomplished, particularly for global disk simulations. In this paper, we combine data from previously published stratified shearing box simulations and new global disk simulations to calibrate several quantitative diagnostics by which one can estimate progress toward numerical convergence of the magnetic field. Using these diagnostics, we find that the established criterion for an adequate numerical description of linear growth of the magneto-rotational instability (the number of cells across a wavelength of the fastest-growing vertical wavenumber mode) can be extended to a criterion for the adequate description of nonlinear MHD disk turbulence, but the standard required is more stringent. We also find that azimuthal resolution, which has received little attention in previous studies, can significantly affect the evolution of the poloidal magnetic field. We further analyze the comparative resolution requirements of a small sample of initial magnetic field geometries; not surprisingly, more complicated initial field geometries require higher spatial resolution. Otherwise, they tend to evolve to qualitatively similar states if evolved for sufficient time. Applying our quantitative resolution criteria to a sample of previously published global simulations, we find that, with perhaps a single exception, they are significantly underresolved, and therefore underestimate the magnetic turbulence and resulting stress levels throughout the accretion flow.
A Study of 13 Powerful Classical Double Radio Galaxies

We have carried out an extensive study of a sample of 13 large, powerful Fanaroff-Riley type II radio galaxies with the Very Large Array in multiple configurations at 330 MHz and 1.4, 5, and 8 GHz. We present the total intensity, polarization, spectral index, and rotation measure maps of the sources. On the whole, the 13 FR II sources have symmetric structures with arm-length ratios close to unity, small misalignment angles, and low values of radio core prominence, suggesting that these radio galaxies lie close to the plane of the sky. We have revisited some well-known radio galaxy correlations using a large combined data set comprising our radio galaxies and others from the literature. We confirm that the hot spot size correlates with the core-hot spot distance. The hot spot spectral index is correlated with and flatter than the lobe spectral index, consistent with the assumptions of spectral aging models. Both the hot spot and lobe spectral index are correlated with redshift. The depolarization asymmetry in the lobes is not correlated with the radio core prominence or misalignment angle, which are statistical indicators of orientation. The 'Liu-Pooley' correlation of lobe depolarization with the lobe spectral index is significant in ourmore » radio galaxy sample. Furthermore, the lobe with the steeper spectral index and greater depolarization is shorter and fatter. The arm-length ratio seems to be correlated with the misalignment angle between the two sides of the radio source and strongly anticorrelated with the axial ratio, consistent with environmental effects and/or a change in the outflow direction. In this sample, asymmetries in the local environments and/or motion of the outflow axis are likely to be more important than relativistic beaming effects.« less
Sharp Lorentz space estimates for rough operators

We demonstrate the $(H^1,L^{1,2})$ or $(L^p,L^{p,2})$ mapping properties of several rough operators. In all cases these estimates are sharp in the sense that the Lorentz exponent 2 cannot be replaced by any lower number.
Microtube gas flows with second-order slip flow and temperature jump boundary conditions

Abstract Second-order slip flow and temperature jump boundary conditions are applied to solve the momentum and energy equations in a microtube for an isoflux thermal boundary condition. The flow is assumed to be hydrodynamically fully developed, and the thermal field is either fully developed or developing from the tube entrance. In general, second-order boundary conditions assuming an effective mean free path model predict a lower slip velocity than a first-order model assuming a hard sphere mean free path model. Heat transfer effects associated with rarefied flow are reduced for the second-order model. The effect of the second-order terms is most significant at the upper limit of the slip regime. For airflow at standard conditions, the maximum second-order change to the Nusselt number is on the order of 15%. The second-order effect is also more significant in the entrance region of the tube. Nusselt numbers are found to increase relative to their no-slip values when temperature jump effects are small. In cases where slip and temperature jump effects are of the same order, or where temperature jump effects dominate, the Nusselt number decreases when compared to traditional no-slip conditions.
Efficient, Single-Step Access to Imidazo[1,5-a]pyridine N-Heterocyclic Carbene Precursors

The three-component coupling reaction of substituted picolinaldehydes, amines, and formaldehyde to produce imidazo[1,5-a]pyridinium ions is reported, providing an efficient method for the preparation of N-heterocyclic carbenes (NHCs). Reactions proceed in high yields under mild conditions, allowing the incorporation of diverse functionality and chiral substituents. Higher order condensations are also described that provide access to multidentate NHC ligands useful for a variety of applications.
Constructing quantum vertex algebras

This is a sequel to [23]. In this paper, we focus on the construction of quantum vertex algebras over ℂ, whose notion was formulated in [23] with Etingof and Kazhdan's notion of quantum vertex operator algebra (over ℂ[[h]]) as one of the main motivations. As one of the main steps in constructing quantum vertex algebras, we prove that every countable-dimensional nonlocal (namely, noncommutative) vertex algebra over ℂ, which either is irreducible or has a basis of PBW type, is nondegenerate in the sense of Etingof and Kazhdan. Using this result, we establish the nondegeneracy of better known vertex operator algebras and some newly constructed nonlocal vertex algebras. We construct a family of quantum vertex algebras closely related to Zamolodchikov–Faddeev algebras.
Electron heating and static sheath enhancement in front of energized RF antennas

Abstract An analytic model has been developed to describe the increased plasma potential and acceleration of ions in the vicinity of an ICRF Faraday shield. This model gives an estimate for the electron distribution function using a heating model for electromotive fields with decorrelation caused by reflection of the electrons from the static sheath at the point where a magnetic field line intersects a grounded wall. The loss rate of the electrons from the system can be calculated from this distribution function. The expected static potential is then estimated by equating electron and ion loss rates, assuming either that the ion loss satisfies the Bohm sheath criterion or that ion gyro-orbits strike a nearby wall. The analytic model for the electrons is in good agreement with a Monte Carlo model using realistic values of the RF electric fields. These RF near-field values have been calculated, including the linear near-field plasma response and the Faraday shield. Results include the findings that a linear model for the RF plasma response is valid for typical experimental parameters and that plasma currents must be included in the RF near-field calculation. It is also found that the static potential is sufficiently increased by electron heating so that it could easily cause impurities to be generated from the antenna structure. Results of the expected static potential are given for various ion species.
Phenomenological model for cross-linked polymer blends

What is the distinction between the patterns made by quenched block copolymer melts and quenched cross-linked polymer blends? If we observe thin films under the condition without flow, it is unlikely that we can distinguish them in critical quench experiments. However, off-critical quenches and moving boundary conditions could exhibit a marked distinction. Such a conclusion is reached with a simple mathematical model of cross-linked polymer blends.