cssi/SciSciGPT-SciSciNet huggingface dataset:
Displaced Capital: A Study of Aerospace Plant Closings

Using equipment‐level data from aerospace plants that closed during the 1990s, this paper studies the process of moving installed physical capital to a new use. The analysis yields three results that suggest significant sectoral specificity of physical capital and substantial costs of redeploying the capital. First, other aerospace companies are overrepresented among buyers of the used capital relative to their representation in the market for new investment goods. Second, even after age‐related depreciation is taken into account, capital sells for a substantial discount relative to replacement cost; the more specialized the type of capital, the greater the discount. Yet, capital sold to other aerospace firms fetches a higher price than capital sold to industry outsiders. Finally, the process of winding down operations and selling the equipment takes several years.
Wave propagation of exciton-polaritons by a wave vector space method

The optical transmission/reflection near a Frenkel exciton resonance [additional boundary condition (ABC) problem] is reexamined by a new A-space method that uses no boundary conditions. The macroscopic nonlocal susceptibility is shown to include surface terms. We obtain a different solution to the problem and derive the ABC needed for a macroscopic real space approach
Atmospheric inversion strength over polar oceans in winter regulated by sea ice

Low-level temperature inversions are a common feature of the wintertime troposphere in the Arctic and Antarctic. Inversion strength plays an important role in regulating atmospheric processes including air pollution, ozone destruction, cloud formation, and negative longwave feedback mechanisms that shape polar climate response to anthropogenic forcing. The Atmospheric Infrared Sounder (AIRS) instrument provides reliable measures of spatial patterns in mean wintertime inversion strength when compared with available radiosonde observations and reanalysis products. Here, we examine the influence of sea ice concentration on inversion strength in the Arctic and Antarctic. Correlation of inversion strength with mean annual sea ice concentration, likely a surrogate for the effective thermal conductivity of the wintertime ice pack, yields strong, linear relationships in the Arctic (r = 0.88) and Antarctic (r = 0.86). We find a substantially greater (stronger) linear relationship between sea ice concentration and surface air temperature than with temperature at 850 hPa, lending credence to the idea that sea ice controls inversion strength through modulation of surface heat fluxes. As such, declines in sea ice in either hemisphere may imply weaker mean inversions in the future. Comparison of mean inversion strength in AIRS and global climate models (GCMs) suggests that many GCMs poorly characterize mean inversion strength at high latitudes.
Lessons for asteroseismology from white dwarf stars

The interpretation of pulsation data for sun-like stars is currently facing challenges quite similar to those faced by white dwarf modelers ten years ago. The observational requirements for uninterrupted long-term monitoring are beginning to be satisfied by successful multi-site campaigns and dedicated satellite missions. But exploration of the most important physical parameters in theoretical models has been fairly limited, making it difficult to establish a detailed best-fit model for a particular set of oscillation frequencies. I review the past development and the current state of white dwarf asteroseismology, with an emphasis on what this can tell us about the road to success for asteroseismology of other types of stars.
The vinylcyclopropane moiety as an efficient intramolecular trap for carbocations. A high yield process for the formation of eleven-membered carbocyclic structures

Abstract Eleven-membered carbocyclic structures can be generated in high yield by the intramolecular trapping of an allyl cation by a vinylcyclopropane moiety.
Catalytic Enantioselective Hetero-Diels-Alder Reactions of an Azo Compound

This communication describes studies in which an azo hetero-Diels−Alder adduct was furnished in high regio- and enantioselectivity using azopyridine as a reagent and silver as a catalyst. The obtained hetero-Diels−Alder adduct was easily converted to the corresponding chiral 1,4-diamino alcohol.
Simultaneous stabilization and simultaneous pole-placement by nonswitching dynamic compensation

In this paper, motivated by questions in fault tolerance, we investigate the existence of a compensator which simultaneously renders a given r-tuple of plants internally stable. Sufficient conditions are derived for simultaneous pole-assignability of the generic r-tuple by dynamic output feedback, which are also shown to be necessary (and equivalent to generic stabilizability) in the case where the number of either input or output channels is one. We also derive an upper bound on the order of a simultaneous pole-assigning compensator. If r = l, this reduces to the condition derived by Brasch and Pearson, while if r = 2, this contains the recent theorem by Vidyasagar and Viswanadham. The cases r ≤ 3 are new.
Resistance anomaly in disordered superconducting films

The authors report on a resistance anomaly in disordered superconducting films containing arrays of irregularly distributed nanoscale holes. At high driving currents, peaks appear in the resistance as a function of temperature, with peak values up to 2% above the classic normal-state resistance. The authors attribute the observed resistance anomaly to dissipation-induced granularity which enhances the contributions from fluctuation-induced reduction of the density of states of the quasiparticles. The granular feature of a disordered superconducting film originates from the inhomogeneous temperature distribution caused by the variation of the local dissipation and/or heat transfer.
Rearranging Residual Claims: A Case for Targeted Stock

This paper describes and analyzes a relatively new method of equity-based restructuring, Targeted Stock. We examine announcement period share price reactions for completed, pending , and canceled offerings. Although the total number of completed transactions to date is small, we document a positive share price reaction on average for this form of equity reorganization, likely due to the greater transparency of particular business segments of a broadly diversified firm and to the increased ability to reward division managers for their specific contributions. We also compare and contrast Targeted Stock with alternative equity reorganization forms. Targeted Stock is most useful for firms in which the benefits of integration and control over corporate operating and financing activities outweigh the benefits of a complete or partial separation of the targeted business unit(s).
Abrogation of Antibody-Induced Arthritis in Mice by a Self-Activating Viridin Prodrug and Association With Impaired Neutrophil and Endothelial Cell Function

Objective To test a novel self-activating viridin (SAV) prodrug that slowly releases wortmannin, a potent phosphoinositide 3-kinase inhibitor, in a model of antibody-mediated inflammatory arthritis. Methods The SAV prodrug was administered to K/BxN mice or to C57BL/6 (B6) mice that had been injected with K/BxN serum. Ankle thickness was measured, and histologic changes were scored after a 10-day disease course (serum-transfer arthritis). Protease activity was measured by a near-infrared imaging approach using a cleavable cathepsin–selective probe. Further near-infrared imaging techniques were used to analyze early changes in vascular permeability after serum injection, as well as neutrophil–endothelial cell interactions. Neutrophil functions were assessed using an oxidative burst assay as well as a degranulation assay. Results SAV prevented ankle swelling in mice with serum-transfer arthritis in a dose-dependent manner. It also markedly reduced the extent of other features of arthritis, such as protease activity and histology scores for inflammation and joint erosion. Moreover, SAV was an effective therapeutic agent. The underlying mechanisms for the antiinflammatory activity were manifold. Endothelial permeability after serum injection was reduced, as was firm neutrophil attachment to endothelial cells. Endothelial cell activation by tumor necrosis factor α was impeded by SAV, as measured by the expression of vascular cell adhesion molecule. Crucial neutrophil functions, such as generation of reactive oxygen species and degranulation of protease-laden vesicles, were decreased by SAV administration. Conclusion A novel SAV prodrug proved strongly antiinflammatory in a murine model of antibody-induced inflammatory arthritis. Its activity could be attributed, at least in part, to the inhibition of neutrophil and endothelial cell functions.
Enhanced anti-diastereo- and enantioselectivity in alcohol-mediated carbonyl crotylation using an isolable single component iridium catalyst.

The cyclometalated iridium complex (S)-I derived from [Ir(cod)Cl]2, 4-cyano-3-nitrobenzoic acid, allyl acetate, and (S)-SEGPHOS is conveniently isolated by precipitation or through conventional silica gel flash chromatography. This single-component precatalyst allows alcohol mediated carbonyl crotylations to be performed at significantly lower temperature, resulting in enhanced levels of anti-diastereo- and enantioselectivity. Most significantly, the chromatographically isolated precatalyst (S)-I enables carbonyl crotylations that are not possible under previously reported conditions involving in situ generation of (S)-I.
An X-Ray Spectroscopic Study of the SMC X-1/Sk 160 System

We have investigated the composition and distribution of the wind of Sk 160, the supergiant companion of the X-ray star SMC X-1, by comparing an X-ray spectrum of the source, obtained with the ASCA observatory, during an eclipse with the computed spectra of reprocessed radiation from circumstellar matter with various density distributions. We show that the metal abundance in the wind of Sk 160 is no greater than a few tenths of solar, as has been determined for other objects in the Magellanic Clouds. We also show that the observed X-ray spectrum is not consistent with the density distributions of circumstellar matter of the spherically symmetric form derived for line-driven winds, nor with the density distribution derived from a hydrodynamic simulation of the X-ray perturbed and line-driven wind by Blondin & Woo.
Total synthesis of (+)-α-onocerin in four steps via four-component coupling and tetracyclization steps

A remarkably short (four steps, 31% overall yield) enantioselective synthesis of the structurally unique C2-symmetric tetracyclic triterpene (+)-α-onocerin (1) has been developed. The brevity of this mechanism depends on the assembly of four fragments (two molecules of a chiral epoxy ketone and two molecules of vinyllithium) to generate the chiral bis-epoxide 4 in one step, and on the efficient formation of all four carbocyclic rings in one step by cation−olefin tetracyclization. New and general methodology for the conversion of vinyl tert-butyldimethylsilyl ethers to vinyl triflates with retention of E or Z olefinic geometry also was utilized in the synthesis of 1. A short enantioselective synthesis of a non-C2-symmetric diastereomer of 1 is also described which uses the new methodology.
The Detectability of Transit Depth Variations due to Exoplanetary Oblateness and Spin Precession

Knowledge of an exoplanet's oblateness and obliquity would give clues about its formation and internal structure. In principle, a light curve of a transiting planet bears information about the planet's shape, but previous work has shown that the oblateness-induced signal will be extremely difficult to detect. Here, we investigate the potentially larger signals due to planetary spin precession. The most readily detectable effects are transit depth variations (T{delta}V's) in a sequence of light curves. For a planet as oblate as Jupiter or Saturn, the transit depth will undergo fractional variations of order 1%. The most promising systems are those with orbital periods of approximately 15-30 days, which are short enough for the precession period to be less than about 40 yr and long enough to avoid spin-down due to tidal friction. The detectability of the T{delta}V signal would be enhanced by moons (which would decrease the precession period) or planetary rings (which would increase the amplitude). The Kepler mission should find several planets for which precession-induced T{delta}V signals will be detectable. Due to modeling degeneracies, Kepler photometry would yield only a lower bound on oblateness. The degeneracy could be lifted by observing the oblateness-induced asymmetry in at least one transitmore » light curve or by making assumptions about the planetary interior.« less
The q-PushASEP: A New Integrable Model for Traffic in 1+1 Dimension

We introduce a new interacting (stochastic) particle system $$q$$ -PushASEP which interpolates between the $$q$$ -TASEP of Borodin and Corwin (Probab Theory Relat Fields 158(1–2):225–400, 2014; see also Borodin et al., Ann Probab 42(6):2314–2382, 2014; Borodin and Corwin, Int Math Res Not 2:499–537, 2015; O’Connell and Pei, Electron J Probab 18(95):1–25, 2013; Borodin et al., Comput Math, 2013) and the $$q$$ -PushTASEP introduced recently (Borodin and Petrov, Adv Math, 2013). In the $$q$$ -PushASEP, particles can jump to the left or to the right, and there is a certain partially asymmetric pushing mechanism present. This particle system has a nice interpretation as a model of traffic on a one-lane highway. Using the quantum many body system approach, we explicitly compute the expectations of a large family of observables for this system in terms of nested contour integrals. We also discuss relevant Fredholm determinantal formulas for the distribution of the location of each particle, and connections of the model with a certain two-sided version of Macdonald processes and with the semi-discrete stochastic heat equation.
NEW RADIOHALOGENATED ALKENYL TELLURIUM FATTY ACIDS

Abstract Radiolabeled long-chain fatty acids have diagnostic value as radiopharmaceutical tools in myocardial imaging. Some applications of these fatty acids are limited due to their natural metabolic degradation in vivo with subsequent washout of the radioactivity from the myocardium. The identification of structural features which will increase the myocardial residence time without decreasing the heart uptake of long-chain fatty acids is of interest. Fatty acids containing the tellurium heteroatom were the first modified fatty acids developed and show unique prolonged myocardial retention and low blood levels. Our detailed studies with radioiodinated vinyliodide substituted tellurium fatty acids demonstrate that heart uptake is a function of the tellurium position. New techniques of tellurium and organoborane chemistry have been developed for the synthesis of a variety of radioiodinated iodoalkenyl tellurium fatty acids.
CAUSIM: A rule-based causal simulation system:

Researchers have felt that expert perfor mance must also rest on knowledge of deep models which relate underlying causal variables to observable facts. Simulation based upon causal knowledge is an ...
Supernova Remnants in the Sedov Expansion Phase: Thermal X-Ray Emission

Improved calculations of X-ray spectra for supernova remnants (SNRs) in the Sedov-Taylor phase are reported, which for the first time include reliable atomic data for Fe L-shell lines. This new set of Sedov models also allows for a partial collisionless heating of electrons at the blast wave and for energy transfer from ions to electrons through Coulomb collisions. X-ray emission calculations are based on the updated Hamilton-Sarazin spectral model. The calculated X-ray spectra are successfully interpreted in terms of three distribution functions: the electron temperature and ionization timescale distributions, and the ionization timescale-averaged electron temperature distribution. The comparison of Sedov models with a frequently used single nonequilibrium ionization (NEI) timescale model reveals that this simple model is generally not an appropriate approximation to X-ray spectra of SNRs. We find instead that plane-parallel shocks provide a useful approximation to X-ray spectra of SNRs, particularly for young SNRs. Sedov X-ray models described here, together with simpler plane shock and single-ionization timescale models, have been implemented as standard models in the widely used XSPEC v11 spectral software package.
The role of redox chemistry in scanning tunneling microscopy imaging of electroactive films

Abstract The dependence of tunneling current I on bias voltage V b in scanning tunneling microscopy (STM) measurements of multilayer electroactive films is interpreted in terms of a redox mechanism involving electron transfer reactions at the STM tip|film and electrode|film interfaces. Analysis suggests that a symmetrical I - V b response is anticipated when the molecular film is sufficiently thick (ca. 2–3 monolayers) that the electron-transfer steps at the STM tip and electrode can be considered as discrete steps in the current-carrying processes. A macroscopic two-electrode thin-layer electrochemical cell is used to mimic the response of an electrode|redox film|STM tip junction. Steady-state symmetrical I - V responses are obtained for the thin-layer cell, even when the solution initially contains only one half of an electroactive redox couple. Tunneling spectroscopic measurements, using a STM, of dry films of protoporphyrin(IX)Fe(III)Cl deposited on highly oriented pyrolytic graphite electrodes are interpreted in terms of the proposed redox mechanism.
Management and outcomes for elderly women with vulvar cancer over time

Objective To examine changes over time in survival and treatment for women diagnosed with vulvar squamous cell carcinoma included in the Surveillance, Epidemiology, and End Results (SEER) Program. Design Retrospective analysis. Setting USA, data obtained from the SEER Program for 1988–2009. Population Women with vulvar squamous cell carcinoma. Methods Women were stratified by age: <50, 50–64, 65–79, and ≥80 years. Differences in survival and treatment patterns were analysed between age groups. Multivariate logistic regression models were constructed to examine treatment patterns. Kaplan–Meier and Cox proportional hazards survival methods were used to assess survival. Main outcome measures Vital status from the date of diagnosis until death, censoring or last follow-up. Results The final study group consisted of 8553 women, 1806 (21.12%) 80 years old. After adjusting for patient and tumour characteristics, older women were less likely to have surgery and more likely to receive radiotherapy. Compared with women under 50 years, women 50–64 had a two-fold higher risk of death (HR 1.91, 95% CI 1.55–2.34); those 65–79 years had a four-fold higher risk of death (HR 4.01, 95% CI 3.32–4.82), and those ≥80 years had a seven-fold higher risk of death (HR 6.98, 95% CI 5.77–8.46). These trends stayed relatively constant over the time periods studied. Conclusions Women over 50 years are at a higher risk of vulvar cancer-specific mortality, which increases with age. These trends stayed relatively constant over the time periods studied.
Some remarks on sign-balanced and maj-balanced posets

Let P be a poset with elements 1,2,...,n. We say that P is sign-balanced if exactly half the linear extensions of P (regarded as permutations of 1,2,...,n) are even permutations, i.e., have an even number of inversions. This concept first arose in the work of Frank Ruskey, who was interested in the efficient generation of all linear extensions of P. We survey a number of techniques for showing that posets are sign-balanced, and more generally, computing their "imbalance." There are close connections with domino tilings and, for certain posets, a "domino generalization" of Schur functions due to Carre and Leclerc. We also say that P is maj-balanced if exactly half the linear extensions of P have even major index. We discuss some similarities and some differences between sign-balanced and maj-balanced posets.
The matrix type of purely infinite simple Leavitt path algebras

Let R denote the purely infinite simple unital Leavitt path algebra L(E). We completely determine the pairs of positive integers (c, d) for which there is an isomorphism of matrix rings M c (R) ≌ M d (R), in terms of the order of [1 R ] in the Grothendieck group K 0(R).
STRUCTURE OF WILD-TYPE YEAST RNA POLYMERASE II AND LOCATION OF RPB4 AND RPB7

The three-dimensional structure of wild-type yeast RNA polymerase II has been determined at a nominal resolution of 24 A. A difference map between this structure and that of the polymerase lacking subunits Rpb4 and Rpb7 showed these two subunits forming part of the floor of the DNA-binding (active center) cleft, and revealed a slight inward movement of the protein domain surrounding the cleft. Surface plasmon resonance measurements showed that Rpb4 and Rpb7 stabilize a minimal pre-initiation complex containing promoter DNA, TATA box-binding protein (TBP), transcription factor TFIIB and the polymerase. These findings suggest that Rpb4 and Rpb7 play a role in coupling the entry of DNA into the active center cleft to closure of the cleft. Such a role can explain why these subunits are necessary for promoter-specific transcription in vitro and for a normal stress response in vivo.
Multiple target tracking in a wide-field-of-view camera system

This paper addresses the use of pulse width modulation (PWM) amplifiers to drive brushless direct current (D.C.) motors in either a trapezoidal or sinusoidal commutation control scheme. A review of amplifier classifications and a comparison of the linear amplifier performance with that of the PWM amplifier is presented. Illustrations show the operational flow of two common power stages (T-bridge and H-bridge) when used with PWM and the resulting electrical equations of current flow are shown. A summary of the advantages and disadvantages of the classes of amplifiers is given. The amplifier discussion is then directed to the comparison of trapezoidal and sinusoidal commutation of the brushless D.C. motor with PWM. The electrical equations and waveforms associated with each method are developed to stress the differences between the two methods. Two servo control loop block diagrams illustrate the differences in electronics required by the two methods.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Feldspar geothermometry of the Hell Canyon Pluton, Boulder Batholith, Montana

The bulk compositions of the groundmass alkali feldspar from the Hell Canyon Pluton is 0.146mole% albite. The composition of the outermost zone of the oscillatory zoned plagioclase is 0.686 mole% albite, whereas the most calcic cores have a composition of 0.43 mole% albite. The structural state of the alkali feldspar is near orthoclase. Both composition of coexisting feldspars and structural state of the alkali feldspar are nearly constant throughout the pluton.
Who Participates in Population Based Studies of Visual Impairment? The Salisbury Eye Evaluation Project Experience

Abstract PURPOSE: To describe characteristics of respondents and nonrespondents to a home questionnaire and comprehensive clinical examination in a population of elderly Americans. METHODS: The SEE project is a population-based study of age-related eye diseases, visual impairment, and functional status of individuals aged 65 to 84. Potential participants were identified using the Health Care Financing Administration Medicare data base for Salisbury, MD: After sending out an introductory letter, a trained interviewer visited potential participants in their homes, obtained their consent to participate, administered a short screening interview that included questions about their general health and vision, and administered an extensive questionnaire on their diet, medical history, and difficulty performing activities related to vision. The interviewer then scheduled an appointment for the participants to visit a central site for an exam. Potential participants could fall into one of two refusal groups; refusal to take part in the study before the home questionnaire or prior to the clinic visit. RESULTS: The overall response rate for the clinic visit was 65%. Compared to individuals with complete exams, the two groups of refusals were older, less likely to have any college education, more likely to report poor health status, and more likely to need help with Independent Activities of Daily Living (IADL’s). Participants with complete home questionnaires that failed to come to the clinic were more likely to have Mini-Mental scores below 25. There were not significant differences by race, gender, or self reported vision status among the three groups. CONCLUSIONS: Population-based studies requiring an in-clinic examination may selectively under-sample those with health and mental difficulties. These differential responses may introduce bias in the study results and need to be addressed when assessing the burden, type and severity of disease in the community. However, self-report of visual status was similar among refusals and participants in this study on vision.
Physical Conditions of Accreting Gas in T Tauri Star Systems

We present results from a low-resolution ( -->R 300) near-infrared spectroscopic variability survey of actively accreting T Tauri stars (TTSs) in the Taurus-Auriga star-forming region. Paschen and Brackett series H I recombination lines were detected in 73 spectra of 15 classical T Tauri systems. The values of the Pa -->nup/Paβ, Br -->nup/Brγ, and Brγ/Pa -->nup H I line ratios for all observations exhibit a scatter of 20% about the weighted mean, not only from source to source, but also for epoch-to-epoch variations in the same source. A representative or global value was determined for each ratio in both the Paschen and Brackett series, as well as the Brγ/Pa -->nup line ratios. A comparison of observed line ratio values was made to those predicted by the temperature- and electron density-dependent models of case B hydrogen recombination line theory. The measured line ratios are statistically well fit by a tightly constrained range of temperatures ( -->T 2000 K) and electron densities ( -->109 cm −3 < ne 1010 cm−3). A comparison of the observed line ratio values to the values predicted by the optically thick and thin local thermodynamic equilibrium cases rules out these conditions for the emitting H I gas. Therefore, the emission is consistent with having an origin in a non-LTE recombining gas. While the range of electron densities is consistent with the gas densities predicted by existing magnetospheric accretion models, the temperature range constrained by the case B comparison is considerably lower than that expected for accreting gas. The cooler gas temperatures will require a nonthermal excitation process (e.g., coronal/accretion-related X-rays and UV photons) to power the observed line emission.
ENTRY REGION HEAT TRANSFER IN ROTATING RADIAL TUBES.

An experimental study of the effect of rotation on the entrance region heat transfer inside straight radially aligned circular tubes is presented. Average coolant passage Nusselt numbers were determined for passage length-to-diameter ratios of 6, 12, and 24 over ranges of radially outward air flows and rotational speeds. Results are presented in terms of the ratio of rotating-to-s tationary heat transfer. Comparisons are made with the rotational heat-transfer enhancement expected for fully developed flow conditions with rotation. The present results, conducted in the absence of entry swirl, show that only a small rotational effect on heat transfer can be expected for relatively short cooling passages.
Surface history of some Apollo 17 lunar soils

Cosmic ray track densities in Apollo 17 soil samples are used to infer surface exposure times of soils from a trench at Van Serg Crater, from on and near a boulder at Camelot Crater, and from the position of the heat flow and neutron flux experiments (the ALSEP site). The topmost 2 cm of soil at Van Serg was exposed for 11 m.y., the top cm at Camelot for 36 m.y. A layering chronology and average deposition rate are proposed for the trench. For all soils the median track densities imply predispositional irradiation in the top 15 cm of the lunar surface for times that were long compared with the actual residence in the stratigraphic positions from which the soils were collected. Van Serg crater is inferred to have been formed approximately 24 m.y. ago.
Improving the future by examining the past: ACM Turing Award Lecture

During the last fifty years, the technology underlying computer systems has improved dramatically. As technology has evolved, designers have made a series of choices in the way it was applied in computers. In some cases, decisions that were made in the twentieth century make less sense in the twenty-first. Conversely, paths not taken might now be more attractive given the state of technology today, particularly in light of the limits the field is facing, such as the increasing gap between processor speed and storage access times and the difficulty of cooling today's computers. In this talk, I'll discuss some of these choices and suggest some possible changes that might make computing better in the twenty-first century.
Acetylation of unsymmetrical diols in the presence of Al2O3

Abstract The effect of the presence of chromatographic grade Al2O3 on the acetylation of a series of unsymmetrical 1,5-diols was investigated. For diols containing both a primary and a secondary hydroxyl group, it was observed that higher yields of the more hindered secondary acetates were formed in the presence of Al2O3 than the corresponding reactions in solution.
Grappling with Distributed Usability: A Cultural-Historical Examination of Documentation Genres Over Four Decades.

Traditional models of usability assume that usability is a quality that can be designed into a particular artifact. Yet constructivist theory implies that usability cannot be located in a single artifact; rather, it must be conceived as a quality of the entire activity in which the artifact is used. This article describes a distributed approach to usability, based on activity theory and genre theory. It then illustrates the approach with a four-decade examination of a traffic accident location and analysis system (ALAS). Using the theoretical framework of genre ecologies, the article demonstrates how usability is distributed across the many official and unofficial (ad hoc) genres employed by ALAS users.
On the weights of mod p Hilbert modular forms

We prove many cases of a conjecture of Buzzard, Diamond and Jarvis on the possible weights of mod p Hilbert modular forms, by making use of modularity lifting theorems and computations in p-adic Hodge theory.
Ridge waveguide distributed Bragg reflector InGaAs/GaAs quantum well lasers

A single growth step ridge waveguide InGaAs/GaAs quantum well laser with one third-order distributed Bragg reflector (DBR) and one cleaved facet is described. The DBR is fabricated with direct write electron beam lithography and transferred into the epilayers by reactive ion etching. These devices operate on a single longitudinal and fundamental lateral mode, with a threshold current of 23 mA and more than 30 dB of sidemode suppression.
Alpha transport and blistering in tokamaks

The particle flux and angular distribution of 3.5 MeV alpha particles impinging on the first wall from uncontained banana orbits in an axisymmetric tokamak reactor have been calculated. The resulting helium concentration profiles in the first wall can give rise to surface exfoliation under specified conditions. The major mitigating factor is the simultaneous surface recession due to sputtering by the D-T charge-exchange neutral flux. For the parameters used in these calculations blistering in high-sputtering-rate materials such as beryllium is unlikely, whereas in low-sputtering-rate materials such as niobium helium-induced surface deformation is quite probable.
Is Grover's Algorithm a Quantum Hidden Subgroup Algorithm?

The arguments given in this paper suggest that Grover's and Shor's algorithms are more closely related than one might at first expect. Specifically, we show that Grover's algorithm can be viewed as a quantum algorithm which solves a non-abelian hidden subgroup problem (HSP). But we then go on to show that the standard non-abelian quantum hidden subgroup (QHS) algorithm can not find a solution to this particular HSP. This leaves open the question as to whether or not there is some modification of the standard non-abelian QHS algorithm which is equivalent to Grover's algorithm.
The influence of an electrostatic pin chuck on EUV mask flatness

The development of a low-distortion mask is of prime importance to Extreme Ultraviolet (EUV) Lithography. The mask consists of a standard ultra low expansion (ULE®) substrate measuring 152.4 mm x 152.4 mm x 6.35 mm, with a 280 nm thick reflective multilayer deposited on the top surface. Nonflatness of the mask patterned surface will manifest itself as image placement errors on the device wafer. Bottom surface nonflatness can interfere with securely holding the mask in the patterning and exposure tools as well as exacerbating patterned surface nonflatness. Of great concern is the effect of the mounting technique employed in the patterning and exposure tools on mask flatness. One such design, the electrostatic pin chuck, consists of a 'bed of pins' on the top surface of the chuck that will support the EUV mask during patterning and exposure. The pin design has been proposed to minimize the likelihood of particulates becoming lodged between the mask and chuck that would adversely distort the mask. To ensure that a chuck of this design will minimize image placement errors while still securely holding the mask, three-dimensional finite element (FE) models have been created to predict the influence of the electrostatic pin chuck on mask flatness. Legendre polynomials were used as input to the models to represent experimentally-measured substrate bottom surface shapes. The FE results illustrate that mechanical modeling provides an invaluable tool for quantifying the influence of mounting techniques on mask flatness, and, ultimately optimizing system parameters to successfully meet the stringent requirements at the 45-nm node (and below).
Comparative analysis of line-drawing modeling schemes

Abstract The computer processing of line drawings necessarily requires that the line drawings be first quantized and then encoded. Invariably, the quantization process forces the computer approximation to connect nodes lying on a lattice. The lattice normally is uniform square (though it could also be rectangular, logarithmic, or curvilinear) and is either explicitly or implicitly defined; its size is determined by the limit in the ability to resolve neighboring points in the quantization process. The coded representation of the drawing may be based on the use of straight or curved segments (approximants). The segments may be restricted either to a small set of fixed lengths or their lengths may take on any of the discrete values permissible on the lattice field. The paper examines some of the possibilities for line drawing modeling and shows that in many cases they may be regarded as special cases of the so-called generalized chain coding scheme. A procedure is developed for computing the relative probabilities of the approximating segments in a line drawing representation. The latter are necessary for any efficient (compact) line-drawing modeling scheme.
Venus diapirs: Thermal or compositional?

The Venus surface exhibits quasi-circular structures with a bimodal size distribution; there are at least 17 large (∼1300–2600-km diameter) crustal plateaus and volcanic rises, which form major geomorphic features, and ∼515 smaller (200-km median diameter) coronae. All of these features—plateaus, rises, and coronae—are interpreted to be the surface signature of mantle diapirs. Diapirs are driven by buoyancy, which is a function of diapir size and diaper-host density contrast, which can be a function of thermal or compositional differences. Plateaus and rises apparently represent the surface signature of deep-mantle thermal diapirs that interacted, respectively, with ancient thin lithosphere and contemporary thick lithosphere. Existing coronae models either do not specify the nature of diapir buoyancy or assume a density difference resulting from thermal differences. I contrast the geological implications of end-member thermal and compositional buoyancy to provide insight into the mechanisms of Venusian diapirism operating at different scales. The analysis indicates that median-size coronae likely represent the surface expression of compositionally driven, rather than thermal, diapirs, whereas plateaus and rises form from large thermal diapirs. The bimodality and surface distribution of Venus' large (plateaus/rises) and small (coronae) diapiric structures might therefore reflect different mechanisms of diapir formation. Thermally driven deep-mantle plumes, initiated along a warm lower boundary layer, rise through the mantle to the lithosphere, forming plateaus and rises; these plumes would transfer heat from the core. Broad mantle upwellings, which presumably formed in response to a cold upper boundary layer, might generate compositional diapirs at relatively shallow levels in the upper mantle; compositional diapirs, rising to form corona chains, would transfer heat from the mantle. Corona clusters result from compositional diapirs spawned locally by plumes of deep-mantle origin; corona clusters therefore would also represent heat transferred from the mantle, but their formation would be triggered by thermal anomalies from the core-mantle boundary. Isolated coronae probably formed only when the lithosphere was thin, because they occur in regions where the lithosphere is currently too thick to transmit small, diapiric signatures to the surface.
Yet another extension of the standard model: Oases in the desert?

We search for conceptually simple extensions of the standard model, and describe here a candidate model which we find attractive. Our starting point is the assumption that off-diagonal CKM mixing matrix elements are directly related by lowest order perturbation theory to the quark mass matrices. This appears to be most easily and naturally implemented by assuming that all off-diagonal elements reside in the down-quark mass matrix. This assumption is in turn naturally realized by introducing three generations of heavy, electroweak-singlet down quarks which couple to the Higgs sector diagonally in flavor, while mass mixing off-diagonally with the light down quarks. Anomaly cancellation then naturally leads to inclusion of electroweak vector-doublet leptons. It is then only a short step to completing the extension to three generations of fundamental $\underset{\ifmmode\bar\else\textasciimacron\fi{}}{27}$ representations of $E(6).$ Consequences of this picture include (1) the hypothesis of ``Stech texture'' for the down-quark mass matrix (imaginary off-diagonal elements) leads to an approximate right unitarity triangle $(\ensuremath{\gamma}\ensuremath{\approx}\ensuremath{\pi}/2),$ and a value of $\mathrm{sin}2\ensuremath{\beta}$ between 0.64 and 0.80. (2) Assuming only that the third generation B couples to the Higgs sector at least as strongly as does the top quark, the mass of the B is roughly estimated to lie between 1.7 TeV and 10 TeV, with lower-generation quarks no heavier. The corresponding guess for the new leptons is a factor two lower, 0.8 TeV to 5 TeV. (3) Within the validity of the model, flavor and $\mathrm{CP}$ violation are ``infrared'' in nature, induced by semi-soft mass mixing terms, not Yukawa couplings. (4) The ``Mexican hat'' structure of the Higgs potential may be radiatively induced by the new heavy down-quark one-loop contributions to the potential. (5) A subset of the precision electroweak experiments are sensitive to the physics induced by the heavy quarks and/or leptons. (6) If the Higgs couplings of the new quarks are flavor symmetric, then there necessarily must be at least one ``oasis'' in the desert, induced by new radiative corrections to the top quark and Higgs coupling constants, and roughly at ${10}^{3}\mathrm{TeV}.$ (7) If the Higgs couplings of the new down quarks are hierarchical and equal to the usual Higgs couplings to right-handed up quarks, then, in the limit in which gauge coupling constants are set to zero, parity violation is also ``infrared,'' induced by semi-soft mass terms.
Descriptive languages and problem solving

Advances in machine problem solving may depend on use of internal languages for description and abstraction of the outcomes of experiments. As more complex problems are attempted there will have to be less trial and error and more systematic analysis of the results of each trial. Learning on the basis of experience will require a phase of refinement in which the machine will attempt, by analysis and inductive inference, to get as much as possible from each experiment.
Sleep and Epilepsy

Over a century of work has confirmed crucial links between sleep and epilepsy. Seizures and some antiepileptic drugs (AEDs) adversely affect the continuity of sleep. However, sleep is fragmented in the absence of seizures or medication, suggesting that sleep instability may be an inherent component of certain forms of epilepsy. In turn, sleep instability can promote seizures, thus forming a vicious cycle. Sleep deprivation provokes seizures and epileptiform discharges in some people with epilepsy. Synchronized nonrapid eye movement (NREM) sleep facilitates seizures, whereas desynchronized rapid eye movement (REM) sleep discourages seizure occurrence. The sleep electroencephalogram (EEG) is useful in the diagnosis and localization of epilepsy, as new epileptic foci can appear in sleep and REM sleep may demonstrate the narrowest localization of the primary focus. Polysomnography (PSG) with expanded EEG aids in the differentiation of seizures and parasomnias and in the diagnosis of primary sleep disorders, such as sleep apnea, that can exacerbate seizures. Treating sleep apnea may lead to improved seizure control. These observations underscore the importance of sleep in the diagnosis and treatment of people with epilepsy.
Hyperbolic automorphisms of free groups

We prove that an automorphism $ {\not o} : F \to F $ of a finitely generated free group F is hyperbolic in the sense of Gromov if it has no nontrivial periodic conjugacy classes. This result was previously claimed (but not proved) in [BF1].
High density recording with SIL-based near-field optical recording

High density rewritable recording and readout characteristics with a solid immersion lens (SIL)-based near-field recording (NFR) are investigated. Substrates for high density are prepared using a phase transition mastering technique. Cover-layers with different refractive index for different effective numerical apertures in the SIL optics are coated on rewritable NFR discs for cover-layer incident near-field recording configuration. Two different effective numerical apertures are chosen between 1.45 and 1.85 to cope with about 70 GB and more than 100 GB per disc, respectively. The performance readout signals is investigated and compared in terms of increasing recording densities with reducing track pitch.
Strained‐Ring and Double‐Bond Systems Consisting of the Group 14 Elements Si, Ge, and Sn

The organometallic chemistry of the Group 14 elements E = Si, Ge, Sn in the 1980's is highlighted by the successful construction and characterization of three systems previously thought to be too reactive to exists: (1) three-membered ring compounds including cyclotrisilane, cyclotrigermane, and cyclotristannane, (2) molecules containing EE double bonds including disilene, digermene, and distannene, and (3) strained polycycles containing a skeleton of Group 14 elements, such as bicyclo[1.1.0]tetrasilane, hexagemaprismane, and octasilacubane. The majority of these numerous compounds now available are fully substituted with bulky ligands to suppress the reactivity intrinsic to the systems. These compounds permit examinations of (1) the variation of physical and chemical properties of a system with these elements and also with the ligands and (2) how two systems are interrelated thermally and photochemically with the intermediacy of the divalent (carbene-like) species. Theoretical calculations on virtually all of the parent compounds discussed in this review are evaluated alongside the experimental results. Some polycycles may constitute a stepping-stone on the way to compounds with a triple bond.
Cu(I)-catalyzed diamination of disubstituted terminal olefins: an approach to potent NK1 antagonist.

This paper describes a diamination process using di-tert-butyldiaziridinone as nitrogen source and CuCl as catalyst. A wide variety of disubstituted terminal olefins can be efficiently diaminated in good yields under mild condition. This diamination process was used to synthesize potent NK1 antagonist Sch 425078.
Convenient prices, currency, and nominal rigidity: Theory with evidence from newspaper prices

Abstract Certain items’ prices are often set to simplify and expedite transactions, by coinciding with available monetary units, requiring few pieces of money, or requiring little change. In this sense, these prices are more convenient than other proximate prices. This paper models a firm that explicitly incorporates convenience into its pricing decisions—where convenience is quantified by the number of currency units in a transaction—and illustrates the theoretical behaviors that can arise. Newspaper cover price data empirically support the theory. Across a broader range of goods and services, convenience appears to play a role in effecting above-average nominal price rigidity.
Conformance with preferred practice patterns in caring for children with esotropia.

PURPOSE To evaluate documentation of the initial evaluation in patients with esotropia, with respect to history, physical examination, care management, and patient education, for the presence of key elements as defined in the American Academy of Ophthalmology's Summary Benchmarks for Preferred Practice Patterns. METHODS Two hundred charts of patients seen at the Pediatrics Service at the Duke Eye Center for an initial diagnosis of esotropia were reviewed relative to both the 2002 (all patients) and 2007 (for those seen in 2007) Preferred Practice Patterns benchmarks for esotropia. Documentation of key elements as defined in the Preferred Practice Patterns was recorded. RESULTS The average total score was 85.8% for all evaluations. On average, 63.6% of the initial history key elements, 99.6% of the initial physical examination key elements, and 94.2% of the care management and patient education key elements were documented. For evaluations performed in 2007 and scored according to the 2007 Preferred Practice Patterns, scores were similar, except that the physical examination subset score average decreased to 90.3% and the family history documentation score increased to 45.5%. CONCLUSION In an academic practice, the process quality of care for strabismus often conforms well to professional practice patterns. However, there are opportunities for improvement in the documentation of key history elements. Additional data are needed from other practice settings and for other conditions to assess the quality of eye care for children.
Effects of signal detuning on phase conjugation

The formulations of degenerate three-wave and four-wave phase conjugation are generalized to include signal-pump detuning. The theory is an extension of grating-dip spectroscopy. The reflection bandpass is shown to be limited by the power-broadened bandwidth (∝1/T1) of the two-level population difference. Unlike for running-wave saturation, the signal-absorption coefficient saturated by a standing wave shows virtually no gain regions.
On the stability of the equilibrium of nonconservative continuous systems with slight damping.

Stability of equilibrium configuration of linearly elastic solid /with or without internal damping/ subjected to partial follower surface tractions