cssi/SciSciGPT-SciSciNet huggingface dataset:
Cross-coupling of aromatic bromides with allylic silanolate salts.

The sodium salts of allyldimethylsilanol and 2-butenyldimethylsilanol undergo palladium-catalyzed cross-coupling with a wide variety of aryl bromides to afford allylated and crotylated arenes. The coupling of both silanolates required extensive optimization to deliver the expected products in high yields. The reaction of the allyldimethylsilanolate takes place at 85 °C in 1,2-dimethoxyethane with allylpalladium chloride dimer (2.5 mol %) to afford 73−95% yields of the allylation products. Both electron-rich and sterically hindered bromides reacted smoothly, whereas electron-poor bromides cross-coupled in poor yield because of a secondary isomerization to the 1-propenyl isomer (and subsequent polymerization). The 2-butenyldimethylsilanolate (E/Z, 80:20) required additional optimization to maximize the formation of the branched (γ-substitution) product. A remarkable influence of added alkenes (dibenzylideneacetone and norbornadiene) led to good selectivities for electron-rich and electron-poor bromides in 4...
Perineal and perirectal sarcomas: report of two cases.

PURPOSE: Perineal sarcomas are rare tumors that are typically of an extensive nature by the time of diagnosis. In this article, two case reports are followed by a brief review of different types of sarcomas that may occur in the perineal and perirectal region. STUDY PATIENTS: This study consists of two cases that are representative of the many types of perineal/perirectal sarcomas. PRINCIPLE CONCLUSIONS: Perineal and perirectal sarcomas are generally of poor prognosis mainly because of delayed diagnosis. Computed tomography and magnetic resonance imaging can be extremely useful to help assess these tumors. It is well known that the most important criterion for diagnosing leiomyosarcomas appears to be the presence of mitotic activity. Anorectal stromal tumors having five or more mitoses per 50 high powered fields are considered to be malignant. The mainstay of treatment is surgical excision with wide margins. Currently, chemotherapeutic and radiotherapy trials are under way.
Human capital externalities and rural–urban migration: Evidence from rural China

Abstract This study examines the determinants of rural–urban migration paying special attention to the role of human capital externalities in the rural sector. Using data from a well-known household survey in China, we find that in rural areas human capital externalities have a discouraging effect on rural–urban migration—everything else being the same, a rural resident from a county rich in human capital is less likely to migrate to the city than his counterpart from another county poor in human capital endowment. We also find some evidence that human capital exerts positive external effects on the likelihood for a rural resident to choose off-farm employment and on labor income in the rural sector. These results are robust to alternative model specifications and estimation methods. One important policy implication from this study is that expanding education opportunities in rural areas can help curtail rural–urban migration and therefore alleviate urban unemployment pressure.
On the Learning Behavior of Adaptive Networks—Part I: Transient Analysis

This paper carries out a detailed transient analysis of the learning behavior of multiagent networks, and reveals interesting results about the learning abilities of distributed strategies. Among other results, the analysis reveals how combination policies influence the learning process of networked agents, and how these policies can steer the convergence point toward any of many possible Pareto optimal solutions. The results also establish that the learning process of an adaptive network undergoes three (rather than two) well-defined stages of evolution with distinctive convergence rates during the first two stages, while attaining a finite mean-square-error level in the last stage. The analysis reveals what aspects of the network topology influence performance directly and suggests design procedures that can optimize performance by adjusting the relevant topology parameters. Interestingly, it is further shown that, in the adaptation regime, each agent in a sparsely connected network is able to achieve the same performance level as that of a centralized stochastic-gradient strategy even for left-stochastic combination strategies. These results lead to a deeper understanding and useful insights on the convergence behavior of coupled distributed learners. The results also lead to effective design mechanisms to help diffuse information more thoroughly over networks.
Thermal and Chemical Evolution of Collapsing Filaments

Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z Almost-Equal-To 0.1 Z{sub Sun} filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form a dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10{sup -3} Z{sub Sun} filaments, the collapse proceeds much more slowly. This is mostly due to the lower initial temperatures, which lead to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare thismore » to NGC 5253, a nearby starbursting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occurs. We find that we achieve similar accretion rates as NGC 5253 but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.« less
Utility of Urine and Blood Cultures in Pyelonephritis

Objective: To determine how often the results of urine and blood cultures led to changes in antibiotic therapy for patients discharged from the hospital with the diagnosis of pyelonephritis. Methods: A retrospective chart review was performed of consecutively admitted patients, 10–90 years old, with an ICD-9 discharge diagnosis of acute pyelonephritis. All patients were admitted to a university-based, tertiary care center and a large HMO medical center from 1993 to 1994. The association of urine and blood culture results with a change in antibiotic therapy was assessed. Results: Of the 194 patients who met inclusion criteria, 189 (97%) had urine cultures obtained at the time of admission and 139 (71%) had blood cultures obtained. Ampicillin, gentamicin, or both were given as initial antibiotics 81% of the time, and isolated organisms from urine or blood were sensitive to the empiric antibiotics 95% of the time. Most (171/189; 90%) urine cultures were positive, but only 9 (5%) of these led to a change in antibiotic therapy. 80% of the urinary pathogens were Escherichia coli, 5% Enterococcus, 5% Proteus, and 4% Klebsiella. Only 40 (29%) of the 139 blood cultures were positive; none prompted a change in antibiotics. There were no cases in which blood and urine cultures grew different pathogens. Conclusions: Urine cultures are useful in directing antibiotic therapy in patients with the discharge diagnosis of acute pyelonephritis and support a change in therapy in 5% of cases. Among the patients in this study, blood culture results did not lead to changes in antibiotic therapy. These findings warrant prospective, mul-ticenter evaluation.
Optical Studies on Antimonide Superlattice Infrared Detector Material

In this study the material quality and optical properties of type II InAs/GaSb superlattices are investigated using transmission and photoluminescence (PL) spectroscopy. The influence of the material quality on the intensity of the luminescence and on the electrical properties of the detectors is studied and a good correlation between the photodetector current-voltage (IV) characteristics and the PL intensity is observed. Studies of the temperature dependence of the PL reveal that Shockley-Read-Hall processes are limiting the minority carrier lifetime in both the mid-IR wavelength and the long-IR wavelength detector material studied. These results demonstrate that PL spectroscopy is a valuable tool for optimization of infrared detectors.
Highly efficient carbonyl allylation of 1,3-dicarbonyl compounds in aqueous medium

Abstract Beta-keto esters undergo efficient carbonyl allylation reactions in aqueous medium through a Barbier-type reaction. The reaction is general and a variety of 1,3-dicarbonyl compounds have been alkylated successfully using allyl bromide or allyl chloride in conjunction with either tin or indium.
Limitations on the Persistence of Iminoxyls: Isolation of tert-Butyl 1,1-Diethylpropyl Ketiminoxyl and Related Radicals

A series of iminoxyl radicals of the general formula R(CNO•)R1, with R and R1 usually tertiary, was synthesized in a search for radicals of increased persistence. Three new radicals were isolated as blue liquids: Et3C(CNO•)Bu-t (1), t-C5H11(CNO•)Bu-t (2), and (t-C5H11)2CNO• (3). Oxidation of oximes Et3C(CNOH)Ph (4H), PhCH2CMe2(CNOH)Bu-t (5H), PhCMe2(CNOH)Bu-t (6H), and Me2CH(CNOH)C5H11-t (7H), among others, did not lead to isolable iminoxyls. A new, convenient synthesis of symmetrical tertiary imines from tert-RCl, tert-RCN, and Na is described. Radical t-Bu2CNO• (8) and cyclohexene readily gave the allylic substitution product, 2,2,4,4-tetramethyl-3-hexanone O-(2‘-cyclohexen-1‘-yl)oxime.
Does Geography Matter for Science-Based Firms? Epistemic Communities and the Geography of Research and Patenting in Biotechnology

The spatial clustering of innovation has been associated with localized knowledge flows among small, knowledge-intensive firms, but knowledge flows may extend beyond regional boundaries through the participation of firm employees in broader knowledge-based communities. This paper analyzes biotechnology firms jointly engaged in technological innovation and open scientific research and proposes that the geography of their collaborations should reflect the distinctive social logics of these activities. I hypothesize that projects involving local ties are more likely to be patented by a firm than are projects involving distant contacts, both because proximity is conducive to innovation and because a small firm's social capital is likely to be greatest in its home region. However, classic studies in the sociology of science show that scientific communities are socially stratified and geographically dispersed. As a result, I hypothesize that ties to distant partners and prestige in scientific communities are positively associated with scientific impact but negatively associated with firm patenting. The analysis focuses on 5,143 collaborative research papers published by a large sample of small biotechnology firms. The average distance among coauthors on a paper is some 1,500 miles, indicating that the firms are engaged in geographically far-flung research networks; however, the distribution of teams in space is strongly bimodal, revealing an important core of regional ties alongside a set of much more distant ties. Regression analysis show that the spatially clustered teams are more likely to publish papers that are subsequently cited in the authoring firms' patents, whereas teams that are globally dispersed produce papers that are more highly cited in the scientific literature, but less cited in the authoring firms' patents. Status in the scientific community has the expected positive effects on paper citations, but a negative effect on patent citations. The results give evidence of different---and in some respects conflicting---logics governing the creation of new technologies on the one hand and valuable ideas in science on the other, highlighting challenges faced by firms that aim to profit from knowledge created in open scientific communities.
Experiments with planning and markets in multiagent systems

Mobile devices are hand-held devices used to deliver time sensitive and locale specific information to the users. Users of multi-user environments with limited resources can be enabled with agents running on mobile devices as assistants to improve their ability to plan activities in the space. This paper discusses experiments to characterize the benefits of planning in such an environment, particularly when the resources can be reserved and the reservations traded in a market. We observe that with tradable reservations the social welfare increases with increase in planning horizon. We also observe that tradable reservations and clairvoyance help the users satisfy their preferences and the constraints imposed by environment.
Dynamic capabilities and venture performance: The effects of venture capitalists

Abstract After going through the initial public offering (IPO), new ventures face increased competition, greater public examination, and increased government scrutiny. Resource base weaknesses and external forces pose severe threats to the survival and success of new ventures. Building from resource-based theory, we first examine and delineate dynamic capabilities from entrepreneurial capabilities in entrepreneurship. We then develop theory to explain how venture capitalists (VCs) endue their ventures with greater dynamic capabilities in order to address these weaknesses and threats. We test our hypotheses on a match-pair sample of VC-backed and non-VC-backed new ventures and find that VC-backed ventures demonstrate greater dynamic capabilities as they relate to product and management development but do not display any greater dynamic capabilities as they relate to legal and government regulation threats. Further analysis also revealed that VC experience and VC reputation were positively related to 1-year stock price returns.
Water Masers as Tracers of Protostellar Disks and Outflows in the Intermediate-Mass Star-forming Region NGC 2071

We have mapped the water maser emission associated with the infrared centers IRS 1 and IRS 3 of the NGC 2071IR star-forming region at four epochs over ~4 months with the Very Long Baseline Array. We detected 269 maser features with ~1 km s-1 line widths and measured 30 proper motions. In each infrared center, the water maser emission appears to trace parts of a protostellar disk and collimated outflow. The disk components are ~9 and ~17 AU long in IRS 3 and IRS 1, respectively, and ~2 AU wide. They are identified as disks by their compact size, elongation parallel to the direction of known IR polarization, central location in the maser maps, small internal proper motions, and proximity to λ1.3 cm continuum emission. The outflows have axes perpendicular to the disks and exhibit proper motions of up to ~42 km s-1. They are outlined by maser emission up to ~260 AU from the protostars. The IRS 3 outflow appears to be conical on one side, while the IRS 1 outflow comprises a narrowly collimated bipolar flow surrounded by outward-facing, funnel-shaped cavities. The detection of water maser emission tracing such compact disk components and specifically conical or funnel-shaped structures is unusual. The fact that the distributions are similar in IRS 3 and IRS 1 may indicate that the two infrared centers are roughly coeval. NGC 2071IR provides a rare opportunity to resolve the structures and dynamics of disks and outflows together and to do so for two protostars that are only ~2000 AU apart (in projection) in a deeply embedded star-forming region of intermediate luminosity.
Nickel-Catalyzed Regiodivergent Opening of Epoxides with Aryl Halides: Co-Catalysis Controls Regioselectivity

Epoxides are versatile intermediates in organic synthesis, but have rarely been employed in cross-coupling reactions. We report that bipyridine-ligated nickel can mediate the addition of functionalized aryl halides, a vinyl halide, and a vinyl triflate to epoxides under reducing conditions. For terminal epoxides, the regioselectivity of the reaction depends upon the cocatalyst employed. Iodide cocatalysis results in opening at the less hindered position via an iodohydrin intermediate. Titanocene cocatalysis results in opening at the more hindered position, presumably via TiIII-mediated radical generation. 1,2-Disubstituted epoxides are opened under both conditions to form predominantly the trans product.
The restructuring of insider-dominated firms: A comparative analysis

We study the effects of different modalities of privatization to insiders on the restructuring process in two former Soviet republics–Georgia and Moldova--using enterprise survey data for 1995-97. Enterprise restructuring was similar in companies where incumbent managers received significant ownership stakes for free and in still state-owned companies. In contrast, the restructuring process was faster in companies bought by their managers. We interpret these results to suggest that managers’ incentives to restructure decrease when they perceive their newly-acquired ownership as a windfall gain.
Approximate recovery of H-infinity loop shapes using fixed-order dynamic compensation

This paper presents a method for designing fixed-order dynamic compensators that approximate the Hm full state feedback, closed-loop transfer function properties from disturbance inputs to controlled outputs. This formulation uses an observer canonical form to represent the dynamic compensator which allows the design to be treated as a modified constant gain output feedback problem. The approximate recovery is accomplished through a unique selection of the quadratic performance index weighting matrices. This design procedure is demonstrated by two design examples. The first example is a simple fourth-order model used to demonstrate the procedure. The second example is a longitudinal flight controller for the F-18/HARV "Supermaneuverable" aircraft. This flight controller is compared to both a full- and reduced-order H^ compensator.
The Impact of Individual Teachers on Student Achievement: Evidence from Panel Data

Teacher quality is widely believed to be important for education, despite little evidence that teachers' credentials matter for student achievement. To accurately measure variation in achievement due to teachers' characteristics-both observable and unobservable-it is essential to identify teacher fixed effects. Unlike previous studies, I use panel data to estimate teacher fixed effects while controlling for fixed student characteristics and classroom specific variables. I find large and statistically significant differences among teachers: a one standard deviation increase in teacher quality raises reading and math test scores by approximately .20 and .24 standard deviations, respectively, on a nationally standardized scale. In addition, teaching experience has statistically significant positive effects on reading test scores, controlling for fixed teacher quality.
Antikaon production and medium effects in heavy-ion collisions at AGS

Abstract Antikaon production in heavy-ion collisions at energies available from the Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory is studied in a relativistic transport (ART) model. We include contributions from the baryon-baryon, meson-baryon, and meson-meson interactions. The final-state interaction of antikaons via both absorption and elastic scattering by nucleons and pions are also considered. To compare with presently available or future experimental data, we have calculated the antikaon rapidity and transverse momentum distributions as well as its collective flow. Medium effects on these observables due to mean field potentials have also been investigated. It is found that both the ratio of antikaon transverse momentum spectrum to that of kaon and their transverse flow are most sensitive to the in-medium properties of kaons and antikaons.
Holographic Measurement and Improvement of the Green Bank Telescope Surface

We describe the successful design, implementation, and operation of a 12 GHz holography system installed on the Robert C. Byrd Green Bank Telescope (GBT). We have used a geostationary satellite beacon to construct high-resolution holographic images of the telescope mirror surface irregularities. These images have allowed us to infer and apply improved position offsets for the 2209 actuators which control the active surface of the primary mirror, thereby achieving a dramatic reduction in the total surface error (from 390 μm to ~240 μm, rms). We have also performed manual adjustments of the corner offsets for a few panels. The expected improvement in the radiometric aperture efficiency has been rigorously modeled and confirmed at 43 GHz and 90 GHz. The improvement in the telescope beam pattern has also been measured at 11.7 GHz with greater than 60 dB of dynamic range. Symmetric features in the beam pattern have emerged which are consistent with a repetitive pattern in the aperture due to systematic panel distortions. By computing average images for each tier of panels from the holography images, we confirm that the magnitude and direction of the panel distortions, in response to the combination of gravity and thermal gradients, are in general agreement with finite-element model predictions. The holography system is now fully integrated into the GBT control system, and by enabling the telescope staff to monitor the health of the individual actuators, it continues to be an essential tool to support high-frequency observations.
The polyhex/polypent topological paradigm: regularities in the isomer numbers and topological properties of select subclasses of benzenoid hydrocarbons and related systems

The informatics on benzenoid hydrocarbons and related systems is reviewed. This informatics involves a collection of algorithms used to discover, process, and analyze patterns in structure/formula data sets. The unique organizational structure that emerges will be useful to chemists with an interest in polycyclic aromatic compounds, environmental chemists, material scientists, and other scientists wishing for a greater understanding of the formation of carbonaceous materials. This tutorial review will show that isomer enumeration can lead to significant chemical insights. The isomer number regularities will be shown to have a structural origin referred to as the polyhex/polypent topological paradigm.
The Effects of E-Government on Trust and Confidence in Government

Trust in government has been declining for more than three decades now. E-government has been proposed as a way to increase citizen trust in government and improve citizen evaluations of government generally. Using two-stage models to analyze recent Pew survey data, this research explores the relationship between e-government use, attitudes about e-government, and trust in government. There is a statistically significant relationship between trust and use of a local government Web site, as well as other positive assessments of federal and local governments. The evidence suggests that e-government can increase process-based trust by improving interactions with citizens and perceptions of responsiveness. The findings are theoretically important for reconciling the conflicting research on the effects of e-government and for understanding variations by level of government. Citizen attitudes toward government, including trust, are core concerns for democratic governance and public administration.
Non-Fourier Heat Conduction in a Semi-infinite Solid Subjected to Oscillatory Surface Thermal Disturbances

Many investigators have explored the effect of non-Fourier conduction in transient processes in recent years. Based on a relaxation model for heat conduction in solids and liquids, the traditional heat diffusion equation is replaced with a hyperbolic equation that accounts for the finite thermal propagation speed. The use of the hyperbolic equation removes the nonphysical phenomenon of the diffusion equation analysis that predicts instantaneous temperature disturbances at all points in the medium for a step heat flux at the boundary. It further removes the peculiarity of an infinite temperature gradient at the boundary as time goes to zero. The objective of this work is to show that the non-Fourier conduction effect can be important even at a long-time after the initial transient if the thermal disturbance is oscillatory with the period of oscillation of the same order of the magnitude as the thermal relaxation time. In particular, the thermal response of a semi-infinite solid subjected to a sinusoidal boundary heat flux condition is generated. The present solution illustrates readily that, in many practical situations such as the repeated irradiation of a solid by a laser with very short pulse width, heat transfer analyses using the traditional Fourier heat diffusion equationmore » can result in significant errors. The current results also suggest that the thermal relaxation time of a solid can be determined by measuring the thermal response of the solid can be determined by measuring the thermal response of the solid irradiated by a high-frequency heat flux.« less
The Black Hole Mass-Bulge Luminosity Relationship for Active Galactic Nuclei from Reverberation Mapping and Hubble Space Telescope Imaging

We investigate the relationship between black hole mass and bulge luminosity for active galactic nuclei (AGNs) with reverberation-based black hole mass measurements and bulge luminosities from two-dimensional decompositions of Hubble Space Telescope host galaxy images. We find that the slope of the relationship for AGNs is 0.76-0.85 with an uncertainty of ~0.1, somewhat shallower than the M BH L 1.0?0.1 relationship that has been fit to nearby quiescent galaxies with dynamical black hole mass measurements. This difference is somewhat perplexing, as the AGN black hole masses include an overall scaling factor that brings the AGN M BH-? relationship into agreement with that of quiescent galaxies. We discuss biases that may be inherent to the AGN and quiescent galaxy samples and could cause the apparent inconsistency in the forms of their M BH-L bulge relationships. Recent work by Graham, however, presents a similar slope of ~0.8 for the quiescent galaxies and may bring the relationship for AGNs and quiescent galaxies into agreement.
A Model of Tradeable Capital Tax Permits

Standard models of horizontal strategic capital tax competition predict that, in a Nash equilibrium, tax rates are inefficiently low due to externalities - capital infl ow to one state corresponds to capital out ow for another state. Researchers often suggest that the federal government impose Pigouvian taxes to correct for these effects and achieve efficiency. We propose an alternative incentive-based regulation: tradeable capital tax permits. Under this system, the federal government would require a state to hold a permit if it wanted to reduce its capital income tax rate from some pre-determined benchmark. These permits would be tradeable across states. We show that, if the federal government sets the correct number of total permits, then social efficiency is achieved. We discuss the advantages of this system relative to the canonical suggestion of Pigouvian taxes.
Electron beam quality limitations and beam conditioning in free electron lasers

Abstract Free electron lasers (FELs) operate over a large portion of the electromagnetic spectrum, i.e. from the μ-wave to the UV. At the high frequency end of the spectrum, FEL operation is severely limited by a number of factors; prominent among them is the electron beam quality (electron axial velocity spread). The axial velocity spread is due to the electron beam's intrinsic energy spread and emittance. The general wavelength limitation in FELs due to electron beam quality is discussed. A method for reducing the axial velocity spread is proposed and analysed. This beam conditioning method redistributes the electrons' energy according to their betatron amplitude. This accomplished by interacting the beam with an axially symmetric, slow, TM waveguide mode.
Uganda's infrastructure : a continental perspective

Uganda has made substantial progress on its infrastructure agenda in recent years. The early and successful ICT reform detonated a huge expansion in mobile coverage and penetration resulting in a highly competitive market. Power sector restructuring has paved the way for a rapid doubling of power generation capacity. Uganda is doing well on the water and sanitation MDGs, and has made effective use of performance contracting to improve utility performance. However, a number of important challenges remain. Despite reforms, the power sector continues to hemorrhage resources due to under-pricing and high distribution losses, while electrification rates are still very low. Providing adequate resources for road maintenance remains a challenge, and further investment is needed to increase rural connectivity and improve road safety. Addressing Uganda's infrastructure challenges will require sustained expenditure of around $1.4 billion per year over the next decade, strongly skewed towards capital expenditure. Uganda already spends approximately $1 billion per year on infrastructure, equivalent to about 11 percent of GDP. A further $0.3 billion a year is lost to inefficiencies, the bulk of which are associated with underpricing and distribution losses in the power sector. Uganda's annual infrastructure funding gap is about $0.4 billion per year, most of which is associated with irrigation as well as water and sanitation infrastructure.
Catalyst synthesis by analogy

Abstract Catalyst synthesis is discussed in terms of the identification of essential similarities that allow new catalysts to be suggested by analogy with known catalytic processes. Microkinetic simulation employing parameters with direct physical and chemical meaning provides an effective means to interpret, coordinate and generalize diverse experimental studies. Microkinetic simulation studies, therefore, can assist in the identification of similarities by consolidating in a quantitative fashion the experimental, theoretical and semi-empirical information relevant to the catalytic process. This procedure serves to focus our chemical intuition, generalize our experience with related catalytic processes, and use more effectively semi-empirical correlations to suggest new catalytic materials.
A Practical Directional Third Harmonic Hybrid Active Filter for Medium-Voltage Utility Applications

An increased level of harmonics due to the proliferation of single-phase nonlinear loads is raising serious concerns among utilities. Historically, passive filters have been proposed to reduce harmonics in medium-voltage (MV) utility applications. However, due to their limitations, utilities are turning their attention to alternative solutions. At the same time, active filters are prohibitively expensive and are unlikely to become a realistic solution in the near future. In this paper, a practical directional third harmonic hybrid active filter is proposed. A novel feature that adjusts the level of compensation provided by the filter based on the loading conditions of its passive components is introduced. Simulation and experimental results are presented. Issues related to utilizing existing VAr support capacitors for retrofit applications thereby achieving cost reduction and fail normal feature for increased reliability are addressed. Cost versus performance curves are developed using factual utility harmonic data. Finally, the impact of a distributed filtering solution based on the proposed filter is shown using a simplified MV distribution system.
Collision of a vortex with a vaporizing droplet

Abstract Three-dimensional interactions between an advecting vortex tube and a vaporizing droplet, described by the Navier–Stokes, energy, and species equations, cause fluctuations in the droplet heating and vaporization, manifested by temporal and time-averaged variations in the droplet Nusselt and Sherwood numbers. Stefan flux not only inhibits the droplet heating, it also ‘blocks’ the influence of vortex collision on the droplet interface inhibiting Nusselt number perturbations. The Stefan flux has a primary effect on the Nusselt number and a secondary one on the Sherwood number. Fluctuations in Sherwood number can be significant in magnitude and exhibit self-similarity in both the temporal and time-averaged response. Derived correlations are demonstrated to be valid for at least three common fuel droplets ( n -heptane, n -octane, n -decane). Furthermore, they quantify the effect of vortex collision on the droplet vaporization and compliment the accepted correlations for droplets in axisymmetric flows. It follows that, in spray combustion systems, vortical structures could significantly affect transport mechanisms, vaporization rates, and local mixture ratios.
Collagen metabolism in skin and periodontal membrane of the marmoset.

— The purpose of the present work was to investigate possible age changes in the rate of collagen formation in the periodontal membrane and to compare the collagen activity in the periodontal membrane with that found in the skin. Twenty-three marmosets (one baby, 14 young adults, and 8 old animals) were injected with 3H-proline and sacrificed 2, 7, and 21 days after injection. Autoradiographs were made from the periodontal tissues and from skin biopsies. The latter were furthermore analyzed with respect to total 3H-activity and specific hydroxyproline activity. In the periodontal membrane the grain counts were highest in the baby and higher in the young adult than in the old marmosets. The same pattern was observed in the skin. Here the grain counts were 8 times lower than in the periodontal membrane. Furthermore the autoradiographs revealed that the collagen activity in the gingival connective tissue was only half of that found in the periodontal membrane. It was concluded that the higher activity in the periodontal membrane was caused by a higher collagen concentration compared to gingival connective tissue and to skin.
Distributional aspects of the divisibility of money: an example

I highlight the importance of distributional aspects of money divisibility by comparing a search-theoretic model with random transfers of indivisible money balances, to one with deterministic transfers of partially divisible balances. Randomization allows price flexibility, as if money were fully divisible. Partial divisibility does not, but allows money redistributions. An example of the relevance of such ‘extensive margin’ aspects of divisibility is provided.
Towards history-based grammars: using richer models for probabilistic parsing

We describe a generative probabilistic model of natural language, which we call HBG, that takes advantage of detailed linguistic information to resolve ambiguity. HBG incorporates lexical, syntactic, semantic, and structural information from the parse tree into the disambiguation process in a novel way. We use a corpus of bracketed sentences, called a Tree-bank, in combination with decision tree building to tease out the relevant aspects of a parse tree that will determine the correct parse of a sentence. This stands in contrast to the usual approach of further grammar tailoring via the usual linguistic introspection in the hope of generating the correct parse. In head-to-head tests against one of the best existing robust probabilistic parsing models, which we call P-CFG, the HBG model significantly outperforms P-CFG, increasing the parsing accuracy rate from 60% to 75%, a 37% reduction in error.
PRACTICAL TOTAL SYNTHESIS OF (+)-CAMPTOTHECIN : THE FULL STORY

Abstract The evolution of our strategy for the synthesis of (+)-Camptothecin and related substances is presented in detail.
3D object recognition using single exposure on-line digital holography

On-line phase shifting digital holography requires recording of multiple holograms. In this paper, we describe a real time 3-D object recognition system using single exposure on-line digital holography. In contrast to 3-D object recognition employing conventional phase shifting scheme which requires multiple exposures, this method requires only one single digital hologram to be synthesized and used to recognize 3-D objects. A benefit of the proposed 3-D recognition method is enhanced practicality of digital holography for 3-D recognition in terms of its simplicity and more robustness to external scene parameters such as moving targets and environmental noise factors. We show experimentally, that the single exposure on-line digital holography based 3-D object recognition method is capable of providing 3-D object recognition. The experimental results are compared with that of the on-line phase shifting digital holographic based 3D recognition.
Further Studies of the Thermal and Photochemical Diels−Alder Reactions of N-Methyl-1,2,4-triazoline-3,5-dione (MeTAD) with Naphthalene and Some Substituted Naphthalenes

MeTAD thermally reacted with naphthalene (2) and methylated naphthalenes to give equilibrium mixtures of starting materials and [4 + 2] cycloadducts. Methyl substitution on the naphthalene ring generally increased both the amount of cycloadduct formed and the rate of cycloaddition relative to 2. The isolated cycloadducts were all thermally labile and quantitatively reverted to the parent naphthalene in the presence of 2,3-dimethyl-2-butene as a trap for liberated MeTAD. The rates of the cycloreversion reactions were affected by substitution patterns but not appreciably by solvent. A mechanism for the cycloaddition reaction is presented that proposes the involvement of a charge-transfer complex. Photochemically, MeTAD demonstrated lower regioselectivity in its reactions with substituted naphthalenes relative to the corresponding thermal reactions.
Antibacterial Activity of and Resistance to Small Molecule Inhibitors of the ClpP Peptidase

There is rapidly mounting evidence that intracellular proteases in bacteria are compelling targets for antibacterial drugs. Multiple reports suggest that the human pathogen Mycobacterium tuberculosis and other actinobacteria may be particularly sensitive to small molecules that perturb the activities of self-compartmentalized peptidases, which catalyze intracellular protein turnover as components of ATP-dependent proteolytic machines. Here, we report chemical syntheses and evaluations of structurally diverse β-lactones, which have a privileged structure for selective, suicide inhibition of the self-compartmentalized ClpP peptidase. β-Lactones with certain substituents on the α- and β-carbons were found to be toxic to M. tuberculosis. Using an affinity-labeled analogue of a bioactive β-lactone in a series of chemical proteomic experiments, we selectively captured the ClpP1P2 peptidase from live cultures of two different actinobacteria that are related to M. tuberculosis. Importantly, we found that the grow...
Flux-correlation approach to characterizing reaction pathways in quantum systems: a study of condensed-phase proton-coupled electron transfer

We introduce a simple method for characterizing reactive pathways in quantum systems. Flux auto-correlation and cross-correlation functions are employed to develop a quantitative measure of dynamical coupling in quantum transition events, such as reactive tunnelling and resonant energy transfer. We utilize the method to study condensed-phase proton-coupled electron transfer (PCET) reactions and to determine the relative importance of competing concerted and sequential reaction pathways. Results presented here include numerically exact quantum dynamics simulations for model condensed-phase PCET reactions. This work demonstrates the applicability of the new method for the analysis of both approximate and exact quantum dynamics simulations.
Spatial Modulation of Repeated Vibration Modes in Rotationally Periodic Structures

When a structure deviates from axisymmetry because of circumferentially varying model features, significant changes can occur to its natural frequencies and modes, particularly for the doublet modes that have non-zero nodal diameters and repeated natural frequencies in the limit of axisymmetry. Of technical interest are configurations in which inertia, dissipation, stiffness, or domain features are evenly distributed around the structure. Aside from the well-studied phenomenon of eigenvalue splitting, whereby the natural frequencies of certain doublets split into distinct values, modes of the axisymmetric structure that are precisely harmonic become contaminated with certain additional wavenumbers. From analytical, numerical, and experimental perspectives, this paper investigates spatial modulation of the doublet modes, particularly those retaining repeated natural frequencies for which modulation is most acute. In some cases, modulation can be sufficiently severe that a mode shape will beat' spatially as harmonics with commensurate wavenumbers combine, just as the superposition of time records having nearly equal frequencies leads to classic temporal beating. An algebraic relation and a diagrammatic method are discussed with a view towards predicting the wavenumbers present in modulated eigenfunctions given the number of nodal diameters in the base mode and the number of equally spaced model features.
Synthesis of N,N-Dimethyl-3-Noradamantanamine-N-Oxide

Abstract N,N-dimethyl-3-noradamantanamine-N-oxide (5), a potential precursor of tricyclo[3.3.1.03,7]nonan-3(7) ene, has been synthesized in two steps involving an Eshweiler-Clark reaction of 3-noradamantanamine followed by m-chloroperoxybenzoic acid oxidation of the resulting N,N-dimethylamino-3-noradamantanamine (4). Thermolysis of 5, however, unexpectedly gave the reduced N,N-dimethylamino product, 4.
Metal-germanium-metal photodetectors on heteroepitaxial Ge-on-Si with amorphous Ge Schottky barrier enhancement layers

We report a metal-Ge-metal photodetector fabricated on a Ge epitaxial layer grown on Si (100) substrate. Amorphous Ge was used to increase the Schottky barrier height, which resulted in a reduction of the dark current by more than two orders of magnitude. The dark current measured on a photodetector having 1 /spl mu/m finger width and 2 /spl mu/m spacing with 25/spl times/50 /spl mu/m/sup 2/ active area was 7.5 /spl mu/A at 3 V. At the wavelength of 1.3 /spl mu/m, the external quantum efficiency was 14.3% (0.15 A/W) without an antireflecting coating. At reverse biases of 1, 2, 3, and 4 V, the 3-dB bandwidth was found to be 1.5, 2.8, 3.1, and 4.3 GHz, respectively.
Predicted stabilities of monatomic anions in water and liquid ammonia at 298.15 K

Abstract Critically evaluated experimental and theoretical atomic electron affinities are assembled and used to derive thermodynamic properties of gas-phase monatomic anions throughout the Periodic Table. The stabilities (as ΔGof) of these anions in water and liquid ammonia are calculated by a semiempirical electrostatic model. The predictions are compared with experimental observations where possible.
Embedding Tree Metrics into Low-Dimensional Euclidean Spaces

We consider embedding metrics induced by trees into Euclidean spaces with a restricted number of dimensions. We show that any weighted tree T with n vertices and L leaves can be embedded into d -dimensional Euclidean space with O (L 1/(d-1) ) distortion. Furthermore, we exhibit an embedding with almost the same distortion which can be computed efficiently. This distortion substantially improves the previous best upper bound of \tilde O (n 2/d ) and almost matches the best known lower bound of Ω(L 1/d ) .
On the negative case of the Singular Yamabe Problem

Let (M, g) be a compact Riemannian manifold of dimension n ≥3, and let Γ be a nonempty closed subset of M. The negative case of the Singular Yamabe Problem concerns the existence and behavior of a complete metric g on M∖Γ that has constant negative scalar curvature and is pointwise conformally related to the smooth metric g. Previous results have shown that when Γ is a smooth submanifold (with or without boundary) of dimension d, there exists such a metric if and only if $$d > \frac{{n - 2}}{2}$$ . In this paper, we consider a more general class of closed sets and show the existence of a complete conformai metric ĝ with constant negative scalar curvature which depends on the dimension of the tangent cone to Γ at every point. Specifically, provided Γ admits a nice tangent cone at p, we show that when the dimension of the tangent cone to Γ at p is less than $$\frac{{n - 2}}{2}$$ then there cannot exist a negative Singular Yamabe metric ĝ on M∖Γ.
The Statistics of Statistical Arbitrage

Hedge funds sometimes use mathematical techniques to “capture” the short-term volatility of stocks and perhaps other types of securities. This sort of strategy resembles market making and is sometimes considered a form of statistical arbitrage. This study shows that for the universe of large-capitalization U.S. stocks, even quite naive techniques can achieve remarkably high information ratios. The methods used are quite general and should be applicable also to other asset classes.
The Control of Beryllium Hazards

The toxicological properties of beryllium and compounds of beryllium are briefly reviewed, together with the historical developmert of the recommendations for maximum permissible beryllium air concentrations. The application of the enclosure technique for the control of beryllium hazards is described. Emphasis is placed on the design objectives of partial and total enclosures and the related function of auxiliary components. Monitoring procedures used to evaluate the performance of enclosures are discussed. (auth)
Triploid fetus: An important consideration in the evaluation of very high maternal serum alpha‐fetoprotein

Two patients referred for evaluation of very high maternal serum alpha-fetoprotein (10-20 multiples of the median) were carrying triploid fetuses with placentas showing features of partial hydatidiform mole. The diagnosis of fetal triploidy should be considered when there is a very high maternal serum alpha-fetoprotein and no ultrasound evidence of open neural tube defect, ventral wall defect, or any other explanation. Therefore, chromosomal analysis of amniotic fluid cells in such cases is essential.
Income distribution, factor endowments, and trade openness

Abstract This paper studies the empirical links among factor endowments, trade and personal income distribution. By using panel data, we show that land and capital intensive countries have a less equal income distribution while skill intensive countries have a more equal income distribution. We also show that the effects of trade openness on inequality depend on factor endowments in a way consistent with several recent case studies but not with the simple Hecksher–Ohlin framework. Our results are robust to the division of the sample according to level of income, the inclusion of different regressors, the use of different measures of trade openness and of relative factor abundance, and tests for possible problems of endogeneity.
Quarks in the Skyrme-'t Hooft-Witten model

The three-flavor Skyrme-'t Hooft-Witten model is interpreted in terms of a quark-like substructure, leading to a new model of explicitly confined color-free “quarks” reminiscent of Gell-Mann's original pre-color quarks, but with unexpected and significant differences.