cssi/SciSciGPT-SciSciNet huggingface dataset:
RECENT DEVELOPMENTS IN ASYMMETRIC CATALYSIS USING SYNTHETIC POLYMERS WITH MAIN CHAIN CHIRALITY

Abstract Some recent developments in the use of main chain chiral polymer catalysts are summarized. These polymers are different from the traditional polymer catalysts that are prepared by anchoring monomeric chiral catalysts to an achiral polymer backbone. Three classes of synthetic main chain chiral polymers are discussed including: (1) helical polymers represented by polypeptides; (2) polymers with flexible chiral chains such as polyesters and polyamides; and (3) polymers of rigid and sterically regular chiral chains represented by chiral conjugated polybinaphthyls. Some of these polymer catalysts have shown high enantioselectivity in asymmetric organic transformations.
4-Aza-7,9-dideazaadenosine, a new cytotoxic synthetic C-nucleoside analogue of adenosine

Abstract The first synthesis of 10 , the pyrrolo[2,1-f][1,2,4]triazine C-nucleoside congener of adenosine is described. The key intermediate ribofuranosyl pyrrole 4 is obtained by the direct C-ribosylation of pyrrolemagnesiumbromide with 2,3,5-tri-O-benzyl ribose followed by an acid-catalyzed dehydration. Vilsmeier formylation of 4 followed by N-amination and CHO → CN conversion affords N-amino nitrile intermediate 7 which can be cyclized with formamidine acetate to the blocked title compound 9 . Hydrogenolytic debenzylation completes the synthesis. In vitro growth inhibitory activities of 10 against leukemic cell lines (0.8 – 15 nM) are comparable to those of 9-deazaadenosine.
Cation induced rearrangement of 8-azabicyclo[3.2.1]octa-2,6-dienes to 6-azabicyclo[3.2.1]oct-2-enes

Abstract Various electrophiles induce the rearrangement of 8-azabicyclo[3.2.1]octa-2,6-dienes to 6-azabicyclo[3.2.1]oct-2-enes.
Electrical and Pharmacologic Cardioversion for Atrial Fibrillation

This article describes electrical and pharmacologic cardioversion for atrial fibrillation and discusses indications for cardioversion and management of pericardioversion anticoagulation. Finally, management strategies are offered for immediate recurrence of atrial fibrillation and cardioversion failure.
Deaths from Narcotism in New York City Incidence, Circumstances, and Postmortem Findings

This report includes introductory background information describing the evolution of narcotic addiction as it is encountered today in the large metropolis of New York City. This study is based on more than thirty years experience of investigating officially the circumstances and determining the cause of all deaths of addicts occurring during that period of time.The statistical, illustrative, and pathologic data indicate an increasing number of deaths from narcotic addiction in the City of New York during the years 1950 through 1964, a total period of fifteen years. Statistical tables with detailed information of yearly and monthly incidence, racial and sex incidence, age distribution, marital status, occupation, geographic distribution by borough and district, character of premises where deceased was found, causes of death and postmortem findings, and present methods used for administration of drugs by addicts are described. The increasing incidence and total number of deaths due to addiction are of great...
Synthesis and applications of masked oxo-sulfinamides in asymmetric synthesis

This short perspective reports on the synthesis and applications of a class of chiral amino carbonyl compounds, masked oxo-sulfinamides where the amine is protected with an N-sulfinyl moiety and the carbonyl group is protected as the ketal or 1,3-dithiane. These polyfunctionalized chiral building blocks are prepared by addition of organometallic reagents to masked oxo-sulfinimines (N-sulfinyl imines) or the addition of oxo-organometallic reagents and lithio-1,3-dithianes to sulfinimines. Because unmasking of the amino and carbonyl groups results in cyclic imines, these chiral building blocks are particularly useful for the asymmetric synthesis of functionalized nitrogen heterocycles, including prolines, pipecolic acids, pyrrolidines, homotropinones, tropinones, and tropane alkaloids such as cocaine and C-1 cocaine analogues.
Convenient synthesis of 1,3-substituted-6-phenylpiperazin-2-ones

The convenient preparation of novel 6-phenylpiperazin-2-ones from simple starting materials via a practical two-step procedure is presented. This methodology involves an initial alkylation of 2-bromoacetophenone with an amino ester followed by a one-pot reductive amination and cyclization step to furnish the desired substituted piperazinones.
Numerical tests of a modified full implicit continuous Eulerian (FICE) scheme with projected normal characteristic boundary conditions for MHD flows

A numerical method has been developed based on a modified full implicit continuous Eulerian (FICE) scheme and projected normal characteristic boundary conditions for simulating MHD flows which undergo a long process of evolution. An astrophysical flow is chosen for illustration of this procedure, and numerical tests are made to verify the computational stability and physically realistic solution. Three computational tests have been accomplished; they are tests of solving methods, characteristic boundary condition, and time steps. The tests show that the program from the modified FICE scheme with proper boundary conditions and time steps can be made numerically stable for a time long enough to obtain physically plausible solutions.
Random Access: An Information-Theoretic Perspective

This paper considers a random access system where each sender is in one of two possible states, active or not active, and the states are only known to the common receiver. Active senders encode data into independent information streams, a subset of which is decoded depending on the collective interference. An information-theoretic formulation of the problem is presented and the set of achievable rates is characterized with a guaranteed gap to optimality. Inner and outer bounds on the capacity region of a two-sender system are tight in the case of a binary-expansion deterministic channel and differ by less than one bit in the case of a Gaussian channel. In systems with an arbitrary number of senders, the symmetric scenario of equal access probabilities and received power constraints is studied and the system throughput, i.e., the maximum achievable expected sum rate, is characterized. It is shown that a simple coding scheme where active senders transmit a single message is optimum for a binary-expansion deterministic channel and achieves within one bit of the optimum in the case of a Gaussian channel. Finally, a comparison with the slotted ALOHA protocol is provided, showing that encoding rate adaptation at the transmitters achieves constant (rather than zero) throughput as the number of users tends to infinity.
Light amplification in a disordered Raman medium

Abstract The amplification of a probe beam by stimulated Raman scattering in a disordered medium is experimentally investigated. The measurements are performed in Ba(NO 3 ) 2 powders with 532-nm pumping and a 563-nm Raman generated probe. The results fit well with Monte Carlo simulations of the experiment.
Tin(IV)-catalyzed lactonization of ω-Hydroxy trifluoroethyl esters

Abstract 1,1,1-Trifluoroethyl esters of ω-hydroxycarboxylic acids were prepared and their conversion to macrocyclic lactones, including ricinelaidic lactone, was studied in the presence of catalytic quantities of tin(IV) reagents; a mechanism involving exchange of alkoxytrialkyltin species is proposed.
Local consistency in parallel constraint satisfaction networks

Abstract In this paper we present several basic techniques for achieving parallel execution of constraint networks. The major result supported by our investigations is that the parallel complexity of constraint networks is critically dependent on subtle properties of the network that do not influence its sequential complexity.
Concise route to a series of novel 3-(tetrazol-5-yl)quinoxalin-2(1H)-ones

This Letter presents a novel three step solution phase protocol to synthesize 3-(tetrazol-5-yl)quinoxalin-2(1H)-ones. The strategy utilizes ethyl glyoxalate and mono-N-Boc-protected-o-phenylenediamine derivatives in the Ugi-Azide multi-component reaction (MCR) to generate a unique 1,5-disubstituted tetrazole. Subsequent acid treatment stimulates a simultaneous Boc deprotection and intramolecular cyclization leading to bis-3,4-dihydroquinoxalinone tetrazoles. Direct oxidation using a stable solid-phase radical catalyst (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) with ceric ammonium nitrate (CAN) in catalytic fashion initiating aerobic oxidation, completes the entire procedure to generate a series of original unique bis-quinoxalinone tetrazoles. The method was also expanded to produce a bis-benzodiazepine tetrazole.
Evaluation of neutron energy spectrum effects and RPV thru-wall attenuation based on molecular dynamics cascade simulations

Abstract Displacement cascade formation in iron has been investigated by the method of molecular dynamics (MD) for cascade energies up to 40 keV. The results of these simulations have been used in the specomp code to obtain effective, energy-dependent cross sections for two measures of primary damage production: (1) the number of surviving point defects expressed as a fraction of the those predicted by the standard secondary displacement model by Norgett et al., 1975 [M.J. Norgett, M.T. Robinson, and I.M. Torrens, Nucl. Eng. Des. 33, (1975) 50–54] and (2) the fraction of the surviving interstitials contained in clusters that formed during the cascade event. The primary knock-on atom (PKA) spectra for iron obtained from the specter code have been used to weight these MD-based damage production cross sections in order to obtain spectrally-averaged values for several locations in commercial fission reactors and test reactors. An evaluation of these results indicates that neutron energy spectrum differences between the various environments do not lead to significant differences between the average primary damage formation parameters. In particular, spectrum-averaged defect production cross sections obtained for PWR and BWR neutron spectra were not significantly different. A representative application of the new defect production cross sections is provided by examining how they vary as a function of depth into the reactor pressure vessel wall. A slight difference was noted between the damage attenuation in a PWR vessel and a BWR vessel. This observation could be explained by a subtle difference in the energy dependence of the neutron spectra. Overall, the simulations indicate that spectrum-averaged defect production cross sections do not vary much among the various environments in light-water moderated fission reactors. As such, the results support the use of atomic displacements per atom (dpa) as a damage correlation parameter and provide guidance for choosing the primary damage source term in kinetic embrittlement models.
On the Pressure Rippling and Roughness Deformation in Elastohydrodynamic Lubrication of Rough Surfaces

The Objective of this paper is to conduct a qualitative analysis on the effects of lubricant shear thinning, lubricant shear heating and the roughness-induced transients on the pressure rippling and roughness deformation that occurs under elastohydrodynamic lubrication (EHL) conditions. To facilitate the analysis, the numerical solutions to an example problem (EHL) line contact between a perfectly smooth surface and a sinusoidal rough surface are presented. This micro-EHL problem is first solved using the conventional model of a Newtonian lubricant and a stationary rough surface under isothermal conditions
Time-dependent models of dense PDRs with complex molecules

We present a study of the chemistry of a dense photon-dominated region (PDR) using a time-dependent chemical model. Our major interest is to study the spatial distribution of complex molecules such as hydrocarbons and cyanopolyynes in the cool dense material bordering regions where star formation has taken place. Our standard model uses a homogeneous cloud of density 2 x 10 4 cm -3 and temperature T = 40 K, which is irradiated by a far-ultraviolet radiation field of intermediate intensity, given by Χ = 100. We find that over a range of times unsaturated hydrocarbons (e.g. C 2 H, C 4 H, C 3 H 2 ) have relatively high fractional abundances in the more external layers of the PDR, whereas their abundances in the innermost layers are several orders of magnitudes lower. On the other hand, molecules that are typical of late-time chemistry are usually more abundant in the inner parts of the PDR. We also present results for models with different density, temperature, intensity of the radiation field and initial fractional abundances. Our results are compared with both high and moderate angular resolution observations of the Horsehead nebula. Our standard model is partially successful in reproducing the observations. Additional models run with different physical parameters are able to reproduce the abundance of many of the observed molecules, but we do not find a single model that fits all the observations at the same time. We discuss the suitability of a time-dependent model of a dense PDR such as ours as an estimator of the age of a PDR, provided that enough observational data exist.
Genetic drift opposes mutualism during spatial population expansion

Mutualistic interactions benefit both partners, promoting coexistence and genetic diversity. Spatial structure can promote cooperation, but spatial expansions may also make it hard for mutualistic partners to stay together, because genetic drift at the expansion front creates regions of low genetic and species diversity. To explore the antagonism between mutualism and genetic drift, we grew cross-feeding strains of the budding yeast Saccharomyces cerevisiae on agar surfaces as a model for mutualists undergoing spatial expansions. By supplying varying amounts of the exchanged nutrients, we tuned strength and symmetry of the mutualistic interaction. Strong mutualism suppresses genetic demixing during spatial expansions and thereby maintains diversity, but weak or asymmetric mutualism is overwhelmed by genetic drift even when mutualism is still beneficial, slowing growth and reducing diversity. Theoretical modeling using experimentally measured parameters predicts the size of demixed regions and how strong mutualism must be to survive a spatial expansion.
Input versus Output Monitoring: Who Is the Residual Claimant?

Abstract We observe that residual claimancy can be a source of rent in a principal-agent relationship. We show that the choice between input or output monitoring will be chiefly determined by the identity of the residual claimant of the principal-agent relationship. The principal will find input monitoring more efficient if the principal is the residual claimant, and he will find output monitoring more efficient if the agent is the residual claimant. If residual claimancy is a choice, the principal will be the residual claimant under input monitoring. Under output monitoring, residual claimancy is not an issue. If both residual claimancy and the monitoring instrument can be chosen, the principal will choose to monitor input and to be the residual claimant. Journal of Economic Literature Classification Numbers: D23, D82, L22.
Isoprenoid-like alkylations in polyketide biosynthesis.

Polyketides are secondary metabolites biosynthesized by the iterative Claisen condensation of malonate units. Despite utilizing only a small set of biochemical transformations, the polyketide biosynthetic machinery yields products of striking structural complexity and diversity. Recently, a new polyketide alkylation pathway was characterized that allows access to “β-branched” structures. This Highlight will describe this alkylation sequence, with special emphasis on its parallels to isoprenoid biosynthesis from primary metabolism and the scope of structures accessible via this pathway.
Convoy Electron Production in Polycrystalline and Monocrystalline Targets

The velocity distribution of electrons ejected close to the forward direction by 0.8-2 MeV/A ions traversing various solid targets, including a Au monocrystal, is measured in coincidence with emerging charge-selected ions. The velocity spectrum is observed to be independent of outgoing projectile velocity and charge state for polycrystalline targets. Measurements on the Au crystal under channeling conditions show dependences on final charge state, and are tentatively explained by assuming that the main contribution to the production yield comes from the non-channeled fraction of the ions. A simple model for the creation of the forward-ejected electrons is proposed, which accounts for most of the experimental findings.
Matrix distributed processing: a set of C++ tools for implementing generic lattice computations on parallel systems

Abstract We present a set of programming tools (classes and functions written in C++ and based on Message Passing Interface) for fast development of generic parallel (and non-parallel) lattice simulations. They are collectively called MDP 1.2 . These programming tools include classes and algorithms for matrices, random number generators, distributed lattices (with arbitrary topology), fields and parallel iterations. No previous knowledge of MPI is required in order to use them. Some applications in electromagnetism, electronics, condensed matter and lattice QCD are presented.
Conscience and convenience: The asylum and its alternatives in progressive America

Conscience and Convenience was quickly recognized for its masterly depiction and interpretation of a major period of reform history. This history begins in a social context in which treatment and rehabilitation were emerging as predominant after America's prisons and asylums had been broadly acknowledged to be little more than embarrassing failures. The resulting progressive agenda was evident: to develop new, more humane and effective strategies for the criminal, delinquent, and mentally ill. The results, as Rothman documents, did not turn out as reformers had planned. For adult criminal offenders, such individual treatment could be accomplished only through the provision of broad discretionary authority, whereby choices could be made between probation, parole, indeterminate sentencing, and, as a measure of last resort, incarceration in totally redesigned prisons. For delinquents, the juvenile court served as a surrogate parent and accelerated and intensified individual treatment by providing for a series of community-based individual and family services, with the newly designed, school-like reformatories being used for only the most intractable cases. For the mentally ill, psychiatrists chose between outpatient treatments, short-term intensive care, or as last resort, long-term care in mental hospitals with new cottage and family-like arrangements. Rothman shows the consequences of these reforms as unmitigated disasters. Despite benevolent intentions, the actual outcome of reform efforts was to take the earlier failures of prisons and asylums to new, more ominous heights. In this updated edition, Rothman chronicles and examines incarceration of the criminal, the deviant, and the dependent in U.S. society, with a focus on how and why these methods have persisted and expanded for over a century and a half despite longstanding evidence of their failures and abuses.
Microbial Engineering for Aldehyde Synthesis

ABSTRACT Aldehydes are a class of chemicals with many industrial uses. Several aldehydes are responsible for flavors and fragrances present in plants, but aldehydes are not known to accumulate in most natural microorganisms. In many cases, microbial production of aldehydes presents an attractive alternative to extraction from plants or chemical synthesis. During the past 2 decades, a variety of aldehyde biosynthetic enzymes have undergone detailed characterization. Although metabolic pathways that result in alcohol synthesis via aldehyde intermediates were long known, only recent investigations in model microbes such as Escherichia coli have succeeded in minimizing the rapid endogenous conversion of aldehydes into their corresponding alcohols. Such efforts have provided a foundation for microbial aldehyde synthesis and broader utilization of aldehydes as intermediates for other synthetically challenging biochemical classes. However, aldehyde toxicity imposes a practical limit on achievable aldehyde titers and remains an issue of academic and commercial interest. In this minireview, we summarize published efforts of microbial engineering for aldehyde synthesis, with an emphasis on de novo synthesis, engineered aldehyde accumulation in E. coli, and the challenge of aldehyde toxicity.
Highly regioselective, catalytic asymmetric reductive coupling of 1,3-enynes and ketones.

Highly regioselective, catalytic asymmetric reductive coupling reactions of 1,3-enynes and ketones have been achieved using catalytic amounts of Ni(cod)2 and a P-chiral, monodentate ferrocenyl phosphine ligand. These couplings represent the first examples of catalytic, intermolecular reductive coupling of alkynes and ketones, enantioselective or otherwise, and afford synthetically useful 1,3-dienes possessing a quaternary carbinol stereogenic center in up to 70% ee.
Bayesian sequential auctions

In many natural settings agents participate in multiple different auctions that are not simultaneous. In such auctions, future opportunities affect strategic considerations of the players. The goal of this paper is to develop a quantitative understanding of outcomes of such sequential auctions. In earlier work (Paes Leme et al. 2012) we initiated the study of the price of anarchy in sequential auctions. We considered sequential first price auctions in the full information model, where players are aware of all future opportunities, as well as the valuation of all players. In this paper, we study efficiency in sequential auctions in the Bayesian environment, relaxing the informational assumption on the players. We focus on two environments, both studied in the full information model in Paes Leme et al. 2012, matching markets and matroid auctions. In the full information environment, a sequential first price cut auction for matroid settings is efficient. In Bayesian environments this is no longer the case, as we show using a simple example with three players. Our main result is a bound of 3 on the price of anarchy in both matroid auctions and matching markets. To bound the price of anarchy we need to consider possible deviations at an equilibrium. In a sequential Bayesian environment the effect of deviations is more complex than in one-shot games; early bids allow others to infer information about the player's value. We create effective deviations despite the presence of this difficulty by introducing a bluffing technique of independent interest.
A Polynomial Combinatorial Algorithm for Generalized Minimum Cost Flow

We propose the first combinatorial solution to the generalized minimum cost flow problem (flow with losses and gains). Despite a rich history dating back to Kantorovich and Dantzig, until now, the only known way to solve the problem in polynomial-time was via general-purpose linear programming techniques. Polynomial combinatorial algorithms were previously known only for the version of our problem without costs. We design the first such algorithms for the version with costs. Our algorithms also find provably good solutions faster than optimal ones, providing the first strongly polynomial approximation schemes for the problem.Our techniques extend to optimize linear programs with two variables per inequality. Polynomial combinatorial algorithms were previously developed for testing the feasibility of such linear programs. We propose the first such methods for the optimization version.
Classical theory of radiative transitions

A semiclassical method of approach to the origin of radiation in a simple quantum transition is reinterpreted and extended. The resulting concepts are applied to an analysis of the Compton effect, yielding the Klein-Nishina formula as usual. More significant is the natural appearance in this case of photonlike behavior of the purely classical electromagnetic fields. The same phenomenon can be hypothesized to occur in any transition in which a quantized-photon nature of radiation appears evident. A similar classical viewpoint taken toward the Lamb shift leads to a straightforward explanation which seems to give very good agreement with experiment. The calculated frequency for the $2{P}_{\frac{1}{2}}\ensuremath{\rightarrow}2{S}_{\frac{1}{2}}$ transition in H is 1064.57 MHz = 0.0355102 ${\mathrm{cm}}^{\ensuremath{-}1}$. The argument also has some important implications for ideas about the physical nature of quantum states.
Flutter of Articulated Pipes at Finite Amplitude

Previous studies of the behavior of pipes conveying fluid have assumed that the fluid velocity relative to the pipe is a known quantity and is unaffected by the motion of the pipe. This approach eliminates the need to find the flow equations of motion, and is adequate for infinitesimal transverse amplitudes of motion of the pipe system, but is incapable of predicting what will be the effect of larger amplitudes. This last shortcoming may be of importance when flow velocities are near critical velocities, that is, velocities at which the system begins to flutter. It is the purpose of the present study to investigate in greater detail the dynamic behavior of pipes in the vicinity of critical velocities.
The Effect of Plasma Heating on Sublimation-Driven Flow in Io's Atmosphere

The atmospheric flow on Io is numerically computed in a flat 2-D axisymmetric geometry for a sublimation atmosphere on the trailing hemisphere subjected to plasma bombardment, UV heating, and IR cooling. Calculations are performed for subsolar vapor pressures of approximately 6.5 x 10(exp -3) Pa (approximately 3 x 10(exp 18) SO2/sq cm) and 6.8 x 10(exp -4) Pa (approximately 4 x 10(exp 17) SO2/sq cm); the latter approximates the vapor pressure of F. P. Fanale et al. (1982). The amount of plasma energy deposited in the atmosphere is 20% of the plasma flow energy due to corotation (J. A. Linker et al., 1988). It is found that plasma heating significantly inflates the upper atmosphere, increasing both the exobase altitude and the amount of surface covered by more than an exospheric column of gas. This in turn controls the supply of the Io plasma torus (M. A. McGrath and R. E. Johnson, 1987). The horizontal flow of mass and energy is also important in determining the exobase altitude; and it is shown that IR cooling can be important, although our use of the equilibrium, cool-to-space approximation for a pure SO2 gas (E. Lellouch et al., 1992) may overestimate this effect. The calculated exobase altitudes are somewhat lower than those suggested by McGrath and Johnson (1987) for supplying the torus, indicating the details of the plasma energy deposition and sputter ejection rate near the exobase, as well as the IR emission from this region need to be examined. In addition, the molecules sublimed (or sputtered) from the surface are transported to the exobase in times short compared to the molecular photodissociation time. Therefore, the exobase is dominated by molecular species and the exobase is supplied by a small region of the surface.
Probability Density Function Modeling of Evaporating Droplets Dispersed in Isotropic Turbulence

A statistical closure scheme is used to obtain an approximate equation for probability density function to predict the statistical properties of interest of collisionless evaporating droplets suspended in isothermal isotropic turbulent flows. The resulting Fokker-Planck equation has nonlinear, time-dependent drift and diffusion coefficients that depend on the statistical properties of the droplet slip velocity. Approximate analytical expressions for these properties are derived, and the equation is solved numerically after implementing the path-integral approach. The time evolution of various statistical properties related to the droplet diameter are then calculated
Experimental determination of the antiaromaticity of cyclobutadiene

Photoacoustic calorimetry was used to quantify the antiaromaticity of 1,3-cyclobutadiene (CBD) by measuring the heat release accompanying its formation via photofragmentation of a polycyclic precursor. In combination with quantum yield measurements and thermochemical calculations, this measurement provides an enthalpy of formation for CBD of 114 ± 11 (2σ) kilocalories per mole (kcal/mol). The extraordinary reactivity of this prototypical antiaromatic hydrocarbon had previously made its heat of formation inaccessible except by theoretical calculations. Relative to a hypothetical strainless, conjugated diene reference, CBD is destabilized by a total of 87 kcal/mol, 32 kcal/mol of which can be attributed to ring strain and 55 kcal/mol to antiaromaticity (compared with 21 kcal/mol for the aromatic stabilization of benzene). Relative to a reference with isolated double bonds, CBD9s antiaromaticity is 48 kcal/mol (compared with 32 kcal/mol for the aromaticity of benzene).
Recognizing substrings of LR(k) languages in linear time

LR parsing techniques have long been studied as being efficient and powerful methods for processing context-free languages. A linear-time algorithm for recognizing languages representable by LR(k) grammars has long been known. Recognizing substrings of a context-free language is at least as hard as recognizing full strings of the language, since the latter problem easily reduces to the former. In this article we present a linear-time algorithm for recognizing substrings of LR(k) languages, thus showing that the substring recognition problem for these languages is no harder than the full string recognition problem. An interesting data structure, the Forest-Structured Stack, allows the algorithm to track all possible parses of a substring without loosing the efficiency of the original LR parser. We present the algorithm, prove its correctness, analyze its complexity, and mention several applications that have been constructed.
Theoretical model of activation of carcinogenic polycyclic benzenoid aromatic hydrocarbons. Possible new classes of carcinogenic aromatic hydrocarbons

Abstract Experimental Iball carcinogenicity indices of polycyclic benzenoid aromatic hydrocarbons (PBAH) are correlated by stepwise linear regression to theoretical reactivity indices. Size and structure factors, possibly related to intercalation, lipophilicity, or enzymatic specificity are included in the analysis. Multiple correlation coefficients of r = 0.971 and r = 0.989 are obtained from linear equations with size factors plus two and three additional parameters respectively. The relationships provide support for recent proposed models for metabolic PBAH activation. The relative stabilities of M-region intermediates are inferred to be more important than those of the bay-region cations. Three types of known, but yet untested PBAH are predicted to be carcinogenic, namely particular benzannelated derivatives of perylene, benzo[g,h,e]perylene and anthanthrene. Other benzannelated derivatives of the same parent structures are predicted to be completely inactive, the position of benzannelation being the critical factor.
Temperature dependence of the electron thermal conductivity coefficient inferred from neutral-beam injection

It is shown that the radial variation of the electron-ion temperature ratio induced by neutral-beam injection in PLT could account for the observed spatial dependence of electron thermal conductivity coefficient. Quantitative evaluations using the experimental temperature and electron thermal conductivity (χe) profiles show consistency of the measured data with the temperature scaling of a finite-beta drift wave turbulence model and also demonstrate the failure of a simple electron temperature power law scaling for χe
Even Simple Programs Are Hard To Analyze

A simple programming language which corresponds in computational power to the class of generalized sequential machines with final states is defined. It is shown that a variety of questions of practical programming interest about the language are of nondeterministic linear space complexity. Extensions to the language are defined (adding arithmetic and array data structures) and their complexity properties are explored. It is concluded that questions about halting, equivalence, optimization, and so on are intractable even for very simple programming languages.
Preparation of Optically Pure ω-Hydroxymethyl Lactams

Abstract Thermal cyclization of L-glutamate and L-α-aminoadipate to the corresponding lactam esters can be achieved without racemization. LiBH4 reduction of the esters provides optically pure hydroxymethyl lactams.
Relaxation and Clustering in a Local Search Framework: Application to Linear Placement

This paper presents two primary results relevant to physical design problems in CAD/VLSI through a case study of the linear placement problem. First a local search mechanism which incorporates a sophisticated neighborhood operator based on constraint relaxation is proposed. The strategy exhibits many of the desirable features of analytical placement while retaining the flexibility and non-determinism of local search. The second and orthogonal contribution is in netlist clustering. We characterize local optima in the linear placement problem through a simple visualization tool—the displacement graph. This characterization reveals the relationship between clusters and local optima and motivates a dynamic clustering scheme designed specifically for escaping such local optima. Promising experimental results are reported.
Active management, fund size, and bond mutual fund returns

Conventional wisdom holds that bonds are relatively homogenous investments compared to equities. Consequently, factors that explain variation in returns among bond mutual funds may differ in magnitude from those for equity mutual funds. In this study, a time-series cross-sectional analysis is employed to investigate the relationship between a bond fund's risk-adjusted return and specific fund attributes. Results indicate that a bond fund's past performance does not predict future performance and that bond fund managers are generally ineffective at increasing risk-adjusted returns. However, unlike equity mutual funds, bond mutual funds do appear to enjoy economies of scale.
A model for the ultrasonic detection of surface-breaking cracks by the scanning laser source technique

A model for the scanning laser source (SLS) technique is presented. The SLS is a novel laser-based inspection method for the ultrasonic detection of small surface-breaking cracks. The generated ultrasonic signal is monitored as a line-focused laser is scanned over the defect. Characteristic changes in the amplitude and the frequency content are observed. The modeling approach is based on the decomposition of the field generated by the laser in a cracked two-dimensional half-space, by virtue of linear superposition, into the incident and the scattered fields. The incident field is that generated by laser illumination of a defect-free half-space. A thermoelastic model has been used which takes account of the effect of thermal diffusion, as well as the finite width and duration of the laser source. The scattered field incorporates the interactions of the incident field with the surface-breaking crack. It has been analyzed numerically by a direct frequency domain boundary element method. A comparison with an experiment for a large defect shows that the model captures the observed phenomena. A simulation for a small crack illustrates the ability of the SLS technique to detect defects smaller than the wavelength of the generated Rayleigh wave.
Total synthesis of polyyne natural products

Abstract This account summarizes the work in the area of polyyne natural product synthesis both by us and by others. Three families of acetylenic natural products are included in the review. The first group involves the tetrayne-containing compounds of minquartynoic acid and its derivatives. This group of natural products is known to have highly potent anti-cancer and anti-HIV properties. The second group is known as the bidensyneosides and they are the glucosides of polyynes. The third group of natural products possesses a C 2 symmetry in their molecular structure and has attracted widespread interest in their total synthesis.
Small computers in a large world

Three years ago, 877 of us gathered in Philadelphia at the first Joint Computer Conference, a meeting organized by a committee representing three professional societies which were then, as now, active in the design and application of electronic computing devices. These are, of course, the AIEE, the Institute of Radio Engineers, and the Association for Computing Machinery (ACM). The theme of that first conference was a review of the state of the art up to that time. In the following two Decembers, in New York, N.Y., and in Washington, D.C., attention was directed first toward the problem of input-output and then toward the problem of reliability. Meanwhile, Western Joint Computer Conferences were held in Los Angeles, Calif., in February of 1953 and 1954, with a third scheduled for the first 3 days of March 1955 at the Hotel Statler in Los Angeles, Calif.
Applications of Seasat to the offshore oil, gas and mining industries

The NASA satellite Seasat-A (to be launched in 1978) has applications to the offshore oil, gas, and mining industries including: (1) improvements in weather and wave forecasting, (2) studies of past wind and wave statistics for planning design requirements, and (3) monitoring ice formation, breakup, and movement in arctic regions. The primary geographic areas which will be monitored by Seasat-A include: the Beaufort Sea, the Labrador Sea, the Gulf of Mexico, the U.S. east coast, West Africa, Equatorial East Pacific, the Gulf of Alaska, and the North Sea. Seasat-A instrumentation used in ocean monitoring consists of a radar altimeter, a radar scatterometer, a synthetic aperture radar, a microwave radiometer, and a visible and infrared radiometer. The future outlook of the Seasat program is planned in three phases: measurement feasibility demonstration (1978-1980), data accessibility/utility demonstration (1980-1983), and operational system demonstration (1983-1985).
Reactivity, photochemistry and thermochemistry of simple metal—ligand ions in the gas phase

Abstract In this review we discuss recent results from our laboratory on the chemistry, photochemistry and thermodynamics of simple metal—ligand ionic species in the gas phase. Using laser desorption coupled to Fourier transform mass spectrometry, we have successfully generated numerous highly unsaturated metal—ligand ions including bare metal carbenes, methyls, hydrides, nitrenes and amides. The combination of photodissociation, ion—molecule reactions and other techniques has made possible the determination of a wide variety of metal—ligand ion bond dissociation energies. Reactivity studies on these species reveal gas phase catalytic cycles including olefin homologation and Fe+ catalysed production of NC bonds from NH3, olefins and N2O. General trends are observed in the reactions of MOH+, MH+, MCH3+, and MNH2+ with alkanes; MO+ and MS+ with alkanes; and MNH+, MCH2+ and MO+ with alkenes.
DYKAT of vinyl aziridines: total synthesis of (+)-pseudodistomin D.

A concise total synthesis of (+)-pseudodistomin D was developed. The absolute stereochemistry was established through a dynamic kinetic asymmetric cycloaddition of an isocyanate to a vinyl aziridine. The piperidine core was constructed through a silver(I)-catalyzed hydroamination of an alkyne and subsequent diastereo- and regioselective reduction.
Total synthesis of methyl picrotoxate via the palladium catalyzed enyne cycloisomerization reaction

Abstract Bifurcation of the synthetic pathway affording total syntheses of picrotoxinin, picrotin and corianin from a common synthetic intermediate derived via the palladium catalyzed enyne cycloisomerization leads to the total synthesis of the picrotoxane sesquiterpene methyl picrotoxate.
Feeding Phenobarbital and Activated Carbon to Accelerate Dieldrin Residue Removal in a Contaminated Dairy Herd

Abstract Feeding of phenobarbital and activated carbon apparently was effective in accelerating removal of dieldrin in a 105-cow dairy herd. After one week of treatment, residue had declined about 64% compared with 36% for the control group. At 22 days milk residue in the treated group was about one-half that of the control group. The time during which the milk had to be withheld from market was shortened by at least one month for the treated group.
A new kind of primitive chondrite, Allan Hills 85085

Allan Hills (ALH) 85085, a chemically and mineralogically unique chondrite whose components have suffered little metamorphism or alteration, is discussed. It is found that ALH 85085 has 4 wt pct chondrules (mean diameter 16 microns), 36 wt pct Fe, Ni, 56 wt pct lithic and mineral silicate fragments, and 2 wt pct trolite. It is suggested that, with the exception of matrix lumps, the components of ALH 85085 formed and accreted in the solar nebula. It is shown that ALH 85085 does not belong to any of the nine chondrite groups and is very different from Kakangari. Similarities between ALH 85085 and Bencubbin and Weatherford suggest that the latter two primitive meteorites may be chondrites with high metal abundances and very large, partly fragmented chondrules.
COSMIC BACKGROUND RADIATION TEMPERATURE ANISOTROPY: POSITION OF FIRST DOPPLER PEAK

The purpose of the Cosmic Background Radiation experiments is to measure the temperature anisotropy via the autocorrelation function. The partial wave l1 corresponding to the first Doppler peak caused by baryon–photon oscillations at the surface of last scattering depends on the present density Ω0 and the cosmological constant contribution ΩΛ. We discuss this dependence on the basis of perspicuous figures.
New N = 1 dualities from M5-branes and outer-automorphism twists

We generalize recent construction of four-dimensional $ \mathcal{N} $ = 1 SCFT from wrapping six-dimensional $ \mathcal{N} $ = (2, 0) theory on a Riemann surface to the case of D-type with outer-automorphism twists. This construction allows us to build various dual theories for a class of $ \mathcal{N} $ = 1 quiver theories of SO-USp type. In particular, we find there are five dual frames to SO(2N)/USp(2N−2)/G 2 gauge theories with (4N−4)/(4N)/8 fundamental flavors, where three of them being non-Lagrangian. We check the dualities by computing the anomaly coefficients and the superconformal indices. In the process we verify that the index of D 4 theory on a certain three punctured sphere with $ {{\mathbb{Z}}_2} $ and $ {{\mathbb{Z}}_3} $ twist lines exhibits expected symmetry enhancement from G 2 × USp(6) to E 7.
Novel Cascade Diode Lasers Based on Type-I Quantum Wells

A novel approach for cascade diode lasers was developed based on type-I quantum wells (QWs). This design adopted the leaky window effect in the GaSb/InAs band alignment for cascade pumping, and exploits the carriers recycling by the cascade pumping and the high optical gain of the type-I QWs. Two-stage cascade lasers were designed and fabricated for 2.45 and 3.0 μm, demonstrating twofold improvement in the internal efficiency. Record continuous-wave (CW) output power of 1.2 W for 2.45 um and 590 mW for 3.0 um were achieved in room temperature (RT), and the devices operate with higher power conversion efficiency at high power level, compared to conventional single-stage diode lasers.
Norm-preserving discretization of integral equations for elliptic PDEs with internal layers I: The one-dimensional case

We investigate the behavior of integral formulations of variable coefficient elliptic partial differential equations in the presence of steep internal layers. In one dimension, the equations that arise can be solved analytically and the condition numbers estimated in various $L^p$ norms. We show that high-order accurate Nystrom discretization leads to well-conditioned finite-dimensional linear systems if and only if the discretization is both norm-preserving in a correctly chosen $L^p$ space and adaptively refined in the internal layer.
Excitation functions in central Au+Au collisions from SIS/GSI to AGS/Brookhaven

Abstract Using the relativistic transport model (ART), we predict the energy dependence of the stopping power, maximum baryon and energy densities, the population of resonance matter as well as the strength of the transverse and radial flow for central Au+Au reactions at beam momentum from 2 to 12 GeV c available at Brookhaven's AGS. The maximum baryon and energy densities are further compared to the predictions of relativistic hydrodynamics assuming the formation of shock waves. We also discuss the Fermi-Landau scaling of the pion multiplicity in these reactions.
Indications and outcomes of reversal of Roux-en-Y gastric bypass

Abstract Background Laparoscopic Roux-en-Y gastric bypass (RYGB) is proven to be a safe and effective treatment of obesity and related co-morbidities. However, there is a small group of patients who are unable to tolerate postoperative complications and ultimately undergo reversal procedures. This study demonstrates indications and postoperative outcomes in 8 patients following RYGB reversal. Methods Retrospective review of 8 patients who required RYGB reversal between July 2009 to October 2013. Data points included demographic characteristics, body mass index (BMI), co-morbidities, reasons for reversal and postoperative outcomes. Results All patients were female with a mean age of 44.5±8.8 years (range, 35–63) and BMI of 30.0±9.8 kg/m 2 (range, 19.3–43.8) before reversal. Reasons for reversal included recurrent anastomotic ulcer (n = 3), intractable nausea and emesis (n = 3), hypocalcemia (n = 1), and neuroglycopenia (n = 1). Mean period from RYGB to reversal was 127.8±95.4 months (range, 21–298) and mean length of hospital stay following reversal was 5.1±3.0 days (range, 2–11). One patient was lost to follow-up. Mean BMI at the last visit was 37.3±12.6 kg/m 2 (range, 24.0–56.5). Two patients (28.6%) maintained the same weight 9 and 11 months after reversal. One returned to her pre-RYGB weight and 4 patients gained some of their weight back after reversal. Three (37.5%) patients required readmissions for abdominal pain and nausea/vomiting, and no patients required reoperations following RYGB reversal. Conclusions Reversal of RYGB to normal anatomy is reasonable in patients with severe or refractory complications.
Characterization of Fuel Regression in a Radial Flow Hybrid Rocket

Reliable ignition and stable combustion have been achieved in a lab-scale radial-e ow hybrid rocket engine. The device utilizes 85% hydrogen peroxide and polyethylene and was tested at chamber pressures ranging from 118 to 238 psia. Fuel regression behavior was characterized with respect to initial geometry and mass e ux. The measured regression rates are greater than observed in axial port designs at the same e ux and chamber pressure levels. Although the regression behavior is effected locally by the three-dimensional e ow structure, the results were more uniform than predicted by lumped parameter ballistics approximations. For this reason, radial-e ow designs with acceptable fuel utilization appear to be feasible.
Exact results and duality for Sp(2N) SUSY gauge theories with an antisymmetric tensor

We study supersymmetric Sp(2N) gauge theories with matter in the antisymmetric tensor representation and F fundamentals. For F = 6 we solve the theory exactly in terms of confined degrees of freedom and a superpotential. By adding mass terms we obtain the theories with F < 6 which we find to exhibit a host of interesting non-perturbative phenomena: quantum-deformed moduli spaces with N constraints, instanton-induced superpotentials and non-equivalent disjoint branches of moduli spaces. We find a simple dual for F = 8 and no superpotential. We show how the F = 4 and F = 2 theories can be modified to break supersymmetry spontaneously and point out that the Sp(6) theory with F = 6 may be very interesting for model builders.