cssi/SciSciGPT-SciSciNet huggingface dataset:
Measurement of Particle Contamination

The impact of particle contamination on spacecraft surfaces is frequently p roportional to the surface area obscured. The degree of obscuration is calculated for the levels of clean1 iness as defined in MIL-STD-1246A after clarifying the meaning of the size frequency distribution used there. However, it is found that shocks, vibration, and scrubbing can distort the distribution and introduce s erious error if small particles are not included in the measurement. Visual appearance of a s urface seems to be proportional to r eflectivity which is proportional to surface o bscuration. Thus, visual appearance seems a more direct measure of the effect of particle contamination t han the quantitative measurements of MIL-STD-1246A.
Advection-Dominated Accretion with Infall and Outflows

We present self-similar solutions for advection-dominated accretion flows with radial viscous force in the presence of outflows from the accretion flow or infall. The axisymmetric flow is treated in variables integrated over polar sections and the effects of infall and outflows on the accretion flow are parametrized for possible configurations compatible with the self-similar solution. We investigate the resulting accretion flows for three different viscosity laws and derive upper limits on the viscosity parameter α. In addition, we find a natural connection to nonrotating and spherical accretion with turbulent viscosity, which is assumed to persist even without differential rotation. Positive Bernoulli numbers for advection-dominated accretion allow a fraction of the gas to be expelled in an outflow, and the upper limit on the viscosity predicts that outflows are inevitable for equations of state close to an ideal gas.
Angular distribution of Rossby wave energy

Abstract It is shown that the extra invariant for systems of the Rossby waves—which was discovered in 1991—provides the missing theoretical argument for the anisotropic accumulation of the Rossby wave energy in the large-scale zonal flow.
WEAK MATRIX ELEMENTS FOR CP VIOLATION

We present preliminary results of matrix elements of four fermion operators relevant to the determination of e and E ' / E using staggered fermions. To calculate the matrix elements relevant to CP violation in Kaon decays it is important to use a lattice formulation which preserves (some) chiral symmetry.
Non-existence of equilibrium in Vickrey, second-price, and English auctions

A simple example shows that equilibria can fail to exist in second price (Vickrey) and English auctions when there are both common and private components to bidders’ valuations and private information is held on both dimensions. The example shows that equilibrium only exists in the extremes of pure private and pure common values, and that existence in standard models is not robust to a slight perturbation.
Synchronous dynamics of a coupled shaft/bearing/housing system with auxiliary support from a clearance bearing: Analysis and experiment

This study examines the response of a flexible rotor supported by load sharing between linear bearings and an auxiliary clearance bearing. The objective of the work is to develop a better understanding of the dynamical behavior of a magnetic bearing supported rotor system interacting with auxiliary bearings during a critical operating condition. Of particular interest is the effect of coupling between the bearing/housing and shaft vibration on the rotordynamical responses. A simulation model is developed and a number of studies are performed for various parametric configurations. An experimental investigation is also conducted to compare and verify the rotordynamic behavior predicted by the simulation studies. A strategy for reducing synchronous shaft vibration through appropriate design of coupled shaft/bearing/housing vibration modes is identified. The results are presented and discussed.
Permuting Diels–Alder and Robinson annulation stereopatterns

Controlled isomerization of the double bond of certain Diels–Alder reaction products provides substrates that, upon oxidation, give rise to products whose gross structure corresponds to that of a Robinson annulation. In these cases, the stereochemistry of the Robinson annulation product reflects the fact that the initial combination occurred in a Diels–Alder mode. Using these principles, we have synthesized carissone and cosmosoic acid. In the latter case, our total synthesis raised serious questions as to the accuracy of the assigned structure of the natural product.
WHY DO MANAGERS ACT FAIRLY IN THE FIRST PLACE? A DAILY INVESTIGATION OF "HOT" AND "COLD" MOTIVES AND DISCRETION

Although considerable research has focused on employee reactions to organizational justice, far less research has examined why managers adhere to rules of justice in the first place. Taking a proactive approach to organizational justice, we address this void by examining managerial motives for adhering to distributive, procedural, informational, and interpersonal rules of justice on a day-to-day basis. Results of an experience-sampling study of 90 managers who completed daily surveys over a three-week period revealed that both "cold" cognitive (i.e., effecting compliance, identity maintenance, and establishing fairness) and "hot" affective (i.e., high positive affect and low negative affect) motives were associated with managerial adherence to justice rules. Moreover, "cold" motives were more strongly associated with justice rule adherence for justice dimensions over which managers perceived less discretion, while "hot" motives were more strongly associated with justice rule adherence for justice dimensions over which managers perceived greater discretion. We discuss the implications of our findings for both theory and practice
Flow channels/fiber impregnation studies for the process modeling/analysis of complex engineering structures manufactured by resin transfer molding

The success of resin transfer molding (RTM) depends upon the complete wetting of the fiber preform. Effective mold designs and process modifications facilitating the improved impregnation of the preform have direct impact on the successful manufacturing of parts. Race tracking caused by variations in permeabilities around bends, corners in liquid composite molding (LCM) processes such as RTM have been traditionally considered undesirable, while related processes such as vacuum assisted RTM (VARTM) and injection molding have employed flow channels to improve the resin distribution. In this paper, studies on the effect of flow channels are explored for RTM through process simulation studies involving flow analysis of resin, when channels are involved. The flow in channels has been modeled and characterized based on equivalent permeabilities. The flow in the channels is taken to be Darcian as in the fiber preform, and process modeling and simulation tools for RTM have been employed to study the flow and pressure behavior when channels are involved. Simulation studies based on a flat plate indicated that the pressures in the mold are reduced with channels, and have been compared with experimental results and equivalent permeability models. Experimental comparisons validate the reduction in pressures with channels and validate the use of equivalent permeability models. Numerical simulation studies show the positive effect of the channels to improve flow impregnation and reduce the mold pressures. Studies also include geometrically complex parts to demonstrate the positive advantages of flow channels in RTM.
Auctions of licences and market structure

This paper studies sequential auctions of licences to participate in a symmetric market game. Assuming that the rate at which industry profits decrease with repeated entry is not too large, at the unique solution either a single firm preempts entry altogether or entry occurs in every stage, depending on the net benefit of complete preemption to an incumbent. If we relax the assumption, a third outcome can occur: two firms may coordinate their choices to avoid further entry. The analysis employs a new refinement of Nash equilibrium, the concept of recursively undominated equilibrium.
Photon counting statistics for blinking CdSe-ZnS quantum dots: a Lévy walk process.

We analyze photon statistics of blinking CdSe-ZnS nanocrystals interacting with a continuous wave laser field, showing that the process is described by a ballistic Levy walk. In particular, we show that Mandel's Q parameter, describing the fluctuations of the photon counts, is increasing with time even in the limit of long time. This behavior is in agreement with the theory of Silbey and co-workers (Jung et al. Chem. Phys. 2002, 284, 181), and in contrast to all existing examples where Q approaches a constant, independent of time in the long time limit. We then analyze the distribution of the time averaged intensities, showing that they exhibit a nonergodic behavior, namely, the time averages remain random even in the limit of a long measurement time. In particular, the distribution of occupation times in the on-state compares favorably to a theory of weak ergodicity breaking of blinking nanocrystals. We show how our data analysis yields information on the amplitudes of power-law decaying on and off time distributions, information not available using standard data analysis of on and off time histograms. Photon statistics reveals fluctuations in the intensity of the bright state indicating that it is composed of several states. Photon statistics exhibits a Levy walk behavior also when an ensemble of 100 dots is investigated, indicating that the strange kinetics can be observed already at the level of small ensembles.
The Impact of Vocational Training for the Unemployed : Experimental Evidence from Turkey

This brief summarizes the updates from the 2014 paper entitled, The Impact of Vocational Training for the Unemployed : Experimental Evidence from Turkey, conducted between between 2010 and 2011 in Turkey. A randomized experiment is used to evaluate a large-scale, active labor market policy: Turkey's vocational training programs for the unemployed. A detailed follow-up survey of a large sample with low attrition enables precise estimation of treatment impacts and their heterogeneity. The average impact of training on employment is positive, but close to zero and statistically insignificant, which is much lower than either program officials or applicants expected. Over the first year after training, the paper finds that training had statistically significant effects on the quality of employment and that the positive impacts are stronger when training is offered by private providers. However, longer-term administrative data show that after three years these effects have also dissipated.
Scaling tests of some lattice fermion actions

Abstract I describe studies of quenched spectroscopy, using crude approximations to fixed point actions for fermions interacting with SU(3) gauge fields. These actions have a hypercubic kinetic term and a complicated lattice anomalous magnetic moment term. They show improved scaling compared to the conventional Wilson action.
Time-Resolved Ultraviolet Observations of the Globular Cluster X-Ray Source in NGC 6624: The Shortest Known Period Binary System*

Using the Faint Object Spectrograph (FOS) aboard the Hubble Space Telescope (HST), we have obtained the first time-resolved spectra of the King et al. (1993) ultraviolet-bright counterpart to the 11 minute binary X-ray source in the core of the globular cluster NGC 6624. This object cannot be readily observed in the visible, even from HST, because of a much brighter star superposed less than 01 away. Our FOS data show a highly statistically significant ultraviolet flux modulation with a period of 11.46 ± 0.04 minutes, very similar to the 685 s period of the known X-ray modulation, definitively confirming the association between the King et al. (1993) ultraviolet counterpart and the intense X-ray source. The ultraviolet amplitude is very large compared with the observed X-ray oscillations: X-ray variations are generally reported as 2%-3% peak to peak, whereas our data show an amplitude of about 16% in the 126-251 nm range. A model for the system by Arons & King (1993) predicts periodic ultraviolet fluctuations in this shortest known period binary system, because of the cyclically changing aspect of the X-ray heated face of the secondary star (perhaps a very low mass helium degenerate). However, prior to our observations, this predicted modulation has not been detected. Employing the Arons & King (1993) formalism, which invokes a number of different physical assumptions, we infer a system orbital inclination 35° i 50°. Among the three best-studied ultraviolet/optical counterparts to the intense globular cluster X-ray sources, two are now thought to consist of exotic double-degenerate ultrashort-period binary systems.
Tandem thiyl radical addition and cyclization of chiral hydrazones using a silicon-tethered alkyne

Abstract A diastereoselective method for addition of a trans-2-(phenylthio)vinyl group to α-hydroxy hydrazones is presented. An ethynyl group, tethered to α-hydroxy hydrazones via a silicon tether, undergoes thiyl radical addition and cyclization under neutral tin-free conditions. In the same pot, desilylation with potassium fluoride or tetrabutylammonium fluoride affords (E)-vinylsulfides. The one-pot process is the synthetic equivalent of an acetaldehyde Mannich reaction with acyclic stereocontrol.
A Note on the Construction of Complex and Quaternionic Vector Fields on Spheres

A relationship between real, complex, and quaternionic vector fields on spheres is given by using a relationship between the corresponding standard inner products. The number of linearly independent complex vector fields on the standard (4n − 1)-sphere is shown to be twice the number of linearly independent quaternionic vector fields plus d ,w hered =1 or 3. DOI: 10.1134/S0001434613010148
Cyclic plasticity and failure of structural components

An analytical approach for low-cycle fatigue prediction is presented. The approach combines a cyclic plasticity model with the finite element method and a damage accumulation criterion for ductile metals. The cyclic plasticity model is based on the concept of the combination of several yield surfaces. The surfaces are related to the material uniaxial stress-strain curve idealized by piecewise linear segments. The damage criterion is based on the Coffin-Manson formulae modified for the mean stress variation effect. It is extended to the multiaxial varying stress-strain field and applied for both the crack initiation and the crack growth processes. The stable slow crack growth rate is approximated by the damage accumulation gradient computed from the cracked finite element models. This procedure requires fatigue testing data of only smooth specimens under constant strain amplitudes. The present approach is illustrated by numerical examples of an aircraft wing stiffened panel subjected to compression, which causes material yielding and residual tension.
Efficient algorithms and software for detection of full-length LTR retrotransposons.

LTR retrotransposons constitute one of the most abundant classes of repetitive elements in eukaryotic genomes. In this paper, we present a new algorithm for detection of full-length LTR retrotransposons in genomic sequences. The algorithm identifies regions in a genomic sequence that show structural characteristics of LTR retrotransposons. Three key components distinguish our algorithm from that of current software — (i) a novel method that preprocesses the entire genomic sequence in linear time and produces high quality pairs of LTR candidates in run-time that is constant per pair, (ii) a thorough alignment-based evaluation of candidate pairs to ensure high quality prediction, and (iii) a robust parameter set encompassing both structural constraints and quality controls providing users with a high degree of flexibility. We implemented our algorithm into a software program called LTR_par, which can be run on both serial and parallel computers. Validation of our software against the yeast genome indicates superior results in both quality and performance when compared to existing software. Additional validations are presented on rice BACs and chimpanzee genome.
Multiple zeros of nonlinear systems

As an attempt to bridge between numerical analysis and algebraic geometry, this paper formulates the multiplicity for the general nonlinear system at an isolated zero, presents an algorithm for computing the multiplicity strucuture, proposes a depth-deflation method for accurate computation of multiple zeros, and introduces the basic algebraic theory of the multiplicity. Furthermore, this paper elaborates and proves some fundamental theorems of the multiplicity, including local finiteness, consistency, perturbation invarance, and depth-deflatability. The proposed algorithms can accurately compute the multiplicity and the multiple zeros using floating point arithmetic even if the nonlinear system is perturbed.
4-Webs in the Plane and Their Linearizability

We investigate the linearizability problem for different classes of 4-webs in the plane. In particular, we apply the linearizability conditions, recently found by Akivis, Goldberg and Lychagin, to confirm that a 4-web MW (Mayrhofer's web) with equal curvature forms of its 3-subwebs and a nonconstant basic invariant is always linearizable (this result was first obtained by Mayrhofer in 1928; it also follows from the papers of Nakai). Using the same conditions, we further prove that such a 4-web with a constant basic invariant (Nakai's web) is linearizable if and only if it is parallelizable. Next we study four classes of the so-called almost parallelizable 4-webs APW a ,a=1,2,3,4 (for them the curvature K=0 and the basic invariant is constant on the leaves of the web foliation X a ), and prove that a 4-web APW a is linearizable if and only if it coincides with a 4-web MW a of the corresponding special class of 4-webs MW. The existence theorems are proved for all the classes of 4-webs considered in the paper.
Zeons, Permanents, the Johnson Scheme, and Generalized Derangements

Starting with the zero-square “zeon algebra,” the connection with permanents is shown. Permanents of submatrices of a linear combination of the identity matrix and all-ones matrix lead to moment polynomials with respect to the exponential distribution. A permanent trace formula analogous to MacMahon's master theorem is presented and applied. Connections with permutation groups acting on sets and the Johnson association scheme arise. The families of numbers appearing as matrix entries turn out to be related to interesting variations on derangements. These generalized derangements are considered in detail as an illustration of the theory.
Brane world gravity in an AdS black hole

Abstract We consider a model of brane world gravity in the context of non-conformal non-SUSY matter. In particular, we modify the earlier strong coupling solution to the glueball spectrum in an AdS 7 black hole by introducing a Randall–Sundrum Planck brane as a UV cut-off. The consequence is a new normalizable zero mass tensor state, which gives rise to an effective Einstein–Hilbert theory of gravity, with exponentially small corrections set by the mass gap to the discrete glueball spectrum. However, the simplest microscopic theory for the Planck brane is found to have a tachyonic instability in the radion mode.
On asymptotic statistics for geometric routing schemes in wireless ad hoc networks

In this paper, we present a methodology employing statistical analysis and stochastic geometry to study geometric routing schemes in wireless ad hoc networks. In particular, we analyze the network-layer performance of one such scheme, the random $ {{ 1}\over { 2}}$ disk routing scheme, which is a localized geometric routing scheme in which each node chooses the next relay randomly among the nodes within its transmission range and in the general direction of the destination. The techniques developed in this paper enable us to establish the asymptotic connectivity and the convergence results for the mean and variance of the routing path lengths generated by geometric routing schemes in random wireless networks. In particular, we approximate the progress of the routing path toward the destination by a Markov process and determine the sufficient conditions that ensure the asymptotic connectivity for both dense and large-scale ad hoc networks deploying the random $ {{ 1}\over { 2}}$ disk routing scheme. Furthermore, using this Markov characterization, we show that the expected length (hop count) of the path generated by the random $ {{ 1}\over { 2}}$ disk routing scheme normalized by the length of the path generated by the ideal direct-line routing, converges to $3\pi /4$ asymptotically. Moreover, we show that the variance-to-mean ratio of the routing path length converges to $9\pi ^{2}/64-1$ asymptotically. Through simulation, we show that the aforementioned asymptotic statistics are in fact quite accurate even for finite granularity and size of the network.
Buckling analysis of a taper-taper adhesive-bonded composite joint

An analytical model of the behavior of an adhesive-bonded taper-taper composite joint under axial compressive loading has been developed using the Ritz Method. The model was based on laminated beam theory. A Fourier series was used to represent the transverse displacement variable and the Ritz Method was used to derive an eigenvalue equation for adhesively bonded taper-taper composite joint. The smallest eigenvalue is the critical buckling load. Finite element analyses were performed on two unidirectional laminated beam joints with various taper angles to verify the analytical model. The effect of varying the taper angle, adhesive thickness, and adhesive modulus on the critical buckling load was investigated analytically.
Bootstrap Prediction Intervals for Autoregression

Abstract The nonparametric bootstrap is applied to the problem of prediction in autoregression. Let {Y t : t = 0, ±1, ±2, …} be a stationary autoregressive process of known order p [AR(p)]. Given a realization of the series up to time t, (y 1, y 2, …., y t ), a 100β% prediction interval for Y t+k is desired. Standard forecasting techniques, which assume that the error sequence of the process {Y t } is Gaussian, rely on the fact that the conditional distribution of Y t+k , given the data, is Gaussian as well. As a nonparametric alternative, the bootstrap provides an estimate of the conditional distribution of Y t+k . The method is similar to other applications of the bootstrap for linear models, because the residuals are resampled. The proposed methodology represents a different approach, since an alternative representation for AR(p) series is used, allowing for bootstrap replicates generated backward in time. It follows that the resulting replicates all have the same conditionally fixed values at the end ...
Three-Dimensional Flow Development in MHD Generators at Part Load

The three-dimensional behavior of flow in magnetohydrodynamic (MHD) generators at design and off-design loading points was investigated. Faraday as well as diagonally connected channels with insulating or conducting sidewalls were considered. The role of MHD body forces in generating axial vorticity and hence secondary flows in the cross stream has been analyzed. For Faraday channels with strong MHD interaction, the generated vorticity is shown to direct the secondary flow from the cathode to the anode wall along the centerline. For diagonally connected channels near short circuit, the generated vorticity is shown to direct the secondary flow from the anode to the cathode wall along the centerline, and vice versa at near open-circuit conditions.
New results for near-millimeter wave isolators and phase shifters based on magnetoplasmons on GaAs substrates

Results are presented for planar “insulated image guide” structures modelling surface magnetoplasmon based non-reciprocal devices for the near-millimeter wave range. Sample results using GaAs substrates show acceptable performance for isolators over a bandwidth of 65 GHz in the 400 GHz range and differential phase shifters over a bandwidth of 30 GHz in the 550 GHz range with a 10% phase shift variation.
Synthesis and characterization of high-Tc superconductors in the Tl-Ca-Ba-Cu-O system

Both Tl2Ca2Ba2Cu3O10 and TlCa3BaCu3O8.5 are investigated for superconductivity as a function of the sintering temperature, time, atmosphere, and quench rate in an effort to synthesize the high-Tc superconducting phase in the thallium system. The samples are characterized by electrical resistivity measurements, X-ray diffraction, and scanning electron microscopy. Samples of starting composition Tl2Ca2Ba2Cu3O10 fired in air at 860-900 C and rapidly quenched show a Tc of 96-107 K. In contrast, specimens of starting composition TlCa3BaCu3O8.5 when baked at 900 C and slowly cooled in oxygen superconduct at 116 K and above and consist of Tl2Ca2Ba2Cu3O(10+x) as the dominant phase. The results also show that, in contrast to the case of YBa2Cu3O(7-x), doping with a small concentration of fluorine sharpens the resistive transition and produces a large Tc increase in thallium-based superconductors.
Multiple realisations of N = 1 vacua in six dimensions

Abstract A while ago, examples of N = 1 vacua and D = 6 were constructed as orientifolds of type IIB string theory compactified on the K3 surface. Among the interesting features of those models was the presence of D5-branes behaving like small instantons, and the appearance of extra tensor multiplets. These are both non-perturbative phenomena from the point of view of heterotic string theory. Although the orientifold models are a natural setting in which to study these non-perturbative heterotic string phenomena, it is interesting and instructive to explore how such vacua are realised in heterotic string theory, M-theory and F-theory, and consider the relations between them. In particular, we consider models of M-theory compactified on K3 × S1/ Z 2 with fivebranes present on the interval. There is a family of such models which yields the same spectra as a subfamily of the orientifold models. By further compactifying on T2 to four dimensions we relate them to heterotic string spectra. We then use heterotic/type IIA duality to deduce the existence of Calabi-Yau 3-folds which should yield the original six-dimensional orientifold spectra if we use them to compactify F-theory. Finally, we show in detail how to take a limit of such an F-theory compactification which returns us to the type IIB orientifold models.
The total synthesis of D-mycinose

Abstract The total synthesis of D -mycinose, 1, from isoascorbic acid, 2 , via a hydroxyl directed hydrogenation is reported.
Attitudes about the use of newborn dried blood spots for research: a survey of underrepresented parents.

Abstract Objective To identify the relative importance of factors that impact parents' attitudes toward use of their child's dried newborn blood spots for research purposes. Methods Respondents were parents aged 18 and older with at least one child aged 17 or younger born in Indiana visiting an urban pediatrics clinic. They were asked to rate the acceptability of hypothetical scenarios involving the research use of blood spots. Three pieces of information varied between the scenarios: 1) who would be conducting the research; 2) whether the child's identity would be linked to the spots; and 3) whether and how often the parents' consent would be sought before the research began. Results A total of 506 predominantly black and low-income parents completed the survey. The conjoint analysis model showed good fit (Pearson's R = 0.998, P Conclusions Parents strongly prefer that consent be sought for each use of their children's blood spots. These findings have implications for future research and policy-making decisions.
Developing Ligands for Palladium(II)-Catalyzed C–H Functionalization: Intimate Dialogue between Ligand and Substrate

Homogeneous transition-metal-catalyzed reactions are indispensable to all facets of modern chemical synthesis. It is thus difficult to imagine that for much of the early 20th century, the reactivity and selectivity of all known homogeneous metal catalysts paled in comparison to their heterogeneous and biological counterparts. In the intervening decades, advances in ligand design bridged this divide, such that today some of the most demanding bond-forming events are mediated by ligand-supported homogeneous metal species. While ligand design has propelled many areas of homogeneous catalysis, in the field of Pd(II)-catalyzed C–H functionalization, suitable ligand scaffolds are lacking, which has hampered the development of broadly practical transformations based on C–H functionalization logic. In this Perspective, we offer an account of our research employing three ligand scaffolds, mono-N-protected amino acids, 2,6-disubstituted pyridines, and 2,2′-bipyridines, to address challenges posed by several synthet...
Synthesis and reactions of 4-isopropylidene-1-aryl-3-methyl-2-pyrazolin-5-ones

The reactions of 4-isopropylidene-1-aryl-3-methyl-2-pyrazolin-5-ones 4a-d were investigated under a variety of conditions. In the presence of thiols or piperidine, 4a-d failed to yield conjugate addition products, presumably due to the steric bulk provided by the two methyl substituents of the isopropylidene side chain. Reaction of 4a-d with hydrazine derivatives gave the 1-aryl-3-methyl-2-pyrazolin-5-ones 3a-d and isopropyl-hydrazones. Treatment of 4a with potassium cyanide yielded a stable conjugate addition product which exists as a mixture of tautomers in different solvents. Also, oxidation of 4a with hydrogen peroxide gave a spiroepoxide 22, while m-chloroperbenzoic acid oxidation afforded both the spiroepoxide 22, and a small quantity of a hydroxyspiroepoxide 23.
The welfare cost of uncertain tax policy

Abstract Frequent shifts in tax policy can increase uncertainty about future tax rates. This paper measures the impact of uncertain tax policy on savings, labor supply, and welfare in the United States. A vector autoregression model is used to measure the uncertain component of wage and capital income taxation during 1929–1975. These parameters are implemented in a two-period model of consumption and labor supply. Removing all uncertainty about future tax policy can lead to an annual welfare gain of 0.4 percent of national income, or about 15 billion dollars in 1986.
Total syntheses of the Securinega alkaloids (+)-14,15-dihydronorsecurinine, (-)-norsecurinine, and phyllanthine.

A new strategy for enantiospecific construction of the Securinega alkaloids has been developed and applied in total syntheses of (+)-14,15-dihydronorsecurinine (8), (−)-norsecurinine (6), and phyllanthine (2). The B-ring and C7 absolute stereochemistry of these biologically active alkaloids originated from trans-4-hydroxy-l-proline (10), which was converted to ketonitrile 13 via a high-yielding eight-step sequence. Treatment of this ketonitrile with SmI2 afforded the 6-azabicyclo[3.2.1]octane B/C-ring system 14, which is a key advanced intermediate for all three synthetic targets. Annulation of the A-ring of (−)-norsecurinine (6) with the required C2 configuration via an N-acyliminium ion alkylation was accomplished using radical-based amide oxidation methodology developed in these laboratories as a key step, providing tricycle 33. Annulation of the D-ring onto α-hydroxyketone 33 with the Bestmann ylide 45 at 12 kbar gave (+)-14,15-dihydronorsecurinine (8). In the securinine series, the D-ring was incorpo...
The selection and training of computer personnel at the social security administration

How many computer systems managers have claimed their individual systems and operating environments contain a unique group of applications?
Friedel oscillation about a Friedel-Anderson impurity

The Friedel oscillations in the vicinity of a Friedel-Anderson (FA) impurity are investigated numerically. For an FA impurity in the local moment limit the normalized amplitude A(ξ) is S-shaped, approximately zero at short distances, approaching two at large distances and crossing the value one at the characteristic length ξ1/2. Surprisingly, the Friedel oscillations of a simple non-interacting Friedel impurity with a narrow resonance at the Fermi level show a very similar behavior of their amplitude A(ξ). A comparison correlates the resonance width and the Kondo energy of the FA impurity with the characteristic length ξ1/2 of the Friedel oscillations.
Asymmetric synthesis of 4-alkoxy-4-alkylcyclohexen-2-ones. Application toward the synthesis of (+)-abscisic acid.

Abstract The chiral bicyclic lactam 3 serves as a useful starting material for the title compounds by steroselective additions with organometallics.
Synthesis of a double-phospholipid

Abstract A 72-membered macrocyclic phopholipid, which is a unimolecular version of the two-molecule unit spanning a membrane bilayer, was synthesized for the first time.
Microwave Sounding of the Giant Planets

Abstract We systematically explore the sensitivity of the microwave spectra of the giant planets to the vertical profiles of temperature and condensible absorbers. We find that the spectrum at centimeter wavelengths is largely insensitive to vertical profile of temperature, but generally is sensitive to the relative humidities (RH) of the condensible absorbers. Under a wide variety of plausible conditions, gaseous ammonia dominates the microwave opacity, and the spectra can be used to retrieve the vertical profile of its relative humidity. We examine the ammonia relative humidity profiles implied by the spectra of Uranus and Saturn. For moderate enhancements of H 2 S above its solar value ( 3 relative humidity at wavelengths longward of 1 cm, out to at least 5 cm, depending on whether there are thick water clouds. The implied vertical variation in the relative humidity of NH 3 is small in the temperature range 140 to 250 K, confined to the range 0.05 to 0.35%. The reported meridional variation in brightness temperatures at 2 and 6 cm can be interpreted as a factor of 10 variation in the relative humidity, with the largest relative humidities occurring near 20°S, where temperatures are coldest. Part of the 6-cm brightness temperature variation may be attributable to meridional variations in the opacity of thick water clouds. On Saturn, the vertical variation of relative humidity is greater. At temperatures less than 152 K, ammonia is saturated, but at deeper levels, it follows a curve such at d ln RH/d ln P = −4.5, which corresponds nearly to a constant mole fraction, down to temperatures >230 K.
Stability of complex hyperbolic space under curvature-normalized Ricci flow

Using the maximal regularity theory for quasilinear parabolic systems, we prove two stability results of complex hyperbolic space under the curvature-normalized Ricci flow in complex dimensions two and higher. The first result is on a closed manifold. The second result is on a complete noncompact manifold. To prove both results, we fully analyze the structure of the Lichnerowicz Laplacian on complex hyperbolic space. To prove the second result, we also define suitably weighted little Holder spaces on a complete noncompact manifold and establish their interpolation properties.