cssi/SciSciGPT-SciSciNet huggingface dataset:
Stability of nonlinear polynomial ARMA models and their inverse

Stability and invertibility of discrete time Polynomial ARMA models are studied in an 'extended neighbourhood' to extend the local results obtained earlier. The analysis combines linear robust control and classical nonlinear system theories. Polynomial ARMA models are used as examples illustrating the theory.
Atmospheric secondary aerosol formation by heterogeneous reactions of aldehydes in the presence of a sulfuric acid aerosol catalyst.

Particle growth by the heterogeneous reaction of aldehydes was evaluated in 0.5 m3 Teflon film bags under darkness in the presence of background seed aerosols. The aldehydes used were as follows: glyoxal, butanal, hexanal, octanal, and decanal. To study acid catalyst effects on aldehyde heterogeneous reactions, one of the Teflon bags was initially filled with seed aerosols composed of ammonium sulfate-aerosol acidified with sulfuric acid. These results were compared to particle growth reactions that contained only ammonium sulfate as a background seed aerosol. The gas-phase aldehydes were then added to the Teflon bags. In selected experiments, 1-decanol was also added to the Teflon bags with aldehydes to clarify particle growth via a heterogeneous hemiacetal/acetal formation in the presence/absence of an acid catalyst. The particle size distribution and growth were measured using a scanning mobility particle sizer (TSI-SMPS), and the results were applied to predicting aerosol growth and size distribution...
Unraveling reservoir compaction parameters through the inversion of surface subsidence observations

In an attempt to derive more information on the parameters driving compaction, this paper explores the feasibility of a method utilizing data on compaction-induced subsidence. We commence by using a Bayesian inversion scheme to infer the reservoir compaction from subsidence observations. The method’s strength is that it incorporates all the spatial and temporal correlations imposed by the geology and reservoir data. Subsequently, the contributions of the driving parameters are unravelled. We apply the approach to a synthetic model of an upscaled gas field in the northern Netherlands. We find that the inversion procedure leads to coupling between the driving parameters, as it does not discriminate between the individual contributions to the compaction. The provisional assessment of the parameter values shows that, in order to identify adequate estimate ranges for the driving parameters, a proper parameter estimation procedure (Markov Chain Monte Carlo, data assimilation) is necessary.
A Model of Strategic Entrepreneurship: The Construct and its Dimensions

Strategic entrepreneurship (SE) involves simultaneous opportunity-seeking and advantage-seeking behaviors and results in superior firm performance. On a relative basis, small, entrepreneurial ventures are effective in identifying opportunities but are less successful in developing competitive advantages needed to appropriate value from those opportunities. In contrast, large, established firms often are relatively more effective in establishing competitive advantages but are less able to identify new opportunities. We argue that SE is a unique, distinctive construct through which firms are able to create wealth. An entrepreneurial mindset, an entrepreneurial culture and entrepreneurial leadership, the strategic management of resources and applying creativity to develop innovations are important dimensions of SE. Herein we develop a model of SE that explains how these dimensions are integrated to create wealth.
Bioorthogonal Chemical Imaging for Biomedicine

Here we will present the physical principle and emerging biomedical applications of stimulated Raman scattering (SRS) microscopy including imaging lipid metabolism, protein synthesis, protein degradation, DNA replication, RNA synthesis, glucose uptake, and drug tracking. Article not available.
The interplay of genetic and environmental factors in craniofacial morphogenesis: holoprosencephaly and the role of cholesterol

Cyclopia, the paradigmatic "face [that] predicts the brain" in severe holoprosencephaly (HPE) (DeMyer et al., 1964), has been recognized since ancient times. Descriptive embryologists and pathologists have noted the continuum of defective separation of the forebrain and loss of central nervous system (CNS) midline structures for more than a century. It has been recognized more recently that inhibitors of cholesterol biosynthesis, whether consumed in native plants by range sheep, or experimentally applied to early embryos, could phenocopy the natural malformation, as could a variety of other teratogens (maternal diabetes, alcohol). Yet it has been less than a decade that the genomic knowledge base and powerful analytic methods have brought the sciences of descriptive, molecular, and genetic embryology within range of each other. In this review, we discuss the clinical presentations and pathogenesis of HPE. We will outline various genetic and teratogenic mechanisms leading to HPE. Lastly, we will attempt to examine the pivotal role of cholesterol and the Sonic Hedgehog (Shh) pathway in this disorder and in normal embryonic forebrain development.
On the twisted K-homology of simple Lie groups

We prove that the twisted K-homology of a simply connected simple Lie group G of rank n is an exterior algebra on n-1 generators tensor a cyclic group. We give a detailed description of the order of this cyclic group in terms of the dimensions of irreducible representations of G and show that the congruences determining this cyclic order lift along the twisted index map to relations in the twisted Spin bordism group of G.
Relative Brauer groups of genus 1 curves

In this paper we develop techniques for computing the relative Brauer group of curves, focusing particularly on the case where the genus is 1. We use these techniques to show that the relative Brauer group may be infinite (for certain ground fields) as well as to determine this group explicitly for certain curves defined over the rational numbers. To connect to previous descriptions of relative Brauer groups in the literature, we describe a family of genus 1 curves, which we call “cyclic type” for which the relative Brauer group can be shown to have a particularly nice description. In order to do this, we discuss a number of formulations of the pairing between the points on an elliptic curve and its Weil-Chatelet group into the Brauer group of the ground field, and draw connections to the period-index problem for genus 1 curves.
The Effect of Limb Kinematics on the Speed of a Legged Robot on Granular Media

Achieving effective locomotion on diverse terrestrial substrates can require subtle changes of limb kinematics. Biologically inspired legged robots (physical models of organisms) have shown impressive mobility on hard ground but suffer performance loss on unconsolidated granular materials like sand. Because comprehensive limb–ground interaction models are lacking, optimal gaits on complex yielding terrain have been determined empirically. To develop predictive models for legged devices and to provide hypotheses for biological locomotors, we systematically study the performance of SandBot, a small legged robot, on granular media as a function of gait parameters. High performance occurs only in a small region of parameter space. A previously introduced kinematic model of the robot combined with a new anisotropic granular penetration force law predicts the speed. Performance on granular media is maximized when gait parameters utilize solidification features of the granular medium and minimize limb interference.
Time resolved electron energy loss spectroscopy of surface kinetics

Abstract Recent experiments and analysis have demonstrated that time resolved electron energy loss Spectroscopy (TREELS) can be applied effectively in the study of surface kinetics and reaction mechanisms. Some general concepts pertaining to precursor mediated dissociation, alkali-promotion, and synthesis reactions on transition metal surfaces have emerged. The dissociation of N 2 on Fe(111) and NO on Rh(100) is observed to occur via a highly inclined or parallel bound precursor state. The effect of K is to increase the stability of the precursor. For NO on K-promoted Rh(100), the dissociation rate constant, containing the activation energy and preexponential factor, is apparently compensated. The formation of OH from coadsorbed O and H on Rh(100) has been fully characterized, establishing the importance of islands and the large scale structure of the reactants. The synthesis of formate (HCOO) from coadsorbed O, H 2 O, and CO on Rh(100) is achieved when the coadsorbed reactants are in close proximity, establishing the importance of local structure.
Europium substitution into intermetallic phases grown in Ca/Zn flux

Abstract Replacement of calcium with europium in the phases Ca 21 Ni 2 Zn 36 and CaNi 2 Zn 3 was attempted to explore the possibility of substitution in metal flux reactions and potential magnetic interactions between closely spaced Eu 2+ ions. Limited substitution occurs when Eu is added to the reaction of nickel in a Ca/Zn flux mixture, up to stoichiometries of Eu 5.8(3) Ca 15.2(3) Ni 2 Zn 36 and Eu 0.42(8) Ca 0.58(8) Ni 2 Zn 3 . Structural characterization and magnetic susceptibility studies on Eu x Ca 21− x Ni 2 Zn 36 phases indicate that the Eu and Ca ions do not form an even solid solution on their sites, but instead segregate in separate regions of the crystals. The europium-rich regions of the samples order ferromagnetically, with T C dependent on the size of the clusters. If the concentration of Eu in the flux is raised above 20 mol%, a new compound Eu 1.63(1) Ca 1.37(1) Ni 2 Zn 3 ( Cmcm , a =4.1150(5) A, b =16.948(2) A, c =10.302(1) A, Z =4, R 1 =0.0396) is produced.
Encoding information flow in Aura

Two of the main ways to protect security-sensitive resources in computer systems are to enforce access-control policies and information-flow policies. In this paper, we show how to enforce information-flow policies in Aura, which is a programming language for access control. When augmented with this mechanism for enforcing information-flow polices, Aura can further improve the security of reference monitors that implement access control.We show how to encode security types and lattices of security labels using Aura's existing constructs for authorization logic. We prove a noninterference theorem for this encoding. We also investigate how to use expressive access-control policies specified in authorization logic as the policies for information declassification.
Asymmetric syntheses of novel amino acids and peptides from acylnitroso-derived cycloadducts

Abstract Oxidative cleavage of cycloadducts of amino acid-derived acylnitroso compounds produces peptides in which the carbon framework of the new carboxy terminal amino acid was generated from cyclopentadiene.
On a Loss of Information in a Transition from Quantum to a Quasi-Classical Regime

By defining information entropy in terms of the probability density |?|2 (? is a wave function in the coordinate representation) it is explicitly shown how a loss of quantum information occurs in a transition from a quantum to a quasi-classical regime.
Neutron Star Kicks from Asymmetric Collapse

Many neutron stars are observed to be moving with spatial velocities, in excess of 500 km s-1. A number of mechanisms have been proposed to give neutron stars these high velocities. One of the leading classes of models proposed invokes asymmetries in the core of a massive star just prior to collapse. These asymmetries grow during the collapse, causing the resultant supernova to be also asymmetric. As the ejecta is launched, it pushes off (or "kicks") the newly formed neutron star. This Letter presents the first three-dimensional supernova simulations of this process. The ejecta is not the only matter that kicks the newly formed neutron star. Neutrinos also carry away momentum and the asymmetric collapse also leads to asymmetries in the neutrinos. However, the neutrino asymmetries tend to damp out the neutron star motions, and even the most extreme asymmetric collapses presented here do not produce final neutron star velocities above 200 km s-1.
Adverse Selection by Markets and the Advantage of Being Late

Among firms entering a market sequentially, operating under imperfect information and hiring workers with the same observable characteristics, it is shown that in the presence of transaction costs or "lock-in" effects each new firm offers a wage above the one previously offered and obtains higher profits than previous entrants. On average, each new firm gets more able workers than the previous firms, and at any point in time those workers employed by firms are less able than those self-employed. Also, it is shown that a Nash equilibrium entry ordering for firms exits.
Variation of transverse momentum in hadronic collisions

The paper presents a detailed parameterization of the transverse momentum in hadronic collisions on multiplicity and on beam momentum. Hadronic collisions are considered at energies below the ultra-high energy domain, on the basis of an uncertainty relation and a naive eikonal model with an impact-parameter-dependent multiplicity.
The differential processing of price in gains and losses: the effects of frame and need for cognition

Perhaps the most fundamental principle of decision theory is that more money is preferred to less: the principle of desired wealth. Based on this and other principles such as reference dependence and loss aversion, researchers have derived and demonstrated mental accounting (MA) rules for multiple outcome situations. Experiment 1 tested the invariance of the desired wealth principle and two mental accounting rules (mixed gain, e.g. $100 gain and a $50 loss; mixed loss, e.g. $100 loss and a $50 gain) across types of decision maker and frame. The desired wealth principle and the MA rule for mixed gains were found to vary depending upon (1) the thoughtfulness of the decision maker (need for cognition, NC), and (2) the frame used to describe gains and losses (e.g. a gain of $x versus a gain of y%). The MA rule for mixed losses, however, was found to be immune to framing effects, even among people who are generally less thoughtful. The differential processing of gains and losses across frames (dollar versus percentage) and individuals (less versus more thoughtful) was tested further in Experiment 2 where evaluations of mixed losses were made at the level of the gestalt as well as the constituent (the gain and the loss being evaluated separately). Framing effects were evidenced only among subjects lower in NC and only when the constituent gain was evaluated. Evaluations of the overall mixed loss and the constituent loss were comparable across situation and individual, suggesting that losses motivate greater processing among people otherwise inclined toward cognitive miserliness. Copyright © 2000 John Wiley & Sons, Ltd.
High-performance liquid chromatographic assay validation of Manumycin A in mouse plasma.

Abstract Manumycin A is a natural antibiotic produced by Streptomyces parvulus that has antineoplastic activity against a variety of human cancers in nude mouse models. We have developed a highly sensitive reverse phase high-performance liquid chromatography (HPLC) method based on ultraviolet (UV) detection for the determination of manumycin A in mouse plasma. Manumycin A was isolated from mouse plasma by solid-phase extraction. A gradient elution of methanol and 0.05 M H3PO4 with 0.2% triethylamine mobile phase was employed and separation was achieved with a C18 analytical column. Manumycin A was detected by UV absorption at 345 nm. Retention time for manumycin A was 8.9±0.2 min. The manumycin A peak was baseline resolved, with the nearest peak at 1.5 min distance and no interfering peaks detected. Inter- and intra-day coefficients of variance were less than 6.1 and 5.1%, respectively. Based on an extracted manumycin A standard plasma sample of 0.25 μg/ml, the assay precision was 99.8% with a mean accuracy of 95.1%. At plasma concentrations of 0.5 and 5 μg/ml, the mean recovery rates of manumycin A were 59.64 and 60.28%, respectively. The lower limit of detection (LLD) for manumycin A was 0.1 μg/ml in mouse plasma. The lower limit of quantification (LLQ) for manumycin A was 0.125 μg/ml. Results of the stability study indicated that when frozen at −80 °C, manumycin A was stable in mouse plasma for up to 2 weeks. This method is useful in quantification of manumycin A in mouse plasma for clinical pharmacology studies in mice.
Investigation of the Symmetric Wetting of Vane-Wall Gaps in Propellant Tanks

Symmetric wetting of a liquid in a vane-wall intersection with a gap is investigated. The geometry is common in surface tension propellant management devices (PMDs) in spacecraft liquid propellant tanks. A theoretical method is applied to determine a critical contact angle in the geometry for a range of parameters. The critical contact angle marks a division between the existence and nonexistence of a single-valued finite height equilibrium capillary surface spanning the entire cross section. When the contact angle is below the critical value, the capillary surface wicks up the gap, which is necessary for proper function of the PMD. The problem and results can also be viewed as determination of a critical gap size for a given contact angle. In addition to analysis, Surface Evolver simulations and drop tower experiments provide results in agreement with the analytical results. Drop tower results also demonstrate that the evolution of the wicking rate mimics that for a solid corner.
Inequality-Equality Constrained Optimization: An Analytical Robustness Comparison of a Feasibility Method Versus L1 Sequential Quadratic Programming

In this work we present an analytical robustness comparison of two methods for inequality-equality constrained optimization or nonlinear programming. The methods compared are (1) a Feasibility Method (FM) and (2) rudimentary sequential quadratic programming with an L1 merit function (L1-SQP). We then also make note of a very recent global convergence result (similar to that of FM) for a new Filter-type SQP algorithm. And, we claim no analytical robustness advantage of FM over the Filter-type SQP algorithm. The problem statement assumptions include nonstationarity of constraint error norms except at zero constraint error, without which we are not aware of any algorithm that is provably guaranteed to converge to a tolerance-feasible stationary point of a penalty function or a Kuhn-Tucker point. Global convergence of FM is proved analytically. Rudimentary L1-SQP is shown to exhibit potential failure even from a feasible starting point, due to an onset of infeasible subproblems.
Compensating operators and stable backward in time marching in nonlinear parabolic equations

Linear and nonlinear parabolic advection–dispersion–reaction equations play a significant role in the geophysical sciences, where they are widely used in modeling contaminant transport in subsurface acquifers and rivers, as well as the dispersion of air pollutants from elevated sources. Environmental forensics aims at reconstructing the contaminant plume history, by solving the governing parabolic equations backward in time. However, such backward parabolic problems are exponentially ill-posed, and present serious computational difficulties. Step by step time-marching schemes are fundamental tools in the numerical exploration of well-posed nonlinear evolutionary partial differential equations. When the initial value problem is ill-posed however, such stepwise numerical schemes are necessarily unconditionally unstable and result in explosive noise amplification. This paper outlines a novel stabilized time-marching procedure for computing nonlinear parabolic equations on 2D rectangular regions, backward in time. Very little is known either analytically, or computationally, about this class of problems. To quench the instability, the procedure uses easily synthesized FFT-based compensating operators at every time step. A fictitious nonlinear image deblurring problem is used to evaluate the effectiveness of this computational approach. The method is compared with a previously introduced, global in time nonlinear Van Cittert iterative procedure. The latter is significantly more time consuming, and impractical on large problems.
Three-dimensional experimental spatial dynamics modelling of a reciprocating Freon compressor housing

Abstract Experimental spatial dynamics modelling encompasses the modelling, postprocessing, and visualization of 3 D spatial dynamic response of structures as statistically-qualified complex-valued continuous vector fields derived from experimental structural dynamics testing. A weighted least-squares discrete finite element formulation has been developed to reconstruct the continuous 3 D velocity response fields from experimental dynamics data. Dynamic 3 D rotations, displacements, and accelerations were naturally derived from the full field velocity response model. Also, dynamic strain and stress fields across the shell elements were extracted by directly postprocessing the dynamic response. A Scanning Laser Doppler Vibrometer (SLDV) was used to measure a single frequency of the 3 D dynamic response in an in situ test of an operating reciprocating Freon compression. The SLDV measured the velocity response at thousands of locations on the compressor housing from multiple, positionally-registered locations. The geometry from a preexisting finite element model provided the shape model of the compressor. An experimentally derived spatial dynamics model of the compressor housing was solved and postprocessed results were obtained.
Space covering by growing rays

We study kinetic and jamming properties of a space covering process in one dimension. The stochastic process is defined as follows. Seeds are nucleated randomly in space and produce rays which grow with a constant velocity. The growth stops upon collision with another ray. For arbitrary distributions of the growth velocity, the exact coverage, velocity and size distributions are evaluated for both simultaneous and continuous nucleation. In general, simultaneous nucleation exhibits a stronger dependence on the details of the growth velocity distribution in the asymptotic time regime. The coverage in the continuous case exhibits a universal t 1 approach to the jammed state, while an inhomogeneous version of the process leads to non-generic t pC decay, with 0 6 pC 6 1 the fraction of right-growing rays.
Aspects of Three-dimensional Spin-4 Gravity

We discuss some interesting holographical aspects of three dimensional higher- spin gravity with a negative cosmological constant in the framework of SL(4,R)×SL(4,R) Chern-Simons theory. Using a recently found technique, we construct explicitly a solution that can be interpreted as spin-4 generalization of the BTZ solution, and demonstrate how W4 symmetry and the higher-spin Ward identities arise from the bulk equations of motion coupled to spin-3 and spin-4 currents. We match the eigenvalues of a Wilson loop along the time-like direction of the BTZ to that of the spin-4 solution, and show that this yields remarkably consistent gravitational thermodynamics for the latter. This furnishes an important, concrete supporting example for a recent proposal to understand spacetime geometries in three-dimensional higher-spin gravity formulated via SL(N,R) × SL(N,R) Chern-Simons theories.
Stereoselective synthesis of dienes from N-allylhydrazones.

A new method for the stereoselective synthesis of dienes from aldehydes and N-allylhydrazine derivatives has been developed. High levels of (E)-stereoselectivity are obtained for a variety of substrates. Addition of a dienophile to the reaction mixture allows a one-flask diene synthesis−cycloaddition sequence.
Auditor reporting behavior when GAAS lack specificity: the case of SAS No. 59

Abstract Statement on Auditing Standards No. 59 did not clearly specify the language to be used in the going concern (GC) report. Subsequent standards prohibited GC reports that failed to use the terms “substantial doubt” and “going concern” and that used conditional language. We find that: (1) most “subsequently prohibited” (SP) GC reports (those that fail to use the terms “substantial doubt” and “going concern” or that use conditional language) contain conditional language and refer to financing and capital issues; (2) practicing CPAs and regulators have concerns about clients pressuring auditors to soften the wording of GC reports, but also recognize the potential for SP GC reports using conditional language to better communicate the auditor’s GC assessment; (3) SP GC reports are associated with more established auditor-client relationships and lower levels of financial distress; and (4) companies receiving SP GC reports appear less likely to declare bankruptcy than companies receiving standard GC reports. There remain many unanswered research questions regarding the public policy implications of “flexible” versus “boilerplate” auditor reporting. Flexible GC reporting currently is allowed under international audit standards, and in the wake of Enron, some have called for flexible, “open-ended” audit reports in the US to enhance auditor communication.
THIOL‐GLYOXYLATE ADDUCTS AS SUBSTRATES FOR RAT KIDNEY L‐α‐HYDROXY ACID OXIDASE

Abstract Rat kidney L-α-hydroxy acid oxidase (EC 1.1.3.15) catalyzes a rapid O2 uptake at pH 7.5 when both glyoxylate and one of a number of various thiols are present. Thiols which are reactive in this system include: ethanethiol, 1-propanethiol, 2-mercaptoethanol, N-acetylcysteamine, propane-1,3-dithiol, dihydrolipoic acid, Coenzyme A, dephospho Coenzyme A, phosphopantetheine, and pantetheine. Notable physiological thiols that are not very reactive include: glutathione, L-cysteine and cysteamine. Presumably the substrate is a thiol-glyoxylate adduct because both the thiol and glyoxylate must be present in order to obtain a rapid enzyme-catalyzed reaction and oxalyl thioesters are the products of the enzymic reactions. Kinetic studies indicate that some of these adducts are better substrates than any others presently known. These and other results imply that a thiol-glyoxylate adduct may be the physiological substrate for L-α-hydroxy acid oxidase. A possible function for this reaction in metabolic control, mediated either by the oxalyl thioester or by oxalate, is briefly considered.
Fast asynchronous systems in dense time

Abstract A testing scenario in the sense of De Nicola and Hennessy is developed to measure the worst-case efficiency of asynchronous systems using dense time. For all three variants considered, it is shown that one can equivalently use discrete time; in the discrete versions, one variant coincides with an approach based on discrete time in Vogler (CONCUR95, Lecture Notes in Computer Science, vol. 962, Springer, Berlin, 1995, pp. 299–312), and thus we can clarify the assumptions behind this approach. The resulting testing-preorders are characterized with some kind of refusal traces and shown to satisfy some properties that make them attractive as faster-than relations. The three testing preorders are incomparable in general, but for some interesting classes of systems implications are shown.
Sparse trace norm regularization

We study the problem of estimating multiple predictive functions from a dictionary of basis functions in the nonparametric regression setting. Our estimation scheme assumes that each predictive function can be estimated in the form of a linear combination of the basis functions. By assuming that the coefficient matrix admits a sparse low-rank structure, we formulate the function estimation problem as a convex program regularized by the trace norm and the $$\ell _1$$ l 1 -norm simultaneously. We propose to solve the convex program using the accelerated gradient (AG) method; we also develop efficient algorithms to solve the key components in AG. In addition, we conduct theoretical analysis on the proposed function estimation scheme: we derive a key property of the optimal solution to the convex program; based on an assumption on the basis functions, we establish a performance bound of the proposed function estimation scheme (via the composite regularization). Simulation studies demonstrate the effectiveness and efficiency of the proposed algorithms.
X-Ray Absorption Spectroscopy of Dimethylcuprates: Evidence for Solvent-Dependent Aggregation.

Dimeric in Et2 O and DMS, monomeric in THF-the degree of aggregation of dimethylcuprates depends on the solvent [Eq. (a)]. The Cu-Cu distance of 2.82 A was determined by EXAFS for a dimethylcuprate reagent derived from cuprous halide. In contrast, with cyanide as the counterion, no dimers are formed.
Explicit Ricci Solitons on Nilpotent Lie Groups

The primary purpose of this paper is to obtain explicit, coordinate-based descriptions of Ricci flow solutions—especially those corresponding to Ricci solitons—on two classes of nilpotent Lie groups. On the odd-dimensional classical Heisenberg groups, we determine the asymptotics of Ricci flow starting at any metric, and use Lott’s blowdown method to demonstrate convergence to soliton metrics. On the groups of real unitriangular matrices, which are more complicated, we describe the solitons and corresponding solutions using a suitable ansatz.
Enyne Metathesis (Enyne Bond Reorganization)

Enyne metathesis is a bond reorganization of an alkene and an alkyne to produce a 1,3-diene (eqs 1 and 2 in Scheme 1). It has been used in both intramolecular and intermolecular applications. Enyne metathesis bears a mechanistic kinship to alkene metathesis; however, it is less-studied than alkene metathesis. The enyne bond reorganization is atom economical and is driven by the enthalpic stability of the conjugated 1,3-diene produced. Stereoselection is often low in intermolecular cases but can be controlled in intramolecular cases. The enyne metathesis can be catalyzed by metal carbenes or “templated” by metal salts. Many of the same metal carbenes that catalyze alkene metathesis can be used to promote enyne metathesis.1 Steven T. Diver grew up in Salt Lake City and attended the University of Utah where he studied with Professor F. G. West as an undergraduate researcher. Diver went on to do his doctoral work with Professor Ed Vedejs at the University of WisconsinsMadison, studying nucleophilic catalysis promoted by phosphines. Diver conducted postdoctoral studies with Professor Stuart Schreiber at Harvard where he used alkene metathesis to make chemical dimerizers. Presumably this is where he got bitten by the metathesis bug. Diver began his independent work at the University at Buffalo−The State University of New York (SUNY−Buffalo) in 1997. Diver’s research group is interested in the application of enyne metathesis to challenging synthetic problems, mechanistic aspects of the enyne metathesis, and catalyst design employing unusual heterocyclic carbene ligands.
SOES Trading and Market Volatility

The National Association of Security Dealers alleges that professional-trader use of the Small Order Execution System (SOES) causes greater security price volatility. We docu? ment bidirectional Granger causality between a proxy for professional SOES trading (the frequency of maximum-sized SOES trades) and a measure of stock price volatility. We find that high levels of volatility precede high levels of maximum-sized SOES trades, suggesting that volatility causes more frequent large SOES trades. Likewise, over a one-minute time interval, high levels of maximum-sized SOES trades cause high volatility. Over longer periods, however, intense maximum-sized SOES trading causes lower volatility. Inter? preted in conjunction with Harris and Schultz (1997), these results suggest that high levels of maximum-sized SOES trades lead to more efficient price discovery. In light of these results, we believe that efforts to eliminate SOES based on volatility considerations are unwarranted.
Quantum spin chains with various defects

Using the density matrix renormalization group (DMRG) method, we study the quantum coherence in one-dimensional disordered Fermi systems. We consider in detail spinless fermions on a ring, and compare the influence of several kinds of impurities in a gapless and a dimerized, gapped system. In the translation-invariant system a so-called site-impurity, which can be realized by a local potential or a change of one link, increases for repulsive interaction and decreases for attractive interaction. The weakening of two neighboring bonds, which is a realization of a so-called bond-impurity, on the other hand, is healed for repulsive interaction, but enhanced for intermediate attractive interactions. This leads to strong suppression of the quantum coherence measured by the phase sensitivity, but not to localization. Adding a local distortion to a dimerized system we find that even the presence of a single site-impurity increases the metallic region found in the dimerized model. For a strong dimerization and a high barrier, an additional sharp maximum, even seen for systems with about 100 sites, occurs in the phase sensitivity. A bond-impurity in the dimerized system also opens a small metallic window in the otherwise isolating regime.
Sensor-Knowledge-Command Fusion Paradigm for Man/Machine Systems

Abstract This paper presents sensing-knowledge-command(SKC) fusion as a fundamental paradigm of implementing cooperative control for an advanced man-machine system. SKC fusion operates on the “SKC fusion network”, representing the connection between sensory data to commands through knowledge. Sensing, knowledge, and command of a human and a machine are merely tapped into the network to provide inputs or stimuli to the network. Such stimuli automatically invokes a SKC fusion process and generates a fused output for cooperative control. Once invoked by stimuli, the SKC fusion process enforces the network to converge to a new equilibrium state through the network dynamics composed of data fusion, feature transformation, and constraint propagation. The SKC fusion process thus integrates redundant information, maintains consistency of the network, identifies faulty data and concepts, and specifies those concepts to be strengthened (for enhancing command reliability) through sensor planning.
The influence of current firm performance on future SME alliance formation intentions: A six-country study

Abstract Although research has implicitly assumed small- or medium-sized enterprises (SMEs) employ alliances to improve performance, few studies have directly investigated how and when current performance levels might prompt firms to cooperate. Based on disparate predictions of the behavioral theory of the firm (BTOF) and threat rigidity thesis, we developed competing hypotheses regarding the impact of performance dissatisfaction on future alliance intentions for firms with and without previous alliance experience. Employing a dataset of 657 SMEs from six countries, results indicate that for firms with alliance experience, increasing managerial dissatisfaction with current performance decreased intentions to employ future alliances, thus supporting the BTOF thesis. Overall, these results highlight the importance that current performance satisfaction plays in influencing future alliance formation intentions.
Supplier Selection Practices among Small Firms in the United States: Testing Three Models

One of the issues investigated in recent studies on small business enterprises involves the role of supply chain management. Supply chain management has become an important part of strategic planning in both large and small businesses in the 1990s as firms increasingly choose outsourcingas an externally-driven strategic growth path. This study examines the supplier selection practices among 78 small business executives in the midwest United States by testing three models: rational/normative, external control, and strategic choice. Although the results show support for all three models, the rational/normative model emerges as the most significant model for predicting the supplier selection practices of small firms.
Thermal reactions of a 2-aryl-1-vinylcyclobutanol

Abstract Thermolysis reactions of the exo (distal) and endo (proximal) isomers of 7-vinyl-6b,8,8a-tetrahydrocyclobut[a]acenaphthylen-7-ol (1a and 1b) have been studied, both in refluxing xylene and in a packed pyrolysis column. These epimers were prepared from the corresponding cyclobutanone (3). An oxy-Cope rearrangement of 1b was not observed under any conditions. Both epimers gave the same thermolysis products, a fused cyclohexanone derivative 15 (a formal [1,3] shift product) and vinyl ketone 16 (a retro-ene product). At temperatures above 250 °C some acenaphthylene was also obtained. The anionic oxy-Cope variant gave only 15. A common diradical intermediate is proposed for the thermal reactions.
L-dominance: An approximate-domination mechanism for adaptive resolution of Pareto frontiers

In Evolutionary Multi-objective Optimization (EMO), the mechanism of ??-dominance has received significant attention because of its ability to guarantee convergence near the Pareto frontier and maintain diversity among solutions at a reasonable computational cost. A noticeable weakness of this mechanism is its inability to vary the resolution it provides of the Pareto frontier based on the frontier's tradeoff properties. We therefore propose a new mechanism--L-dominance, based on the Lame curve--as an alternative to ??-dominance in EMO. The geometry of the Lame curve naturally supports a greater concentration of Pareto solutions in regions of significant tradeoff between objectives. This variable resolution of solutions allows an algorithm using L-dominance to generate fewer solutions to describe the Pareto frontier as a whole while maintaining a desired concentration of solutions where the frontier requires greater detail. The L-dominance mechanism is analyzed theoretically and by simulation on five test problems, and is shown to result in increasingly significant computational gains as the dimensionality of problems increases.
Model-based strategies for high-level robot vision

Abstract The higher levels of a sensory system for a robot manipulator are described. The sensory system constructs and maintains a representation of the world in a form suitable for fast responses to questions posed by other robot subsystems. This is achieved by separating the sensing processes from the descriptive processes, allowing questions to be answered without waiting for the sensors to respond. Four groups of processes are described. Predictive processes (world modellers) are needed to set up initial expectations about the world and to generate predictions about sensor responses. Processes are also needed to analyze the sensory input. They make use of the predictions in analyzing the world. A third essential function is matching, which involves comparing the sensed data with the expectations, and provides errors that help to servo the models to the world. Finally, the descriptive process constructs and maintains the internal representation of the world. It constructs the representation from the sensed information and the expectations, and contains at all times everything known about the world. The sensory system is responsive to changes in the world, but can also deal with interruptions in sensing, and can supply information that may not be available by sensing the world directly.
The rotational spectrum and molecular structure of the benzene–hydrogen chloride complex

The microwave spectrum of the weakly bound complex benzene–HCl was studied in the gas phase using Fourier transform microwave spectroscopy carried out in a Fabry–Perot cavity with a pulsed supersonic nozzle as the molecular source. Several R‐branch a‐dipole transitions have been observed for benzene–H 35Cl, benzene–D 35Cl, benzene–H 37Cl, and benzene(d6)–H 35Cl. The spectrum was characteristic of a symmetric top, indicating that the time averaged displacement of the H and Cl atoms from the benzene C6 axis is zero. Deuterium substitution of HCl demonstrated that the acidic proton lies between the Cl atom and the benzene ring. The chlorine nuclear quadrupole coupling constant χClaa, was measured for all four isotopic species and is interpreted in terms of a projection of the chlorine quadrupole coupling constant in free HCl, averaged over two degenerate vibrational ground state bending modes involving the angles between the benzene C6 axis and the HCl bond axis. The spectroscopic constants for benzene–HCl are: aNumbers in parentheses represent one standard deviation in the fit.
Strange vision : ganglion cells as circadian photoreceptors

A novel photoreceptor of the mammalian retina has recently been discovered and characterized. The novel cells differ radically from the classical rod and cone photoreceptors. They use a unique photopigment, most probably melanopsin. They have lower sensitivity and spatiotemporal resolution than rods or cones and they seem specialized to encode ambient light intensity. Most surprisingly, they are ganglion cells and, thus, communicate directly with the brain. These intrinsically photosensitive retinal ganglion cells (ipRGCs) help to synchronize circadian rhythms with the solar day. They also contribute to the pupillary light reflex and other behavioral and physiological responses to environmental illumination.
Nuclear moments of inertia at high spins

Abstract Nuclei with highest angular momentum are discussed. The production of high spin states, and the basic ideas associated with high spin physics are reviewed. Recent developments from “continuum” γ-ray studies are presented: the measurement of different average moments of inertia gives new information on the interplay between collective and single particle aspects at high spins. Finally, the exciting possibility of resolving the “continuum” spectra with new detector systems is examined.
Applications of Diamond Turning to Infrared Optical Systems

Diamond turning is immediately applicable to the fabrication of infrared optical components because presently available machines can meet the reduced absolute accuracies required at 10 micrometers. An initial survey of infrared sensor programs at the Honeywell Radiation Center has been conducted to predict the near term and future demand for diamond-turned optical components. Not only does the fabrication process promise significant cost savings as compared to conventional lapping and polishing methods, but, as in the case of aspheric lenses, wider applications are also sought to reduce weight and space requirements. In addition, broader usage of diamond-turned aspherics reduces total parts count and assembly and alignment time, provided proper tools and test equipment are employed. The potential cost savings of diamond-turned vs conventionally fabricated optics are summarized for contracts at the Radiation Center. The savings were calculated by subtracting the difference in fabrication costs and multiplying by the number of items expected to be produced into the mid-1980s. Technical fallout potential of the diamond-turning process is also noted in the apparent ability of a coated sample to pass a 24-hour salt fog test.
THE USE OF FAST NEUTRON DETECTION FOR MATERIALS ACCOUNTABILITY

For many years at LLNL, we have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of our techniques have been developed specifically for the relatively low efficiency (a few percent) inherent in man-portable systems. Historically, thermal neutron detectors (mainly 3He) were used, taking advantage of the high thermal neutron interaction cross-sections, but more recently we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics that respond over 1000 times faster (nanoseconds versus tens of microseconds) than thermal neutron detectors. Fast neutron detection offers considerable advantages, since the inherent nanosecond production timescales of fission and neutron-induced fission are preserved and measured instead of being lost in the thermalization of thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of high efficiency counters. Faster detector response times and sensitivity to neutron momentum show promise in measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed neutron sources (e.g., Pu oxide or Mixed Cm and Pu). Here we report on measured results with our existing liquid scintillator array and promote the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator becomes competitive and even surpasses the precision of 3He counters measuring correlated pairs in modest (kg) samples of plutonium.
Financial Sophistication and Housing Leverage Among Older Households

Increasing mortgage debt among older households has been cited as evidence of financial distress caused by low financial knowledge, poor lending practices, and an increased appetite for debt. This paper investigates whether housing leverage among older households is related to financial sophistication, tax effects, and a desire to increase portfolio allocation to risky assets. Results indicate a time trend in low housing leverage, but no trend in high housing leverage. While housing leverage increases with liquidity constraints, it also increases with financial sophistication, and tax and portfolio incentives are strongly related to high housing leverage. The incentive to borrow against home value created by the deductibility of mortgage interest appears to encourage greater housing leverage and vulnerability to housing price shocks.
Space Processing Viewed by a Scientist-Astronaut

Space Processing is a fledgling and somewhat controversial subject. The scientific community as well as NASA have not yet quite made up their minds as to what to do with Space Processing. The scientific society views Space Processing with some suspicion, and rightfully so. They’re not sure whether this is something real or just a Class “A” con job. NASA has made a lot of promises to this program and has delivered very little. Space Processing has a good chance of becoming a self-fulfilled prophecy. Therefore, responsibility is laid on the shoulders of those of us who believe in this program to convince the scientific community that there is something real there and lobby NASA that they should either “put up or shut up.” This is one of the reasons why I took up the challenge to fly in the Space Shuttle and to live and train with these “Space jocks” for a total of about three years.
Asymmetric synthesis of pyrrolidinoindolines. Application for the practical total synthesis of (-)-phenserine

A versatile route to enantiopure 3,3-disubstituted oxindoles and 3a-substituted pyrrolidinoindolines is described in which diastereoselective dialkylation of enantiopure ditriflate 10 with oxindole enolates is the central step. These reactions are rare examples of alkylations of prostereogenic enolates with chiral sp3 electrophiles that proceed with high facial selectivity (10−20:1). The scope of this method is explored, and a model to rationalize the sense of stereoselection is advanced. This dialkylation chemistry was used to synthesize (−)-phenserine on a multigram scale in six steps and 43% overall yield from 5-methoxy-1,3-dimethyloxindole (27) and to complete a short formal total synthesis of (−)-physostigmine (2).