cssi/SciSciGPT-SciSciNet huggingface dataset:
Are chromospheric nanoflares a primary source of coronal plasma

It has been suggested that the hot plasma of the solar corona comes primarily from impulsive heating events, or nanoflares, that occur in the lower atmosphere, either in the upper part of the ordinary chromosphere or at the tips of type II spicules. We test this idea with a series of hydrodynamic simulations. We find that synthetic Fe XII (195) and Fe XIV (274) line profiles generated from the simulations disagree dramatically with actual observations. The integrated line intensities are much too faint; the blueshifts are much too fast; the blue-red asymmetries are much too large; and the emission is confined to low altitudes. We conclude that chromospheric nanoflares are not a primary source of hot coronal plasma. Such events may play an important role in producing the chromosphere and powering its intense radiation, but they do not, in general, raise the temperature of the plasma to coronal values. Those cases where coronal temperatures are reached must be relatively uncommon. The observed profiles of Fe XII and Fe XIV come primarily from plasma that is heated in the corona itself, either by coronal nanoflares or a quasi-steady coronal heating process. Chromospheric nanoflares might play a role in generating waves that provide this coronal heating.
The selective synthesis of acetonitrile from carbon monoxide, hydrogen, and ammonia over MO/SiO2

Abstract The selective synthesis of acetonitrile from CO/H2/NH3 over Mo/SiO2 was investigated. The effects of temperature, space velocity, and reactant compositions on conversion and selectivity were explored with a two-level factorial designed experiment. High selectivities (37–96% excluding CO2) were achieved at reasonably high conversions (29–64%). The product's carbon number distribution differed significantly from that obtained from a CO/H2 feed under identical conditions. The results are explained in terms of three competing reactions: water-gas shift, Fischer-Tropsch synthesis, and nitrile synthesis. Other experiments are described that indicate a nitrile synthesis mechanism involving a CN intermediate which further reacts with a carbon species to form the acetonitrile. A mechanistic hypothesis involving an isocyanide ligand is proposed.
Nonequilibrium dynamics of weakly and strongly paired superconductors.

We study small oscillations of the order parameter in weakly and strongly paired superconductors driven slightly out of equilibrium, in the collisionless approximation. While it was known for quite some time that the amplitude of the oscillations in a weakly paired superconductor decays as ${t}^{\ensuremath{-}1/2}$, we show that in a superconductor sufficiently strongly paired so that its fermions form bound states usually referred to as molecules, these oscillations decay as ${t}^{\ensuremath{-}3/2}$. The transition between these two regimes happens when the chemical potential of the superconductor vanishes; thus, the behavior of the oscillations can be used to distinguish weakly and strongly paired superconductors. Finally, we interpret the result in the strongly paired superconductor as the probability of the molecular decay as a function of time.
Why new issues are underpriced

This paper presents a model for the underpricing of initial public offerings. The argument depends upon the existence of a group of investors whose information is superior to that of the firm as well as that of all other investors. If the new shares are priced at their expected value, these priveleged investors crowd out the others when good issues are offered and they withdraw from the market when bad issues are offered. The offering firm must price the shares at a discount in order to guarantee that the uninformed investors purchase the issue.
Free And Forced Response Of An Axially Moving String Transporting A Damped Linear Oscillator

Abstract The transverse response of a cable transport system, which is modelled as an ideal, constant tension string travelling at constant speed between two supports with a damped linear oscillator attached to it, is predicted for arbitrary initial conditions, external forces and boundary excitations. The exact formulation of the coupled system reduces to a single integral equation of Volterra type governing the interaction force between the string and the payload oscillator. The time history of the interaction force is discontinuous for non-vanishing damping of the oscillator. These discontinuities occur at the instants when transverse wavefronts propagating along the string interact with the oscillator. The discontinuities are treated using the theory of distributions. Numerical algorithms for computing the integrals involving generalized functions and for solution of the delay-integro-differential equation are developed. The response analysis shows a discontinuous velocity history of the payload attachment point. Special conditions leading to absence of the above discontinuities are given.
Design and analysis of a mesh-based wireless network-on-chip

Network-on-chip (NoC) architecture is regarded as a solution for future on-chip interconnects. However, the performance advantages of conventional NoC architectures are limited by the long latency and high power consumption due to multi-hop long-distance communication among processing elements. To solve these limitations, we employed on-chip wireless communication as express links for transferring data so that transfer latency can be reduced. A hybrid NoC architecture utilizing both wired and wireless communication approaches is proposed in this paper. We also devised a deadlock-free routing algorithm that is able to make efficient use of the incorporated wireless links. Moreover, simulated annealing optimization techniques were applied to find optimal locations for wireless routers. Cycle-accurate simulation results showed a significant improvement in transfer latency. Area and power consumption analysis demonstrates the feasibility of our proposed NoC architecture.
UDC: a self-adaptive uneven clustering protocol for dynamic sensor networks

The resource constraints of sensor networks challenge researchers to design efficient applications to minimise resource consumption. 'Sensor databases' benefit from aggregate queries since in most cases a small amount of descriptive information about the queried upon objects is satisfactory to users. Clustering protocols have been designed to support such queries and to alleviate the burden of networks. This paper presents a novel clustering protocol, named Uneven Density Clustering (UDC) spatially, to support aggregation queries aiming to prolong the lifetime of sensor networks. Unlike other clustering protocols, UDC forms distributed sensor nodes into spatially uneven clusters according to local network conditions. In short, clustered by UDC, the nodes nearby a central base station are grouped into smaller clusters, while distant nodes need to be clustered into larger groups to save resources. Our simulation results exemplify that UDC can extend the lifetime of sensor networks up to twice as long as other clustering protocols do.
Shock wave oscillation driven by turbulent boundary layer fluctuations

Pressure fluctuations due to the interaction of a shock wave with a turbulent boundary layer were investigated. A simple model is proposed in which the shock wave is convected from its mean position by velocity fluctuations in the turbulent boundary layer. Displacement of the shock is assumed limited by a linear restoring mechanism. Predictions of peak root mean square pressure fluctuation and spectral density are in excellent agreement with available experimental data.
Complete linear proofs of systems of linear inequalities

Rabin has investigated the difficulty of proving that a set of linear forms is simultaneously positive by the evaluation of analytic functions. In this paper we study this same question under the restriction that each analytic function itself be linear. A complete result is given in the case that the original set of linear forms are simultaneously positive on a subspace having at least one extreme point. Applications are then given. In particular, it is shown that the proof that a real number x"1 is maximal out on the set {x"1,...,x"m} requires evaluation of m-1 linear forms even if x"1 is known in advance to be exceeded by at most one x"i for 2@?i@?m.
Modal-space active damping of a plane grid - Experiment and theory

This paper first reviews a theory of multiple-actuator modal-space active damping (control) which uses spectral filtering for modal estimation; then it describes an experiment in which the control technique was applied in analog form to a laboratory plane grid structure having a dozen modes under 10 Hz. Experimental observations and corresponding theoretical calculations are presented. Active damping of five modes, including a closely spaced pair, was attempted with the use of five control actuators. However, coupling between the two close modes and their filters produced a mild system instability. Subsequently, a stable four-mode controller was produced by disabling the control of the mode that had driven the instability. The spectral filtering played an unexpectedly dominant and counterproductive role in the active damping process.
Microbump creation system for advanced packaging applications

Recently, DuPont Wafer Level Packaging Solutions has developed a photoresist/remover chemistry system to address the micro-bump market with a new family of dry films capable of imaging the required less than 50 micron pitch, and cleanly remove them. The focus of the presentation will be twofold. The first part will focus on the process development and characterization of the 40 micron thick DuPont MXAdvance * 140 dry film candidate with 2:1 aspect resolution ratio on a 40 micron pitch application with 30 – 40 micron high pillars/micro-bumps. The second part will review the results of the DuPont EKC162™ remover tests and its impact on copper and lead free, and or solder electro-deposition processes. Together, the combination of a high resolution dry film and effective remover chemistry that strips the photoresist cleanly from the wafers offers customers a viable process for producing micro-bump technologies.
Pyrene-Appended Fluorescent Tweezers Generated via the Weak-Link Approach and Their Halide Recognition Properties.

Abstract Through the Weak-Link Approach, fluorescent condensed and open Cu(I) tweezer complexes were prepared and characterized. These complexes exhibit fluorescence-sensitive binding properties for halide anions. The solid-state structure of a non-fluorescent Rh(I) tweezer analogue, determined by X-ray crystallography, shows that the counter anion, Cl−, is trapped inbetween the two amide groups of the tweezer arms through hydrogen bonds. Although the tweezer binds Cl−, the open complex also binds Cl−, showing that the main role of the metal is to increase the local concentration of the pyrenyl amide moieties so that 2:1 binding can take place.
The rational design of potential chemotherapeutic agents: synthesis of bryostatin analogues.

The bryostatins are a unique family of cancer chemotherapeutic candidates isolated from marine bryozoa. While their molecular mode of action is not known, these macrolactones exhibit high affinities for protein kinase C (PKC) isozymes, compete for the phorbol ester binding site on PKC, and stimulate kinase activity in vitro and in vivo. Unlike the phorbol esters, they do not act as tumor promoters. Despite promising biological properties, the supply of these compounds is limited by the difficulty of their isolation from natural sources and their synthetic complexity. A new class of bryostatin analogues which retain the putative recognition domain of the bryostatins but are simplified through deletions and modifications in the C1-C14 spacer domain have been designed using computer models. A convergent synthesis has been realized for the production, in gram quantities, of these recognition and spacer domains whose coupling allows for the generation of a range of analogues. The final closure process involves a novel macrotransacetalization reaction which proceeds with complete stereoselectivity. The solution structures of two synthetic analogues were determined by NMR spectroscopy and found to be very similar to the previously reported structures of bryostatins 1 and 10. In addition, these structures appear to indicate that the stereochemistry of the C3 hydroxyl group plays a significant role in the conformation of the macrolactone. All analogues bound strongly to a mixture of PKC isozymes, and several exhibited significant levels of in vitro growth inhibitory activity against human cancer cell lines. Taken together, this work provides important steps toward the development and understanding of simplified, synthetically accessible analogues of the bryostatins as potential chemotherapeutic agents.
An Addendum to Krein's Formula

Abstract We provide additional results in connection with Krein's formula, which describes the resolvent difference of two self-adjoint extensionsA1andA2of a densely defined closed symmetric linear operatorȦwith deficiency indices (n, n),n ∈ N ∪ {∞}. In particular, we explicitly derive the linear fractional transformation relating the operator-valued Weyl–TitchmarshM-functionsM1(z) andM2(z) corresponding toA1andA2.
Multitaper Spectral Analysis and Wavelet Denoising Applied to Helioseismic Data

Estimates of solar normal mode frequencies from helioseismic observations can be improved by using Multitaper Spectral Analysis (MTSA) to estimate spectra from the time series, then using wavelet denoising of the log spectra. MTSA leads to a power spectrum estimate with reduced variance and better leakage properties than the conventional periodogram. Under the assumption of stationarity and mild regularity conditions, the log multitaper spectrum has a statistical distribution that is approximately Gaussian, so wavelet denoising is asymptotically an optimal method to reduce the noise in the estimated spectra. We find that a single m-upsilon spectrum benefits greatly from MTSA followed by wavelet denoising, and that wavelet denoising by itself can be used to improve m-averaged spectra. We compare estimates using two different 5-taper estimates (Stepian and sine tapers) and the periodogram estimate, for GONG time series at selected angular degrees l. We compare those three spectra with and without wavelet-denoising, both visually, and in terms of the mode parameters estimated from the pre-processed spectra using the GONG peak-fitting algorithm. The two multitaper estimates give equivalent results. The number of modes fitted well by the GONG algorithm is 20% to 60% larger (depending on l and the temporal frequency) when applied to the multitaper estimates than when applied to the periodogram. The estimated mode parameters (frequency, amplitude and width) are comparable for the three power spectrum estimates, except for modes with very small mode widths (a few frequency bins), where the multitaper spectra broadened the modest compared with the periodogram. We tested the influence of the number of tapers used and found that narrow modes at low n values are broadened to the extent that they can no longer be fit if the number of tapers is too large. For helioseismic time series of this length and temporal resolution, the optimal number of tapers is less than 10.
Weak Ties in Networked Communities

Communities with high levels of social capital are likely to have a higher quality of life than communities with low social capital. This is due to the greater ability of such communities to organize and mobilize effectively for collective action because they have high levels of social trust, dense social networks, and well-established norms of mutuality (the major features of social capital). Communities with “bridging” social capital (weak ties across groups) as well as “bonding” social capital (strong ties within groups) are the most effective in organizing for collective action. People who belong to multiple groups act as bridging ties. When people with bridging ties use communication media, such as the Internet, they enhance their capability to educate community members and to organize, as needed, for collective action. This article summarizes evidence from stratified household survey data in Blacksburg, VA, showing that people with weak (bridging) ties across groups have higher levels of community i...
Transient bright "halos" on the South Polar Residual Cap of Mars: Implications for mass-balance

Abstract Spacecraft imaging of Mars’ south polar region during mid-southern summer of Mars year 28 (2007) observed bright halo-like features surrounding many of the pits, scarps and slopes of the heavily eroded carbon dioxide ice of the South Polar Residual Cap (SPRC). These features had not been observed before, and have not been observed since. We report on the results of an observational study of these halos, and spectral modeling of the SPRC surface at the time of their appearance. Image analysis was performed using data from MRO’s Context Camera (CTX), and High Resolution Imaging Science Experiment (HiRISE), as well as images from Mars Global Surveyor’s (MGS) Mars Orbiter Camera (MOC). Data from MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) were used for the spectral analysis of the SPRC ice at the time of the halos. These data were compared with a Hapke reflectance model of the surface to constrain their formation mechanism. We find that the unique appearance of the halos is intimately linked to a near-perihelion global dust storm that occurred shortly before they were observed. The combination of vigorous summertime sublimation of carbon dioxide ice from sloped surfaces on the SPRC and simultaneous settling of dust from the global storm, resulted in a sublimation wind that deflected settling dust particles away from the edges of these slopes, keeping these areas relatively free of dust compared to the rest of the cap. The fact that the halos were not exhumed in subsequent years indicates a positive mass-balance for flat portions of the SPRC in those years. A net accumulation mass-balance on flat surfaces of the SPRC is required to preserve the cap, as it is constantly being eroded by the expansion of the pits and scarps that populate its surface.
Simulations of Discrete Quantum Systems in Continuous Euclidean Time.

We propose a new method to study path integrals for discrete quantum systems in which we work directly in the Euclidean time continuum. The method is of general interest. Here it is applied to the Heisenberg quantum antiferromagnet using a continuous-time version of a loop cluster algorithm. This algorithm is exploited to confirm the predictions of chiral perturbation theory in the extreme low temperature regime, down to $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.01J$. A fit of the low-energy parameters of chiral perturbation theory gives excellent agreement with previous results and with experiments.
On Cluster Variables of Rank Two Acyclic Cluster Algebras

In this note, we find an explicit formula for the Laurent expression of cluster variables of coefficient-free rank two cluster algebras associated with the matrix $${{\left(\begin{array}{ll} 0 &c \\ -c &0 \end{array}\right)}}$$ , which manifestly shows that a large number of coefficients are non-negative. As a corollary, we obtain an explicit expression for the Euler-Poincare characteristics of the corresponding quiver Grassmannians.
Feasibility of the controlled-NOT gate from certain model Hamiltonians

The controlled-NOT (CNOT) gate is widely used in quantum circuits and in current and proposed quantum computing technologies. We investigate the feasibility and minimal implementation of CNOT from specific model Hamiltonian operators that have appeared in the literature. We follow an algebraic approach that provides an analytic solution. Our results are relevant to effective two-qubit Hamiltonians currently being considered for spin-based, superconductivity-based and other implementations of quantum computing.
Observation of an ionospheric disturbance caused by a gamma-ray burst

A first observation of an ionospheric disturbance from a gamma-ray burst is reported. The burst, GB30801, occurred at 22:14:18 UT on August 1, 1983, and was one of the strongest ever observed. The total fluence was 0.002 erg/sq cm, most of which occurred in the first 4 s of the burst. Simultaneously, a change was observed in the amplitude of a VLF radio signal from a transmitter in Rugby, England indicative of an ionospheric disturbance. Weaker disturbances were also recorded at the same receiving site on signals from VLF stations in Annapolis, Maryland and Lualualei, Hawaii. The times of the burst and the disturbances are coincident within the 10-s resolution of the VLF recording system. No similar disturbances were observed within 60 hr around the time of the burst. In the future, a network of VLF burst monitors may provide measurements of the total ionizing energy fluence from a burst, as well as some limited directional information.
ROSAT Evidence for Intrinsic Oxygen Absorption in Cooling Flow Galaxies and Groups

The existence of large quantities of gas that have cooled and dropped out of the hot phase in massive elliptical galaxies, groups, and clusters is the key prediction of the inhomogeneous cooling flow scenario. Using spatially resolved, deprojected ROSAT Position Sensitive Proportional Counter (PSPC) spectra of 10 of the brightest cooling flow galaxies and groups with low Galactic column densities, we have detected intrinsic absorption over energies ~0.4-0.8 keV at the 2 σ/3 σ level in half of the sample. Since no intrinsic absorption is indicated for energies below ~0.4 keV, the most reasonable model for the absorber is collisionally ionized gas at temperatures T = 105-6 K with most of the absorption arising from ionized states of oxygen but with a significant contribution from carbon and nitrogen. The soft X-ray emission of this warm gas can also explain the sub-Galactic column densities of cold gas inferred within the central regions of most of the systems. (This could not be explained by an absorber composed only of dust.) Attributing the absorption to ionized gas reconciles the large columns of cold H and He inferred from Einstein and ASCA with the lack of such columns inferred from ROSAT. Within the central ~10-20 kpc, where the constraints are most secure, the mass of the ionized absorber is consistent with most (perhaps all) of the matter deposited by a cooling flow over the lifetime of the flow. Since the warm absorber produces no significant H or He absorption, the large absorber masses are consistent with the negligible atomic and molecular H inferred from H I and CO observations of cooling flows. It is also found that if T 2 × 105 K, then the optical and far-ultraviolet emission implied by the warm gas does not violate published constraints. An important theoretical challenge is to understand how the warm temperature is maintained and how the gas is supported gravitationally, and we discuss possible solutions to these problems that would require fundamental modification of the standard cooling flow scenario. Finally, we discuss how the prediction of warm ionized gas as the product of mass dropout in these and other cooling flows can be verified with new Chandra and XMM observations.
Maze routing with buffer insertion and wiresizing

The authors propose an elegant formulation of the Maze Routing with Buffer Insertion and Wiresizing problem as a graph-theoretic shortest path problem. This formulation provides time and space performance improvements over previously proposed dynamic programming based techniques. Routing constraints such as wiring obstacles and restrictions on buffer locations and types are easily incorporated in the formulation. They construct a buffer planning (BP)-graph such that the length of every path in this graph is equal to the Elmore delay. Therefore, finding the minimum Elmore delay path becomes a finite shortest path problem. The buffer choices and insertion locations are represented as the vertices in the BP-graph. The interconnect wires are sized by constructing a look-up table for buffer-to-buffer wiresizing solutions. The authors also provide a technique that is able to tremendously improve the runtime. Experiments show improvements over previously proposed methods.
Jets in Astrophysics: a Review

We discuss observations used to infer the presence of accretion disks in astrophysical sources and the disks' association with evidence for astrophysical jets. We highlight some important results from past and current literature that show parallels between the temporal behavior of an active galaxy (NGC 5128) and a galactic microquasar (GRS 1915+105). In addition, we note the remarkable observations of the time history of SCO X-1 from VLBI data at radio frequencies.
Diastereoselective cyclopropanation via homochiral ketals. Dioxolane structural effects

Abstract A series of 2-cyclohexen-1-one ketals related to 2-cyclohexen-1-one 1,4-di- O -benzyl-L-threitol ketal but possesing different dioxolane appendages was prepared and subjected to Simmons-Smith cycloproponation. The observed diastereoselectivity decreased when oxygen was present in the appendages. In the absence of appendage oxygen, the sense of the observed diastereoselectivity was found to depend upon dioxolane chirality. The amount of diastereoselectivity observed was remarkably independent of the nature of the appendages.
Frameshift Mutagenesis and Microsatellite Instability Induced by Human Alkyladenine DNA Glycosylase

Human alkyladenine DNA glycosylase (hAAG) excises alkylated purines, hypoxanthine, and etheno bases from DNA to form abasic (AP) sites. Surprisingly, elevated expression of hAAG increases spontaneous frameshift mutagenesis. By random mutagenesis of eight active site residues, we isolated hAAG-Y127I/H136L double mutant that induces even higher rates of frameshift mutation than does the wild-type hAAG; the Y127I mutation accounts for the majority of the hAAG-Y127I/H136L-induced mutator phenotype. The hAAG-Y127I/H136L and hAAG-Y127I mutants increased the rate of spontaneous frameshifts by up to 120-fold in S. cerevisiae and also induced high rates of microsatellite instability (MSI) in human cells. hAAG and its mutants bind DNA containing one and two base-pair loops with significant affinity, thus shielding them from mismatch repair; the strength of such binding correlates with their ability to induce the mutator phenotype. This study provides important insights into the mechanism of hAAG-induced genomic instability.
Chain compounds based on transition metal backbones: new life for an old topic.

A new link in the chain: After a long period of inactivity, research into one-dimensional compounds based on linear arrays of transition metals is experiencing a renaissance. Recently, oligomeric and polymeric chains have been reported for a variety of transition metals. One such compound of a particularly exotic variety is depicted here, in which a {Pd 4 } 2+ unit is surrounded by a “π-electron sheath” of conjugated polyene ligands.
Pathogenesis of retinopathy of prematurity

Retinopathy of prematurity (ROP) is a blinding disease, initiated by delayed retinal vascular growth after premature birth. There are both oxygen-regulated and non-oxygen-regulated factors, which contribute to both normal vascular development and retinal neovascularization. One important oxygen-regulated factor, critical to both phases of ROP, is vascular endothelial growth factor (VEGF). A critical non oxygen-regulated growth factor is insulin-like growth factor (IGF-1). In knockout mice, lack of IGF-1 prevents normal retinal vascular growth, despite the presence of VEGF, important to vessel development. In vitro, low IGF-1 prevents vascular endothelial growth factor-induced activation of Akt, a kinase critical for vascular endothelial cell survival. Premature infants who develop ROP have lower levels of serum IGF-1 than age-matched infants without disease. Conclusion: IGF-1 is critical to normal vascular development. Low IGF-1 predicts ROP and restoration of IGF-1 to normal levels may prevent ROP.
The virtual Haken conjecture: Experiments and examples

A 3-manifold is Haken if it contains a topologically essential surface. The Virtual Haken Conjecture says that every irreducible 3-manifold with innite fundamental group has a nite cover which is Haken. Here, we discuss two interrelated topics concerning this conjecture. First, we describe computer experiments which give strong evidence that the Virtual Haken Conjecture is true for hyperbolic 3-manifolds. We took the complete HodgsonWeeks census of 10,986 small-volume closed hyperbolic 3-manifolds, and for each of them found nite covers which are Haken. There are interesting and unexplained patterns in the data which may lead to a better understanding of this problem. Second, we discuss a method for transferring the virtual Haken property under Dehn lling. In particular, we show that if a 3-manifold with torus boundary has a Seifert bered Dehn lling with hyperbolic base orbifold, then most of the Dehn lled manifolds are virtually Haken. We use this to show that every non-trivial Dehn surgery on the gure-8 knot is virtually Haken. AMS Classication numbers Primary: 57M05, 57M10 Secondary: 57M27, 20E26, 20F05
Referees and the Publications Crisis

Routine refereeing by peers of manuscripts submitted to scholarly journals is a logical and effective device that can obviate ‘crankiness, irrelevance and gross incompetence’ [Ziman, 1970a] on the one hand and minimize editorial arbitrariness on the other. As reviewed by Zuckerman and Merton [1971], the device has historical roots that extend back to the beginning of the first scholarly journals, such as Transactions of the Royal Society, and Journal des Scavans. The growth of science since World War II and the pressure of burgeoning manuscript submission appear to have been important factors in making automatic peer review nearly universal in American and British Commonwealth natural science journals and in international journals influenced by Anglo-North Americans. A 1962 survey cited by Zuckerman and Merton [1971] found that 71% of 156 physical and biological science journals in 13 countries made use of referees.
Fluid random surfaces with extrinsic curvature. II

Abstract We present the results of an extension of our previous work on large-scale simulations of dynamically triangulated toroidal random surfaces embedded in R 3 with extrinsic curvature. We find that the extrinsic-curvature specific heat peak ceases to grow on lattices with more than 576 nodes and that the location of the peak λ c also stabilizes. The evidence for a true crumpling transition is still weak. If we assume it exists we can say that the finite-size scaling exponent α / ηd is very close to zero or negative. On the other hand our new data does rule out the observed peak as being a finite-size artifact of the persistence length becoming comparable to the extent of the lattice.
Partial dissociation of water on Ru(0001)

Initial water deposition on the moderately reactive precious metal surface Ru(0001) has been thought to produce an ice-like bilayer. However, calculations from first principles show that the wetting layer observed on Ru(0001) cannot be formed of undissociated water molecules. An energetically favorable alternative, consistent with the remarkable observation that the wetting layer's oxygen atoms are nearly coplanar, is a half-dissociated monolayer wherein water molecules and hydroxyl fragments are hydrogen-bonded in a hexagonal structure and hydrogen atoms bind directly to the metal.
Direct butyrolactone production using tin hydride

Use of HSnBu3 for the reductive cyclization of suitable alpha-bromo allylic esters affords 2,3-disubstituted butyrolactones.
Frequency Domain Structural System Identification by Observability Range Space Extraction

This paper presents the Frequency Domain Observability Range Space Extraction (FORSE) identification algorithm. FORSE is a singular value decomposition based identification algorithm which constructs a state space model directly from frequency domain data. The concept of system identification by observability range space extraction was developed by generalizing the Q-Markov Covariance Equivalent Realization and Eigensystem Realization Algorithm. The numerical properties of FORSE are well behaved when applied to multi-variable and high dimensional structural systems. It can achieve high modeling accuracy by properly overparameterizing the system. The effectiveness of this algorithm for structural system identification is demonstrated using the MIT Middeck Active Control Experiment (MACE). MACE is an active structural control experiment to be conducted in the Space Shuttle middeck. Results of ground experiments using this algorithm will be discussed.
Triazolbenzo[d]thiazoles: efficient synthesis and biological evaluation as neuroprotective agents.

Abstract A number of (1 H -1,2,3-triazol-1-yl)benzo[ d ]thiazoles were synthesized utilizing a versatile Cu-catalyzed azide–alkyne click reaction (CuAAC) on tautomeric benzo[4,5]thiazolo[3,2- d ]tetrazole ( 1 ) and 2-azidobenzo[ d ]thiazole ( 2 ) starting materials. Moreover, one of the resulting products of this investigation, triazolbenzo[ d ]thiazole 22 , was found to possess significant neuroprotective activity in human neuroblastoma (SH-SY5Y) cells.
Efficient solid state photocyclization of sterically congested α-o-tolyl ketones despite “poor” geometries for hydrogen abstraction

Abstract Several α-mesityl and α-(o-tolyl)acetophenones undergo photocyclization to 2-indanols almost quantitatively when irradiated as crystals, even those that undergo significant competing α-cleavage or 1,3-aryl shift in solution. The requisite triplet δ-hydrogen abstraction apparently can occur at what appears to be a “bad” geometry. One ketone, α-(o-tolyl)propiophenone, partially rearranges to the β-isomer, which arises from disproportionation of the radicals formed by initial α-cleavage.
Consistent updates in dual representation systems

Abstract Dual representation systems rely on a parametric model to create and to manipulate the boundary representation of a solid. Parametric and boundary representations remain consistent if they continue to model the same solid, after updates applied to the parametric model and/or to the boundary representation. We consider the problem of verifying the consistency between the boundary representation and the CSG representation that is a restricted case of parametric representation. We determine the necessary and sufficient conditions for consistency of the two representations, identify the required computational utilities, and describe two implemented and tested algorithms. Our algorithms rely on sign-invariant space decompositions and can be used to verify consistency of other representations, including parametric definitions such as feature attachments. They could also be used to verify consistency of boundary and parametric representations in different systems, or corresponding representations in integrated modeling environments.
The development of food search behavior by rats: the effects of hippocampal damage and haloperidol.

Food deprived rats were required to locate four pellets of food located in 4 of 16 holes in an enclosed arena. Three groups of animals were studied in 11 testing sessions: rats with bilateral hippocampal damage; rats with bilateral neocortical damage; and an unoperated group. Half of each group received haloperidol and half received saline injection 20 min before Sessions 4 through 10. No injections were given on the first three sessions or on the final, 11th session. Animals with hippocampal lesions visited more nonfood holes than control animals and did not develop consistent sequences of food-hole visits. The administration of haloperidol reduced the number of consistent sequences of food seeking behaviors by intact animals without significantly affecting the efficiency of performance as measured by the number of nonfood holes visited. Haloperidol reduced the number of visits to nonfood holes of animals with hippocampal lesions.
Measuring Consumer and Competitive Impact with Elasticity Decompositions

Abstract Marketing investments are designed to change consumer behavior in ways that help goods compete in the marketplace. Previous research has focused on using elasticity decompositions to measure how these investments affect either consumer decision making or competing goods. On the one hand, decision-based decompositions attribute the growth in own-good demand to changes in the consumers' decision-making processes. On the other hand, unit-based and share-based decompositions attribute the same growth to either rivalrous or nonrivalrous sources. The objective of this article is to provide a clear and accurate method that simultaneously attributes the growth in own-good demand to changes in (1) consumers' decisions, (2) competitive demand, and (3) competitive market share. The author accomplishes this by settling some confusion about what the decision- and share-based decompositions mean, by discussing how each of the decompositions are related to the others, and by discussing the research questions th...
Tick Size, Spreads, and Liquidity: An Analysis of Nasdaq Securities Trading near Ten Dollars

Abstract Quoted and effective bid–ask spreads on Nasdaq are two to four cents per share narrower, ceteris paribus, when stocks trade with a smaller tick size below $10 per share. There is no evidence of a reduction in liquidity with the smaller tick size. The largest spread reductions occur for stocks whose market makers avoid odd-eighth quotes. This finding provides support for models implying that changes in the tick size can affect equilibrium spreads on a dealer market and indicates that the relation between tick size and market quality is more complex than the imposition of a constraint on minimum spread widths. Journal of Economic Literature Classification Numbers: G29, D34, N20.
The Frobenius-Schur indicator in conformal field theory

Abstract An analogue of the classical Frobenius-Schur indicator is introduced in order to distinguish between real and pseudo-real self-conjugate primary fields, and an explicit expression for this quantity is derived from the trace of the braiding operator.
Stability analysis of two-dimensional models of three-dimensional convection.

Analytical and numerical methods are used to study the linear stability of spatially periodic solutions for various two-dimensional equations which model thermal convection in fluids. This analysis suggests new model equations that will be useful for investigating questions such as wave-number selection, pattern formation, and the onset of turbulence in large-aspect-ratio Rayleigh-B\'enard systems. In particular, we construct a nonrelaxational model that has stability boundaries similar to those calculated for intermediate Prandtl-number fluids.
Efficient waveform coding of speech using vector quantization

A vector quantizer operates on blocks (vectors) of k contiguous samples of the input signal, rather than on isolated samples as in scalar quantization. Rate-distortion theory guarantees a performance arbitrarily close to optimal for waveform vector quantizers if the dimension of the vector, k, is sufficiently large. The main obstacle in using this result is implementational complexity. A vector quantizer of dimension k operating at a rate of r bits/component requires a number of computations of the order of k2('kr) and a memory of the same order. Various suboptimal vector quantization techniques, such as tree structured codebooks or multi-stage quantizers, achieve an important reduction in computational complexity. The resulting quantizers compare favorably with scalar quantization, but the achieved overall performance is not competitive with sophisticated scalar coding systems using compression techniques such as transform coding, linear prediction, and adaptive methods. A different approach for achieving a viable waveform coding system is to exploit the performance of a low dimensionality vector quantizer by combining it with other waveform compression techniques. In this approach the vector quantizer becomes a building block in the waveform coding system. Consequently, the entire system must be designed as a vector processing system as a result of the presence of the vector quantizer. The main goal of the study is to present and analyze a waveform coding system in which a low dimensionality vector quantizer is used in an adaptive differential coding scheme. In the encoding process, a locally generated prediction of the current input vector is subtracted from the current vector and the error vector is coded by a vector quantizer. Each frame, consisting of many vectors, is classified into one of m statistical types. This classification determines which one of m fixed predictors and of m vector quantizers will be used for coding the current frame. This system is called Adaptive Differential Vector Coding (ADVC). The design methods for ADVC are developed for two different fidelity criteria: the standard mean square error and the energy weighted mean square error. The ADVC system was designed and tested by simulations for the encoding of speech waveforms. A typical simulation result for the ADVC system is a signal to noise ratio slightly larger than 20 dB at a rate of 2 bits/sample. These results were obtained inside a training sequence represented by a speech file with 6 different talkers, four male and two female, totaling about 16 sec. of speech, sampled at 8 KHz (130,000 samples). This performance is competitive with the best known results for waveform speech coding including such high complexity methods as tree and trellis encoding. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI
Embedding loop quantum cosmology without piecewise linearity

An important goal is to understand better the relation between full loop quantum gravity (LQG) and the simplified, reduced theory known as loop quantum cosmology (LQC), directly at the quantum level. Such a firmer understanding would increase confidence in the reduced theory as a tool for formulating predictions of the full theory, as well as permitting lessons from the reduced theory to guide further development in the full theory. This paper constructs an embedding of the usual state space of LQC into that of standard LQG, that is, LQG based on piecewise analytic paths. The embedding is well defined even prior to solving the diffeomorphism constraint, at no point is a graph fixed and at no point is the piecewise linear category used. This motivates for the first time a definition of operators in LQC corresponding to holonomies along non-piecewise linear paths, without changing the usual kinematics of LQC in any way. The new embedding intertwines all operators corresponding to such holonomies, and all elements in its image satisfy an operator equation which classically implies homogeneity and isotropy. The construction is made possible by a recent result proven by Fleischhack. Communicated by P Singh
Measuring monetary policy interdependence

Abstract This paper measures the degree of monetary policy interdependence between major industrialized countries from a new perspective. The analysis uses a special data set on central bank issued policy rate targets for 14 OECD countries. Methodologically, our approach is novel in that we separately examine monetary interdependence due to (1) the coincidence in time of when policy actions are executed from (2) the nature and magnitude of the policy adjustments made. The first of these elements requires that the timing of events be modeled with a dynamic discrete duration design. The discrete nature of the policy rate adjustment process that characterizes the second element is captured with an ordered response model. The results indicate there is significant policy interdependence among these 14 countries during the 1980–1998 sample period. This is especially true for a number of European countries which appeared to respond to German policy during our sample period. A number of other countries appeared to respond to U.S. policy, though this number is smaller than that suggested in preceding studies. Moreover, the policy harmonization we find appears to work through channels other than formal coordination agreements.
Supersymmetric null-surfaces

Single trace operators with the large R-charge in supersymmetric Yang-Mills theory correspond to the null-surfaces in AdS(5) x S-5. We argue that the moduli space of the null-surfaces is the space of contours in the super-grassmanian parametrizing the complex (2|2)-dimensional subspaces of the complex (4|4)-dimensional space. The odd coordinates on this super-grassmanian correspond to the fermionic degrees of freedom of the superstring.
Custodial nonabelian gauge symmetries in realistic superstring derived models

Abstract A well known problem in supersymmetric models is the presence of, lepton and baryon number violating, dimension four operators. The traditional R-parity solution may not be suitable if one tries to incorporate supersymmetry into a Planck scale theory. I propose a different solution in the context of realistic string models. I show that realistic string models can give rise to custodial nonabelian gauge symmetries under which only the leptons or quarks transform. I explain how such symmetries arise in a class of free fermionic models that are based on Z 2 × Z 2 orbifold with standard embedding. The custodial symmetries forbid proton decay from dimension four operators while allowing R-parity violation.
Quasi-Three-Dimensional Laminar Boundary-Layer Separations in Supersonic Flow

A numerical algorithm is presented for solving laminar, steady, supersonic interacting boundary-layer flows for quasi-three-dimensional configurations. The interaction problem is treated as a boundary-value problem and a salient feature of the scheme is the direct implementation of the downstream boundary condition. Solutions are presented for axisymmetric and swept (yawed) compression ramps for both adiabatic and heat transfer conditions over a Mach number range of 2-6. The results are in good agreement with experimental data and existing theories for axisymmetric cases. For the swept (yawed) configurations, lack of experimental data makes a direct comparison impossible, but the present solutions are found to be in qualitative agreement with earlier studies. In addition it is shown that the trends obtained here for the sweep effects are well predicted by a simple extension of the two-dimensional asymptotic theory.
Accounting for context in plan recognition, with application to traffic monitoring

Typical approaches to plan recognition start from a representation of an agent's possible plans, and reason evidentially from observations of the agent's actions to assess the plausibility of the various candidates. A more expansive view of the task (consistent with some prior work) accounts for the context in which the plan was generated, the mental state and planning process of the agent, and consequences of the agent's actions in the world. We present a general Bayesian framework encompassing this view, and focus on how context can be exploited in plan recognition. We demonstrate the approach on a problem in traffic monitoring, where the objective is to induce the plan of the driver from observation of vehicle movements. Starting from a model of how the driver generates plans, we show how the highway context can appropriately influence the recognizer's interpretation of observed driver behavior.