cssi/SciSciGPT-SciSciNet huggingface dataset:
STATIC AND DYNAMIC EVALUATION OF QoS PROPERTIES

Efficient utilization of modern high bandwidth communication networks relies on statistical multiplexing of many logical channels through one physical channel. Communication requests typically include some statistical characterization of the requested connection (such as pick value, mean values, etc). The task of the network management procedure is to accommodate as many communication requests as possible while keeping the failure (e.g. overflow) probability bounded by a pre-specified parameter. When the network consists of one link, the task reduces to evaluating the probability that a sum of random variables does not exceed a given bound. Techniques such as the method of effective bandwidth give a practical solution for the one link problem. In this paper we address the more realistic setting of estimating QoS properties of multi-link networks with arbitrary patterns. The related optimization problem for that setting is #P-complete even for the most simple communication characteristics. Our main result is an efficient Monte-Carlo method for estimating the failure probability of a general network. Our method is particularly useful in a dynamic setting in which communication requests are dynamically added and eliminated from the system. The amortized cost in our solution of updating the estimate after each change is proportional to the fraction of links involved in the change rather than to the total number of links in the network.
Design issues for mixed media packet switching networks

In this paper we present some of the important design issues for packet switching networks with both satellite and terrestrial components---which we call mixed media packet switching networks. Satellite packet switching has considerable promise for low cost, high bandwidth data communications. However there is inherent high delay in satellite links which does not appear in ground links. Therefore a mix of the two communications media offers the advantages of low-cost/high bandwidth together with low-delay communications where required. In this paper we examine a number of tradeoffs which offer guidelines for the design and optimum utilization of mixed media networks.
Nonlocal Models of Cosmic Acceleration

I review a class of nonlocally modified gravity models which were proposed to explain the current phase of cosmic acceleration without dark energy. Among the topics considered are deriving causal and conserved field equations, adjusting the model to make it support a given expansion history, why these models do not require an elaborate screening mechanism to evade solar system tests, degrees of freedom and kinetic stability, and the negative verdict of structure formation. Although these simple models are not consistent with data on the growth of cosmic structures many of their features are likely to carry over to more complicated models which are in better agreement with the data.
On the local quotient structure of Artin stacks

Abstract We show that near closed points with linearly reductive stabilizer, Artin stacks are formally locally quotient stacks by the stabilizer. We conjecture that the statement holds etale locally and we provide some evidence for this conjecture. In particular, we prove that if the stabilizer of a point is linearly reductive, the stabilizer acts algebraically on a miniversal deformation space, generalizing the results of Pinkham and Rim. We provide a generalization and stack-theoretic proof of Luna’s etale slice theorem which shows that GIT quotient stacks are etale locally quotients stacks by the stabilizer.
Strategic Management of Cost Efficiencies in Networks: Cross‐country Evidence on European Branch Banking

This paper examines the role of cost efficiencies on efficient management of branch networks in the contemporary European commercial banking industry. The analysis, which could be generalised to other industries, indicates that larger banks are more likely to have heavily utilised branch networks than smaller banks and to exhibit fewer cost efficiencies from building more branches. The finding of this result within each country suggests the role of internal firm size regardless of competitive conditions. The similar cross-country finding suggests the impact of factors such as market structure/concentration levels and type of non-price competition. Larger banks can generate less income per unit asset deployed. Cross-border efficiency might be improved by greater use of banks with under-used networks by banks with over-used networks.
The surprise element: jumps in interest rates

Abstract That information surprises result in discontinuous interest rates is no surprise to participants in the bond markets. We develop a class of Poisson–Gaussian models of the Fed Funds rate to capture surprise effects, and show that these models offer a good statistical description of short rate behavior, and are useful in understanding many empirical phenomena. Jump (Poisson) processes capture empirical features of the data which would not be captured by Gaussian models, and there is strong evidence that existing Gaussian models would be well-enhanced by jump and ARCH-type processes. The analytical and empirical methods in the paper support many applications, such as testing for Fed intervention effects, which are shown to be an important source of surprise jumps in interest rates. The jump model is shown to mitigate the non-linearity of interest rate drifts, so prevalent in pure-diffusion models. Day-of-week effects are modelled explicitly, and the jump model provides evidence of bond market overreaction, rejecting the martingale hypothesis for interest rates. Jump models mixed with Markov switching processes predicate that conditioning on regime is important in determining short rate behavior.
Synthesis of β,γ-unsaturated amides via palladium-promoted coupling of organomercurials and vinylic β-lactams

The reaction of aryl or vinylic mercurials, Li2PdCl4 and vinylic β-lactams affords good yields of the corresponding ring-opened β,γ-unsaturated amides.
Computing the Loewner Driving Process of Random Curves in the Half Plane

We simulate several models of random curves in the half plane and numerically compute the stochastic driving processes that produce the curves through the Loewner equation. Our models include models whose scaling limit is the Schramm-Loewner evolution (SLE) and models for which it is not. We study several tests of whether the driving process is Brownian motion, as it is for SLE. We find that testing only the normality of the process at a fixed time is not effective at determining if the random curves are an SLE. Tests that involve the independence of the increments of Brownian motion are much more effective. We also study the zipper algorithm for numerically computing the driving function of a simple curve. We give an implementation of this algorithm which runs in a time O(N1.35) rather than the usual O(N2), where N is the number of points on the curve.
A combinatorial approach to diffeomorphism invariant quantum gauge theories

Quantum gauge theory in the connection representation uses functions of holonomies as configuration observables. Physical observables (gauge and diffeomorphism invariant) are represented in the Hilbert space of physical states; physical states are gauge and diffeomorphism invariant distributions on the space of functions of the holonomies of the edges of a certain family of graphs. Then a family of graphs embedded in the space manifold (satisfying certain properties) induces a representation of the algebra of physical observables. We construct a quantum model from the set of piecewise linear graphs on a piecewise linear manifold, and another manifestly combinatorial model from graphs defined on a sequence of increasingly refined simplicial complexes. Even though the two models are different at the kinematical level, they provide unitarily equivalent representations of the algebra of physical observables in separable Hilbert spaces of physical states (their s-knot basis is countable). Hence, the combinator...
An SU(2) anomaly

A new restriction of fermion quantum numbers in gauge theories is derived. For instance, it is shown that an SU(2) gauge theory with an odd number of left-handed fermion doublets (and no other representations) is mathematically inconsistent.
A Chandra Observation of the Diffuse Emission Centered on the Low-Mass X-Ray Binary 4U 1755–33

We present an analysis of a Chandra observation of the field surrounding the low-mass X-ray binary 4U 1755-33, which has been in quiescence since 1996. In 2003, Angelini & White reported the appearance of a narrow 7'-long jetlike feature centered on the position of 4U 1755-33 using the XMM-Newton telescope. Although the source and jet are not visibly apparent in our Chandra ACIS-S image, there is a significant excess (4-6 σ) of counts in a region that encloses the jet when compared to adjacent regions. We examined a knot of emission in the jet that was detected by XMM-Newton but not by Chandra and calculated that if the knot flux observed by XMM-Newton was concentrated in a point source, Chandra would have easily detected it; we therefore conclude that this knot of emission is diffuse. In summary, we suggest that the jetlike feature found previously in the XMM-Newton data is quite diffuse and likely a true jet and that it is not due to a chance alignment of discrete point sources or pointlike regions of emission associated with internal shocks.
Rotating Waves as a Stall inception Indication in Axial Compressors

Stall inception has been studied in two low speed compressors (a single-stage and a three-stage) and in a high speed three-stage compressor, using temporally and spatially resolved measurements. In all three machines, rotating stall was preceded by a period in which small amplitude waves were observed travelling around the circumference of the machine at a speed slightly less than the fully developed rotating stall cell speed. The waves evolved smoothly into rotating stall without sharp changes in phase or amplitude, implying that, in the machines tested, the prestall waves and the fully developed rotating stall are two stages of the same phenomenon. The growth rate of these disturbances was in accord with that predicted by current analytical models. The prestall waves were observed both with uniform and with distorted inflow, but were most readily discerned with uniform inflow. Engineering uses and limitations of these waves are discussed.Copyright © 1990 by ASME
Open- and short-circuit experiments with a nonequilibrium MHD generator using both cold and hot insulator walls

Insulator wall temperature effect on supersonic two temperature MHD generator channel flow at open and short circuit conditions
MicroCT Liver Contrast Agent Enhancement Over Time, Dose, and Mouse Strain

The aim of this study was to examine strain differences in the uptake of Fenestra liver contrast agent (LC) in Nude, C57, and severe-combined immunodeficient (SCID) mice. In addition, we aimed to determine optimum dosing and to determine if there are positron emission tomography (PET)-attenuation effects on 2-deoxy-2[F-18]fluoro-d-glucose (FDG) values due to Fenestra LC. Nude, C57, and SCID mice were injected via tail vein at 5.0, 7.5, 10.0, and 15.0 ml/kg with contrast agent and imaged using micro computed tomography (microCT) 2 h after uptake and then daily up to 7 days. Mice were imaged by microPET/CT with FDG, with or without contrast agent. Significant variations in contrast were observed between mouse strains. SCID mice had significantly more spleen uptake of contrast than the other strains, and C57 mice had significantly more liver uptake of contrast than other strains. Across all strains, the spleen showed significantly higher uptake and duration of contrast than liver. Only the heart showed a significant attenuation of FDG uptake following contrast administration. Strain-specific variations in Fenestra LC uptake and signal duration were observed. At 7.5 ml/kg, this contrast agent is effective for imaging for 1 day, whereas at 15 ml/kg, it can be used up to 1 week. Fenestra LC does not appear to attenuate FDG uptake at 15 ml/kg for most tissues; therefore, it can be used in conjunction with microPET imaging studies.
Tauberian theory for multivariate regularly varying distributions with application to preferential attachment networks

Abel-Tauberian theorems relate power law behavior of distributions and their transforms. We formulate and prove a multivariate version for non-standard regularly varying measures on \(\mathbb {R}_{+}^{p}\) and then apply it to prove that the joint distribution of in- and out-degree in a directed edge preferential attachment model has jointly regularly varying tails.
Asymptotics of Block Toeplitz Determinants and the Classical Dimer Model

We compute the asymptotics of a block Toeplitz determinant which arises in the classical dimer model for the triangular lattice when considering the monomer-monomer correlation function. The model depends on a parameter interpolating between the square lattice (t = 0) and the triangular lattice (t = 1), and we obtain the asymptotics for 0 < t ≤ 1. For 0 < t < 1 we apply the Szego Limit Theorem for block Toeplitz determinants. The main difficulty is to evaluate the constant term in the asymptotics, which is generally given only in a rather abstract form.
Structural and Functional Aspects of Metal Sites in Biology

For present purposes, a protein-bound metal site consists of one or more metal ions and all protein side chain and exogenous bridging and terminal ligands that define the first coordination sphere of each metal ion. Such sites can be classified into five basic types with the indicated functions: (1) structural -- configuration (in part) of protein tertiary and/or quaternary structure; (2) storage -- uptake, binding, and release of metals in soluble form: (3) electron transfer -- uptake, release, and storage of electrons; (4) dioxygen binding -- metal-O{sub 2} coordination and decoordination; and (5) catalytic -- substrate binding, activation, and turnover. The authors present here a classification and structure/function analysis of native metal sites based on these functions, where 5 is an extensive class subdivided by the type of reaction catalyzed. Within this purview, coverage of the various site types is extensive, but not exhaustive. The purpose of this exposition is to present examples of all types of sites and to relate, insofar as is currently feasible, the structure and function of selected types. The authors largely confine their considerations to the sites themselves, with due recognition that these site features are coupled to protein structure at all levels. In themore » next section, the coordination chemistry of metalloprotein sites and the unique properties of a protein as a ligand are briefly summarized. Structure/function relationships are systematically explored and tabulations of structurally defined sites presented. Finally, future directions in bioinorganic research in the context of metal site chemistry are considered. 620 refs.« less
Finding missing markets (and a disturbing epilogue) : evidence from an export crop adoption and marketing intervention in Kenya

In much of the developing world, many farmers grow crops for local or personal consumption despite export options that appear to be more profitable. Thus many conjecture that one or several markets are missing. This paper reports on a randomized controlled trial conducted by DrumNet in Kenya that attempts to help farmers adopt and market export crops. DrumNet provides smallholder farmers with information about how to switch to export crops, makes in-kind loans for the purchase of the agricultural inputs, and provides marketing services by facilitating the transaction with exporters. The experimental evaluation design randomly assigns pre-existing farmer self-help groups to one of three groups: (1) a treatment group that receives all DrumNet services, (2) a treatment group that receives all DrumNet services except credit, or (3) a control group. After one year, DrumNet services led to an increase in production of export oriented crops and lower marketing costs; this translated into household income gains for new adopters. However, one year after the study ended, the exporter refused to continue buying the cash crops from the farmers because the conditions of the farms did not satisfy European export requirements. DrumNet collapsed in this region as farmers were forced to sell to middlemen and defaulted on their loans. The risk of such events may explain, at least partly, why many seemingly more profitable export crops are not adopted.
Catalytic, Enantioselective [4 + 2]-Cycloadditions of Ketene Enolates and o-Quinones: Efficient Entry to Chiral, α-Oxygenated Carboxylic Acid Derivatives

We report catalytic, enantioselective [4 + 2]-cycloadditions of o-quinones with ketene enolates (derived from readily available acid chlorides) using cinchona alkaloid derivatives as catalysts to produce products in high enantiomeric excess (ee) and good to excellent yields. The thermodynamic driving force for these reactions is due in part to the restoration of aromaticity to the products. The resulting chiral, bicycloadducts can be synthetically manipulated in a variety of useful ways, for example to provide a flexible synthesis of α-oxygenated carboxylic acid derivatives.
Evidence for Wave Heating of the Quiet-Sun Corona

We have measured the energy and dissipation of Alfvenic waves in the quiet Sun. A magnetic field model was used to infer the location and orientation of the magnetic field lines along which the waves are expected to travel. The waves were measured using spectral lines to infer the wave amplitude. The waves cause a non-thermal broadening of the spectral lines, which can be expressed as a non-thermal velocity v nt. By combining the spectroscopic measurements with this magnetic field model, we were able to trace the variation of v nt along the magnetic field. At each footpoint of the quiet-Sun loops, we find that waves inject an energy flux in the range of 1.3-5.5 × 105 erg cm–2 s–1. At the minimum of this range, this amounts to more than 80% of the energy needed to heat the quiet Sun. We also find that these waves are dissipated over a region centered on the top of the loops. The position along the loop where the damping begins is strongly correlated with the length of the loop, implying that the damping mechanism depends on the global loop properties rather than on local collisional dissipation.
Low loss etchless silicon photonic waveguides

We demonstrate low loss silicon waveguides fabricated without silicon etching by selective oxidation. We show propagation losses of 0.3dB/cm (λ=1.55µm), roughness of 0.3nm RMS, and 0.0002dB loss for a 90° bend with 20µm bending radius.
Oxidative Heck Vinylation for the Synthesis of Complex Dienes and Polyenes

We introduce an oxidative Heck reaction for selective complex diene and polyene formation. The reaction proceeds via oxidative Pd(II)/sulfoxide catalysis that retards palladium-hydride isomerizations which previously limited the Heck manifold’s capacity for furnishing stereodefined conjugated dienes. Limiting quantities of nonactivated terminal olefins (1 equiv) and slight excesses of vinyl boronic esters (1.5 equiv) that feature diverse functionality can be used to furnish complex dienes and polyenes in good yields and excellent selectivities (generally E:Z = >20:1; internal:terminal = >20:1). Because this reaction only requires prior activation of a single vinylic carbon, improvements in efficiency are observed for synthetic sequences relative to ones featuring reactions that require activation of both coupling partners.
IMPACTS OF A SUPERSONIC SHOCK FRONT ON STAR FORMATION IN THE BULLET CLUSTER

We use the Bullet Cluster (1E0657-56) to investigate the extent to which star formation in cluster galaxies is influenced by ram pressure from supersonic gas (Mach 3) during a cluster merger. While the effects of ram pressure have been studied for individual galaxies infalling into galaxy clusters, this system provides a unique opportunity to investigate the impact of dramatic merger events on the cluster galaxy population. In this analysis, we use Spitzer IRAC data to study star formation. At the redshift of the cluster, the 6.2 μm PAH feature is redshifted into the 8 μm band, enabling use of the m 4.5 – m 8 color as a proxy for specific star formation rate. We find that the color distribution on the two sides of the shock differs by less than 2σ, and conclude that ram pressure from the shock front has no dramatic, immediate impact on the star formation of cluster galaxies in the Bullet Cluster.
Comparison of Heliospheric In Situ Data with the Quasi-steady Solar Wind Models

The standard theory for the solar-heliospheric magnetic field is the so-called quasi-steady model in which the field is determined by the observed magnetic flux at the photosphere and the balance between magnetic and plasma forces in the corona. In this model, the solar magnetic flux that opens to the heliosphere can increase or decrease as the photospheric flux evolves. The most sophisticated implementation of the quasi-steady theory is the SAIC model, which solves the fully time-dependent 3D MHD equations for the corona and wind until a steady state is achieved. In order to test the quasi-steady theory, we compare the 3D MHD model with observations of the heliospheric flux using multipoint measurements from the VHM instrument on the Ulysses spacecraft from 1991 to 2005 and from magnetic field measurements from various spacecraft at L1 compiled into the OMNI data set from 1976 through 2005. We also compare the observations to the predictions of the potential-field source-surface model, an older and simpler implementation of the quasi-steady theory. During solar maximum, ICMEs significantly disturb the heliospheric magnetic field, making our comparisons difficult. We find that the MHD model compares well with the general trends of the observed heliospheric fluxes. Variations on short timescales, presumably due to local effects, are missed by the model, but the long-term evolution is well matched. The model disagrees with observations most when Ulysses is in slow wind or ICME-related flows. The model underestimates the flux at solar maximum; however, this is to be expected, given the large number of ICMEs in the heliosphere at this time. We discuss the possible sources of discrepancy between the observations and the quasi-steady models.
LEADERSHIP PRACTICES RELATED TO UNINTENTIONAL INJURY PREVENTION AT SCHOOLS

Background A safe school environment for pupils is ensured by law in Finland. However, according to national School Health Promotion Study in 2010/2011 almost every fourth 8th and 9th grader (14-15-year-olds) reported they had got into at least one school injury requiring services of a public health nurse or a doctor. Objectives The aim of this study was to find out what common practices comprehensive schools have related to prevention of unintentional school injuries, and what has changed over time. Methods In 2011 altogether 2011 and in 2009 1803 comprehensive schools (72% and 63% of all schools in Finland) answered to a nationwide questionnaire sent to principals. Results In 2011, 87% of schools reported that the promotion of health, welfare and safety was described in their school curriculum. Monitoring and evaluating health, welfare and safety was described in the curriculum of 60%. 71% monitored injuries at school and 62% on the way to or from school: compared to previous study there was a slight increase. There was an increase from 40% to 55% in triennially assessing the health and safety of the school environment and community, as ordered by a government decree since July 2009. The most recent assessment by schools identified a danger of unintentional injury indoors in 23% and outdoors in 26% of the schools. Contribution to the field According to the results it seems that legislation might further support implementing safety practice that was formerly only recommended nationally. Also monitoring safety practices at national level provides valuable information for the basis of policymaking. This is an abstract of a presentation at Safety 2012, the 11th World Conference on Injury Prevention and Safety Promotion, 1-4 October 2012, Michael Fowler Center, Wellington, New Zealand. Full text does not seem to be available for this abstract.
On the feasibility of charged wormholes

While wormhole spacetimes are predictions of the general theory of relativity, specific solutions may not be compatible with quantum field theory. This paper modifies the charged wormhole model of Kim and Lee with the aim of satisfying an extended version of a quantum inequality due to Ford and Roman. The modified metric may be viewed as a solution of the Einstein fields equations representing a charged wormhole that is compatible with quantum field theory.
Rearrangement of 3-Acyl Derivatives of L-Ascorbic Acid

Abstract Evidence of rearrangement of 3-acyl derivatives of ascorbic acid to 2-acyl derivatives has been found for carbon and phosphorus acyl groups. The observations are consistent with intramolecular rearrangement through a cyclic intermediate in which the acyl group is bonded to both the 2- and 3-oxygen atoms of ascorbic acid. A rate of rearrangement has been measured for the 3-diphenylphosphinate ester. Calculated results indicate an increase in negative atomic charge at O-2 in the 3-acyl esters but a decrease in the charge of O-3 in the 2-acyl esters.
Commitment Devices Using Initiatives to Change Behavior

Unhealthy behaviors are responsible for a large proportion of health care costs and poor health outcomes.1 Surveys of large employers regularly identify unhealthy behaviors as the most important challenge to affordable benefits coverage. For this reason, employers increasingly leverage incentives to encourage changes in employees’ health-related behaviors. According to one survey, 81% of large employers provide incentives for healthy behavior change.2 In this Viewpoint, we discuss the potential and limitations of an approach that behavioral science research has shown can be used to influence health behaviors but that is distinct from incentives: the use of commitment devices (Table).3
Diffraction effects from giant segmented mirror telescopes

Ultra-high contrast imaging with giant segmented mirror telescopes will involve light levels of order 10 -6 times that of the central diffraction spike or less. At these levels it is important to quantify accurately a variety of diffraction effects, including segmentation geometry, intersegment gaps, obscuration by the secondary mirror and its supports, and segment alignment and figure errors, among others. We describe an accurate method for performing such calculations and present preliminary results in the context of the California Extremely Large Telescope.
Radiative heat conduction and the magnetorotational instability

A photon or a neutrino gas, semicontained by a non-diffusive particle species through scattering, comprises a rather peculiar magnetohydrodynamic fluid where the magnetic field is truly frozen only to the comoving volume associated with the mass density. Although radiative diffusion precludes a formal adiabatic treatment of compressive perturbations, we cast the energy equation in quasi-adiabatic form by assuming a negligible rate of energy exchange among species on the time-scale of the perturbation. This leads to a simplified dispersion relation for toroidal, non-axisymmetric magnetorotational modes when the accretion disc has comparable stress contributions from diffusive and non-diffusive components. The properties of the modes of fastest growth are shown to depend strongly on the compressibility of the mode, with a reduction in growth rate consistent with the results of Blaes & Socrates for axisymmetric modes. A clumpy disc structure is anticipated on the basis of the polarization properties of the fastest-growing modes. This analysis is accurate in the near-hole region of locally cooled, hyper-accreting flows if the electron gas becomes moderately degenerate such that non-conductive, thermalizing processes with associated electron–positron release (i.e. neutrino annihilation and neutrino absorption on to nuclei) are effectively blocked by high occupation of the Fermi levels.
Ridge formation and de-spinning of Iapetus via an impact-generated satellite

Abstract We present a scenario for building the equatorial ridge and de-spinning Iapetus through an impact-generated disk and satellite. This impact puts debris into orbit, forming a ring inside the Roche limit and a satellite outside. This satellite rapidly pushes the ring material down to the surface of Iapetus, and then itself tidally evolves outward, thereby helping to de-spin Iapetus. This scenario can de-spin Iapetus an order of magnitude faster than when tides due to Saturn act alone, almost independently of its interior geophysical evolution. Eventually, the satellite is stripped from its orbit by Saturn. The range of satellite and impactor masses required is compatible with the estimated impact history of Iapetus.
Efficient Localization of Discontinuities in Complex Computational Simulations

Surrogate models for computational simulations are input-output approximations that allow computationally intensive analyses, such as uncertainty propagation and inference, to be performed efficiently. When a simulation output does not depend smoothly on its inputs, the error and convergence rate of many approximation methods deteriorate substantially. This paper details a method for efficiently localizing discontinuities in the input parameter domain, so that the model output can be approximated as a piecewise smooth function. The approach comprises an initialization phase, which uses polynomial annihilation to assign function values to different regions and thus seed an automated labeling procedure, followed by a refinement phase that adaptively updates a kernel support vector machine representation of the separating surface via active learning. The overall approach avoids structured grids and exploits any available simplicity in the geometry of the separating surface, thus reducing the number of model ...
Effects of two-phase flow on the deflagration of porous energetic materials

The combustion behavior of energetic materials (e.g., solid propellants) has long been of interest in the fields of propulsion and pyrotechnics. In many such applications, it is becoming increasingly clear that two-phase flow effects play an important role, especially since, during combustion, most homogeneous solid propellants develop thin multi-phase layers at their surfaces in which finite-rate exothermic reactions occur. In addition, there is a growing interest in the behavior of porous energetic solids, since even initially dense materials can develop significant void fractions if, at any time, they are exposed to abnormal thermal environments. The deflagration characteristics of such ``damaged`` materials may then differ significantly from those of the pristine material due, at least in part, to gas flow in the solid/gas preheat region. The presence of gas in the porous solid in turn results in a more pronounced two-phase effect in the multi-phase surface layer, such as in the liquid melt region of nitramine propellants, which thus tend to exhibit extensive bubbling in an exothermic foam layer. The present analysis is largely applicable to this latter class of propellants.
The Spectra of T Dwarfs. II. Red Optical Data

We present 6300-10100 A spectra for a sample of 13 T dwarfs observed using LRIS mounted on the Keck 10m Telescope.
Average singlet–triplet coupling properties of biacetyl and methylglyoxal using quantum beat spectroscopy

We have observed quantum beats in the reversible intersystem crossing of simple α‐dicarbonyls, and we have analyzed them to obtain information concerning the density of interacting states and the average intramolecular coupling energy. We have analyzed most of the biacetyl quantum beats using a method based on the properties of random matrices which is described elsewhere and we present the results here. We also present an analysis based on perturbation theory using the Fourier transforms of the quantum beats which is appropriate for understanding the methylglyoxal quantum beats. The density of vibrationally hot triplet states which interact with excited singlet states that are connected to the ground electronic state via optical excitation (∼22 000 cm−1) is found to increase with the amount of vibrational excitation in the accessible singlet state at roughly the same rate as the overall density of triplet vibrational stress increases. We find satisfactory agreement between the density obtained from the quantum beats and that calculated using well known analytical formulas and direct state counting. The density of interacting states increases with the rotational quantum number of the initially excited singlet rovibronic state. The average value of the magnitude of the spin–orbit interaction is 1–10 MHz independent of the amount of vibrational–rotational excitation present. Radiationless transitions in these highly excited molecules are evidently not subject to any overriding selection rules other than spatial symmetry, and conservation of total energy, total angular momentum, and nuclear spin. The biacetyl quantum beats are collisionally quenched with helium at the same rate as the overall fluorescence. The cross section for this process is roughly 300±200 A2.
Comparison of eight variations of a higher-order theory for cylindrical shells

A geometrically nonlinear higher-order transverse shear theory was used. Three attributes were varied. These included: 1) the order of the thickness expansions used to approximate the shell shape factors, 2) the order of the assumed linear displacement Field, and 3) the nonlinearity of transverse shear strain. Several cylindrical shell problems were investigated using a finite element code with a 36 degree of freedom cylindrical shell element-MACSYMA, a symbolic manipulation code was used to formulate the element independent stiffness arrays for each variation
Non-extensive statistical mechanics and particle spectra in elementary interactions

Abstract We generalize Hagedorn's statistical theory of momentum spectra of particles produced in high-energy collisions using Tsallis’ formalism of non-extensive statistical mechanics. Suitable non-extensive grand canonical partition functions are introduced for both fermions and bosons. Average occupation numbers and moments of transverse momenta are evaluated in an analytic way. We analyse the energy dependence of the non-extensitivity parameter q as well as the q -dependence of the Hagedorn temperature. We also take into account the multiplicity. As a final result we obtain formulas for differential cross sections that are in very good agreement with e + e − annihilation experiments.
Intensities of Balmer Emission Lines in Stellar Spectra

Contours of the Balmer emission lines in the spectra of fourteen stars of spectral class $\mathrm{Be}$ have been measured on twenty-seven spectrograms. In many stars the lines are broad and flat-topped, with steep outer edges, while in others they are double. The contours are explained by Doppler effect caused by the rotation of a nebula surrounding the star. The mean relative total intensities are: $\ensuremath{\beta}:\ensuremath{\gamma}:\ensuremath{\delta}:\ensuremath{\epsilon}=10:6.2:5.2:(5.4)$. The slow decrement in intensity agrees with the hypothesis that the bright lines are caused mostly by recombination. Lines produced in this way must be strongest (other things being equal) in a medium containing a maximum number of atoms of the next stage of ionization. This agrees with the observed strength of the emission lines of Fe II and of H in the earlier subdivisions of spectral class $B$.
Maximally localized Wannier functions for GW quasiparticles

We review the formalisms of the self-consistent GW approximation to many-body perturbation theory and of the generation of optimally localized Wannier functions from groups of energy bands. We show that the quasiparticle Bloch wave functions from such GW calculations can be used within this Wannier framework. These Wannier functions can be used to interpolate the many-body band structure from the coarse mesh of Brillouin-zone points on which it is known from the initial calculation to the usual symmetry lines, and we demonstrate that this procedure is accurate and efficient for the self-consistent GW band structure. The resemblance of these Wannier functions to the bond orbitals discussed in the chemical community led us to expect differences between density-functional and many-body functions that could be qualitatively interpreted. However, the differences proved to be minimal in the cases studied. Detailed results are presented for ${\text{SrTiO}}_{3}$ and solid argon.
Silver-Catalyzed Rearrangement of Propargylic Sulfinates to Allenic Sulfones

Treatment of propargylic sulfinate esters with 2 mol % of silver hexafluoroantimonate results in the rapid formation of allenic sulfones in essentially quantitative yield.
A dissipative dynamical systems approach to stability analysis of time delay systems

In this paper the concepts of dissipativity and the exponential dissipativity are used to provide sufficient conditions for guaranteeing asymptotic stability of a time delay dynamical system. Specifically, representing a time delay dynamical system as a negative feedback interconnection of a finite-dimensional linear dynamical system and an infinite-dimensional time delay operator, we show that the time delay operator is dissipative with respect to a quadratic supply rate and with a storage functional involving an integral term identical to the integral term appearing in standard Lyapunov–Krasovskii functionals. Finally, using stability of feedback interconnection results for dissipative systems, we develop sufficient conditions for asymptotic stability of time delay dynamical systems. The overall approach provides a dissipativity theoretic interpretation of Lyapunov–Krasovskii functionals for asymptotically stable dynamical systems with arbitrary time delay. Copyright © 2004 John Wiley & Sons, Ltd.
Failure analysis of shallow trench isolated ESD structures

Abstract Scanning-electron microscopes and atomic-force microscopes are used to analyze surface and sub-surface ESD-induced failure mechanisms in 0.25- and 0.5-μm shallow trench isolated CMOS technology ESD structures and n-channel MOSFETs; ESD failure-mechanism types are characterized and classified, and additional failure-analysis techniques and tools are discussed.
Association Between Vaginal Douching and Acute Pelvic Inflammatory Disease

The vaginal douching habits of 100 consecutive municipal hospital patients with verified pelvic inflammatory disease (cases) were compared with those of 762 randomly selected controls (random controls) and 119 women thought to have pelvic inflammatory disease but in whom the diagnosis was not confirmed by laparoscopy and/or endometrial biopsy specimen (internal controls). Because patients had been symptomatic for no more than 3 weeks, current douching was arbitrarily defined as any douching during the previous 2 months. Current douching was more common among those with pelvic inflammatory disease than among random controls or internal controls. Among current douchers, pelvic inflammatory disease was significantly related to frequency of douching. For example, when cases were compared with random controls, those who douched three or more times per month were 3.6 times more likely than those who douched less than once per month to have confirmed pelvic inflammatory disease. A logistic regression model was used to adjust for demographic, behavioral, and other possible confounding variables. Even after adjustments, douching during the previous 2 months remained associated with pelvic inflammatory disease. These data suggest that among these women vaginal douching may be a risk factor for pelvic inflammatory disease.
Possibility for exciton Bose-Einstein condensation in carbon nanotubes

We demonstrate a possibility for exciton Bose-Einstein condensation in individual small-diameter (~1-2 nm) semiconducting carbon nanotubes. The effect occurs under the exciton-interband-plasmon coupling controlled by an external electrostatic field applied perpendicular to the nanotube axis. It requires fields ~1 V/nm and temperatures below 100 K that are experimentally accessible. The effect offers a testing ground for fundamentals of condensed matter physics in one dimension and opens up perspectives to develop tunable coherent polarized light source with carbon nanotubes.
A generalized approach to q -Markov covariance equivalent realizations for discrete systems

Abstract A new algorithm is developed which constructs q-Markov covariance equivalent realizations (q-Markov COVERs) of multivariable linear discrete time systems. A q-Markov COVER is a state realization which matches exactly a finite portion of the impulse response sequence (Markov parameters) and output autocorrelation sequence (covariance parameters) of a linear system. The algorithm generates the q-Markov COVERs starting with only the basic data, namely the q-Markov parameters and the q covariance parameters. The algorithm leads to a parameterization of all minimal stable q-Markov COVERs which can be constructed. Since the data are easily computed from a given state space model, the algorithm presented will be useful for both realization and model reduction of multivariable linear discrete time systems. An example is presented to demonstrate the algorithm.
Tantalum Cobalt Nitride Photocatalysts for Water Oxidation under Visible Light

Tantalum cobalt nitride photocatalysts were prepared using a simple drop coating method on a Ta foil substrate followed by thermal ammonia treatment, and their photoelectrochemical (PEC) properties for water oxidation under visible light were studied. The resulting Ta0.9Co0.1Nx films showed a photocurrent of ca. 1.5 mA/cm2 (12 times higher than that of Ta3N5) under 100 mW/cm2 visible light irradiation at 0.7 V vs Ag/AgCl in a 0.1 M Na2SO4 aqueous solution (pH 11). The good PEC performance was attributed to the introduction of cobalt and the formation of cobalt nitride, which efficiently facilitates electron transfer and suppresses the recombination of photogenerated electron–hole pairs. Some cobalt nitride could further be oxidized to generate cobalt oxide, which serves as an efficient electrocatalyst for water oxidation. The enhanced visible light activity and film stability under light irradiation make tantalum cobalt nitride a promising semiconductor for PEC water oxidation.
Search problems in groups and branching processes

In this paper, we study complexity of randomly generated instances of Dehn search problems in finitely presented groups. We use Crump–Mode–Jagers (CMJ) processes to show that most of the random instances are easy. Our analysis shows that for any choice of a finitely presented platform group in Wagner–Magyarik public key encryption protocol the majority of random keys can be broken by a polynomial time algorithm.
High-Redshift Galaxy Kinematics: Constraints on Models of Disk Formation

Integral field spectroscopy of galaxies at redshift -->z ~ 2 has revealed a population of early-forming, rotationally supported disks. These high-redshift systems provide a potentially important clue to the formation processes that build disk galaxies in the universe. A particularly well-studied example is the -->z = 2.38 galaxy BzK 15504, which was shown by Genzel and coworkers to be a rotationally supported disk despite the fact that its high star formation rate and short gas consumption timescale require a very rapid acquisition of mass. Previous kinematical analyses have suggested that -->z ~ 2 disk galaxies like BzK 15504 did not form through mergers because their line-of-sight velocity fields display low levels of asymmetry. We perform the same kinematical analysis on a set of simulated disk galaxies formed in gas-rich mergers of the type that may be common at high redshift, and show that the remnant disks display low velocity field asymmetry and satisfy the criteria that have been used to classify high-redshift galaxies as disks observationally. Further, we compare one of our remnants to the bulk properties of BzK 15504 and show that it has a star formation rate, gas surface density, and a circular velocity-to-velocity dispersion ratio that matches BzK 15504 remarkably well. We suggest that observations of high-redshift disk galaxies like BzK 15504 are consistent with the hypothesis that gas-rich mergers play an important role in disk formation at high redshift.
Agency Problems, Information Asymmetries, and Convertible Debt Security Design

Abstract This paper proposes and implements a security design framework to assess why corporate managers issue convertible debt. We examine three theories that make predictions about the design of convertible debt. Our results suggest that some issuers design convertible debt to mitigate asset substitution problems, while others design it to reduce adverse selection problems. We also find that issuers vary convertible debt security design over the business cycle in response to time variation in asset substitution and adverse selection problems. Overall, the results indicate that corporate managers actively alter convertible debt security design to mitigate costly external finance problems. Journal of Economic Literature Classification Number: G32
Continuous spectrum of the 3D Euler equation is a solid annulus

In this Note we give a description of the continuous spectrum of the linearized Euler equations in three dimensions. Namely, for all but countably many times t∈R, the continuous spectrum of the evolution operator Gt is given by a solid annulus with radii etμ and etM, where μ and M are the smallest and largest, respectively, Lyapunov exponents of the corresponding bicharacteristic-amplitude system of ODEs.
Alkyl Coupling on Copper, Silver, and Gold: Correlation Between the Coupling Rate and the Metal-Alkyl Bond Strength

Abstract Recent studies have shown that high coverages of alkyl groups can be generated and isolated on metal surfaces under ultrahigh vacuum conditions by the thermal [Zaera, F., Acc. Chem. Res. 25, 260 (1992)] and photochemical [Zhou, X. -L., Zhu, X. -Y., and White, J. M., Surf. Sci. Rep. 13, 74 (1991)] dissociation of alkyl halides. This paper describes studies in which these approaches have been employed to study the coupling of methyl groups generated on a Au(111) surface. The coupling rate, as measured by temperature-programmed reaction experiments, is found to be sensitive to the structure of the surface. For a well-annealed surface, coupling occurs at ∼ 270 K, but for a sputtered and incompletely annealed surface, coupling occurs at ∼ 350 K. An interesting and unexpected finding is that coadsorbing P(CH 3 ) 3 with the methyl groups on a Au(100) surface inhibits the coupling reaction so that methyl radical desorption is observed. Similarities between the rates of methyl coupling and methyl radical desorption have also been observed previously for a Cu(111) surface, suggesting a correlation between the methyl coupling rate and the metal-alkyl bond strength. Such a correlation can account for the trends in the coupling rates reported for alkyl groups on Ag(111), Au(100), Cu(111), and Cu(110). The coupling rate is fastest on surfaces and for alkyl groups that are expected to form the weakest carbon-metal bonds.
FACTORS INFLUENCING THE CHOICE OF FACILITIES AND TECHNIQUES FOR AERONAUTICAL DEVELOPMENT

Factors influencing development of both wind tunnel and flight test technology for determining aerodynamic derivatives of aircraft motions