cssi/SciSciGPT-SciSciNet huggingface dataset:
Evidence for a Physically Compact Narrow-Line Region in the Seyfert 1 Galaxy NGC 5548*

We have combined Hubble Space Telescope/Faint Object Spectrograph and ground-based spectra of the Seyfert 1 galaxy NGC 5548 to study the narrow emission lines over the 1200-10000 A region. All of the spectra were obtained when the broad emission line and continuum fluxes were at a historically low level, allowing us to determine accurately the contribution of the narrow-line region (NLR) to the emission lines. We have generated multicomponent photoionization models to investigate the relative strength of the high-ionization lines compared to those in Seyfert 2 galaxies and the weakness of the narrow Mg II λ2800 line. We present evidence for a high-ionization component of NLR gas that is very close to the nucleus (~1 pc). This component must be optically thin to ionizing radiation at the Lyman edge (i.e., τ0 ≈ 2.5) to avoid producing [O I] and Mg II in a partially ionized zone. The very high ionization lines (N V, [Ne V], [Fe VII], [Fe X]) are stronger than the predictions of our standard model, and we show that this may be due to supersolar abundances and/or a "blue bump" in the extreme ultraviolet (although recent observations do not support the latter). An outer component of NLR gas (at only ~70 pc from the continuum source) is needed to produce the low-ionization lines. We show that the outer component may contain dust, which further reduces the Mg II flux by depletion and by absorption of the resonance photons after multiple scatterings. We show that the majority of the emission in the NLR of NGC 5548 must arise within ~70 pc from the nucleus. Thus, the NLR in this Seyfert 1 galaxy is very physically compact, compared to the typical NLR in Seyfert 2 galaxies.
The Planck sorption cooler: Using metal hydrides to produce 20 K

Abstract The Jet Propulsion Laboratory has built and delivered two continuous, closed cycle, hydrogen Joule–Thomson (J–T) cryocoolers for the ESA Planck mission, which will measure the anisotropy in the cosmic microwave background. The metal hydride compressor consists of six sorbent beds containing LaNi 4.78 Sn 0.22 alloy and a low-pressure storage bed of the same material. Each sorbent bed contains a separate gas-gap heat switch that couples or isolates the bed with radiators during the compressor operating cycle. ZrNiH x hydride is used in this heat switch. The Planck compressor produces hydrogen gas at a pressure of 48 bar by heating the hydride to ∼450 K. This gas passes through a cryogenic cold-end consisting of a tube-in-tube heat exchanger, three pre-cooling stages to bring the gas to nominally 52 K, a J–T value to expand the gas into the two-phase regime at ∼20 K, and two liquid–vapor heat exchangers that must remove 190 and 646 mW of heat, respectively. Gas evaporated from the liquid phase is recovered by three hydride beds at ∼0.3 bar and 270 K. Each cooler was designed to provide 1 W cooling at ∼20 K for a total input power of 470 W, excluding electronics. The performance of these coolers is mainly a function of the compressor interface and final pre-cooling stage temperatures. We present results from the testing of these two coolers for the input power, cooling power, temperature, and temperature fluctuations over the flight allowable ranges for these interfaces.
Synthesis and structure of the Zintl compounds Na2BaTt4 (Tt = Si, Ge)

Abstract The isotypic title compounds ate obtained from reactions of stoichiometric mixtures of the elements in welded Ta containers at 700–800 °C. The structure of Na 2 BaSi 4 was determined by single-crystal X-ray diffraction (orthorhombic, Ima2 (No. 46), Z = 8, a = 9.524, b = 17.980(3), c = 8.570(3) A). The compound crystallizes in a novel structure type with Na + and Ba 2+ cations and two crystallographically-independent isolated Si 4 4− anions. The anions are nearly regular tetrahedra with bond distances of 2.385(3) to 2.448(4) A and bond angles between 59.2 and 61.7°. The overall structure may be described as a distorted face-centered-cubic array of Si 4 4− anions in which Na + and Ba 2+ atoms occupy all tetrahedral and octahedral holes in an ordered way. The result is closely related to the topology of f.c.c. Li 3 Bi type but with ordering of the two cations. Magnetic measurements showed that Na 2 BaSi 4 is diamagnetic, and its family can be formulated in terms of oxidation states as Zintl phases (Na + ) 2 Ba 2+ (Tt 4 4− ).
Oxidation States of Chromium Dissolved in Glass Determined by X‐ray Photoelectron Spectroscopy

The oxidation states of chromium dissolved in binary sodium silicate glasses were analyzed by X-ray photoelectron spectroscopy (XPS). The measured “equilibrium” Cr6+ fractions in glasses with varying Na2O contents are shown to be in good agreement with results obtained by other techniques reported in the literature. XPS was then used to analyze the interface of a sodium silicate glass/chromium alloy (Inconel 718) seal. It is shown that Cr2+ and Cr3+ were the major chromium species dissolved in the glass interfacial region.
Super-resolution, Extremal Functions and the Condition Number of Vandermonde Matrices

Super-resolution is a fundamental task in imaging, where the goal is to extract fine-grained structure from coarse-grained measurements. Here we are interested in a popular mathematical abstraction of this problem that has been widely studied in the statistics, signal processing and machine learning communities. We exactly resolve the threshold at which noisy super-resolution is possible. In particular, we establish a sharp phase transition for the relationship between the cutoff frequency (m) and the separation (Δ). If m > 1/Δ + 1, our estimator converges to the true values at an inverse polynomial rate in terms of the magnitude of the noise. And when m
New tripodal Cu(II) complexes containing imidazole ligands

Abstract A new class of imidazole containing tripodal ligands has been synthesized containing from 0–3 imidazole pendants. Copper(II) complexes of the formulas [Cu(L)Cl] + and [Cu(L)(1-MeIm)] 2+ have been prepared and studied by UV-Vis and EPR spectroscopies and cyclic voltammetry. The X-ray crystal structures of [Cu(bipa)Cl] + and [Cu(tmima)Cl] + have been determined. Electrochemical and electronic spectral data suggest that the donor strengths of the tripods decrease in the following order: tpa > bpia > bipa > tmima. Results from EPR suggest that the complexes with tmima are more distorted than those of tpa.
Preserving flat directions during inflation

Abstract Supersymmetry is generally broken by the non-vanishing vacuum energy density present during inflation. In supergravity models, such a source of supersymmetry breaking typically makes a contribution to scalar masses of order m 2 ∼ H 2 , where H 2 ∼ V M p 2 is the Hubble parameter during inflation. We show that in supergravity models which possess a Heisenberg symmetry, supersymmetry breaking makes no contribution to scalar masses, leaving supersymmetric flat directions flat at tree-level. One-loop corrections in general lift the flat directions, but naturally give small negative squared masses ∼ −g 2 H 2 (4π) 2 for all flat directions that do not involve the stop. No-scale supergravity of the SU(N,1) type and the untwisted sectors from orbifold compactifications are special cases of this general set of models. We point out the importance of the preservation of flat directions for baryogenesis.
The structure of mutual fund charges

Abstract This paper provides an explanation for the diversity in investment strategies and fees of open-end mutual funds. Mutual funds seek to dissuade redemptions through front- and back-end load fees. The empirical evidence is consistent with model predictions that such fees dissuade redemptions in open-end funds, and that funds hold more cash when there is uncertainty about redemptions. Furthermore, funds with load and redemption fees hold less cash that their no-load counterparts. The results suggest that aggressive funds are sensitive to cash flows and are likely to rely on fees to dissuade redemptions.
Percolation and cluster distribution. I. Cluster multiple labeling technique and critical concentration algorithm

A new approach for the determination of the critical percolation concentration, percolation probabilities, and cluster size distributions is presented for the site percolation problem. The novel "cluster multiple labeling technique" is described for both two- and three-dimensional crystal structures. Its distinctive feature is the assignment of alternate labels to sites belonging to the same cluster. These sites are members of a simulated finite random lattice. An algorithm useful for the determination of the critical percolation concentration of a finite lattice is also presented. This algorithm is especially useful when applied in conjunction with the cluster multiple labeling technique. The basic features of this technique are illustrated by applying it to a small planar square lattice. Numerical results are given for a triangular subcrystal containing up to 9 000 000 sites. These results compare favorably with the exact value of the infinite lattice critical percolation concentration.
Suppressed magnetization at the surfaces and interfaces of ferromagnetic metallic manganites

What happens to ferromagnetism at the surfaces and interfaces of manganites? With the competition between charge, spin, and orbital degrees of freedom, it is not surprising that the surface behaviour may be profoundly different to that of the bulk. Using a powerful combination of two surface probes, tunnelling and polarized x-ray interactions, this paper reviews our work on the nature of the electronic and magnetic states at manganite surfaces and interfaces. The general observation is that ferromagnetism is not the lowest energy state at the surface or interface, which results in a suppression or even loss of ferromagnetic order at the surface. Two cases will be discussed ranging from the surface of the quasi-2D bilayer manganite (La(2-2x)Sr(1+2x)Mn(2)O(7)) to the 3D perovskite (La(2/3)Sr(1/3)MnO(3))/SrTiO(3) interface. For the bilayer manganite, which is ferromagnetic and conducting in the bulk, these probes present clear evidence for an intrinsic insulating non-ferromagnetic surface layer atop adjacent subsurface layers that display the full bulk magnetization. This abrupt intrinsic magnetic interface is attributed to the weak inter-bilayer coupling native to these quasi-two-dimensional materials. This is in marked contrast to the situation for the non-layered manganite system (La(2/3)Sr(1/3)MnO(3)/SrTiO(3)), whose magnetization near the interface is less than half the bulk value at low temperatures and decreases with increasing temperature at a faster rate than that for the bulk.
Venture Capitalists and Cooperative Start-up Commercialization Strategy

This paper examines the possible impact of venture capital (VC) backing on the commercialization direction of technology-based start-ups by asking: To what extent (if at all) do VC-funded start-ups engage in cooperative commercialization strategies (strategic alliances or technology licensing, or both) relative to a comparable set of start-ups, and with what consequences? To address these questions, I assemble a novel data set that matches firms receiving a federal research and development subsidy through the U.S. Small Business Innovative Research program to VC-funded firms by observable characteristics in five technology-intensive industries. These data allow decoupling of cooperative activity resulting from start-up development via the passage of calendar time from that due to association with VCs. An analysis of the 696 start-ups in the sample (split by an external funding source) suggests substantial boosts in both cooperative activity associated with VC-backed firms and in the likelihood of an initial public offering.
Computer simulation of low-energy excitations in amorphous silicon with voids

Abstract We use empirical molecular dynamics technique to investigate the low-energy vibrations in a large 4096 atom model for pure amorphous silicon and a set of models with voids of different size based on it. Numerical vibrational eigenvalues and eigenvectors for our models are obtained by exact diagonalization of their dynamical matrices. Our calculations show that localized low-energy vibrational excitations of rather complex structure are present in amorphous silicon models with voids. According to their spatial localization patterns we make an attempt to classify these excitations as modes associated with the void and `mixed' modes associated with the interaction of the void with strained regions of silicon network.
Charmonium absorption in the meson-exchange model

Abstract We review the meson-exchange model for charmonium absorption by hadrons, including the construction of the interaction Lagrangians, the determination of the coupling constants, form factors, and the predicted cross sections for J /ψ absorptions. Uncertainties in form factors and constraints from chiral symmetry are also discussed.
Use of aryl chlorides as electrophiles in Pd-catalyzed alkene difunctionalization reactions.

The development of conditions that allow use of inexpensive aryl chlorides as electrophiles in Pd-catalyzed alkene carboamination and carboetherification reactions is described. A catalyst composed of Pd(OAc)2 and S-Phos minimizes N-arylation of the substrate and prevents formation of mixtures of regioisomeric products. A number of heterocycles, including pyrrolidines, isoxazolidines, tetrahydrofurans, and pyrazolidines, are efficiently generated with this method.
Payload fairing separation dynamics

Launch vehicle fairings protect payloads from aerodynamic loads during atmospheric flight. Once the launch vehicle is outside the atmosphere, the fairing is jettisoned. For Titan and Delta launch systems, payload fairing separation is accomplished by detonation of an explosive charge in the separation joints. The resulting high-pressure gases force the fairing segments apart at the separation joints and thrust the sectors away from the launch vehicle. To predict the gas pressure accurately, one needs to formulate the thermodynamic processes of the charge in the separation joint at ignition, the subsequent gas flow, the nonlinear shearing of the rivets that hold the fairing segments together, and the dynamic interaction between the gas and the flexible fairing structure. An analytical procedure based on a coupled gas/structure model has been developed to simulate the fairing separation events. The procedure was validated by comparing the analysis results with full-scale payload fairing separation test data obtained by the Titan IV launch vehicle program.
Microcavities using holey fibers

Microcavities have been formed by placing mirrors on the ends of a short section of holey fiber. These microcavities may be useful for enhancing nonlinear effects at single-photon intensities.
Bézier Curve Path Planning for Parafoil Terminal Guidance

Autonomous parafoil terminal guidance plays a critical role in landing accuracy but is inherently difficult due to underactuation and path disturbances caused by winds. Terminal path planners must generate flight paths that deliver the parafoil as close as possible to the destination while landing into the wind. This paper presents a novel path-planning scheme capable of highly general trajectory shapes that enable successful path planning from a wide set of initial conditions in constrained three-dimensional environments. The path-planning approach parameterizes the two-point boundary value guidance solution in the form of one or more Bezier curves that connect the current parafoil location with a final approach point downwind of the target. Online nonlinear optimization of curve parameters allows for path regeneration given changing winds. Furthermore, generality of the trajectory shape provides a wide set of initial conditions at which terminal guidance may be initiated in obstacle-constrained scenario...
Reconstruction from divergent beams: A comparison of algorithms with and without rebinning

Abstract The divergent mode of data collection is used in computerized tomography to reduce data collection time. In this note we compare two approaches to reconstruction from such data: (i) reconstruction by an algorithm especially designed for divergent geometry; and (ii) interpolation of data so as to estimate what the parallel mode of data collection would provide, followed by reconstruction by an algorithm designed for parallel geometry.
Parameter inference for an individual based model of chytridiomycosis in frogs

Individual based models (IBMs) and Agent based models (ABMs) have become widely used tools to understand complex biological systems. However, general methods of parameter inference for IBMs are not available. In this paper we show that it is possible to address this problem with a traditional likelihood-based approach, using an example of an IBM developed to describe the spread of chytridiomycosis in a population of frogs as a case study. We show that if the IBM satisfies certain criteria we can find the likelihood (or posterior) analytically, and use standard computational techniques, such as MCMC, for parameter inference.
A Feedback Compensator Design Procedure for Switching Regulators

State feed-back compensators and observer-controller compensators are designed for switching regulators whose dynamic response can be approximated by sets of first-order linear differential equations. It is shown that by selecting appropriate performance weighting factors, the designer can achieve a compensated regulator with desired dynamic and steady-state performance characteristics.
Wonderful blowups associated to group actions

A group action on a smooth variety provides it with the natural stratification by irreducible components of the fixed point sets of arbitrary subgroups. We show that the corresponding maximal wonderful blowup in the sense of MacPherson-Procesi has only abelian stabilizers. The result is inspired by the abelianization algorithm of Batyrev.
Thermal convection at low Rayleigh number from concentrated sources in porous media

A simple mathematical theory is proposed for the analysis of natural convective motion, at low Rayleigh number, from a concentrated source of heat in a fluid-saturated porous medium. The theory consists of retaining only the leading terms of series expansions of the dependent variables in terms of the Rayleigh number, is thus linear, and is valid only in the limit of small Rayleigh number. Based on fundamental results for a variety of isolated sources, superposition is used to provide solutions for situations of practical interest. Special emphasis is given to the analysis of sub-seabed disposal of nuclear waste. 8 figures.
Characteristics of Optical Fiber Waveguides

The design and performance of optical cables, connector hardware and communication systems are governed by the light transmission and coupling characteristics of waveguide fibers. These characteristics depend upon waveguide design and materials as well as manufacturing tolerances. Measurement methods and limitations are discussed, and use and interpretation of waveguide specifications in designing optical links and predicting overall performance are shown.
ANALYSIS AND CONTROL OF TORQUE PULSATIONS IN CURRENT FED INDUCTION MOTOR DRIVES

ABSTRACT Three types of feedback compensation schemes are described which can be used to reduce the torque pulsations which normally occur when induction machines are supplied from a current source inverter. The approach is verified both by a detailed computer simulation and also by test results from an actual system. Limitations of the method near zero slip frequency (no load) is discussed and a means suggested for elimination of the problem.
Closed-form of the power spectral density for full response M -ary CPFSK modulation

Abstract In recent years, continuous phase modulation (CPM) scheme has gained increasing attention due to its attractive spectra properties. The continuous-phase frequency shift keying (CPFSK) modulation scheme has previously been studied and much effort has been spent to find simple analytical and numerical methods for computing the spectrum of CPFSK signals [1–16]. Some authors have derived formulas for the autocorrelation and power spectral density (PSD) functions of CPFSK signals, but the calculations are extremely laborious requiring numerical integration in two dimensions involving truncation errors. This paper presents a special method of analyzing the spectral properties of M -ary CPFSK for full response signaling. The autocorrelation function is presented in closed-form thereby avoiding truncation. The Fourier transform is used to find the power spectral density function, which is also expressed in closed-form. The effect of the system parameters, i.e. the size of the alphabet, the modulation index, and others on the system bandwidth and PSD are analyzed. The conditions under which the spectrum contains discrete lines are outlined. The continuous part of PSD is expressed in exponential form, and a large number of PSDs have been computed and plotted in a relatively short time and samples are presented in the paper. Finally, it is shown that systems with normalized modulation indices Δ = 1/ M offer superior performance in terms of bandwidth and power efficiency for different schemes.
Synthetic Sequence Design for Signal Location Search

We present a new approach to identify the locations of critical DNA or RNA sequence signals which couples large-scale synthesis with sophisticated designs employing combinatorial group testing and balanced Gray codes. Experiments in polio and adenovirus demonstrate the efficiency and generality of this procedure. In this paper, we give a new class of consecutive positive group testing designs, which offer a better tradeoff of cost, resolution, and robustness than previous designs for signal search. Let n denote the number of distinct regions in a sequence, and d the maximum number of consecutive positives regions which can occur. We propose a design which improves on the consecutive-positive group testing designs of Colbourn. Our design completely identifies the boundaries of the positive region using t tests, where t≈log2(1.27n/d)+0.5log2(log2(1.5n/d))+d.
Calculations of the Flow of Natural Gas Through Critical Flow Nozzles

Mass flow rate calculation of methane and natural gas mixtures through critical flow nozzles
Initiating Change That Perseveres

It is an honor and a pleasure to participate with Ed Lindblom in this conference. Ed has just ended a very important kind of diagnosis of impairment in our capacity to initiate social change. Lindblom, as usual, tackles some of the most profound questions in our society, indeed in all societies. He calls for more than incremental change. He calls for major rethinking and reengineering of features of our society. I agree with much of the diagnosis, but I have some doubts about what actions to take in response.
Sugaring-out: A novel phase separation and extraction system

Abstract In this study, we made a novel observation that by introducing a monomeric sugar or a disaccharide into an acetonitrile–water solution, the acetonitrile (ACN) can be separated from water to form a new phase. The two-phase formation triggered by sugar addition was visualized with Sudan I. The ability of different sugars to form an ACN–water two-phase system and the effect of glucose and xylose concentration on the phase separation were studied. The distribution of syringic acid, furfural, para-coumaric acid, ferulic acid and 5-hydroxymethyl furfural in the upper ACN phase and lower water phase was examined. The lower concentration limit for the two-phase formation for glucose and xylose at 1 °C was 15 and 25 g/L, respectively. At higher temperatures, the concentration needed for phase separation increased. Addition of polysaccharides (starch and dextran) did not result in phase separation. The distribution coefficient of the five organic compounds in the ACN–water two-phase system was in the range of 1.7–8.9 when the corresponding sugar concentration was 15–50 g/L. The phase ratio of the five organic compounds in the two-phase system was in the range of 0.1–0.5. The new two-phase system may find applications in the separation of chemicals having different solubility in water and in ACN.
THE GROUPS OF RICHARD THOMPSON AND COMPLEXITY

We prove new results about the remarkable infinite simple groups introduced by Richard Thompson in the 1960s. We give a faithful representation in the Cuntz C⋆-algebra. For the finitely presented simple group V we show that the word-length and the table size satisfy an n log n relation. We show that the word problem of V belongs to the parallel complexity class AC1 (a subclass of P), whereas the generalized word problem of V is undecidable. We study the distortion functions of V and show that V contains all finite direct products of finitely generated free groups as subgroups with linear distortion. As a consequence, up to polynomial equivalence of functions, the following three sets are the same: the set of distortions of V, the set of Dehn functions of finitely presented groups, and the set of time complexity functions of nondeterministic Turing machines.
Negotiated Order: The Fourth Amendment, Telephone Surveillance, and Social Interactions, 1878–1968

In the United States the words “telephone surveillance” bring to mind contemporary security concerns about smart phone tracking, the NSA warrantless wiretapping scandal, and the telecommunications provisions of the Patriot Act. Yet telephone surveillance is as old as telephony itself, dating back to the nearly simultaneous commercialization of the telephone and phonograph. This article examines telephone surveillance by American law enforcement agencies from the inception of telephone service to the passage of the Federal Wiretap Law in 1968, focusing on the challenges an advancing, proliferating, and shrinking technology posed for Fourth Amendment law. To highlight the technological, institutional, and cultural interactions that have shaped Fourth Amendment jurisprudence, the article deploys Jack Balkin's theory of cultural software and Anslem Strauss's concept of a negotiated order and brings together major cases, federal legislation, and evidence of government surveillance. The article argues that duri...
The effects of optical smoothing techniques on filamentation in laser plasmas

The effect of the induced spatial incoherence (ISI) and the random phase screen (RPS) optical smoothing techniques on the filamentation instability in laser plasmas has been investigated numerically and analytically. A two‐dimensional time‐dependent laser–plasma propagation code, including both ponderomotive and thermal‐conduction dominated filamentation, is used to simulate the laser–plasma interaction. The results of these simulations are compared to the predictions of a simple theory that describes the filamentation of both coherent light and spatially and temporally incoherent light. It is shown that filaments driven by the thermal mechanism tend to cluster together and produce greater large scale nonuniformities in the laser illumination than the ponderomotively driven filaments. The RPS optical smoothing technique is found to reduce filamentation only if fast focusing optics (f/♯≲5) are used. The ISI smoothing method suppresses filamentation for fast or slow focusing optics, and requires only moderate laser bandwidth (Δω/ω≂0.1%). In general, the ISI smoothing method provides the best suppression of filamentation. Under common laboratory conditions, filamentation is pronounced at longer laser wavelengths (1.06 μm–0.53 μm), suggesting that current experiments may be dominated by filamentation effects. Optical smoothing methods can suppress, but not eradicate, filamentation effects at these wavelengths. The optical smoothing methods are most effective in short‐wavelength (0.25 μm) laser‐driven plasmas. At 0.25 μm laser wavelength, ISI is found to completely eliminate filamentation effects in both time‐averaged and instantaneous intensity distributions.
New vacua for type II string theory

Abstract Lorentz-invariant expectation values for antisymmetric tensor field strengths in Calabi-Yau compactification of IIA string theory are considered. These are found to impart magnetic and/or electric charges to the dilation hypermultiplet. This results in a potential which can have supersymmetric minima at zero coupling or at conifold points in the moduli space. The latter occurs whenever the dilaton charge is aligned with that of the light black hole at the conifold. It is shown that there is a flat direction extending from the conifold along which there is a black hole condensate whose strength is of order the string coupling g s . It is speculated that these new vacua correspond to string compactification on generalized Calabi-Yau spaces which have c 1 = 0 but are not Kahler.
Baryon number transport via gluonic junctions

Abstract A novel non-perturbative gluon junction mechanism is introduced within the HIJING/B nuclear collision event generator to calculate baryon number transport and hyperon production in pA and AA collisions. This gluonic mechanism can account for the observed large mid-rapidity valence baryon yield in Pb+Pb at 160 AGeV and predicts high initial baryon densities at RHIC. However, the highly enhanced Λ– Λ yield and the baryon transverse momentum flow observed in this reaction can only be partially described.
Dusty wind-blown bubbles

Spurred by recent observations of 24 ?m emission within wind-blown bubbles (WBBs), we study the role that dust can play in such environments and build an approximate model of a particular WBB, N49. First, we model the observations with a dusty WBB, and then ask whether dust could survive within N49 to its present age (estimated to be 5 ? 105 to 106 yr). We find that dust sputtering and especially dust-gas friction would imply relatively short timescales (t ~ 104 yr) for dust survival in the wind-shocked region of the bubble. To explain the 24 ?m emission, we postulate that the grains are replenished within the WBB by destruction of embedded, dense cloudlets of interstellar medium gas that have been overrun by the expanding WBB. We calculate the ablation timescales for cloudlets within N49 and find approximate parameters for the embedded cloudlets that can replenish the dust; the parameters for the cloudlets are roughly similar to those observed in other nebula. Such dust will have an important effect on the bubble: including simple dust cooling in a WBB model for N49, we find that the luminosity is higher by approximately a factor of 6 at a bubble age of about 104 yr. At ages of 107 yr, the energy contained in the bubble is lower by about a factor of 8 if dust is included; if dust must be replenished within the bubble, the associated accompanying gas mass will also be very important to WBB cooling and evolution. While more detailed models are certainly called for, this work illustrates the possible strong importance of dust in WBBs, and is a first step toward models of dusty WBBs.
EPR experiment and 2-photon interferometry: Report of a 2-photon interference experiment

After a very brief review of the historical EPR experiments, this paper reports a new two-photon interference type EPR experiment. A two-photon state was generated by optical parametric down conversion. Pairs of light quanta with degenerate frequency but divergent directions of propagation were sent to two independent Michelson interferometers. First- and second-order interference effects were studied. Different from other reports, we observed that the second-order interference visibility vanished when the optical path difference of the interferometers were much less than the coherence length of the pumping laser beam. However, we also observed that the second-order interference behaved differently depending on whether the interferometers were set at equal or different optical path differences.
Decohering histories and open quantum systems

I briefly review the decohering histories or consistent histories formulation of quantum theory, due to Griffiths, Omn?s, and Gell-Mann and Hartle (and the subject of my graduate work with George Sudarshan). I also sift through the many meanings that have been attached to decohering histories, with an emphasis on the most basic one: Decoherence of appropriate histories is needed to establish that quantum mechanics has the correct classical limit. Then I will describe efforts to find physical mechanisms that do this. Since most work has focused on density matrix versions of decoherence, I'll consider the relation between the two formulations, which historically has not been straightforward. Finally, I'll suggest a line of research that would use recent results by Sudarshan to illuminate this aspect of the classical limit of quantum theory.
A high resolution method for measuring cosmic ray composition beyond 10 TeV

Abstract The accurate determination of the elemental composition of cosmic rays at high energies is expected to provide crucial clues on the origin of these particles. Previous direct measurements of composition have been limited by experiment collecting power, resulting in marginal statistics above 1014 eV, precisely the region where the “knee” of the cosmic ray energy spectrum is starting to develop. In contrast, indirect measurements using extensive air showers can produce sufficient statistics in this region but generate elemental measurements which have relatively large uncertainties. Here we discuss a technique which has become possible through the use of modern ground-based Cerenkov imaging detectors. We combine a measurement of the Cerenkov light produced by the incoming cosmic ray nucleus in the upper atmosphere with an estimate of the total nucleus energy produced by the extensive air shower initiated when the particle interacts deeper in the atmosphere. The emission regions prior to and after the first hadronic interaction can be separated by an imaging Cerenkov system with sufficient angular and temporal resolution. Monte Carlo simulations indicate an expected charge resolution of ΔZ/Z
The policy significance of inequality decompositions

Economists are now familiar with ‘between’ and ‘within’ group inequality decompositions, for race, gender, spatial units, etc. But what exactly is the normative significance of the empirical results produced by these decompositions? This paper raises some basic questions about policy interpretations of decompositions that are found in the literature.
Object tracking using multiple camera video streams

Two synchronized cameras are utilized to obtain independent video streams to detect moving objects from two different viewing angles. The video frames are directly correlated in time. Moving objects in image frames from the two cameras are identified and tagged for tracking. One advantage of such a system involves overcoming effects of occlusions that could result in an object in partial or full view in one camera, when the same object is fully visible in another camera. Object registration is achieved by determining the location of common features in the moving object across simultaneous frames. Perspective differences are adjusted. Combining information from images from multiple cameras increases robustness of the tracking process. Motion tracking is achieved by determining anomalies caused by the objects' movement across frames in time in each and the combined video information. The path of each object is determined heuristically. Accuracy of detection is dependent on the speed of the object as well as variations in direction of motion. Fast cameras increase accuracy but limit the speed and complexity of the algorithm. Such an imaging system has applications in traffic analysis, surveillance and security, as well as object modeling from multi-view images. The system can easily be expanded by increasing the number of cameras such that there is an overlap between the scenes from at least two cameras in proximity. An object can then be tracked long distances or across multiple cameras continuously, applicable, for example, in wireless sensor networks for surveillance or navigation.
Investigation of N2O Production from 266 and 532 nm Laser Flash Photolysis of O3/N2/O2 Mixtures

Tunable diode laser absorption spectroscopy has been employed to measure the amount of N2O produced from laser flash photolysis of O3/N2/O2 mixtures at 266 and 532 nm. In the 532 nm photolysis expe...
Edaxadiene: A New Bioactive Diterpene from Mycobacterium tuberculosis

Mycobacterium tuberculosis remains a widespread and devastating human pathogen. Presented here is the characterization of an atypical class I diterpene cyclase from M. tuberculosis that catalyzes an unusual cyclization reaction in converting the known M. tuberculosis metabolite halimadienyl diphosphate to a further cyclized novel diterpene, which we have termed edaxadiene, as it directly inhibits maturation of the phagosomal compartment in which the bacterium is taken up during infection.
Upper mantle structure beneath the Hawaiian swell: Constraints from the ocean seismic network pilot experiment

[1] Data from two broadband, ocean-bottom seismographic stations deployed ∼225 km southwest of Oahu, Hawaii during the Ocean Seismic Network Pilot Experiment provide constraints on upper mantle structure beneath the Hawaiian swell. Receiver functions show that the mantle transition zone is thinned by >50 km relative to reference model PA5, which, in the absence of compositional changes, implies excess temperatures of >350 K in the transition zone. The combination of the measurements reported here and the thickness variations reported by Li et al. [2000] imply that the transition zone is thinned by 30 ± 15 km over an along-swell dimension of at least 700 km. At ∼80 km depth, P-to-S converted phases are identified from the Gutenberg discontinuity marking the lid of the oceanic low-velocity zone and the base of the lithosphere. Shear-wave splitting measurements imply that fast-polarization azimuths are intermediate between the absolute plate-motion vector and the fossil spreading direction; multi-event stacked values of o and δt are −80° and 1.5 s, respectively.
An experimental investigation of several low- area-ratio water jet pumps.

Several low-area-ratio jet pumps were evaluated experimentally in water. Principal geometrical variables investigated were area ratio, throat length, and nozzle spacing. Diffuser geometry was also varied, but to a lesser degree. Experimental values of efficiency and head ratio were compared to a one-dimensional theoretical prediction method previously found to be applicable to moderate and high-area-ratio pumps. Two related cavitation prediction parameters were developed and compared to experimental data.
Hypospadias Trends in Two US Surveillance Systems

Objective. Hypospadias is a common congenital anomaly, the cause of which is unknown. Unexplained increases in the rates of hypospadias occurred in five European countries in the 1970s and 1980s. We examined data from two birth defects surveillance systems in the United States for evidence of similar trends. Methodology. The Metropolitan Atlanta Congenital Defects Program (MACDP) provided birth prevalence rates from 1968 to 1993. The nationwide Birth Defects Monitoring Program (BDMP) provided rates from 1970 to 1993. MACDP data are population-based and could be categorized by the severity of the hypospadias. BDMP data allowed analysis of rate trends for the four census regions of the United States. Results. Data from both surveillance systems showed an approximate doubling of hypospadias rates in the 1970s and 1980s. MACDP data showed that the rate of severe cases increased while the ratio of mild to severe cases decreased. BDMP data showed that hypospadias rates increased markedly in all four regions of the United States. Conclusions. The observed increases are unlikely to be attributable to increased sensitivity of the surveillance systems or the identification of more mild cases by physicians over time, because either trend would have increased rather than decreased the ratio of mild to severe cases. If real, these trends represent the largest number of cases and the first report of an increase in hypospadias rates outside of Europe. Additional investigation of a possible increase in hypospadias rates is warranted.
Hybrids and quark confinement

Abstract It has become traditional to assume that the Dirac structure of the phenomenological quark confinement potential is scalar ⊗ scalar. We use the heavy quark expansion of the Coulomb gauge QCD Hamiltonian and the Flux Tube model to demonstrate that this is true but in the effective sense only. The demonstration contains some surprises: confinement is actually vector ⊗ vector and it is nonperturbative mixing between ordinary and hybrid Q Q states which generates the scalar-like spin dependent potential at order 1 m q 2 . Thus the existence of hybrids is crucial to establishing well-known spin splitting phenomenology. Finally, the resolution also indicates that the gluonic degrees of freedom in a hybrid must be of a collective nature.
Categorizing others in a large game

Abstract We study the efficiency of categorization of other agents as a way of saving cognitive resources in the settings of a large normal-form game. We assume that, when an agent categorizes (partitions) her opponents, she only has information about the average strategy in each category. A strategy profile is a conjectural categorical equilibrium (CCE) with respect to a given categorization profile if every player's strategy is a best response to some consistent conjecture about the strategies of her opponents. It is shown that, for a wide family of games and for a particular categorization profile, every CCE is an approximate Nash equilibrium when the number of players is large. This result demonstrates the potential of categorization as an efficient way to store information in complex environments. Although possessing a coarse description of their opponents' strategies, agents behave as if they see the full picture.
The use of computer graphic simulation in the development of robotic systems

This paper describes the use of computer graphic simulation techniques to resolve critical design and operational issues for robotic systems. Use of this technology will result in greatly improved systems and reduced development costs. The major design issues in developing effective robotic systems are discussed and the use of ROBOSIM, a NASA developed simulation tool, to address these issues is presented. Three representative simulation case studies are reviewed: off-line programming of the robotic welding development cell for the Space Shuttle Main Engine (SSME); the integration of a sensor to control the robot used for removing the Thermal Protection System (TPS) from the Solid Rocket Booster (SRB); and the development of a teleoperator/robot mechanism for the Orbital Maneuvering Vehicle (OMV).
Chemical solution growth of ferroelectric oxide thin films and nanostructures

Chemical solution deposition (CSD) provides a low-cost, versatile approach for processing of thin and ultrathin ferroelectric films, as well as short and high aspect ratio ferroelectric nanostructures. This review discusses the state of the art in the processing of ferroelectric oxide thin films and nanostructures by CSD, with special emphasis on nucleation and growth phenomena. The effects of choice of precursor solution, substrate and bottom electrode stack, and thermal treatment conditions on the nucleation and growth are examined. Furthermore, methods to control ferroelectric thin film's microstructure, including phase content, texture, grain size and chemical homogeneity, are reviewed. Lastly, current CSD-based methods for processing of ferroelectric oxide nanostructures are presented with special consideration of the structural development, as well as advantages and shortcomings associated with each method. Lead zirconate-titanate, Pb(ZrxTi1−x)O3 (PZT), and barium titanate, BaTiO3 (BT), are used throughout the discussion, as specific examples for CSD processing of perovskite ferroelectrics.
EXPLORING THE INTERSTELLAR MEDIA OF OPTICALLY COMPACT DWARF GALAXIES

We present new Very Large Array H I spectral line, archival Sloan Digital Sky Survey, and archival Spitzer Space Telescope imaging of eight star-forming blue compact dwarf galaxies that were selected to be optically compact (optical radii <1 kpc). These systems have faint blue absolute magnitudes (M B –17), ongoing star formation (based on emission-line selection by the Hα or [O III] lines), and are nearby (mean velocity = 3315 km s–1 45 Mpc). One galaxy in the sample, ADBS 113845+2008, is found to have an H I halo that extends 58 r-band scale lengths from its stellar body. In contrast, the rest of the sample galaxies have H I radii to optical-scale-length ratios ranging from 9.3 to 26. The size of the H I disk in the "giant disk" dwarf galaxy ADBS 113845+2008 appears to be unusual as compared with similarly compact stellar populations.
Knotted list structures

In (3) Perlis and Thornton describe a list structure language the central innovation of which is that the last word of each list specifies the location of the head of the list of which it is the terminal word. They call such list structures threaded lists. Beyond this, however, they hypothesize Sequencing Tables and associated sequencing modes (e, l, and w). The sequencing modes make possible forms of traversing list structures which leave the lists themselves undisturbed in memory. Since the Sequence Table can contain true names as well as aliases for particular list structures and since lists are undisturbed by sequencing, many programs may sequence through lists in different manners, at various rates, but still simultaneously. This partially mitigates against the need to store many copies of a list and becomes critical in multiple computer systems in which it may be expected that a number of sub-programs operate on a single list structure (under various aliases) independently. This note describes a generalization of the threaded list. The name given to such generalized threaded list structures is knotted list structures (KLS). The generalization consists essentially of replacing the thread link which Perlis and Thornton place in the R or link position of the last list cell of a list (or sub-list with a Control List (CL) which is attached to the list structure and which contains, among other information, a push down list capable of storing many thread links. The chief advantage of this scheme is that it permits a sub-list to be a sub-list of many lists, something which ordinary threaded lists do not permit. All other advantages of threaded lists are kept.
Developments in international mode of entry analysis

Theories on international trade and investment as well as those relating the nature of the product to the length of the channel suggest that mode of entry decisions should result from the analysis of a wide variety of factors. The purpose of this article is to show how such theories might be related to practice through the development of decision support tools. Emphasis is given to a microcomputer software package developed to aid international mode of entry assessment.