cssi/SciSciGPT-SciSciNet huggingface dataset:
Copernicus observations of interstellar absorption at Lyman alpha

Column densities NH of atomic hydrogen have been derived for 40 OB stars from spectral scans at Lyman alpha obtained by the Copernicus (OAO-3) satellite. The stars are all between 60 and 1100 pc away with a range of mean densities n sub H of 0.01 to 2.5 atoms cm-3. The gas to color-excess ratio in clouds varies from 1 to 3 times the mean outside of clouds. The presence of molecular hydrogen correlates with E(B-V), but the best tracer for H2 is atomic hydrogen. The mean density of the gas for all 40 stars is much smaller than the mean of 0.7 atoms cm-3 obtained from 21-cm observations, because the brightest stars with less than average amounts of matter in the line of sight were selected for observation.
Fast and secure distributed read-only file system

Internet users increasingly rely on publicly available data for everything from software installation to investment decisions. Unfortunately, the vast majority of public content on the Internet comes with no integrity or authenticity guarantees. This paper presents the self-certifying read-only file system, a content distribution system providing secure, scalable access to public, read-only data.The read-only file system makes the security of published content independent from that of the distribution infrastructure. In a secure area (perhaps off-line), a publisher creates a digitally signed database out of a file system's contents. The publisher then replicates the database on untrusted content-distribution servers, allowing for high availability.The read-only file system avoids performing any cryptographic operations on servers and keeps the overhead of cryptography low on clients, allowing servers to scale to a large number of clients. Measurements of an implementation show that an individual server running on a 550-Mhz Pentium III with FreeBSD can support 1,012 connections per second and 300 concurrent clients compiling a large software package.
Strong coupling expansion of Calabi-Yau compactification

Abstract In a certain strong coupling limit, compactification of the E8 × E8 heterotic string on a Calabi-Yau manifold X can be described by an eleven-dimensional theory compactified on X × S 1 / Z 2 . In this limit, the usual relations among low-energy gauge couplings hold, but the usual (problematic) prediction for Newton's constant does not. In this paper, the equations for unbroken supersymmetry are expanded to the first non-trivial order, near this limit, verifying the consistency of the description and showing how, in some cases, if one tries to make Newton's constant too small, strong coupling develops in one of the two E8's. The lower bound on Newton's constant (beyond which strong coupling develops) is estimated and is relatively close to the actual value.
Constraints on Association of Single-Pulse Gamma-Ray Bursts and Supernovae

We explore the hypothesis, similar to one recently suggested by Bloom and colleagues, that some nearby supernovae are associated with smooth, single-pulse gamma-ray bursts, possibly having no emission above ~300 keV. We examine BATSE bursts with durations longer than 2 s, fitting those which can be visually characterized as single-pulse events with a lognormal pulse model. The fraction of events that can be reliably ascertained to be temporally and spectrally similar to the exemplar, GRB 980425—possibly associated with SN 1998bw—is 4/1573 or 0.25%. This fraction could be as high as 8/1573 (0.5%) if the dimmest bursts are included. Approximately 1.5% of bursts are morphologically similar to GRB 980425 but have emission above ~300 keV. A search of supernova catalogs containing 630 detections during BATSE's lifetime reveals only one burst (GRB 980425) within a 3 month time window and within the total 3 σ BATSE error radius that could be associated with a Type Ib/c supernova. Thus, we find no further evidence to support a single-pulse GRB and SN Ib/c connection. We also find no tendency for any set of single-pulse GRBs to fall near the supergalactic plane, whereas SNe of Type Ib/c do show this tendency—evidence that the two phenomena are not related.
Do Financial Incentives Help Low-Performing Schools Attract and Keep Academically Talented Teachers? Evidence from California

This study capitalizes on a natural experiment that occurred in California between 2000 and 2002. In those years, the state offered a competitively allocated $20,000 incentive called the Governor's Teaching Fellowship (GTF) aimed at attracting academically talented, novice teachers to low-performing schools and retaining them in those schools for at least four years. Taking advantage of data on the career histories of 27,106 individuals who pursued California teaching licenses between 1998 and 2003, we use an instrumental variable strategy to estimate the unbiased impact of the GTF on the decisions of recipients to begin working in low-performing schools within 2 years after licensure program enrollment. We estimate that GTF recipients would have been less likely to teach in low-performing schools than observably similar counterparts had the GTF not existed, but that acquiring a GTF increased their probability of doing so by 28 percentage points. Examining retention patterns, we find that 75 percent of both GTF recipients and nonrecipients who began working in low-performing schools remained in such schools for at least four years. © 2010 by the Association for Public Policy Analysis and Management.
The structural response of a rail accelerator

The transient response of a 0.4 by 0.6 cm rectangular bore rail accelerator was analyzed using a three-dimensional finite-element code. Results are presented for the case of a 210-kA current input and 5-cm arc length. Typically, the copper rail deflected to a peak value of 0.08 mm in compression and then oscillated at an amplitude of 0.02 mm. Simultaneously the insulating side wall of glass fabric base, epoxy resin laminate (G-10) was compressed to a peak value of 0.13 mm and rebounded to a steady state in extension. Projectile pinch or blow-by due to the rail (or side-wall) extension or compression, respectively, can be identified by examining the time history of the rail (or side-wall) displacement. For the case presented, the effect of blow-by was most significant at the side wall characterized by mm-size displacement in compression. Dynamic stress calculations indicate that the G-10 supporting material behind the rail is subjected to over 21 MPa - at which the G-10 could fail if the laminate was not carefully oriented. Results for a polycarbonate resin (Lexan) side wall show much larger displacements and stresses than for G-10. Therefore the tradeoff between the transparency of Lexan and the mechanical strength of G-10 for side-wall material is obvious. Displacement calculations from the modal method are smaller than the results from the direct integration method by almost an order of nagnitude, because the high-frequency effect is neglected. However, this effect is significant and dominating for a highly-impulsive, wave-propagation problem such as the rail accelerator structure.
Limits to Image Reconstruction from Restricted Angular Input

Distortion in an object due to the unavailability of some Fourier components in a cone-shaped region is analyzed. The results throw light on the factors that limit the accuracy in reconstructing objects from limited-angle input in practice. It is also shown that norm- or entropy-related reconstruction methods are not expected to improve the fidelity of the reconstructed images; only more a priori knowledge of exact nature on the object can serve this purpose.
Discovery of a High-Latitude Accreting Millisecond Pulsar in an Ultracompact Binary

We have identified the third known accretion-powered millisecond pulsar, XTE J0929-314, with the Rossi X-Ray Timing Explorer. The source is a faint, high Galactic latitude X-ray transient (d 5 kpc) that was in outburst during 2002 April-June. The 185 Hz (5.4 ms) pulsation had a fractional rms amplitude of 3%-7% and was generally broad and sinusoidal, although occasionally double-peaked. The hard X-ray pulses arrived up to 770 ?s earlier than the soft X-ray pulses. The pulsar was spinning down at an average rate of = (-9.2 ? 0.4) ? 10-14 Hz s-1; the spin-down torque may arise from magnetic coupling to the accretion disk, a magnetohydrodynamic wind, or gravitational radiation from the rapidly spinning pulsar. The pulsations were modulated by a 43.6 minute ultracompact binary orbit, yielding the smallest measured mass function (2.7 ? 10-7 M?) of any stellar binary. The binary parameters imply an 0.01 M? white dwarf donor and a moderately high inclination. We note that all three known accreting millisecond pulsars are X-ray transients in very close binaries with extremely low mass transfer rates. This is an important clue to the physics governing whether or not persistent millisecond pulsations are detected in low-mass X-ray binaries.
Experimental and computational characterization of a modified GEC cell for dusty plasma experiments

A self-consistent fluid model developed for simulations of micro-gravity dusty plasma experiments has for the first time been used to model asymmetric dusty plasma experiments in a modified Gaseous Electronics Conference (GEC) reference cell with gravity. The numerical results are directly compared with experimental data and the experimentally determined dependence of global discharge parameters on the applied driving potential and neutral gas pressure is found to be well matched by the model. The local profiles important for dust particle transport are studied and compared with experimentally determined profiles. The radial forces in the midplane are presented for the different discharge settings. The differences between the results obtained in the modified GEC cell and the results first reported for the original GEC reference cell are pointed out.
Semi-Classical Limit and Minimum Decoherence in the Conditional Probability Interpretation of Quantum Mechanics

The Conditional Probability Interpretation of Quantum Mechanics replaces the abstract notion of time used in standard Quantum Mechanics by the time that can be read off from a physical clock. The use of physical clocks leads to apparent non-unitary and decoherence. Here we show that a close approximation to standard Quantum Mechanics can be recovered from conditional Quantum Mechanics for semi-classical clocks, and we use these clocks to compute the minimum decoherence predicted by the Conditional Probability Interpretation.
Long-Range Correlations in Deep-Inelastic Scattering

Multiplicity correlations between the current and target regions of the Breit frame in deep-inelastic scattering processes are studied. It is shown that the correlations are sensitive to the first-order perturbative QCD effects and can be used to extract the behaviour of the boson-gluon fusion rates as a function of the Bjorken variable. The behaviour of the correlations is derived analytically and analyzed using a Monte Carlo simulation.
A flexible architecture for building data flow analyzers

Data flow analysis is a versatile technique that can be used to address a variety of analysis problems. Typically, data flow analyzers are hand-crafted to solve a particular analysis problem. The cost of constructing analyzers can be high and is a barrier to evaluating alternative analyzer designs. We describe an architecture that facilitates the rapid prototyping of data flow analyzers. With this architecture, a developer chooses from a collection of pre-existing components or, using high-level component generators, constructs new components and combines them to produce a data flow analyzer. In addition to support for traditional data flow analysis problems, this architecture supports the development of analyzers for a class of combined data flow problems that offer increased precision. This architecture allows developers to investigate quickly and easily a wide variety of analyzer design alternatives and to understand the practical design tradeoffs better. We describe our experience using this architecture to construct a variety of different data flow analyzers.
Filter for strangeness in $J^{PC}$ exotic four-quark states

Symmetrization selection rules for the decay of four–quark states to two J=0 mesons are analysed in a non – field theoretic context with isospin symmetry. The OZI allowed decay of an isoscalar $J^{PC}=\{1,3,\ldots\}^{-+}$ exotic state to $\eta^{'}\eta$ or $f_0^{'}f_0$ is only allowed for four–quark components of the state containing one $s\bar{s}$ pair, providing a filter for strangeness content in these states. Decays of four–quark $a_0$ states are narrower than otherwise expected. If the experimentally observed $1^{-+}$ enhancement in $\eta\pi$ is resonant, it is qualitatively in agreement with being a four–quark state.
Sales Loss Determination in Food Contamination Incidents: An Application to Milk Bans in Hawaii

This article presents a procedure for estimating sales loss following a food contamination incident with application to the case of heptachlor contamination of fresh fluid milk in Oahu, Hawaii, in 1982. A major finding is that media coverage following the incident had a significant impact on milk purchases and that negative coverage had a larger effect than positive coverage. This conclusion implies that public statements by producers or government to assure the public of safe food supplies may be ineffective in restoring consumer confidence following the discovery of a food safety problem.
Effect of a brief educational intervention on the attitudes of young women toward the intrauterine device.

STUDY OBJECTIVE: The intrauterine device (IUD) is underused by young women who are at high risk for unintended pregnancy. We aimed to assess the impact of a brief educational intervention on the attitudes of young women toward intrauterine contraception and to assess characteristics associated with a change in attitude. DESIGN SETTING AND PARTICIPANTS: This is a planned secondary analysis of a survey of 144 women aged 14-24 years which assessed attitudes toward the IUD. INTERVENTION: The analysis was planned to fully examine the impact of a 3-minute educational intervention about the IUD given during administration of the survey which included risks and benefits of IUD use costs side effects and a demonstration of the IUD insertion and removal process. MAIN OUTCOME MEASURE: Proportions of participants with a positive attitude toward the IUD before and after the intervention were compared using McNemars chi-square test for paired proportions. Factors associated with a change in attitude toward the IUD were evaluated using multivariable analysis. RESULTS: Before the educational intervention 14.7% (21/143) had both heard of the IUD and expressed a positive attitude toward it. After the intervention this proportion increased to 53.8% (77/143) (P < .01). The increase in proportion with a positive attitude was consistent for all subpopulations. In multivariable analysis the only significant predictor of a positive change in attitude toward the IUD was a history of voluntary sexual activity (adjusted odds ratio 10.3 95% confidence interval 2.0-53.1). CONCLUSIONS: A brief educational intervention significantly improves the attitude of young sexually active women toward the IUD. Copyright 2010 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.
Swift Observations of the Cooling Accretion Disk of XTE J1817-330

The black hole candidate X-ray transient XTE J1817-330 was observed by the Swift satellite over 160 days of its 2006 outburst with the XRT and UVOT instruments. At the start of the observations, the XRT spectra show that the 0.6-10 keV emission is dominated by an optically thick, geometrically thin accretion disk with an inner disk temperature of ~0.8 keV, indicating that the source was in a high/soft state during the initial outburst phase. We tracked the source through its decline into the low/hard state with the accretion disk cooling to ~0.2 keV and the inner disk radius consistent with the innermost stable circular orbit at all times. Furthermore, the X-ray luminosity roughly follows LX T4 during the decline, consistent with a geometrically stable blackbody. These results are the strongest evidence yet obtained that accretion disks do not automatically recede after a state transition, down to accretion rates as low as 0.001LEdd. Meanwhile, the near-UV flux does not track the X-ray disk flux and is well in excess of what is predicted if the near-UV emission is from viscous dissipation in the outer disk. The strong correlation between the hard X-ray flux and the near-UV flux, which scale as L, indicate that reprocessed emission is most likely the dominate contribution to the near-UV flux. We discuss our results in the context of accretion disks and the overall accretion flow geometry in accreting black holes.
Learning by Doing and Dynamic Regulation

From experience, regulated monopolists learn to employ cost-reducing innovations. We characterize the optimal regulation of an innovating monopolist with unknown costs. Regulatory policy is designed to minimize current costs of service while encouraging development of cost-saving innovations. We find that under optimal regulation, (i) innovation is encouraged by light-handed regulation allowing the monopolist to earn greater information rents while providing greater service, (ii) innovation occurs in the absence of long-term agreements when private information is recurring, and (iii) innovation is more rapid in a durable franchise, and the regulator prefers durable franchises for exploiting learning economies.
Electron Capture and Nuclear Matrix Elements of Be 7

BS>The Be/sup 7/ electron capture rate from continuum orbits is calculated as a function of electron temperature and concentration, and the effect on the decay rate of the statistical distribution of electrons, the electron-nucleus Coulomb intetaction, relativistic and nuclear size corrections, the imperfect overlap between Initial and final atomic states, and electron screening in bound decay, is considered. Experimental information on Be/sup 7/ and Li/sup 7/ is analyzed to obtain accurate experimental Gamow-Teller matrix elements for both the ground- and excited-state transitions and compare these matrix elements with the predictions of some simple nuclear models. This comparison supports the conclusion that near the beginning of the 1p nuclear shell L-S coupling is better satisfied than j-j coupling. (auth)
Limits to Tertiary Astrometric Companions in Binary Systems

The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) has monitored 37 subarcsecond binary systems to determine whether their Keplerian orbits are perturbed by faint astrometric companions to either star. Software has been developed to evaluate the regions in a companion mass-period phase space in which the PHASES observations can exclude the possibility of face-on orbit perturbations. We present results for eight systems for which astrometric companions with masses as small as those of giant planets can be excluded.
Hypohalogenation of functionally substituted acetylenic norbornenes

Hypohalogenation of norbornenes containing a triple bond and various functional groups in the side chain was performed using mixtures of aqueous solutions of hydrochloric or hydrobromic acid (or sodium or potassium bromide) and hydrogen peroxide. The reaction was found to involve addition of electrophilic reagent generated in situ (HOBr or HOCl) at the endocyclic double bond with formation of the corresponding halohydrins. The latter underwent dehydrohalogenation by the action of alklai to give exo-5,6-epoxybicyclo[2.2.1]-heptane derivatives in high yields. Kinetic relations holding in the hypobromination process were established, and the initial rates and activation parameters were calculated.
Local smoothing effects for the water-wave problem with surface tension

Abstract The water-wave problem with a one-dimensional free surface of infinite depth is considered, based on the formulation as a second-order nonlinear dispersive equation. The local smoothing effects are established under the influence of surface tension, stating that on average in time solutions acquire locally 1/4 derivative of smoothness as compared to the initial state. The analysis combines energy methods with techniques of Fourier integral operators. To cite this article: H. Christianson et al., C. R. Acad. Sci. Paris, Ser. I 347 (2009).
Real-time monitoring and control of plasma etching

Process control strategies have been developed for reactive ion etching of silicon and silicon dioxide in CFJO2 and CF/H2 plasmas. Four measured variables four manipulated variables and six performance variables were considered for both chemistries. Relative gain array analysis and singular value decomposition were used to select manipulated/process variable control loop pairings for feedback control and to evaluate potential difficulties in control system performance. Block relative gain analysis of multivariable interactions in the process indicated that single loop feedback control would be inadequate for control of both CF/H2 and CFJO2 etching which was subsequently verified by simulation. Multivariable control (partial decoupling) was much more effective in reducing dynamic fluctuations in the process variables. Closed loop simulations have demonstrated a quality of control sufficient for manufacturing purposes. Singular value decomposition was also used to determine which process variable (measured in real-time) correlated best with a given performance variable. Empirical input-output models developed by response surface methodology were used for the above analyses. For the CF/H2 system functions based on semi-theoretical reasoning of process variables were also investigated. For example the function of [F](DC Bias)25/[CF2] was found to be more indicative of process performance than the absolute values of these process variables. Unfortunately this work reveals the need for more real-time measurable process variables in order to achieve sufficient process performance.
Effective Conformal Descriptions of Black Hole Entropy

It is no longer considered surprising that black holes have temperatures and entropies. What remains surprising, though, is the universality of these thermodynamic properties: their exceptionally simple and general form, and the fact that they can be derived from many very different descriptions of the underlying microscopic degrees of freedom. I review the proposal that this universality arises from an approximate conformal symmetry, which permits an effective “conformal dual” description that is largely independent of the microscopic details.
DESIGN STUDY OF A SQUARE SOLAR SAIL ARCHITECTURE

The impact on the achievable performance and some key structural characteristics in 100 m square solar sails of design conditions and parameters is explored. Upper bound performance is addressed with an architecture of manageable mechanics and likely ultimate structural efficiency in its class due to uniaxial tensioning in each quadrant: the stripped sail. The designs are performed with a limit point-friendly approach. These innovations are justified by reviewing response fundamentals including sail billow, boom mechanics, and operational failure modes. The observations and conclusions advance the state of the art in sail design and provide guidance for future engineering. ac bj L, E F p Reu r, d t, S, s 77 p <j
Terminal attractors in neural networks

A new type of attractor (terminal attractors) for content-addressable memory, associative memory, and pattern recognition in artificial neural networks operating in continuous time is introduced. The idea of a terminal attractor is based upon a violation of the Lipschitz condition at a fixed point. As a result, the fixed point becomes a singular solution which envelopes the family of regular solutions, while each regular solution approaches such an attractor in finite time. It will be shown that terminal attractors can be incorporated into neural networks such that any desired set of these attractors with prescribed basins is provided by an appropriate selection of the synaptic weights. The applications of terminal attractors for content-addressable and associative memories, pattern recognition, self-organization, and for dynamical training are illustrated.
Lund’s Elliptic Orbit Forced Response Analysis: The Keystone of Modern Rotating Machinery Analysis

A total understanding of rotating machinery vibration analysis requires evaluation of critical speed placement, forced response sensitivity to imbalance, linear onset of instability prediction and full non-linear response analysis. Of these four areas of analysis, only the first three are applied as a basic design tool in modern turbo-machinery analysis. The prediction of multi-mass flexible rotor steady-state elliptic orbit response, including bearing damping and support flexibility, has been and remains in this author's opinion, to be the basic workhorse and keystone of machinery design. This has now been true for over 35 years. The person responsible for developing this basic method of analysis has been a longtime friend of many engineers worldwide. This paper is written to acknowledge this contribution, one of many in fact, made by Jorgen W Lund and is presented in memory of his life's work at this occasion of honoring his contributions to our profession. A short section on the methods and understanding gained from the basic analysis will be presented. Finally, some personal reflections will be given concerning Jorgen Lund.
Comments on the x-ray edge and recoil problems

Some particular cases of the x-ray edge and recoil problems are examined. The usual independent-particle theory is evaluated exactly for the case in which the excitation introduces a full virtual level into the conduction band. These results make contact with studies of rare-gas pair absorption in metals and also afford a comparison with earlier theories. Some aspects of the difficulties introduced by the electron-electron interactions in real metals are also discussed.
Differential effects of serum heat treatment on chemotaxis and phagocytosis by human neutrophils.

Neutrophils, in cooperation with serum, are vital gatekeepers of a host’s microbiome and frontline defenders against invading microbes. Yet because human neutrophils are not amenable to many biological techniques, the mechanisms governing their immunological functions remain poorly understood. We here combine state-of-the-art single-cell experiments with flow cytometry to examine how temperature-dependent heat treatment of serum affects human neutrophil interactions with “target” particles of the fungal model zymosan. Assessing separately both the chemotactic as well as the phagocytic neutrophil responses to zymosan, we find that serum heat treatment modulates these responses in a differential manner. Whereas serum treatment at 52°C impairs almost all chemotactic activity and reduces cell-target adhesion, neutrophils still readily engulf target particles that are maneuvered into contact with the cell surface under the same conditions. Higher serum-treatment temperatures gradually suppress phagocytosis even after enforced cell-target contact. Using fluorescent staining, we correlate the observed cell behavior with the amounts of C3b and IgG deposited on the zymosan surface in sera treated at the respective temperatures. This comparison not only affirms the critical role of complement in chemotactic and adhesive neutrophil interactions with fungal surfaces, but also unmasks an important participation of IgGs in the phagocytosis of yeast-like fungal particles. In summary, this study presents new insight into fundamental immune mechanisms, including the chemotactic recruitment of immune cells, the adhesive capacity of cell-surface receptors, the role of IgGs in fungal recognition, and the opsonin-dependent phagocytosis morphology of human neutrophils. Moreover, we show how, by fine-tuning the heat treatment of serum, one can selectively study chemotaxis or phagocytosis under otherwise identical conditions. These results not only refine our understanding of a widely used laboratory method, they also establish a basis for new applications of this method.
Steric Effects in Stress Corrosion Fracture of Glass

Previous studies show that stress corrosion crack growth in glass is controlled by chemically enhanced crack tip bond rupture reactions. The brittle nature of fracture in glass suggests that the region where bond rupture reactions occur must be on the order of the atomic spacings in the material. Crack growth kinetics and zeolite diffusion data were used to determine the relation between molecular size and reactivity at the crack tip. Crack growth rates in silica glass were measured in the presence of a series of chemical species that have comparable chemical features and systemically increasing molecular diameters. Results show that chemically active species with diameters greater than 0.5 nm are ineffective as stress corrosion agents. A comparison of crack growth results and zeolite diffusion measurements was used to conclude that the opening to the crack tip is less than or equal to 0.5 nm. This crack tip dimension is consistent with the concept of atomic scale brittle fracture in slicia glass.
Study of SiC-whisker-reinforced ZrO2 ceramics using the sol-gel method

Tetragonal ZrO2-SiC whisker composite powders have been synthesized by the sol-gel method. Analysis reveals that SiC whiskers are homogeneously dispersed in the composite powder, the matrix being ultrafine metastable tetragonal ZrO2. The sintering properties of the composite have been investigated. SiC whiskers favour an increase in content of metastable tetragonal ZrO2. When the SiC whisker content is high, the critical stress intensity factor (KIC) decreases.
From machine learning to machine reasoning

A plausible definition of "reasoning" could be "algebraically manipulating previously acquired knowledge in order to answer a new question". This definition covers first-order logical inference or probabilistic inference. It also includes much simpler manipulations commonly used to build large learning systems. For instance, we can build an optical character recognition system by first training a character segmenter, an isolated character recognizer, and a language model, using appropriate labelled training sets. Adequately concatenating these modules and fine tuning the resulting system can be viewed as an algebraic operation in a space of models. The resulting model answers a new question, that is, converting the image of a text page into a computer readable text. This observation suggests a conceptual continuity between algebraically rich inference systems, such as logical or probabilistic inference, and simple manipulations, such as the mere concatenation of trainable learning systems. Therefore, instead of trying to bridge the gap between machine learning systems and sophisticated "all-purpose" inference mechanisms, we can instead algebraically enrich the set of manipulations applicable to training systems, and build reasoning capabilities from the ground up.
Limit groups for relatively hyperbolic groups, II: Makanin-Razborov diagrams

Let be a torsion-free group which is hyperbolic relative to a collection of free abelian subgroups. We construct Makanin–Razborov diagrams for . We also prove that every system of equations over is equivalent to a finite subsystem, and a number of structural results about –limit groups.
A Geometric Approach to Tree Shape Statistics

This article presents a new way to quantify the descriptive ability of tree shape statistics. Where before, tree shape statistics were chosen by their ability to distinguish between macroevolutionary models, the resolution presented in this paper quantifies the ability of a statistic to differentiate between similar and different trees. This is termed the geometric approach to differentiate it from the model-based approach previously explored. A distinct advantage of this perspective is that it allows evaluation of multiple tree shape statistics describing different aspects of tree shape. After developing the methodology, it is applied here to make specific recommendations for a suite of three statistics that may prove useful in applications. The article ends with an application of the statistics to clarify the impact of taxa omission on tree shape.
Strength of Multiple Parallel Biological Bonds

Multivalent interactions play a critical role in a variety of biological processes on both molecular and cellular levels. We have used molecular force spectroscopy to investigate the strength of multiple parallel peptide-antibody bonds using a system that allowed us to determine the rupture forces and the number of ruptured bonds independently. In our experiments the interacting molecules were attached to the surfaces of the probe and sample of the atomic force microscope with flexible polymer tethers, and the unique mechanical signatures of the tethers determined the number of ruptured bonds. We show that the rupture forces increase with the number of interacting molecules and that the measured forces obey the predictions of a Markovian model for the strength of multiple parallel bonds. We also discuss the implications of our results to the interpretation of force spectroscopy measurements in multiple bond systems.
Design of a compact coaxial magnetized plasma gun for magnetic bubble expansion experiments

We will discuss the design of a compact coaxial magnetized plasma gun and its associated hardware systems in detail. The plasma gun is used for experimental studies of magnetic bubble expansion into a lower pressure background plasma, as a model for extragalactic radio lobes. The gun is powered by a 120µF, 10kV ignitron-switched capacitor bank. High-pressure gas is puffed into an annular gap between inner and outer coaxial electrodes. The applied high voltage ionizes the gas and creates a radial current sheet. The ∼100kA discharge current generates toroidal flux; poloidal flux is provided by using an external bias magnet. The axial J×B force ejects plasma out of the gun. If the J×B force exceeds the magnetic tension of the poloidal flux by a sufficient amount then a detached magnetized plasma will be formed. Using spatially resolved magnetic probe array measurements and high speed camera, we are studying the evolution of this plasma “bubble” as it interacts with a pre-existing lower pressure background plasma which is provided by helicon source (HelCat). The poster will discuss the plasma bubble formation system including the power system, gas valve control system, bias flux power system, and the magnetic probe diagnostic in detail. Experimental data will also be provided.
A Fast-Marching Time-Domain Layered Finite-Element Reduction-Recovery Method for High-Frequency VLSI Design

A fast-marching time-domain layered finite-element reduction-recovery (LAFE-RR) method is proposed for high-frequency modeling and simulation of large-scale integrated circuits. This method increases the time step of the LAFE-RR method by three orders of magnitude. In addition, it preserves the computational efficiency of the LAFE-RR method, i.e., the matrix reduction is achieved analytically from a three-dimensional layered system to a single-layer one regardless of the original problem size, and the sparsity of the reduced single-layer system matrix is the same as that of the original system matrix. The method applies to any arbitrarily-shaped multilayer structure. Numerical and experimental results are given to demonstrate its validity.
ADVANCES AND NEW CONCEPTS IN ORAL AND MAXILLOFACIAL PATHOLOGY

Improvement in the treatment of patients has come through new surgical techniques, improved modalities of therapy, and better understanding of disease processes. The role of the pathologist is to elucidate and clarify the pathogenesis of disease. For many years, advances in the understanding of neoplastic disease have been achieved by pathologists through the recognition and classification of tumors via standard light microscopy using routine hematoxylin and eosin staining, occasionally complemented by specific histochemical stains. The advent of electron microscopy yielded further morphologic information but was limited in application by its expense, the size of the operating unit, and the requirement of fresh tissue. Over the past 2 decades, further characterization of tumors became feasible using newly developed diagnostic techniques. In addition, the ease of obtaining tissue samples has been enhanced by new approaches such as fine-needle aspiration biopsy. Analysis of the molecular characteristics of certain tumors has become the standard of care, contributing to more specific classification and treatment recommendations. Recent molecular biologic advances have made such analyses not only possible but relatively convenient. Labeled probes have been developed that help to analyze nucleic acid sequences. Techniques used to identify and quantify the nucleic acid content of cells include filter hybridization (dot blot, Southern blot, Northern blot, etc.), DNA or RNA in-situ hybridization, quantification of argyrophilic nucleolar organizer regions (AgNOR), and flow cytometric analysis. Cellular proteins other than nucleic acids can be recognized by immunohistochemistry and Western blot techniques. The use of polymerase chain reaction (PCR) has added to the efficacy of many of these techniques by providing a means of nucleic-acid amplification during testing. This technique allows the amplification of small quantities of nucleic acid (body fluid, peripheral white cells, aspirates, cytology, etc.). It is critical to distinguish among various types of tumors, because treatment is often determined by tumor type. For example, it is no longer acceptable to rely on clinical and microscopic evaluation alone to determine if a malignant round-cell tumor represents a leukemic infiltrate, lymphoma, neuroblastoma, rhabdomyosarcoma, or poorly differentiated carcinoma. Instead, immunohistochemical markers are used to help distinguish whether the tissue of origin is epithelial, neurogenic, myogenic, lymphoid, or metastatic. DNA and RNA in-situ hybridization are available to identify intracellular pathogens. AgNOR and flow cytometric analysis are used to evaluate cell kinetics in an attempt to predict biologic behavior of tumors and patient response to treatment. The focus of this discussion is not meant to be inclusive of all of the most recent diagnostic techniques currently available, but it presents an overview of the most commonly applied new approaches to diagnosis.
Why Is China So Competitive? Measuring and Explaining China's Competitiveness

This paper evaluates factors responsible for the competitiveness of China in the world economy and relative to its East Asian rivals. China has been highly successful in capturing world export markets. Chinese competitiveness is not just a matter of an undervalued exchange and extremely low labor costs. It reflects primarily the coincidence of favorable cost conditions with improvements in China’s ability to produce products that meet world market specifications. These improvements are closely related to foreign participation in China’s economy through foreign direct investment and joint venture enterprises.
Discussion of Which Institutional Investors Trade Based on Private Information about Earnings and Returns

The large and increasing presence of institutional investors both as owners of public companies and as traders in the U.S. stock markets has important implications for both firms' decisions and stock price behavior. Much academic research in accounting and finance has been conducted to understand these implications. The main questions addressed in the literature typically fall into one of four categories. (1) Whether and how institutional ownership affects firms' behaviors. This includes research analyzing the relation between institutional ownership and a variety of firms' decisions such as investment, financing, corporate governance and financial reporting choices. (2) Whether institutional investors achieve high enough returns to justify their costs. This includes research evaluating the performance of institutions such as actively managed mutual funds and hedge funds whose primary goal is to maximize (net-of-fee) returns. (3) Whether and how institutional investors' trading affects stock price behavior, such as stock price volatility and stock market liquidity. (4) Whether and how institutional investors improve stock price efficiency. The research question entertained in Bushee and Goodman (hereafter, BG): "Which institutional investors trade based on private information?" is
Market viability via absence of arbitrage of the first kind

It is shown that, in a semimartingale financial market model, there is equivalence between absence of arbitrage of the first kind (a weak viability condition) and the existence of a strictly positive process that acts as a local martingale deflator on nonnegative wealth processes.
Direct synthesis of liquid-phase dioxygen difluoride

Abstract Dioxygen difluoride (O 2 F 2 ) was produced directly in the liquid phase at temperatures above −154°C. An O 2 /F 2 gas mixture was heated to 700°C and was then rapidly cooled on the outer surface of stainless steel tubes. The tubes were refrigerated by a liquid oxygen bath pressurized to >7600 torr with helium. Six grams of O 2 F 2 were produced in less than an hour. Color of the viscous liquid in the O 2 F 2 generator ranged from copper red to straw yellow. Different O x F y compounds existed simultaneously on the tubes; explanations for this phenomenon are suggested. Audible “pings” and pressure excursions occurred when liquid O 2 F 2 dripped onto uncooled portions of the apparatus. An orifice at the hot/cold interface was important in obtaining significant reaction rates.
An approach to nonlinear feedback control with applications to robotics

A control problem involving a mechanical system with generalized coordinates q∈Rm is considered. The error in tracking a desired input yd∈Rp is e=E(q,yd)∈Rm. If E satisfies simple conditions, it leads to a nonlinear control law that assures e(t)→0 as t→∞. The law is robust in that small changes in it do not produce large steady-state errors or loss of stability. In this theory a unified framework is presented for treating a number of problems in the control of mechanical manipulators.
An Analysis of the Impedance of Polycrystalline Beta‐Alumina

A procedure is described in this paper for distinguishing in the measured electrical properties of polycrystalline β‐alumina, the separate contributions of the grain boundaries and of the crystal, i.e., the grain interiors. This separation is brought about through the use of a model for these properties. Certain quantitative consequences of the model are developed and compared with experimental results. For most sintered β‐alumina ceramic, the electrical properties are determined more by the characteristics of the grain boundaries than by those of the interior of the grains.
XMM–Newton observes flaring in the polar UZ For during a low state

During an XMM-Newton observation, the eclipsing polar UZ For was found in a peculiar state with an extremely low X-ray luminosity and occasional X-ray and ultraviolet (UV) flaring. For most of the observation, UZ For wasonly barely detected in X-rays and ∼800 times fainter than during a high state previously observed with ROSAT. A transient event, which lasted ∼900 s, was detected simultaneously by the X-ray instruments and, in the UV, by the Optical Monitor. The transient was likely caused by the impact of 10 1 7 -10 1 8 g of gas on the main accretion region of the white dwarf. The X-ray spectrum of the transient is consistent with ∼7 keV thermal bremsstrahlung from the shock-heated gas in the accretion column. A soft blackbody component resulting from reprocessing of X-rays in the white dwarf atmosphere is not seen. The increase in the UV flux during the transient was likely caused by cyclotron radiation from the shock-heated gas. Two more flaring events were detected by the Optical Monitor while the X-ray instruments were not operating. We conclude from our analysis that the unusual flaring behaviour during the low state of UZ For was caused by intermittent increases of the mass transfer rate owing to stellar activity on the secondary. In addition to the transient events, the Optical Monitor detected a roughly constant UV flux consistent with 11 000-K blackbody radiation from the photosphere of the white dwarf. We find a small orbital modulation of the UV flux caused by a large, heated pole cap around the main accretion region.
HISAT: a fast spliced aligner with low memory requirements

HISAT (hierarchical indexing for spliced alignment of transcripts) is a highly efficient system for aligning reads from RNA sequencing experiments. HISAT uses an indexing scheme based on the Burrows-Wheeler transform and the Ferragina-Manzini (FM) index, employing two types of indexes for alignment: a whole-genome FM index to anchor each alignment and numerous local FM indexes for very rapid extensions of these alignments. HISAT's hierarchical index for the human genome contains 48,000 local FM indexes, each representing a genomic region of ∼64,000 bp. Tests on real and simulated data sets showed that HISAT is the fastest system currently available, with equal or better accuracy than any other method. Despite its large number of indexes, HISAT requires only 4.3 gigabytes of memory. HISAT supports genomes of any size, including those larger than 4 billion bases.
Signal-to-noise ratio of Gaussian-state ghost imaging

The signal-to-noise ratios of pseudothermal and biphoton ghost imagers are derived and compared by means of a unified Gaussian-state analysis.
Do Japanese Firms Price Discriminate in North America

INCE the early 1980s, there has been a continuing, energetic and 45 sophisticated effort to assess the economic consequences of the Canadian-US Free Trade Agreement (CUSTA) and the North American Free Trade Agreement (NAFTA). ' This work has been conducted both in an academic setting, in government and in private sector consulting firms. The most interesting of these studies have employed computable general equilibrium (CGE) models to characterise the US, Canadian and Mexican economies and their interrelationships. The dimensions specified in these models typically include a number of industrial sectors, the form of technology, demand, the clearing of factor markets and goods markets, external relationships and trade policy. Most of these studies find that CUSTA and NAFTA, while having little effect on the United States, can have a significant impact on the structure and operation of the Canadian and Mexican economies. While much of the CGE research agrees as to conclusions, these findings rest very heavily on how technology, productivity, and most importantly, on how the behaviour of capital is modelled. By any reasonable criterion, much of the modelling in these areas is crudely done.2 Moreover, by the standards of sectoral research, these models are highly aggregated and non-tariff trade policy, in particular, is treated at an extremely rudimentary level. It has not been generally recognised that another tradition of research in international economics might be helpful for evaluating the consequences of trade liberalisation and FTAs. The slow pace of adjustment of exchange rate changes in the 1970s and again in the midand late 1980s triggered substantial research efforts which continue today. In empirical work explaining the slow response of