cssi/SciSciGPT-SciSciNet huggingface dataset:
A RIGOROUS TREATMENT OF A FOLLOW-THE-LEADER TRAFFIC MODEL WITH TRAFFIC LIGHTS PRESENT ∗

Traffic flow on a unidirectional roadway in the presence of traffic lights is modeled. Individual car responses to green, yellow, and red lights are postulated and these result in rules governing the acceleration and deceleration of individual cars. The essence of the model is that only specific cars are directly affected by the lights. The other cars behave according to simple follow-the-leader rules which limit their speed by the spacing between them and the car directly ahead. The model has a number of desirable properties; namely, cars do not run red lights, cars do not smash into one another, and cars exhibit no velocity reversals. In a situation with multiple lights operating in-phase, we get, after an initial start-up period, a constant number of cars through each light during any green-yellow period. Moreover, this flux is less by one or two cars per period than the flux obtained in discretized versions of the idealized Lighthill--Whitham--Richards model which allows for infinite accelerations.
Riesz transform, Gaussian bounds and the method of wave equation

For an abstract self-adjoint operator L and a local operator A we study the boundedness of the Riesz transform AL−α on Lp for some α > 0. A very simple proof of the obtained result is based on the finite speed propagation property for the solution of the corresponding wave equation. We also discuss the relation between the Gaussian bounds and the finite speed propagation property. Using the wave equation methods we obtain a new natural form of the Gaussian bounds for the heat kernels for a large class of the generating operators. We describe a surprisingly elementary proof of the finite speed propagation property in a more general setting than it is usually considered in the literature.
Impregnant composition in dispenser cathodes

Abstract The compositions of impregnants inside B-type dispenser cathodes containing barium calcium aluminates were examined by means of quantitative microprobe analysis. The impregnant inside the porous tungsten structure was supported with plastic in order to prevent damage when the cathode was sectioned. The impregnant compositions were found to be consistently deficient in CaO when compared to the nominal composition. Variations and reproducibility in composition are discussed.
Spatial Dynamics of Deformable Multibody Systems With Variable Kinematic Structure: Part 2—Velocity Transformation

In Part 1 of these two companion papers, the spatial system kinematic and dynamic equations are developed using the Cartesian and elastic coordinates in order to maintain the generality of the formulation. This allows introducing general forcing functions and adding and/or deleting kinematic constraints. In control applications, however, it is desirable to determine the joint forces associated with the joint variables. On the other hand the use of the joint coordinates to formulate the dynamic equations leads to a complex recursive formulation based on loop closure equations. In this paper a velocity transformation technique applicable to spatial multibody systems that consist of interconnected rigid and deformable bodies is developed. The Cartesian variables are expressed in terms of the joint and elastic variables. The resulting kinematic relationships are then employed to determine the joint forces associated with the joint variables. A spatial robot manipulator that manipulates an object is presented as a numerical example to exemplify the development presented in this paper.
Syntheses of 1-, 2-, 3- and 4-acridinecarbaldehydes

The four acridinecarbaldehydes, namely, acridine-1-carbaldehyde, acridine-2-carbaldehyde, acridine-3-carbaldehyde, and acridine-4-carbaldehyde have been synthesized for the first time.
Emittance Measurements of High Charge State Argon Beams from a PIG Source

The emittances of beams of Ar4+ to Ar8+ have been measured in the axial and radial planes. The extraction voltage was 10 kV and the magnetic field was varied from about .5 to .6 Tesla. The anode slit was varied in its distance from the arc which was run both dc and pulsed. The emittance was found to be nearly independent of charge state but to increase with total beam current. A small bowing of the arc column was discovered, which made evaluation of mirror field effects difficult.
Petawatt laser absorption bounded

The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. Petawatt laser-matter interactions could open the way to fusion energy or compact particular accelerators, but predicting the amount of light absorbed in these interactions is challenging. New analysis by Levy et al.reveals the theoretical upper and lower limits of this absorption.
Supports of Measures in a free additive convolution semigroup

In this paper, we study the supports of measures in the free additive convolution semigroup $\{\mu^{\boxplus t}:t>1\}$, where $\mu$ is a Borel probability measure on $\mathbb{R}$. We give a formula for the density of the absolutely continuous part of $\mu^{\boxplus t}$ and use this formula to obtain certain regularizing properties of $\mu^{\boxplus t}$. We show that the number $n(t)$ of the components in the support of $\mu^{\boxplus t}$ is a decreasing function of $t$ and give equivalent conditions so that $n(t)=1$ for sufficiently large $t$. Moreover, a measure $\mu$ so that $\mu^{\boxplus t}$ has infinitely many components in the support for all $t>1$ is given.
On two channel flavor anisotropic and one channel compactified Kondo models

Abstract We reinvestigate the two channel flavor anisotropic model (2CFAK) and one channel compactified Kondo model (1CCK). For these two models, all the possible fixed points and their symmetries are identified; the finite size spectra, the electron conductivity and pairing susceptibility are calculated. It is shown that the only non-Fenni liquid (NFL) fixed point of the 2CFAK is the NFL of the two channel Kondo model (2CK) with the symmetry O (3) × O (5). Any flavor anisotropies between the two channels drive the system to the Fermi liquid (FL) fixed point with the symmetry O (4) × O (4) where one of the two channels suffers the phase shift π 2 and the other remains free. The NFL fixed point of the 1CCK has the symmetry O (3) × O (1) and has the same thermodynamics as the NFL fixed point of the 2CK. However, in contrast to the 2CK, its conductivity shows T 2 behavior and there is no pairing susceptibility divergence. Any anisotropies between the spin and isospin sectors drive the system to the FL fixed point with the symmetry O (4) where the electrons suffer the phase shift π 2 . The connection and differences between the two models are explicitly demonstrated. The recent conjectures and claims on the NFL behaviors of the two models are commented on.
Experiments and Models of the Magneto Rheological Behavior of High Weight Percent Suspensions of Carbonyl Iron Particles in Silicone Oil

Flow properties of magnetorheological (MR) fluids are greatly altered by the application of a magnetic field. The design, optimization, and control of novel devices that exploit MR fluid behavior in multidegree of freedom applications require three dimensional models characterizing the coupling of magnetic behavior to mechanical behavior in MR fluids. The authors have derived 3D MR fluid models based on multiscale kinetic theory. The underlying bases of the models are summarized, with phenomenological empiricism distinguished from multiscale first principles, and the models' ability to capture the experimentally measured mechanical response of a MR fluid-based damper to specified magnetic fields is assessed. The results of this comparison are that the kinetic theory-based models both relate macroscale MR fluid behavior to a first-principles description of magnetomechanical coupling at the microscale and possess the flexibility to best match the measured behavior of a particular MR fluid device observed in our experiments.
Individuals’ Decision to Co-Donate or Donate Alone: An Archival Study of Married Whole Body Donors in Hawaii

Funding came from Harvard University and the University of Hawaii. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. (Harvard University; University of Hawaii)
Bias From Classical and Other Forms of Measurement Error

We consider the implications of an alternative to the classical measurement-error model, in which the observed, mismeasured data are optimal predictions of the true values, given some information set. In this model, any measurement error is uncorrelated with the reported value and, by necessity, correlated with the true value of interest. In a regression model, such measurement error in the regressor does not lead to bias, whereas measurement error in the dependent variable leads to bias toward 0. In general, the measurement-error model, together with the information set, is critical for determining the bias in econometric estimates.
Dealing with server corruption in weakly consistent replicated data systems

Providing high availability and the ability to share data despite the weak connectivity of mobile computing raises the problem of trusting replicated data servers that may be corrupt. This is because servers must be run on portable computers, and these machines are less secure and thus less trustworthy than those traditionally used to run servers. We describe the kinds of problems one must be prepared to deal with, noting that even users of secured, non‐portable computers are at risk if servers trust all authorized peers. We show that high availability through data replication on portable computers need not be mutually exclusive with various levels of data security one might want. We give three solutions to this trust problem for a simple example architecture, achieving progressively higher levels of security with progressively higher costs. We then show how to solve this trust problem for the more complex architecture of Bayou, a weakly consistent replicated data system we built at Xerox PARC.
Light Echoes in Kerr Geometry: A Source of High-Frequency QPOs from Random X-Ray Bursts

We propose that high-frequency quasi-periodic oscillations (HFQPOs) can be produced from randomly formed X-ray bursts (flashes) by plasma interior to the ergosphere of a rapidly rotating black hole. We show by direct computation of their orbits that the photons comprising the observed X-ray light curves, if due to a multitude of such flashes, are significantly affected by the black hole's dragging of inertial frames; the photons of each such burst arrive to an observer at infinity in multiple (double or triple), distinct "bunches" separated by a roughly constant time lag of Δ tlag/M 14, regardless of the bursts' azimuthal position. We argue that every other such "bunch" represents photons that follow trajectories with an additional orbit around the black hole at the photon circular orbit radius (a photon "echo"). The presence of this constant lag in the response function of the system leads to a QPO feature in its power density spectra, even though the corresponding light curve consists of a totally stochastic signal. This effect is by and large due to the black hole spin and is shown to gradually diminish as the spin parameter a decreases or the radial position of the burst moves outside the static limit surface (ergosphere). Our calculations indicate that for a black hole with Kerr parameter of a/M = 0.99 and mass of M = 10 M☉, the QPO is expected at a frequency of νQPO ~ 1.3–1.4 kHz. We discuss the plausibility and observational implications of our model results, as well as its limitations.
Paths and consistency in additive cost sharing

We provide a direct proof of a representation theorem for additive cost sharing methods as sums of path methods. Also, by directly considering the paths that generate some common additive cost sharing methods (Aumann-Shapley, Shapley Shubik, and Serial Cost) we show that they are consistent. These results follow directly from a simple sufficient condition for consistency: being generated by an associative path. We also introduce a new axiom, dummy consistency, which is quite mild. Using this, we also show that the Aumann-Shapley and Serial Cost methods are the unique (additive) consistent extension of their restriction on all two agent problems, while the Shapley-Shubik method has multiple consistent extensions but a unique anonymous scale invariant one.
Catalytic Meerwein−Pondorf−Verley Reduction by Simple Aluminum Complexes

Catalytic MPV reduction was successfully carried out using simple aluminum precatalysts. Alkylaluminum reagents were converted to a low-aggregation aluminum alkoxide that was highly active for the MPV reduction of several carbonyl substrates in high yield (50−99%) using iPrOH as the reducing agent. A high degree of cis/trans selectivity was achieved in the reduction of 2-methylcyclohexanone (cis/trans = 20/80) by iPrOH. When chiral hydride sources were utilized in the reduction of 2-chloroacetophenone, high enantioselectivity (68−80% ee) was observed.
Controlling the abandonment of automobiles: Mandatory deposits vs fines

There is no abstract for this paper, but what it establishes is that a first-best policy intervention would set optimal mandatory deposits on automobiles. Moreover, a littering fine for abandonment of automobiles is seen to be second-best, either with or without a mandatory deposit, leading to inefficiency.
Engineering Aerothermal Analysis for X-34 Thermal Protection System Design

Design of the thermal protection system for any hypersonic flight vehicle requires determination of both the peak temperatures over the surface and the heating-rate history along the flight profile. In this paper, the process used to generate the aerothermal environments required for the X-34 Testbed Technology Demonstrator thermal protection system design is described as it has evolved from a relatively simplistic approach based on engineering methods applied to critical areas to one of detailed analyses over the entire vehicle. A brief description of the trajectory development leading to the selection of the thermal protection system design trajectory is included. Comparisons of engineering heating predictions with wind-tunnel test data and with results obtained using a Navier- Stokes flowfield code and an inviscid/boundary layer method are shown. Good agreement is demonstrated among all these methods for both the ground-test condition and the peak heating flight condition. Finally, the detailed analysis using engineering methods to interpolate the surface-heating-rate results from the inviscid/boundary layer method to predict the required thermal environments is described and results presented.
On a generalization of the master cyclic group polyhedron

We study the master equality polyhedron (MEP) which generalizes the master cyclic group polyhedron (MCGP) and the master knapsack polyhedron (MKP). We present an explicit characterization of the polar of the nontrivial facet-defining inequalities for MEP. This result generalizes similar results for the MCGP by Gomory (1969) and for the MKP by Araoz (1974). Furthermore, this characterization gives a polynomial time algorithm for separating an arbitrary point from MEP. We describe how facet-defining inequalities for the MCGP can be lifted to obtain facet-defining inequalities for MEP, and also present facet-defining inequalities for MEP that cannot be obtained in such a way. Finally, we study the mixed-integer extension of MEP and present an interpolation theorem that produces valid inequalities for general mixed integer programming problems using facets of MEP.
Large N universality of the two-dimensional Yang-Mills string

Abstract We exhibit the gauge-group independence (“universality”) of all normalized non-intersecting Wilson loop expectation values in the large N limit of two-dimensional Yang-Mills theory. This universality is most easily understood via the string theory reformulation of these gauge theories. By constructing an isomorphism between the string maps contributing to normalized Wilson loop expectation values in the different theories, we prove the large N universality of these observables on any surface. The string calculation of the Wilson loop expectation value on the sphere also leads to an indication of the large N phase transition separating strong- and weak-coupling phases.
ON THE NATURE OF CONTINUOUS PHYSICAL QUANTITIES IN CLASSICAL AND QUANTUM MECHANICS

Within the traditional Hilbert space formalism of quantum mechanics, it is not possible to describe a particle as possessing, simultaneously, a sharp position value and a sharp momentum value. Is it possible, though, to describe a particle as possessing just a sharp position value (or just a sharp momentum value)? Some, such as Paul Teller, have thought that the answer to this question is No -- that the status of individual continuous quantities is very different in quantum mechanics than in classical mechanics. On the contrary, I shall show that the same subtle issues arise with respect to continuous quantities in classical and quantum mechanics; and that it is, after all, possible to describe a particle as possessing a sharp position value without altering the standard formalism of quantum mechanics.
Synthesis of aminomethyl and amino analogs of 5-benzylacyclouridine and 5-benzyloxybenzylacyclouridine

Amino analogs of BAU (5-benzylacyclouridine) and BBAU (5-benzyloxybenzylacyclouridine) and their 2′-hydroxymethyl derivatives were synthesized for evaluation as inhibitors of uridine phosphorylase and hence potential cancer chemotherapeutic agents. Both aminomethyl analogs were found to be potent inhibitors of this enzyme and good potentiators of the anti-tumor action of FUdR.
LITHIUM IN THE INTERMEDIATE-AGE OPEN CLUSTER, NGC 3680

High-dispersion spectra centered on the Li 6708 A line have been obtained for 70 potential members of the intermediate-age open cluster NGC 3680, with an emphasis on stars in the turnoff region of the cluster color-magnitude diagram (CMD). A measurable Li abundance has been derived for 53 stars, 39 of which have radial velocities and proper motions consistent with cluster membership. After being transferred to common temperature and abundance scales, previous Li estimates have been combined to generate a sample of 49 members, 40 of which bracket the cluster Li-dip. Spectroscopic elemental analysis of eight giants and five turnoff stars produces [Fe/H] = –0.17 ± 0.07 (sd) and –0.07 ± 0.02 (sd), respectively. We also report measurements of Ca, Si, and Ni which are consistent with scaled-solar ratios within the errors. Adopting [Fe/H] = –0.08 (Section 3.6), Y 2 isochrone comparisons lead to an age of 1.75 ± 0.1 Gyr and an apparent modulus of (m – M) = 10.30 ± 0.15 for the cluster, placing the center of the Li-dip at 1.35 ± 0.03 M ☉. Among the giants, five of the nine cluster members are now known to have measurable Li with A(Li) near 1.0. A combined sample of dwarfs in the Hyades and Praesepe is used to delineate the Li-dip profile at 0.7 Gyr and [Fe/H] = +0.15, establishing its center at 1.42 ± 0.02 M ☉ and noting the possible existence of a secondary dip on its red boundary. When evolved to the typical age of the clusters NGC 752 (age = 1.45 Gyr, (m – M) = 8.4), IC 4651 (age = 1.5 Gyr, (m – M) = 10.4), and NGC 3680, the Hyades/Praesepe Li-dip profile reproduces the observed morphology of the combined Li-dip within the CMDs of the intermediate-age clusters while implying a metallicity dependence for the central mass of the Li-dip given by M/M ☉ = 1.38 ± 0.04 + 0.4 ± 0.2 [Fe/H]. The implications of the similarity of the Li-dichotomy among giants in NGC 752 and IC 4651 and the disagreement with the pattern among NGC 3680 giants are discussed.
The passenger vessel services act and America's cruise tourism industry

Abstract The Passenger Vessel Services Act (PVSA) of 1886, a cabotage law, attempts to shield U.S. maritime shipping from foreign competition. It also applies to the U.S. cruise ship industry. The PVSA requires foreign cruise ships that carry passengers between U.S. ports to also stop at foreign ports. Norwegian Cruise Line America (NCLA), which operates one U.S. flagged cruise ship in Hawaii, wants the U.S. Customs and Border Protection to require foreign cruise ships offering Hawaii itineraries from the U.S. west coast to spend more time in foreign ports. We analyze the merits of NCLA's proposal. We argue that rather than making the PVSA even more protectionist, the law should be repealed.
Parallel biological sequence comparison using prefix computations

We present practical parallel algorithms using prefix computations for various problems that arise in pairwise comparison of biological sequences. We consider both constant and affine gap penalty functions, full-sequence and subsequence matching, and space-saving algorithms. Commonly used sequential algorithms solve the sequence comparison problems in O(mn) time and O(m + n) space, where m and n are the lengths of the sequences being compared. All the algorithms presented in this paper are time optimal with respect to the sequential algorithms and can use O(n/log n) processors where n is the length of the larger sequence. While optimal parallel algorithms for many of these problems are known, we use a simple framework and demonstrate how these problems can be solved systematically using repeated parallel prefix operations. We also present a space-saving algorithm that uses O(m + n/p) space and runs in optimal time where p is the number of the processors used. We implemented the parallel space-saving algorithm and provide experimental results on an IBM SP-2 and a Pentium cluster.
Testing vision: one cone at a time

In humans, gaining experimental access to single sensory receptors - photoreceptors specifically - is a challenge, yet it is crucial for learning how the signals arising from each receptor are transformed into perception. By combining adaptive-optics microstimulation with high-speed eye tracking, we show that retinal function can be probed at the level of the individual cone photoreceptor in living eyes. This talk will describe the development and applications of our adaptive optics confocal imaging system which we use to track, target and deliver visible light stimuli to single cones or selections of cones. Highlighted applications will include our ongoing efforts to learn about the neural circuits that underlie human spatial and color vision.
Synthesis and CB1 cannabinoid receptor affinity of 4-alkoxycarbonyl-1,5-diaryl-1,2,3-triazoles.

A series of 4-alkoxycarbonyl-1,5-diaryl-1,2,3-triazoles were synthesized regioselectively using click chemistry and evaluated at CB1 cannabinoid receptors. The n-propyl ester 11 (Ki = 4.6 nM) and phenyl ester 14 Ki = 11 nM) exhibited the most potent affinity of the series. The wide range of pharmacological effects of cannabinoid and endogenous cannabinoid ligands, are mediated by two subtypes of transmembrane G-protein coupled receptors: CB1 and CB2. 1–4 CB1 receptors are expressed in the central nervous system (CNS) with high density in the cerebellum, hippocampus and striatum. 5 CB1 receptors are found in some
Sliding Mode Control of Magnetic Bearings: A Hardware Perspective

The physical hardware of magnetic bearing systems has a very strong impact on the application of sliding mode control to this technology. Finite current slew rates affect the character of achievable reaching conditions; flexible rotors demand the use of state observers which then affect achievable robustness; finite controller throughput and use of switching power amplifiers has substantial impact on how chatter should be addressed. This paper formulates the sliding mode control problem for realistic rotor/magnetic actuator systems considering rotor flexibility and finite amplifier voltages. The structure of the resulting class of controllers is examined for both rigid and for flexible rotors. It is demonstrated that, fundamentally, these controllers are conventional linear state observer-based controllers acting through high-speed switching amplifiers as in conventional magnetic bearing technology.
Synthesis of Nucleoside 3′-Thiophosphates in One Step Procedure

Abstract A mild and efficient one-step method of thiophosphorylation was devised for acid-sensitive nucleosides. The procedure is based on thiophosphorylation of nucleoside magnesium alkoxide by 2-chloro-2-thio-1,3,2-dioxaphospholane. The utility and efficiency of this method combined with deprotection of the resulting cyclic triester were demonstrated by its application to the synthesis of both adenosine 3′- and 5′-thiophosphates. The procedure does not require protection of the exocyclic amino group and can be successfully used for the thiophosphorylation of nucleosides that are unusually sensitive to depurination.
Anomalous Low States and Long-term Variability in the Black Hole Binary LMC X-3

Rossi X-my Timing Explorer observations of the black hole binary LMC X-3 reveal an extended very low X-ray state lasting from 2003 December 13 until 2004 March 18, unprecedented both in terms of its low luminosity (>15 times fainter than ever before seen in this source) and long duration (approx 3 times longer than a typical low/hard state excursion). During this event little to no source variability is observed on timescales of approx hours-weeks, and the X-ray spectrum implies an upper limit of 1.2 x 10(exp 35) erg/s, Five years later another extended low state occurs, lasting from 2008 December 11 until 2009 June 17. This event lasts nearly twice as long as the first, and while significant variability is observed, the source remains reliably in the low/hard spectral state for the approx 188 day duration. These episodes share some characteristics with the "anomalous low states" in the neutron star binary Her X-I. The average period and amplitude of the Variability of LMC X-3 have different values between these episodes. We characterize the long-term variability of LMC X-3 before and after the two events using conventional and nonlinear time series analysis methods, and show that, as is the case in Her X-I, the characteristic amplitude of the variability is related to its characteristic timescale. Furthermore, the relation is in the same direction in both systems. This suggests that a similar mechanism gives rise to the long-term variability, which in the case of Her X-I is reliably modeled with a tilted, warped precessing accretion disk.
Impure altruism in dictators' giving☆

Abstract We design an experiment to test whether incomplete crowding out in dictator games can be rationalized by the impurely altruistic preferences. By giving the recipients an endowment of varying levels, we create an environment in which crowding out may occur. We find that the behavior of 66% of the dictators can be rationalized by the impurely altruistic utility function.
Magnetic resonance imaging of occult fractures of the proximal femur

The evaluation of the painful hip in the elderly osteoporotic patient with normal plain radiographs can be difficult. We studied 15 osteopenic patients with normal plain radiographs and suspected hip fractures with magnetic resonance (MR) imaging and found MR to be an excellent aid in detecting occult fractures. A clear fracture was seen in 10 of the 15 patients, who then underwent surgical repair based on the MR study. The remaining patients had no MR-demonstrable fracture and were successfully treated nonoperatively. Some believe that a negative bone scan in this population of patients should be repeated within 3 days prior to a definitive “no fracture” decision being made. Unfortunately, bone scanning lacks spatial resolution, and increased osteoblastic activity may be caused by other pathologic processes besides fracture. Two of the 15 patients had MR-demonstrated bone infarcts near the fracture. One patient also had femoral head osteonecrosis on the side of the fracture. One patient with metastatic prostatic carcinoma had a hip fracture and one patient with metastatic breast carcinoma had no fracture. Not only is MR imaging an excellent technique for delineating occult fractures, but due to its spatial resolution, associated bone disorders adjacent to fractures can be detected in most instances. From a cost perspective, rapid diagnosis and early treatment of an occult femoral fracture is advisable. A reduced hospital stay pending diagnosis and the early institution of definitive therapy also decrease the chance that a simple non-displaced fracture will displace and require more complex management with resultant increased morbidity and cost. We propose that, especially in elderly, osteopenic patients with normal plain radiographs and a high index of suspicion for hip fracture, MR can serve as the sole additional imaging study in most instances.
Superconductivity from finite-U valence fluctuations

Abstract The finite- U pairing mechanism of Newns is explored by an adaptation of our previous U = ∞ variational treatment of the Anderson lattice. This pairing mechanism is found to be opposed by a magnetic tendency arising from Gutzwiller renormalization of the hybridization. This competition restricts superconductivity to the parameter regime Δ≳ U . This competition also reproduces the parabolic rise and fall of T c in La 2− x Sr x CuO 4 with increasing x . Re-analysis of the photoemission and BIS data for CuO reveals that indeed Δ≳ U for this compound, contrary to previous work.
The margin of safety principle and corporate strategy

Purpose – This paper seeks to analyze the applicability of the time‐tested margin of safety principle from value investing to corporate strategy.Design/methodology/approach – The main source of this paper is the book Margin of Safety, supplementation materials, including a discussion with the book's author, Seth Klarman, were also referenced.Findings – The paper finds that the margin of safety principle is broadly applicable to corporate strategy in areas such as M&A, hedging, balance sheet management, share buybacks, special dividends, divestments, and cash management. Each of these areas is discussed in the paper and illustrated by way of timely examples as part of the analysis.Research limitations/implications – Further research could be conducted into valuation methods in general, including the method practiced by noted value investors. Research could also be conducted into the margin of safety principle and its applications in corporate strategy, corporate finance, strategic risk management, sharehol...
On conformal properties of the dualized sigma-models

Abstract We have calculated the first-order β-functions for a σ-model (with dilaton) dualized with respect to an arbitrary Lie group that acts without isotropy. We find that non-abelian duality preserves conformal invariance for semi-simple groups, but in general there is an extra contribution to the β-function proportional to the trace of the structure constants, which cannot be absorbed into an additional dilaton shift. Two particular examples, a Bianchi V cosmological background and the G ⊗ G WZW model, are discussed.
Applications of extended X-ray absorption fine-structure spectroscopy to studies of bimetallic nanoparticle catalysts

Extended X-ray absorption fine structure (EXAFS) spectroscopy has been used to study short range order in heterometallic alloys for almost four decades. In this critical review, experimental, theoretical and data analytical approaches are revisited to examine their power, and limitations, in studies of bimetallic nanocatalysts. This article covers the basics of EXAFS experiments, data analysis, and modelling of nanoscale clusters. It demonstrates that, in the best case scenario, quantitative information about the nanocatalyst's size, shape, details of core–shell architecture, as well as static and dynamic disorder in metal–metal bond lengths can be obtained. The article also emphasizes the main challenge accompanying such insights: the need to account for the statistical nature of the EXAFS technique, and discusses corrective strategies.
Optimization of a 90Sr/90Y radiation source train stepping for intravascular brachytherapy

A steepest-descent gradient algorithm is developed to optimize the stepping of a 90Sr/90Y radiation source train (RST) for intravascular brachytherapy (IVB). The objective function is to deliver a uniform dose in a coronary target vessel and minimize the dose in adjacent normal vessel tissue at the proximal and distal edges of the coronary target vessel. Based on the target length and number of dwell points (number of steps), the algorithm modulates the dwell times and corresponding dwell positions that optimize the weighted addition of staggered EGS4 Monte Carlo (MC) calculated dose distribution from a single RST. Stepping treatment plans are generated for target vessel lengths of 3.0, 3.3, and 3.8 cm. For both the unoptimized and optimized plans, the dose heterogeneity in the target vessel wall, and length of nontarget vessel receiving 3 Gy, is assessed to compare plans. Optimization results show a 14% dose uniformity within the target is achievable for all vessel lengths. Further, the dose in the adjacent normal tissue is lower in the optimized plans than the unoptimized plans. The work presented in this paper provides a model to address the finite length of RST in IVB treatments. While the results presented are specific to the 90Sr/90Y RST, the methods should apply to other finite length RSTs.
Simulation of the Matrix Bingham–von Mises–Fisher Distribution, With Applications to Multivariate and Relational Data

Orthonormal matrices play an important role in reduced-rank matrix approximations and the analysis of matrix-valued data. A matrix Bingham–von Mises–Fisher distribution is a probability distribution on the set of orthonormal matrices that includes linear and quadratic terms in the log-density, and arises as a posterior distribution in latent factor models for multivariate and relational data. This article describes rejection and Gibbs sampling algorithms for sampling from this family of distributions, and illustrates their use in the analysis of a protein–protein interaction network. Supplemental materials, including code and data to generate all of the numerical results in this article, are available online.
The dynamics of particle disks: III. Dense and spinning particle disks

The kinetic theory of planetary rings developed by Araki and Tremaine (1986) and Araki (1988) is extended and refined, with a focus on the implications of finite particle size: (1) nonlocal collisions and (2) finite filling factors. Consideration is given to the derivation of the equations for the local steady state, the low-optical-depth limit, and the steady state at finite filling factors (including the effects of collision inelasticity, spin degrees of freedom, and self-gravity). Numerical results are presented in extensive graphs and characterized in detail. The importance of distinguishing effects (1) and (2) at low optical depths is stressed, and the existence of vertical density profiles with layered structures at high filling factors is demonstrated.
Modular categories, integrality and Egyptian fractions

It is a well-known result of Etingof, Nikshych and Ostrik that there are finitely many inequivalent integral modular categories of any fixed rank n. This follows from a double-exponential bound on the maximal denominator in an Egyptian fraction representation of 1. A na¨ove computer search approach to the classification of rank n integral modular categories using this bound quickly overwhelms the computer's memory (for n � 7). We use a modified strategy: find general conditions on modular categories that imply integrality and study the classification problem in these limited settings. The first such condition is that the order of the twist matrix is 2,3,4 or 6 and we obtain a fairly complete description of these classes of modular categories. The second condition is that the unit object is the only simple non-self-dual object, which is equivalent to odd-dimensionality. In this case we obtain a (linear) improvement on the bounds and employ number-theoretic techniques to obtain a classification for rank at most 11 for odd-dimensional modular categories.
Comparative toxicity of acephate in laboratory mice, white-footed mice, and meadow voles.

The LD50 (95% confidence limits) of the organophosphorus insecticide acephate was estimated to be 351, 380, and 321 mg/kg (295–416, 280–516, and 266–388 mg/kg) for CD-1 laboratory mice (Mus musculus), white-footed mice (Peromyscus leucopus noveboracensis), and meadow voles (Microtus pennsylvanicus), respectively. In a second study, these species were provided mash containing 0, 25, 100, and 400 ppm acephate for five days. Brain and plasma cholinesterase activities were reduced in a dose-dependent manner to a similar extent in the three species (inhibition of brain acetyl-cholinesterase averaged for each species ranged from 13 to 22% at 25 ppm, 33 to 42% at 100 ppm, and 56 to 57% at 400 ppm). Mash intake, body or liver weight, plasma enzyme activities (alkaline phosphatase, alanine and aspartate aminotransferase), hepatic enzyme activities (aniline hydroxylase, 7-ethoxycoumarin O-deethylase, and glutathione S-transferase), and cytochrome content (P-450 and b5) were not affected by acephate ingestion, although values differed among species. In a third experiment, mice and voles received 400 ppm acephate for 5 days followed by untreated food for up to 2 weeks. Mean inhibition of brain acetylcholin-esterase for the three species ranged from 47 to 58% on day 5, but by days 12 and 19, activity had recovered to 66 to 76% and 81 to 88% of concurrent control values. These findings indicate that CD-1 laboratory mice, white-footed mice, and meadow voles are equally sensitive to acephate when maintained under uniform laboratory conditions. Several factors (e.g., behavior, food preference, habitat) could affect routes and degree of exposure in the field, thereby rendering some species of wild rodents ecologically more vulnerable to organophosphorus insecticides
On discrete alphabets for the two-user Gaussian interference channel with one receiver lacking knowledge of the interfering codebook

In multi-user information theory it is often assumed that every node in the network possesses all codebooks used in the network. This assumption is however impractical in distributed ad-hoc and cognitive networks. This work considers the two-user Gaussian Interference Channel with one Oblivious Receiver (G-IC-OR), i.e., one receiver lacks knowledge of the interfering cookbook while the other receiver knows both codebooks. We ask whether, and if so how much, the channel capacity of the G-IC-OR is reduced compared to that of the classical G-IC where both receivers know all codebooks. Intuitively, the oblivious receiver should not be able to jointly decode its intended message along with the unintended interfering message whose codebook is unavailable. We demonstrate that in strong and very strong interference, where joint decoding is capacity achieving for the classical G-IC, lack of codebook knowledge does not reduce performance in terms of generalized degrees of freedom (gDoF). Moreover, we show that the sum-capacity of the symmetric G-IC-OR is to within O(log(log(SNR))) of that of the classical G-IC. The key novelty of the proposed achievable scheme is the use of a discrete input alphabet for the non-oblivious transmitter, whose cardinality is appropriately chosen as a function of SNR.
High current hollow cathode phenomena

Experimental results show that the energies of ions produced near a hollow cathode orifice can be several times the anode-to-cathode potential difference generally considered available to accelerate them. These energies (of order 50 eV) are sufficient to induce substantial sputter erosion rates. Increases in discharge current (to 60 A) cause the energies and current densities of these jet ions to increase substantially. A model describing jet ion generation is proposed. The effects of discharge current on cathode internal pressure are also examined experimentally and described phenomenologically.
Self-Consistent Models of Perfect Triaxial Galaxies

We have used Schwarzschild’s (1979) method to study the variety of self-consistent solutions available to the family of triaxial “perfect ellipsoids” (de Zeeuw 1985). The time-averaged density at 240 points within the mass model is computed for each of 1065 orbits distributed regularly in phase space and covering all four major orbit families. The underdetermined linear system thereby defined is solved in two ways. First, Lucy’s (1974) iterative scheme is used to find a “smooth” solution, lying in the interior of the (mathematically-allowed) solution space. Second, linear programming is used, with linear combinations of the x and z components of the total angular momentum as cost functions, to delineate the boundary of the projection of the solution space in the L x − L z plane. The above procedure is applied to 21 figures, with axis ratios, b/a and c/a, chosen at equal intervals of 1/8.
Duration of sovereign debt renegotiation

Abstract In the period since 1990, sovereign debt renegotiations take an average of five years for bank loans but only one year for bonds. We provide an explanation for this finding by highlighting one key difference between bank loans and bonds: bank loans are rarely traded, while bonds are heavily traded on the secondary market. In our theory, the secondary market plays a crucial information revelation role in shortening renegotiations. Consider a dynamic bargaining game with incomplete information between a government and creditors. The creditors' reservation value is private information, and the government knows only its distribution. Delays in reaching agreements arise in equilibrium because the government uses costly delays to screen the creditors' reservation value. When the creditors trade on the secondary market, the market price conveys information about their reservation value, which lessens the information friction and reduces the renegotiation duration. We find that the secondary market tends to increase the renegotiation payoff of the government but decrease that of the creditors while increasing the total payoff. We then embed these renegotiation outcomes in a simple sovereign debt model to analyze the ex ante welfare implications. The secondary market has the potential to increase the government ex ante welfare when the information friction is severe.
Transverse thermal conductance of thermosetting composite materials during their cure

The transverse thermal conductance of thermosetting advanced composite materials during their cure was modeled analytically and then investigated experimentally. AS4/3501-6 graphite/epoxy was used for the experiments. A model for the effective transverse conductivity of a material with cylinders arranged in rectangular order, first derived by Lord Rayleigh, was modified to account for the possible effects of a fiber/resin contact resistance and for the transversely anisotropic behavior of the composites' thermal conductivity. A model was derived that accounts for the effect of resin heat generation on the measured thermal conductivity of an uncured thermosetting composite. These models were investigated experimentally using a guarded hot plate apparatus to measure the thermal conductivity of the graphite/epoxy laminates as a function of independent cure variables. Good agreement was found between the models and the experimental data. 80 refs.
Controlling Pandemic Flu: The Value of International Air Travel Restrictions

Background Planning for a possible influenza pandemic is an extremely high priority, as social and economic effects of an unmitigated pandemic would be devastating. Mathematical models can be used to explore different scenarios and provide insight into potential costs, benefits, and effectiveness of prevention and control strategies under consideration. Methods and Findings A stochastic, equation-based epidemic model is used to study global transmission of pandemic flu, including the effects of travel restrictions and vaccination. Economic costs of intervention are also considered. The distribution of First Passage Times (FPT) to the United States and the numbers of infected persons in metropolitan areas worldwide are studied assuming various times and locations of the initial outbreak. International air travel restrictions alone provide a small delay in FPT to the U.S. When other containment measures are applied at the source in conjunction with travel restrictions, delays could be much longer. If in addition, control measures are instituted worldwide, there is a significant reduction in cases worldwide and specifically in the U.S. However, if travel restrictions are not combined with other measures, local epidemic severity may increase, because restriction-induced delays can push local outbreaks into high epidemic season. The per annum cost to the U.S. economy of international and major domestic air passenger travel restrictions is minimal: on the order of 0.8% of Gross National Product. Conclusions International air travel restrictions may provide a small but important delay in the spread of a pandemic, especially if other disease control measures are implemented during the afforded time. However, if other measures are not instituted, delays may worsen regional epidemics by pushing the outbreak into high epidemic season. This important interaction between policy and seasonality is only evident with a global-scale model. Since the benefit of travel restrictions can be substantial while their costs are minimal, dismissal of travel restrictions as an aid in dealing with a global pandemic seems premature.
Revolutionaries and Spies

Abstract Revolutionaries and Spies is a game, G ( G , r , s , k ) , played on a graph G between two teams: one team consists of r revolutionaries, the other consists of s spies. To start, each revolutionary chooses a vertex as its position. The spies then do the same. (Throughout the game, there is no restriction on the number of revolutionaries and spies that may be positioned on any given vertex.) The revolutionaries and spies then alternate moves with the revolutionaries going first. To move, each revolutionary simultaneously chooses to stay put on its vertex or to move to an adjacent vertex. The spies move in the same way. The goal of the revolutionaries is to place k of their team on some vertex v in such a way that the spies cannot place one of their spies at v in their next move; this is a win for the revolutionaries. If the spies can prevent this forever, they win. There is no hidden information; the positions of all revolutionaries and spies is known to both sides at all times. We will present a number of basic results as well as the result that if G ( Z 2 , r , s , 2 ) is a win for the spies, then s ≥ 6 ⌊ r 8 ⌋ . (Here allowable moves in Z 2 consist of one-step horizontal, vertical or diagonal moves.)