cssi/SciSciGPT-SciSciNet huggingface dataset:
Iron line and diffuse hard x-ray emission from the starburst galaxy m82

We examine the properties of the diffuse hard X-ray emission in the classic starburst galaxy M82. We use new Chandra ACIS-S observations in combination with reprocessed archival Chandra ACIS-I and XMM-Newton observations. We find that E ~ 6.7 keV Fe Heα emission is present in the central |r| < 200 pc, |z| < 100 pc of M82 in all data sets, in addition to a possibly nonthermal X-ray continuum and marginally significant E = 6.4 keV Fe Kα line emission. No statistically significant Fe emission is found in the summed X-ray spectra of the pointlike X-ray sources or the ULXs in the two epochs of Chandra observation. The total nuclear region iron line fluxes in the 2004 April 21 XMM-Newton observation are consistent with those of the Chandra-derived diffuse component, but in the 2001 May 6 XMM-Newton observation they are significantly higher and also both E = 6.4 and 6.9 keV iron lines are detected. We attribute the excess iron line emission to the ULX in its high state. In general, the iron K-shell luminosity of M82 is dominated by the diffuse component. The total X-ray luminosity of the diffuse hard X-ray emission is LX,2-8 keV ~ 4.4 × 1039 ergs s-1 in the E = 2-8 keV energy band, and the 6.7 keV iron line luminosity is LX,6.7 keV ~ (1.1-1.7) × 1038 ergs s-1. The 6.7 keV iron line luminosity is consistent with that expected from the previously unobserved metal-enriched merged SN ejecta that is thought to drive the larger scale galactic superwind. The iron line luminosity implies a thermal pressure within the starburst region of P/k ~ 2 × 107 K cm-3, consistent with independent observational estimates of the starburst region pressure.
AVID and beyond: Lessons learned

The implantable cardioverter defibrillator (ICD) has been approved by the Food and Drug Administration since 1985 and is widely used in practice. Until very recently, however, the efficacy of the ICD has depended on large published series of retrospective studies analyzing ventricular tachycardia and fibrillation patients. The recently published antiarrhythmics versus implantable defibrillator (AVID) trial is the first prospective randomized trial to show clearly that the ICD is more effective than drug therapy (amiodarone or sotalol) in patients who have survived an out-of-hospital cardiac arrest or have syncopal or hemodynamically significant ventricular tachycardia. The survival advantages probably holds true only for patients with an ejection fraction under 35% who have either coronary disease or other forms of cardiomyopathy. The survival advantage in this trial – which was halted prematurely because of the results noted – was short-lived (2.6 months) and expensive. The results of this trial will clearly define the role of the ICD in everyday clinical practice and will be of invaluable benefit to patients, physicians, and insurers alike. The results of the AVID trial as well as other post-event and pre-event trials are summarized in the manuscript. A number of substudies have already resulted from the AVID study and are also presented.
Algebraic density property of Danilov–Gizatullin surfaces

A Danilov–Gizatullin surface is an affine surface V which is the complement of an ample section S for the ruling of a Hirzebruch surface. The remarkable theorem of Danilov and Gizatullin states that the isomorphism class of V depends only on the self-intersection number (S.S). In this paper we apply the theorem of Danilov–Gizatullin to prove that the Lie algebra generated by the complete algebraic vector fields on V coincides with the set of all algebraic vector fields of V.
Equation of state for pion condensed neutron star matter

Abstract We include the effect of the Δ-isobar resonance in the equation of state for neutron star matter in the presence of a pion condensate. We find matter undergoing a first order phase transition after a seconf order phase transition at a much lower density.
Effect of abutment modeling on the seismic response of bridge structures

Abutment behavior significantly influences the seismic response of certain bridge structures. Specifically in the case of short bridges with relatively stiff superstructures typical of highway overpasses, embankment mobilization and inelastic behavior of the soil material under high shear deformation levels dominate the response of the bridge and its column bents. This paper investigates the sensitivity of bridge seismic response with respect to three different abutment modeling approaches. The abutment modeling approaches are based on three increasing levels of complexity that attempt to capture the critical components and modes of abutment response without the need to generate continuum models of the embankment, approach, and abutment foundations. Six existing reinforced concrete bridge structures, typical of Ordinary Bridges in California, are selected for the analysis. Nonlinear models of the bridges are developed in OpenSees. Three abutment model types of increasing complexity are developed for each bridge, denoted as roller, simplified, and spring abutments. The roller model contains only single-point constraints. The spring model contains discrete representations of backfill, bearing pad, shear key, and back wall behavior. The simplified model is a compromise between the efficient roller model and the comprehensive spring model. Modal, pushover, and nonlinear dynamic time history analyses are conducted for the six bridges using the three abutment models for each bridge. Comparisons of the analysis results show major differences in mode shapes and periods, ultimate base shear strength, as well as peak displacements of the column top obtained due to dynamic excitation. The adequacy of the three abutment models used in the study to realistically represent all major resistance mechanisms and components of the abutments, including an accurate estimation of their mass, stiffness, and nonlinear hysteretic behavior, is evaluated. Recommendations for abutment modeling are made.
Adjoints of elliptic cone operators

We study the adjointness problem for the closed extensions of a general b -elliptic operator A ∈ x -ν Diff m b ( M ; E ), ν 0, initially defined as an unbounded operator A : C ∞ c ( M ; E ) ∈ x μ L 2 b ( M ; E ) → x μ L 2 b ( M ; E ), μ ∈ [inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="01i" /]. The case where A is a symmetric semibounded operator is of particular interest, and we give a complete description of the domain of the Friedrichs extension of such an operator.
Administrative Reorganization and Configurational Context: The Contingent Effects of Age, Size, and Change in Size

The administrative reorganization of top-level managers in 200 colleges and universities was examined over a ten-year period. Findings showed that organizational size, age, and change in size work ...
Permutation invariant lattices

We say that a Euclidean lattice in? R n is permutation invariant if its automorphism group has non-trivial intersection with the symmetric group? S n , i.e., if the lattice is closed under the action of some non-identity elements of? S n . Given a fixed element ? ? S n , we study properties of the set of all lattices closed under the action of? ? : we call such lattices ? -invariant. These lattices naturally generalize cyclic lattices introduced by Micciancio (2002, 2007), which we previously studied in?Fukshansky and Sun (2014). Continuing our investigation, we discuss some basic properties of permutation invariant lattices, in particular proving that the subset of well-rounded lattices in the set of all ? -invariant lattices in? R n has positive co-dimension (and hence comprises zero proportion) for all? ? different from an n -cycle.
NASA's Far-IR/Submillimeter Roadmap Missions SAFIR and SPECS

Abstract The Single Aperture Far-Infrared (SAFIR) Telescope, a 10 m class, background-limited observatory, and the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS), a kilometer maximum baseline far-IR/submillimeter (FIR/SMM) interferometer, were recently added to the NASA space science roadmap. We briefly describe the process that led to this adoption, explain the need for high angular resolution and sensitivity in the FIR/SMM, describe the two roadmap missions, and discuss associated practical considerations, including the new technology requirements and the potential opportunity for international collaboration.
An analysis of splitting failures during the drawing of tungsten wire

Abstract A model is proposed to describe crack formation (referred to as wire splitting) that can occur during wire drawing of commercial tungsten lamp wire. In the proposed model, wire splitting is said to occur in response to residual tensile hoop stresses that are generated during wire drawing. The resistance of tungsten wire to crack formation is said to be controlled by the degree of polygonization that has taken place during wire drawing. It was found that wire splitting did not occur when high wire drawing temperatures were maintained throughout the seven wire drawing passes that were studied. Previous work in which dynamic recovery mechanisms were quantified for various wire sizes and drawing temperatures allowed us to show that the drawing temperature, for a given wire size, above which wire splits were not detected coincided well with the onset temperature of dynamic polygonization.
Fatigue Of Welded Structural Steel In Sea Water

The findings of an investigation on fatigue of modified taper cantilever beam, ABS DH32 steel specimens, measuring 24.4 X 152 mm (1 by 6 in.) in the cross section of the weld, using a reverse bend constant deflection technique are reported. All variables were selected so as to approximate as closely as possible the conditions which exist at welded joints of offshore structures but allowing up to 108 cycles to be developed in one year. Information regarding development and progression of fatigue cracks was provided by in situ visual examination and by strain gage measurements. Cycles-to-initiation and cycles-to-failure data are discussed with regard to influence upon the fatigue process of numerous factors, including stress range, cyclic frequency, seawater, corrosion state, temperature, and weld defects. Projections are made regarding appropriateness of design procedures and criteria for mitigation of fatigue of offshore structures. 35 references.
A dynamical mechanism for the selection of physical states in ‘geometric quantization schemes’

Abstract Geometric quantization procedures go usually through an extension of the original theory (pre-quantization) and a subsequent reduction (selection of the physical states). In this context we describe a full geometrical mechanism which provides dynamically the desired reduction.
Infrared observations of the helix planetary nebula

We have mapped the Helix (NGC 7293) planetary nebula (PN) with the IRAC instrument on the Spitzer Space Telescope. The Helix is one of the closest bright PNs and therefore provides an opportunity to resolve the small-scale structure in the nebula. The emission from this PN in the 5.8 and 8 μm IRAC bands is dominated by the pure rotational lines of molecular hydrogen, with a smaller contribution from forbidden line emission such as [Ar III] in the ionized region. The IRAC images resolve the "cometary knots," which have been previously studied in this PN. The "tails" of the knots and the radial rays extending into the outer regions of the PN are seen in emission in the IRAC bands. IRS spectra on the main ring and the emission in the IRAC bands are consistent with shock-excited H_2 models, with a small (~10%) component from photodissociation regions. In the northeast arc, the H_2 emission is located in a shell outside the Hα emission.
The cohomology of the McLaughlin group and some associated groups

The group of order 27; Syl2(M22)=H seems quite remarkable – being the Sylow 2-subgroup of three of the sporadics, M22; M23;McL, as well as the simple group of Lie type PSU 4(3). Also, it is a particularly nice index two subgroup of Syl2(Ly). We are interested in determining the mod(2) cohomology of these groups, and throughout this note all cohomology groups will be taken with F2 coe cients, so the coe cients will generally be suppressed. We use the standard Atlas (see [Co]) notation. We have already determined the rings H∗(M22)⊂H∗(H), [AM2] and H∗(M23)⊂H∗(H); [M]. In this article we determine the rings H∗(PSU4(3))⊂H∗(H) and H∗(McL)⊂H∗(H) :
Tiling the Integers with Translates of One Finite Set

Abstract A settiles the integersif and only if the integers can be written as a disjoint union of translates of that set. We consider the problem of finding necessary and sufficient conditions for a finite set to tile the integers. For sets of prime power size, it was solved by D. Newman (1977,J. Number Theory9, 107–111). We solve it for sets of size having at most two prime factors. The conditions are always sufficient, but it is unknown whether they are necessary for all finite sets.
h/e Magnetic Flux Modulation of the Energy Gap in Nanotube Quantum Dots

We report experiments on quantum dot single-electron-tunneling (SET) transistors made from short multiwall nanotubes and threaded by magnetic flux. Such systems allow us to probe the electronic energy spectrum of the nanotube and its dependence on the magnetic field. Evidence is provided for the interconversion between gapped (semiconducting) and ungapped (metallic) states. Our tubes exhibit h/e-period magnetic flux dependence, in agreement with simple tight-binding calculations.
Digital light deflectors.

Several electrooptic digital light deflection techniques have been proposed. The maximum number of resolvable deflection positions for all methods is determined, essentially, by economic reasons, the tolerable amount of background light, and aberrations. In this paper, three different types of deflection methods (split angle, total internal reflection, Wollaston prism) are described. Design, construction details, and performance of three deflector models are reported. Combined deflection systems use the advantageous properties of each of these methods to economically obtain the maximum number of resolvable deflection positions. A suggested combination to achieve 1024×1024 positions arranged in a two-dimensional field would consist of one total internal reflection stage, seven stages of split angles, and two stages of Wollaston prisms for each dimension.
Phylogenetic Stochastic Mapping Without Matrix Exponentiation

Phylogenetic stochastic mapping is a method for reconstructing the history of trait changes on a phylogenetic tree relating species/organism carrying the trait. State-of-the-art methods assume that the trait evolves according to a continuous-time Markov chain (CTMC) and works well for small state spaces. The computations slow down considerably for larger state spaces (e.g., space of codons), because current methodology relies on exponentiating CTMC infinitesimal rate matrices-an operation whose computational complexity grows as the size of the CTMC state space cubed. In this work, we introduce a new approach, based on a CTMC technique called uniformization, which does not use matrix exponentiation for phylogenetic stochastic mapping. Our method is based on a new Markov chain Monte Carlo (MCMC) algorithm that targets the distribution of trait histories conditional on the trait data observed at the tips of the tree. The computational complexity of our MCMC method grows as the size of the CTMC state space squared. Moreover, in contrast to competing matrix exponentiation methods, if the rate matrix is sparse, we can leverage this sparsity and increase the computational efficiency of our algorithm further. Using simulated data, we illustrate advantages of our MCMC algorithm and investigate how large the state space needs to be for our method to outperform matrix exponentiation approaches. We show that even on the moderately large state space of codons our MCMC method can be significantly faster than currently used matrix exponentiation methods.
Toward a General Route to the Eunicellin Diterpenes: The Asymmetric Total Synthesis of Deacetoxyalcyonin Acetate

A novel approach to the hydroisobenzofuran core utilizing a TiCl4-mediated [4+3] annulation is reported. This [4+3] annulation protocol provides a short, general route to the hydroisobenzofuran core present in the eunicellin diterpenes. Using this annulation, a short synthesis (17 steps) of deacetoxyalcyonin acetate, a member of the eunicellin family, has been achieved.
2,3-Anhydro sugars in glycoside bond synthesis. Highly stereoselective syntheses of oligosaccharides containing α-and β-arabinofuranosyl linkages

The ever-increasing discovery of biologically important events mediated by carbohydrates has generated great interest in the synthesis of oligosaccharides and the development of new methods for glycosidic bond formation. In this paper, we report that 2,3-anhydrofuranose thioglycosides (1, 5) and glycosyl sulfoxides (2, 6), in which the hydroxyl groups C-2 and C-3 are “protected” as an epoxide, glycosylate alcohols with an exceptionally high degree of stereocontrol. The predominant or exclusive product of reactions with this fundamentally new class of glycosylating agent is that in which the newly formed glycosidic bond is cis to the epoxide moiety. We further demonstrate that subsequent nucleophilic opening of the epoxide moiety proceeds under basic conditions to give products in high yield and with good to excellent regioselectivity. The major ring-opened products possess the arabino stereochemistry, and thus this methodology constitutes a new approach for the synthesis of arabinofuranosides. In the epox...
An upper bound on Q-star masses

Q-stars (the gravitational generalization of Q-balls, strongly bound bulk matter that can appear in field theories of strongly interacting hadrons) are the only known compact objects consistent with the known bulk structure of nuclei and chiral symmetry that evade the Rhoades-Ruffini upper bound of 3.2 M(.). Generic bounds are quite weak: MQ-star(400 M(.). If, however, the authors assume that the 1.558 ms pulsar is a Q-star, equilibrium and stability criteria of a rotating fluids place a much stronger upper bound of MQ-star<or=5.3 M(.) on such models under certain special assumptions. This has important implications for heavy compact objects such as Cygnus X-1.
Precision electroweak observables in the minimal moose little Higgs model

Little Higgs theories, in which the Higgs particle is realized as the pseudo-Goldstone boson of an approximate global chiral symmetry have generated much interest as possible alternatives to weak scale supersymmetry. In this paper we analyze precision electroweak observables in the Minimal Moose model and find that in order to be consistent with current experimental bounds, the gauge structure of this theory needs to be modified. We then look for viable regions of parameter space in the modified theory by calculating the various contributions to the S and T parameters.
Methods for direct alkene diamination, new & old

The 1,2-diamine moiety is a ubiquitous structural motif present in a wealth of natural products, including non-proteinogenic amino acids and numerous alkaloids, as well as in pharmaceutical agents, chiral ligands and organic reagents. The biological activity associated with many of these systems and their chemical utility in general has ensured that the development of methods for their preparation is of critical importance. While a wide range of strategies for the preparation of 1,2-diamines have been established, the diamination of alkenes offers a particularly direct and efficient means of accessing these systems. The purpose of this review is to provide an overview of all methods of direct alkene diamination, metal-mediated or otherwise.
Toward a More Complete Understanding of Noncovalent Interactions Involving Aromatic Rings

Noncovalent interactions involving aromatic rings, which include π-stacking interactions, anion-π interactions, and XH−π interactions, among others, are ubiquitous in chemical and biochemical systems. Despite dramatic advances in our understanding of these interactions over the past decade, many aspects of these noncovalent interactions have only recently been uncovered, with many questions remaining. We summarize our computational studies aimed at understanding the impact of substituents and heteroatoms on these noncovalent interactions. In particular, we discuss our local, direct interaction model of substituent effects in π-stacking interactions. In this model, substituent effects are dominated by electrostatic interactions of the local dipoles associated with the substituents and the electric field of the other ring. The implications of the local nature of substituent effects on π-stacking interactions in larger systems are discussed, with examples given for complexes with carbon nanotubes and a small...
On Random Walks with a General Moving Barrier

Random walks with a general, nonlinear barrier have found recent applications ranging from reionization topology to refinements in the excursion set theory of halos. Here we derive the first-crossing distribution of random walks with a moving barrier of arbitrary shape. Such a distribution is shown to satisfy an integral equation that can be solved by a simple matrix inversion, without the need for Monte Carlo simulations, making this useful for exploring a large parameter space. We discuss examples in which common analytic approximations fail, a failure that can be remedied using the method described here.
Ares I-X Flight Test Vehicle Similitude to the Ares I Crew Launch Vehicle

The Ares I-X Flight Test Vehicle is the first in a series of flight test vehicles that will take the Ares I Crew Launch Vehicle design from development to operational capability. Ares I-X is scheduled for a 2009 flight date, early enough in the Ares I design and development process so that data obtained from the flight can impact the design of Ares I before its Critical Design Review. Decisions on Ares I-X scope, flight test objectives, and FTV fidelity were made prior to the Ares I systems requirements being baselined. This was necessary in order to achieve a development flight test to impact the Ares I design. Differences between the Ares I-X and the Ares I configurations are artifacts of formulating this experimental project at an early stage and the natural maturation of the Ares I design process. This paper describes the similarities and differences between the Ares I-X Flight Test Vehicle and the Ares I Crew Launch Vehicle. Areas of comparison include the outer mold line geometry, aerosciences, trajectory, structural modes, flight control architecture, separation sequence, and relevant element differences. Most of the outer mold line differences present between Ares I and Ares I-X are minor and will not have a significant effect on overall vehicle performance. The most significant impacts are related to the geometric differences in Orion Crew Exploration Vehicle at the forward end of the stack. These physical differences will cause differences in the flow physics in these areas. Even with these differences, the Ares I-X flight test is poised to meet all five primary objectives and six secondary objectives. Knowledge of what the Ares I-X flight test will provide in similitude to Ares I - as well as what the test will not provide - is important in the continued execution of the Ares I-X mission leading to its flight and the continued design and development of Ares I.
Quantum quench across a holographic critical point

We study the problem of quantum quench across a critical point in a strongly coupled field theory using AdS/CFT techniques. The model involves a probe neutral scalar field with mass-squared m 2 in the range −9/4 < m 2 < −3/2 in a AdS 4 charged black brane background. For a given brane background there is a critical mass-squared, $ m_c^2 $ such that for $ {m^2} < m_c^2 $ the scalar field condenses. The theory is critical when $ {m^2} = m_c^2 $ and the source for the dual operator vanishes. At the critical point, the radial operator for the bulk linearized problem has a zero mode. We study the dynamics of the order parameter with a time dependent source J (t), or a null-time dependent bulk mass m(u) across the critical point. We show that in the critical region the dynamics for an initially slow variation is dominated by the zero mode : this leads to an effective description in terms of a Landau-Ginsburg type dynamics with a linear time derivative. Starting with an adiabatic initial condition in the ordered phase, we find that the order parameter drops to zero at a time t ⋆ which is later than the time when $ (m_c^2 - {m^2}) $ or J hits zero. In the critical region, t ⋆, and the departure of the order parameter from its adiabatic value, scale with the rate of change, with exponents determined by static critical behavior. Numerical results for the order parameter are consistent with these expectations.
Optimal Control with Budget Constraints and Resets

We consider both discrete and continuous control problems constrained by a fixed budget of some resource, which may be renewed upon entering a preferred subset of the state space. In the discrete case, we consider deterministic shortest path problems on graphs with a full budget reset in all preferred nodes. In the continuous case, we derive augmented PDEs of optimal control, which are then solved numerically on the extended state space with a full/instantaneous budget reset on the preferred subset. We introduce an iterative algorithm for solving these problems efficiently. The method's performance is demonstrated on a range of computational examples, including optimal path planning with constraints on prolonged visibility by a static enemy observer.
Traffic analysis and display for the San Francisco Vessel Traffic System

Abstract To help improve harbor safety in the face of increasing shipping volume and vessel sites, an experimental Vessel Traffic System has been designed, fabricated, and installed in San Francisco Harbor. The Traffic Analysis and Display portion of the system uses computer generated synthetic map and text displays to provide an interactive system for up to three operators. A series of services has been designed which enable the operators to obtain radar contact information and to enter, modify, and recall text information through a series of simple keyboard actions. In addition to the interactive working displays, 4 supporting displays have been provided for designated map segments of the harbor, along with two alpha numeric displays for summary text information. A set of symbols has been developed to allow quick recognition of the vessel traffic situation by the operators. A control computer connected to three interactive display computers and five passive display units provides complete radar contact processing and display, as well as quick response to independent operator requests for information or services. The operators can put vessels into any one of 3 basic categories which allows them to keep the vessels sorted and easily follow the progress of the important ones through the harbor. A background program supplements the operator actions by looking for and reporting specific trouble situations, such as collision warnings, allowing an operator to concentrate on a particular situation without fear of missing a major problem elsewhere in the harbor.
Decompositions of Monomial Ideals in Real Semigroup Rings

Irreducible decompositions of monomial ideals in polynomial rings over a field are well-understood. In this article, we investigate decompositions in the set of monomial ideals in the semigroup ring where A is an arbitrary commutative ring with identity. We classify the irreducible elements of this set, which we call m-irreducible, and we classify the elements that admit decompositions into finite intersections of m-irreducible ideals.
How fast is the k-means method?

We present polynomial upper and lower bounds on the number of iterations performed by the k-means method (a.k.a. Lloyd's method) for k-means clustering. Our upper bounds are polynomial in the number of points, number of clusters, and the spread of the point set. We also present a lower bound, showing that in the worst case the k-means heuristic needs to perform Ω(n) iterations, for n points on the real line and two centers. Surprisingly, the spread of the point set in this construction is polynomial. This is the first construction showing that the k-means heuristic requires more than a polylogarithmic number of iterations. Furthermore, we present two alternative algorithms, with guaranteed performance, which are simple variants of the k-means method.
Computer-animated model of accommodation and presbyopia.

Purpose To understand, demonstrate, and further research the mechanisms of accommodation and presbyopia. Setting Private practice, Little Silver, New Jersey, USA. Design Experimental study. Methods The CAMA 2.0 computer-animated model of accommodation and presbyopia was produced in collaboration with an experienced medical animator using Autodesk Maya animation software and Adobe After Effects. Results The computer-animated model demonstrates the configuration and synchronous movements of all accommodative elements. A new classification of the zonular apparatus based on structure and function is proposed. There are 3 divisions of zonular fibers; that is, anterior, crossing, and posterior. The crossing zonular fibers form a scaffolding to support the lens; the anterior and posterior zonular fibers work reciprocally to achieve focused vision. The model demonstrates the important support function of Weiger ligament. Dynamic movement of the ora serrata demonstrates that the forces of ciliary muscle contraction store energy for disaccommodation in the elastic choroid. The flow of aqueous and vitreous provides strong evidence for our understanding of the hydrodynamic interactions during the accommodative cycle. The interaction may result from the elastic stretch in the choroid transmitted to the vitreous rather than from vitreous pressue. The model supports the concept that presbyopia results from loss of elasticity and increasing ocular rigidity in both the lenticular and extralenticular structures. Conclusion The computer-animated model demonstrates the structures of accommodation moving in synchrony and might enhance understanding of the mechanisms of accommodation and presbyopia. Financial Disclosure Dr. Goldberg is a consultant to Acevision, Inc., and Bausch & Lomb.
Localization of virtual classes

We prove a localization formula for virtual fundamental classes in the context of torus equivariant perfect obstruction theories. As an application, the higher genus Gromov-Witten invariants of projective space are expressed as graph sums of tautological integrals over moduli spaces of stable pointed curves (generalizing Kontsevich's genus 0 formulas). Also, excess integrals over spaces of higher genus multiple covers are computed.
Incremental Convex Hull Algorithms Are Not Output Sensitive

A polytope is the bounded intersection of a finite set of half-spaces of $ \Bbb R$ $^d$ . Every polytope can also be represented as the convex hull conv $ \cal V $ of its vertices (or extreme points) $ \cal V $ . The convex hull problem is to convert from the vertex representation to the half-space representation or (equivalently by geometric duality) vice versa. Given an ordering v 1 . . . v n of the input vertices, after some initialization an incremental convex hull algorithm constructs half-space descriptions $ \cal H $ n-k . . . $\cal H$ n where $\cal H$ i is the half-space description of conv {v 1 . . . v i } . Let m i denote | $ \cal H$ i |, and let m denote m n . Let φ (d) denote $ d/\lceil \sqrt{d} \rceil-1 $ ; in this paper we give families of polytopes for which m n-1 ∈ Ω m φ(d) ) for any ordering of the input. We also give a family of 0/1 -polytopes with a similar blowup in intermediate size. Since m n-1 is not bounded by any polynomial in m , n , and d , incremental convex hull algorithms cannot in any reasonable sense be considered output sensitive. It turns out that the same families of polytopes are also hard for the other main types of convex hull algorithms known.
Topology on the Spaces Of Orderings of Groups

A natural topology on the space of left orderings of an arbitrary semi-group is introduced here. This space is proved to be compact, and for free abelian groups it is shown to be homeomorphic to the Cantor set. An application of this result is a new proof of the existence of universal Grobner bases.
Quasiperiodic spectra and orthogonality for iterated function system measures

We extend classical basis constructions from Fourier analysis to attractors for affine iterated function systems (IFSs). This is of interest since these attractors have fractal features, e.g., measures with fractal scaling dimension. Moreover, the spectrum is then typically quasi-periodic, but non-periodic, i.e., the spectrum is a “small perturbation” of a lattice. Due to earlier research on IFSs, there are known results on certain classes of spectral duality-pairs, also called spectral pairs or spectral measures. It is known that some duality pairs are associated with complex Hadamard matrices. However, not all IFSs X admit spectral duality. When X is given, we identify geometric conditions on X for the existence of a Fourier spectrum, serving as the second part in a spectral pair. We show how these spectral pairs compose, and we characterize the decompositions in terms of atoms. The decompositions refer to tensor product factorizations for associated complex Hadamard matrices.
The many approaches to the study of monopolistic competition

Abstract What are the key questions in the study of monopolistic competition, oligopoly theory and allied topics dealing with competition among the few? A specification and discussion of some of these questions is given. In particular both problems and their resolution in studying oligopoly in a closed economy and the reconciliation of cooperative and non-cooperative models of oligopolistic competition with general equilibrium theory is discussed. Some problems with dynamics are noted. In particular the limitations of the non-cooperative equilibrium solution are considered. Questions are raised concerning the domain of application of perfect equilibria, the treatment of subjective probabilities and non-symmetric information.
THE IMPACT OF SN 1987A WITH ITS CIRCUMSTELLAR RING

The envleope of SN 1987A will strike its circumstellar ring in 12 +/- 3 yr after explosion (A.D. 1999+/-3), the exact time depending weakly on the uncertain density of diffuse gas between the supernova and the ring. The impact will drive a radiative shock into the ring with velocity approximatley 200-400 km s(exp -1). The shocked ring will become a bright optical and ultraviolet emsiison-line source. A bright arc will suddenly appear at the near side of the ring and grow into an entire ring about 11 months later. The luminosities of the brightest lines, H-alpha H-alpha, N v lambda lambda 1238, 1242, and O VI lambda lambda 1032, 1038 will rise rapidly to approxminately 10(exp 36)-10(exp 37) ergs s(exp -1) and remain bright for several years after impact. The emission lines from the shocked ring will have FWHM approximatley 300-600 km s(exp -1) and complex profiles that will depend on position and will be sensitive to the details of the density distribution of gas in the ring. Strong EUV radiation from the shock will photoionize the unshocked ring, causing emission of narrow FWHM equivalent to 15 km s(exp -1) H-alpha, H-beta and (O III) lambda lambda 4959, 5007 lines with luminosities approximatley 10(exp 35) ergs s(exp -1).The EUV radiation will probably cause the nebulosity beyond the ring to become visable again. The EUV radiation may also illuminate the unshocked outer supernova envelope, causing visible emission of broad FWHM equivalent to 10(exp 4) km s(exp -1) H-alpha and H-beta lines.
ON CRITICAL POINTS OF PROPER HOLOMORPHIC MAPS ON THE UNIT DISK

We prove that a proper holomorphic map on the unit disk in the complex plane is uniquely determined up to post-composition with a Moebius transformation by its critical points.
The spacetime approach to quantum mechanics

Abstract Feynman's sum-over-histories formulation of quantum mechanics is reviewed as an independent statement of quantum theory in spacetime form. It is different from the usual Schrodinger-Heisenberg formulation that utilizes states on spacelike surfaces because it assigns probabilities to different sets of alternatives. In a sum-over-histories formulation, alternatives at definite moments of time are more restricted than in usual quantum mechanics because they refer only to the coordinates in terms of which the histories are defined. However, in the context of the quantum mechanics of closed systems, sum-over-histories quantum mechanics can be generalized to deal with spacetime alternatives that are not “at definite moments of time”. An example in field theory is the set of alternative ranges of values of a field averaged over a spacetime region. An example in particle mechanics is the set of the alternatives defined by whether a particle never crosses a fixed spacetime region or crosses it at least once. The general notion of a set of spacetime alternatives is a partition (coarse-graining) of the histories into an exhaustive set of exclusive classes. With this generalization the sum-over-histories formulation can be said to be in fully spacetime form with dynamics represented by path integrals over spacetime histories and alternatives defined as spacetime partitions of these histories. When restricted to alternatives at definite moments of times this generalization is equivalent to Schrodinger-Heisenberg quantum mechanics. However, the quantum mechanics of more general spacetime alternatives does not have an equivalent Schrodinger-Heisenberg formulation. We suggest that, in the quantum theory of gravity, the general notion of “observable” is supplied by diffeomorphism invariant partitions of spacetime metrics and matter field configurations. By generalizing the usual alternatives so as to put quantum theory in fully spacetime form we may be led to a covariant generalized quantum mechanics of spacetime free from the problem of time.
Granulocyte-Macrophage-Colony Stimulating Factor in Metastatic Renal Cell Carcinoma. A Phase II Trial

BACKGROUND Due to lack of success with standard chemotherapy and only modest success with immunotherapy, metastatic renal cell carcinoma (RCC) is associated with a poor prognosis. Granulocyte-macrophage-colony stimulating factor (GM-CSF) is a cytokine with potential antitumor activity, including stimulation of tumor necrosis factor (TNF) and interleukin-1 secretion. It is also a potent growth factor for and activator of antigen-presenting dendritic cells. GM-CSF toxicity may be mediated by TNF, and inhibition of TNF release by pentoxifylline (PTX) may ameliorate these toxic effects. The authors conducted a Phase II trial to determine the activity of GM-CSF in metastatic RCC and to study the effect of PTX on GM-CSF toxicity. METHODS Twenty-four eligible patients with metastatic RCC received 10 μg/kg of GM-CSF per day, administered subcutaneously, on a 14-days-on/14-days-off schedule. Twelve patients received concurrent PTX at a dose of 400 mg administered orally 4 times per day. RESULTS One patient experienced prolonged stability of disease after having progressive disease on entry. Two other patients experienced substantial slowing of their progressive disease while on study. One of these patients had rapidly progressing metastases on other immunotherapy before receiving GM-CSF. Toxicity was not diminished in patients treated with PTX; it included hyperleukocytosis, nausea, vomiting, pain, fever, skin reactions, myalgia, and fatigue. CONCLUSIONS GM-CSF at the dose and schedule described in this report has minor activity against metastatic RCC, and PTX does not ameliorate its side effects. Cancer 1998;82:1352-8. © 1998 American Cancer Society.
The Parity protected, multithreaded register files on the 90-nm itanium microprocessor

The integer and floating-point register files of the 90-nm generation Itanium Microprocessor are described. A pulsed, shared word line technique enables a 22 ported integer array with only 12 word lines per register. An in-register ripple parity system provides soft error detection with no impact to operand bypass or pipeline depth while keeping consuming less that 6% of the total register datapath area. The register file implements temporal multi-threading by multiplexing the read and write ports to two storage nodes enabling registers to write both foreground and background threads to the same register at the same time. Thread switching completes in one cycle. The register files are fabricated in a 7-layer 90-nm process and operate up to 2.0 GHz while consuming 400 mW per register array.
Semi-hadronic tau decays at CLEO

Abstract We describe recent results from the CLEO experiment on semi-hadronic decays of the tau lepton. We discuss the analysis of sub-structure in the decays τ− → π−π0ντ, (3π)−ντ, (4π)−ντ, and ηX−ντ. Various applications of these results are also discussed.
CAN A LONG NANOFLARE STORM EXPLAIN THE OBSERVED EMISSION MEASURE DISTRIBUTIONS IN ACTIVE REGION CORES

All theories that attempt to explain the heating of the high-temperature plasma observed in the solar corona are based on short bursts of energy. The intensities and velocities measured in the cores of quiescent active regions, however, can be steady over many hours of observation. One heating scenario that has been proposed to reconcile such observations with impulsive heating models is the "long nanoflare storm," where short-duration heating events occur infrequently on many sub-resolution strands; the emission of the strands is then averaged together to explain the observed steady structures. In this Letter, we examine the emission measure distribution predicted for such a long nanoflare storm by modeling an arcade of strands in an active region core. Comparisons of the computed emission measure distributions with recent observations indicate that the long nanoflare storm scenario implies greater than five times more 1 MK emission than is actually observed for all plausible combinations of loop lengths, heating rates, and abundances. We conjecture that if the plasma had "super coronal" abundances, the model may be able to match the observations at low temperatures.
Diaminophosphine oxides as preligands for Ni-catalyzed Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids

Abstract The first investigation of air- and moisture-stable diaminophosphine oxides as preligands in the Ni-catalyzed Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids has been reported. The results show that under the optimized reaction conditions, the new catalytic system with a Ni(II) σ-aryl complex as precatalyst and a diaminophosphine oxide as preligand tolerates a variety of functional groups and is efficient for both electron-rich and electron-deficient aryl chlorides, though it shows higher efficiency for activated arylboronic acids than deactivated ones. Steric effects were observed for both aryl chlorides and arylboronic acids.
Base-Station Assisted Device-to-Device Communications for High-Throughput Wireless Video Networks

We propose a new scheme for increasing the throughput of video files in cellular communications systems. This scheme exploits (1) the redundancy of user requests as well as (2) the considerable storage capacity of smartphones and tablets. Users cache popular video files and-after receiving requests from other users-serve these requests via device-to-device localized transmissions. The file placement is optimal when a central control knows a priori the locations of wireless devices when file requests occur. However, even a purely random caching scheme shows only a minor performance loss compared to such a “genie-aided” scheme. We then analyze the optimal collaboration distance, trading off frequency reuse with the probability of finding a requested file within the collaboration distance. We show that an improvement of spectral efficiency of one to two orders of magnitude is possible, even if there is not very high redundancy in video requests.
EXPERIENCE-DEPENDENT INFORMATION DIFFUSION AND PRODUCT QUALITY

In a monopoly market for an experience good the diffusion of product-quality information may depend on whether or not the information is favorable. To capture this asymmetry, our model uses as its information source a quality survey which suffers from response bias. Consumers may attempt to adjust for bias, but are not required to do so correctly. As a result, quality under perfect information need not be, and usually will not be, higher than quality under imperfect information. In addition, the externality exerted by informed consumers on uninformed consumers may not be the traditional beneficial externality. (JEL L15)
Trisections and Totally Real Origami

1. CONSTRUCTIONS IN GEOMETRY. The study of methods that accomplish trisections is vast and extends back in time approximately 2300 years. My own favorite method of trisection from the Ancients is due to Archimedes, who performed a “neusis” between a circle and line. Basically a neusis (or use of a marked ruler) allows the marking of points on constructed objects of unit distance apart using a ruler placed so that it passes through some known (constructed) point P . Here is Archimedes’ trisection method (see Figure 1): Given an acute angle between rays r and s meeting at the point O, construct a circle K of radius one at O, and then extend r to produce a line that includes a diameter of K . The circle K meets the ray s at a point P . Now place a ruler through P with the unit distance CD lying with C on K and D on the ray opposite to r . That the angle ODP is the desired trisection is easy to check using the isosceles triangles DCO and COP and the exterior angle of the triangle PDO. As one sees when trying this for oneself, there is a bit of “fiddling” required to make everything line up as desired; that fiddling is also essential when one does origami.
Interhemispheric transfer in schizophrenics, depressives, and normals with schizoid tendencies

Although several studies suggest that schizophrenics suffer from an impairment in the interhemispheric transfer (IHT) of information, methodological weaknesses in these studies preclude clear interpretation of their results. This study addresses these criticisms in order to provide a clearer test of the IHT theory. Schizophrenics, depressives, normal controls, and normals with schizoid tendencies were assessed on five measures of IHT (verbal and nonverbal dichotic listening, intermanual transfer, bimanual block design, finger sequence repetition) and two measures of unilateral hemispheric processing (lateral eye movements, auditory thresholds). RESULTS consistently failed to support an IHT deficit interpretation of schizophrenia. Schizoid normals had a significantly greater right-ear advantage on verbal dichotic listening than both psychiatric groups, a result suggesting enhanced left-hemisphere activation in schizoid normals. It is concluded that the IHT theory requires stronger empirical substantiation than has been obtained to date to warrant further consideration as a central theory of schizophrenia. Language: en
Systolic arrays for integer Chinese remaindering

Abstract This paper presents time-minimal and processor-time-minimal systolic arrays for computing a process dependence graph corresponding to the mixed-radix conversion algorithm. The arrays are particularly suitable for implementation of algorithms from the applications of residue number systems on programmable systolic/wavefront arrays and in VLSI. Examples of such applications are exact solution of linear equations and computation of pseudo-inverses of matrices.