cssi/SciSciGPT-SciSciNet huggingface dataset:
Ramond-Ramond Couplings of Noncommutative D-branes

Abstract We propose the leading couplings, in an α ′ expansion, of D-branes to Ramond–Ramond (RR) potentials in a constant NS–NS B-field for an arbitrary choice of noncommutative parameter. The proposal is motivated by some string amplitude computations. The zero momentum couplings are topological in nature and include Elliott's formula involving the noncommutative Chern character. The finite momentum couplings are given by smearing the zero momentum operators along an open Wilson line. Comparisons between the RR couplings in different descriptions lead to a better understanding of the field redefinitions between gauge field variables (the Seiberg–Witten map) and help constrain α ′ corrections. In particular we recover the Seiberg–Witten map conjectured by one of the authors in hep-th/0011125. We also discuss the dynamics of the transverse scalar fields and find evidence for a new derivative-driven dielectric effect.
Time-reversal symmetry and universal conductance fluctuations in a driven two-level system.

In the presence of time-reversal symmetry, quantum interference gives strong corrections to the electric conductivity of disordered systems. The self-interference of an electron wave function traveling time-reversed paths leads to effects such as weak localization and universal conductance fluctuations. Here, we investigate the effects of broken time-reversal symmetry in a driven artificial two-level system. Using a superconducting flux qubit, we implement scattering events as multiple Landau-Zener transitions by driving the qubit periodically back and forth through an avoided crossing. Interference between different qubit trajectories gives rise to a speckle pattern in the qubit transition rate, similar to the interference patterns created when coherent light is scattered off a disordered potential. Since the scattering events are imposed by the driving protocol, we can control the time-reversal symmetry of the system by making the drive waveform symmetric or asymmetric in time. We find that the fluctuations of the transition rate exhibit a sharp peak when the drive is time symmetric, similar to universal conductance fluctuations in electronic transport through mesoscopic systems. © 2013 American Physical Society.
The relevance of occult axillary micrometastasis in ductal carcinoma in situ: a clinicopathologic study with long-term follow-up.

BACKGROUND Ductal carcinoma in situ (DCIS) represents 20% of newly diagnosed breast carcinoma cases. Historically, the incidence of axillary metastasis in DCIS has been small (1–2%) and its significance has been debated. It is widely known that serial sections of lymph nodes coupled with keratin immunohistochemistry (IHC) increases identification of micrometastasis. The advent of sentinel lymph node evaluation underscores the need to reevaluate the significance of occult micrometastases in DCIS. METHODS Patients with DCIS and negative axillary lymph nodes from 1974 to 1992 were selected from the Saint Barnabas Medical Center Tumor Registry. All diagnoses were confirmed, and paraffin blocks were retrieved after acceptance into the study. Seven serial sections were obtained from each block and evaluated with two cytokeratin IHC stains. Clinical follow-up ranged from 10 to 28 years. RESULTS One hundred two patients were included in the study. Micrometastases were identified in 13 patients (13%), mostly on 1 level and composed of microscopic clusters in the subcapsular sinus. Seven of these lymph node–positive patients (58%) had high-grade comedo DCIS, 4 (33%) had intermediate grades of various types of DCIS, and one had a low-grade micropapillary DCIS. The overall disease recurrence rate was 12%, but micrometasis was not detected in any of the patients who developed disease recurrence. CONCLUSIONS Serial IHC evaluation of lymph nodes dramatically increased the identification of occult micrometastasis. However, IHC detected micrometastasis has no apparent clinical significance in DCIS, based on the current long-term clinicopathologic study. Therefore, the authors questioned the significance of occult micrometastasis, identified by IHC, in DCIS of any type and extent. Further evaluation and follow-up of lymph node micrometastases in patients with invasive tumors of various sizes are needed. The current findings would not support altering the stage of patients with DCIS and micrometastasis detected by IHC only. Cancer 2003. © 2003 American Cancer Society.
Adaptive Evolution on Neutral Networks

We study the evolution of large but finite asexual populations evolving in fitness landscapes in which all mutations are either neutral or strongly deleterious. We demonstrate that despite the absence of higher fitness genotypes, adaptation takes place as regions with more advantageous distributions of neutral genotypes are discovered. Since these discoveries are typically rare events, the population dynamics can be subdivided into separate epochs, with rapid transitions between them. Within one epoch, the average fitness in the population is approximately constant. The transitions between epochs, however, are generally accompanied by a significant increase in the average fitness. We verify our theoretical considerations with two analytically tractable bitstring models.
Thermal/structural dynamic analysis via approximate analytical approach

Abstract The present paper uses a classical Galerkin weighted residual formulation to obtain the approximate analytical solution of a thermally loaded beam executing free flexural vibrations. The approach used is one where the time variable is considered in the same manner as the spatial variable, and is included in the basis functions. The basis functions used in the approach are polynomials obtained from the terms of a power series, with the condition of nullity on the boundary. This choice simplifies the algebraic manipulations considerably and yields close form expressions for components of the system matrix. The latter also simplifies the numerical computation of coefficients of the approximating polynomial. The approach provides benefits in terms of increased accuracy and lower computational costs.
Sub-sub-leading soft-graviton theorem in arbitrary dimension

The CHY formula which describes an n-point tree level scattering amplitude for scalars, gluons or gravitons in arbitrary dimension [22], is used to prove the sub-sub-leading soft-graviton theorem recently proposed by Cachazo and Strominger [13].
Elementary divisors of the Shapovalov form on the basic representation of Kac–Moody algebras

We calculate the invariant factors of the standard lattice VZ inside the basic representation of untwisted Kac–Moody algebras of ADE-type. This, in turn, gives the invariant factors of Cartan matrices for symmetric groups in prime characteristic as well as for the Iwahori–Hecke algebra at roots of unity.
Iterated function systems, Ruelle operators, and invariant projective measures

We introduce a Fourier-based harmonic analysis for a class of discrete dynamical systems which arise from Iterated Function Systems. Our starting point is the following pair of special features of these systems. (1) We assume that a measurable space X comes with a finite-to-one endomorphism r: X → X which is onto but not one-to-one. (2) In the case of affine Iterated Function Systems (IFSs) in R d , this harmonic analysis arises naturally as a spectral duality defined from a given pair of finite subsets B, L in R d of the same cardinality which generate complex Hadamard matrices. Our harmonic analysis for these iterated function systems (IFS) (X,μ) is based on a Markov process on certain paths. The probabilities are determined by a weight function W on X. From W we define a transition operator R w acting on functions on X, and a corresponding class H of continuous R w -harmonic functions. The properties of the functions in H are analyzed, and they determine the spectral theory of L 2 (μ). For affine IFSs we establish orthogonal bases in L 2 (μ). These bases are generated by paths with infinite repetition of finite words. We use this in the last section to analyze tiles in R d .
Perturbations of orthogonal polynomials with periodic recursion coefficients

The results of Denisov-Rakhmanov, Szegő-Shohat-Nevai, and Killip-Simon are extended from asymptotically constant orthogonal polynomials on the real line (OPRL) and unit circle (OPUC) to asymptotically periodic OPRL and OPUC. The key tool is a characterization of the isospectral torus that is well adapted to the study of perturbations.
Simplified normal limits and automated quantitative assessment for attenuation-corrected myocardial perfusion SPECT.

Background We aimed to compare normal limits and the detection of coronary artery disease (CAD) with attenuation-corrected (AC) and non-attenuation-corrected (NC) myocardial perfusion single photon emission computed tomography (MPS) by use of a recently improved automated quantification technique.
Cornering new physics in b → s transitions

We derive constraints on Wilson coefficients of dimension-six effective operators probing the b → s transition, using recent improved measurements of the rare decays B s → μ + μ −, B → Kμ + μ − and B → K * μ + μ − and including all relevant observables in inclusive and exclusive decays. We consider operators present in the SM as well as their chirality-flipped counterparts and scalar operators. We find good agreement with the SM expectations. Compared to the situation before winter 2012, we find significantly more stringent constraints on the chirality-flipped coefficients due to complementary constraints from B → Kμ + μ − and B → K * μ + μ − and due to the LHCb measurement of the angular observable S 3 in the latter decay. We also list the full set of observables sensitive to new physics in the low recoil region of B → K * μ + μ −.
Beyond Affordability: The Impact of Nonfinancial Barriers on Access for Uninsured Adults in Three Diverse Communities

Most proposals to improve access for uninsured adults focus on removing financial barriers to health care. Health services researchers have long recognized, however, that access to care is a multidimensional concept consisting of both financial and nonfinancial dimensions. While financial barriers faced by those without health insurance have been well-documented, it is not known to what degree nonfinancial barriers limit access for those without coverage. In this study we sought to identify the types and frequencies of nonfinancial access barriers faced by low-income uninsured adults, as well as determine how frequently nonfinancial barriers coexist with financial access barriers in this population. We conducted a telephone survey of 1,118 low-income uninsured adults in Alameda, California, Austin, Texas, and Southern Maine who had enrolled in local access programs funded through the Robert Wood Johnson Foundation’s Communities in Charge initiative. Financial barriers were the most often cited barrier to access in each of the three groups, though nonfinancial barriers were often cited as well. Across all three populations, one-third to one-half of respondents with financial access barriers also cited one or more nonfinancial barriers as contributing to their problems accessing health care. Our results suggest that many uninsured adults face nonfinancial health care barriers in addition to their well-documented financial challenges. Health reform efforts must address both types of barriers in order to maximally improve access for the uninsured population.
Simulation and control of a 20-kHz spacecraft power system

A detailed computer representation of four Mapham inverters connected in a series-parallel arrangement has been implemented. System performance is illustrated by computer traces for the four Mapham inverters connected to a Litz cable with parallel resistance and DC receiver loads at the receiving end of the transmission cable. Methods of voltage control and load sharing between the inverters are demonstrated. The computer representation is used to design and demonstrate the advantages of a feedforward voltage-control strategy. It is shown that with a computer simulation of this type, the performance and control of spacecraft power systems can be investigated with relative ease and facility. >
Extremal Betti Numbers and Applications to Monomial Ideals

Recall that the (Mumford-Castelnuovo) regularity of M is the least integer ρ such that for each i all free generators of Fi lie in degree ≤ i + ρ, that is βi,j = 0, for j > i + ρ. In terms of Macaulay [Mac] regularity is the number of rows in the diagram produced by the “betti” command. A Betti number βi,j = 0 will be called extremal if βl,r = 0 for all l ≥ i, r ≥ j+1 and r − l ≥ j − i, that is if βi,j is the nonzero top left “corner” in a block of zeroes in the Macaulay “betti” diagram. In other words, extremal Betti numbers account for “notches” in the shape of the minimal free resolution and one of them computes the regularity. In this sense, extremal Betti numbers can be seen as a refinement of the notion of Mumford-Castelnuovo regularity. In the first part of this note we connect the extremal Betti numbers of an arbitrary submodule of a free S-module with those of its generic initial module. In the second part, which can be read independently of the first, we relate extremal multigraded Betti numbers in the minimal resolution of a square free monomial ideal with those of the monomial ideal corresponding to the Alexander dual simplicial complex. Our techniques give also a simple geometric proof of a more precise version of a recent result of Terai [Te97] (see also [FT97] for a homological reformulation and related results), generalizing Eagon and Reiner’s theorem [ER96] that a StanleyReisner ring is Cohen-Macaulay if and only if the homogeneous ideal corresponding to the Alexander dual simplicial complex has a linear resolution. We are grateful to David Eisenbud for useful discussions.
Parageometric outer automorphisms of free groups

We study those fully irreducible outer automorphisms o of a finite rank free group F r which are parageometric, meaning that the attracting fixed point of o in the boundary of outer space is a geometric R-tree with respect to the action of F r , but o itself is not a geometric outer automorphism in that it is not represented by a homeomorphism of a surface. Our main result shows that the expansion factor of o is strictly larger than the expansion factor of o -1 . As corollaries (proved independently by Guirardel), the inverse of a parageometric outer automorphism is neither geometric nor parageometric, and a fully irreducible outer automorphism o is geometric if and only if its attracting and repelling fixed points in the boundary of outer space are geometric R-trees.
Geomagnetically trapped radiation

This review covers the major developments in radiation-belt phenomenology of the past four years (1970–1973). This has been a period characterized by consolidation and refinement of ideas and measurements related to geomagnetically trapped particles. Significant progress has been made in understanding ion and electron pitch-angle distributions within the context of radial diffusion and pitch-angle diffusion, respectively. Comparison of alpha-particle and proton distributions has helped to clarify the relative strengths of known radial-diffusion mechanisms. Careful measurements have indicated the directional flux of cosmic-ray-albedo neutrons, which constitute (through beta decay) a major source of high-energy (≳ 20 MeV) inner-belt protons. Inclusion of radial-diffusion and geomagnetic-secular effects has brought the theory of the inner proton belt into reasonable agreement with observation. At very lowL values (L ≲ 1.2) atmospheric collisions have been found to facilitate the radial transport of 40 keV protons and 2 MeV electrons. The plasmapause has been identified as an important boundary for plasma instabilities (wave-particle interactions) that lead to particle precipitation and red-arc excitation. Suggestions have followed for artificially simulating such plasmaspheric effects by magnetospheric injection of cold barium or lithium plasma.
Resource Restricted Computability Theoretic Learning: Illustrative Topics and Problems

Computability theoretic learning theory (machine inductive inference) typically involves learning programs for languages or functions from a stream of complete data about them and, importantly, allows mind changes as to conjectured programs. This theory takes into account algorithmicity but typically does not take into account feasibility of computational resources. This paper provides some example results and problems for three ways this theory can be constrained by computational feasibility. Considered are: the learner has memory limitations, the learned programs are desired to be optimal, and there are feasibility constraints on learning each output program as well as other constraints to minimize postponement tricks.
Evaluating traditional share—Price and residual demand measures of market power in the catsup industry

In this paper we specify a price determination model which can test both the traditional positive interbrand price—share hypothesis and the negative intrabrand relationship predicted by residual demand analysis. We evaluate this relationship empirically using three-dimensional panel data from the catsup industry. We find support for both hypothesized relationships, and conclude that market power exists in this industry. Further, we conclude that the results depend critically on the characteristics of the data set to be analyzed.
Laser-Velocimeter Surveys of Merging Vortices in a Wind Tunnel

The merger of two vortices was studied with a laser velocimeter designed to measure the two cross-stream components of velocity. Measurements were made at several downstream distances in the vortex wake shed by two semispan wings mounted on the wind tunnel walls. The velocity data provided well difined contours of cross-flow velocity, stream function and vorticity. Downstream of the merger point the vorticity was shown to be independent of the downstream distance for small radii, and at larger radii was dependent on the distance from the wing rather than from the merger point. Upstream of the merger point a multicell vorticity pattern was shown.
Effect of a single dose of ethanol on developing peripheral nerve of chick embryos.

Fetal Alcohol syndrome (FAS) is a condition occurring in some children of mothers who have consumed alcohol during pregnancy. It is characterized by physical and mental growth retardation, craniofacial anomalies and derangements of numerous body systems. A particular distressing feature of FAS is affection of the nervous system, which manifest as motor and sensory derangements and neurobehavioral deficits. However, no specific changes in the brain and spinal cord that could conclusively explain these neuronal defects have been reported. The aim of this study was to investigate the effects of a single high dose of ethanol exposure during early gestation on the peripheral nerve, with a view to understanding the neuronal disorders appearing in FAS. A chick model of FAS was used and embryos were exposed to 5%, 10% and 15% ethanol immediately after hatching. The effects on general growth and development and on the peripheral nerve of ethanol-exposed embryos were examined following the full period of gestation. There was a significant reduction in crown-rump length, head circumference and body weight in ethanol-exposed chicks as compared with appropriate control groups. The degree of growth retardation among the different alcohol exposed groups was dose dependent and significant prenatal embryo mortality was seen in those exposed to 15% ethanol. In embryos that survived the exposure to 15% ethanol, features of myelin degeneration were observed in the peripheral nerve in the majority of cases. No features of myelin degeneration were observed in embryos exposed to 5% and 10% ethanol or in the control groups. This study demonstrates the direct toxic effects of a single high dose of ethanol on developing embryos in general and the peripheral nerves in particular. Accordingly the pathological changes observed in peripheral nerves could account for some of the neurobehavioral deficits observed in FAS.
Randomized Composable Core-sets for Distributed Submodular Maximization

An effective technique for solving optimization problems over massive data sets is to partition the data into smaller pieces, solve the problem on each piece and compute a representative solution from it, and finally obtain a solution inside the union of the representative solutions for all pieces. This technique can be captured via the concept of composable core-sets, and has been recently applied to solve diversity maximization problems as well as several clustering problems [7,15,8]. However, for coverage and submodular maximization problems, impossibility bounds are known for this technique [15]. In this paper, we focus on efficient construction of a randomized variant of composable core-sets where the above idea is applied on a random clustering of the data. We employ this technique for the coverage, monotone and non-monotone submodular maximization problems. Our results significantly improve upon the hardness results for non-randomized core-sets, and imply improved results for submodular maximization in a distributed and streaming settings. The effectiveness of this technique has been confirmed empirically for several machine learning applications [22], and our proof provides a theoretical foundation to this idea.In summary, we show that a simple greedy algorithm results in a 1/3-approximate randomized composable core-set for submodular maximization under a cardinality constraint. Our result also extends to non-monotone submodular functions, and leads to the first 2-round MapReduce-based constant-factor approximation algorithm with O(n) total communication complexity for either monotone or non-monotone functions. Finally, using an improved analysis technique and a new algorithm PseudoGreedy, we present an improved 0.545-approximation algorithm for monotone submodular maximization, which is in turn the first MapReduce-based algorithm beating factor 1/2 in a constant number of rounds.
A hybrid adaptive control scheme using sampled data and intersampling compensation

An adaptive control problem for continuous-time systems using discrete adaptation technique is examined. We propose a hybrid adaptive scheme whose controller parameters are updated only at sampling instants using sampled data. In order to establish stability for the closed-loop adaptive system, an additional feedback loop is designed to compensate possible poor intersampling behavior. A stability analysis is given for the resulting adaptive control system. Furthermore, it is shown that the intersampling compensation can be designed such that for any given sampling rate, the asymptotic tracking performance of the closed-loop hybrid adaptive control system can be made arbitrarily close to that of the continuous adaptive control system.
Search space reduction in QoS routing

To provide real-time service or engineer constrained-based paths, networks require the underlying routing algorithm to be able to find low-cost paths that satisfy given quality-of-service constraints. However, the problem of constrained shortest (least-cost) path routing is known to be NP-hard, and some heuristics have been proposed to find a near-optimal solution. However, these heuristics either impose relationships among the link metrics to reduce the complexity of the problem which may limit the general applicability of the heuristic, or are too costly in terms of execution time to be applicable to large networks. In this paper, we focus on solving the delay-constrained minimum-cost path problem, and present a fast algorithm to find a near-optimal solution. This algorithm, called delay-cost-constrained routing (DCCR), is a variant of the k-shortest-path algorithm. DCCR uses a new adaptive path weight function together with an additional constraint imposed on the path cost, to restrict the search space. Thus, DCCR can return a near-optimal solution in a very short time. Furthermore, we use a variant of the Lagrangian relaxation method proposed by Handler and Zang [Networks 10 (1980) 293] to further reduce the search space by using a tighter bound on path cost. This makes our algorithm more accurate and even faster. We call this improved algorithm search space reduction + DCCR (SSR + DCCR). Through extensive simulations, we confirm that SSR + DCCR performs very well compared to the optimal but very expensive solution.
Microstructure-Level Modeling of Ductile Iron Machining

A microstructure-level model for simulation of machining of cast irons using the finite element method is presented. The model explicitly combines ferritic and pearlitic grains with graphite nodules to produce the ductile iron structure. The behaviors of pearlite, ferrite, and graphite are captured individually using an internal state variable model for the material model. The behavior of each phase is dependent on strain, strain rate, temperature, and amount of damage. Extensive experimentation was conducted to characterize material strain rate and temperature dependency of both ferrite and pearlite. The model is applied to orthogonal machining of ductile iron. The simulation results demonstrate the feasibility of successfully capturing the influence of microstructure on machinability and part performance. The stress, strain, temperature, and damage results obtained from the model are found to correlate well with experimental results found in the literature. Furthermore, the model is capable of handling various microstructures in other heterogeneous materials such as steels.
Magnetic merging in colliding flux tubes

We develop an analytical theory of reconnection between colliding, twisted magnetic flux tubes. Our analysis is restricted to direct collisions between parallel tubes and is based on the collision dynamics worked out by Bogdan (1984). We show that there is a range of collision velocities for which neutral point reconnection of the Parker-Sweet type can occur, and a smaller range for which reconnection leads to coalescence. Mean velocities within the solar convection zone are probably significantly greater than the upper limit for coalescence. This suggests that the majority of flux tube collisions do not result in merging, unless the frictional coupling of the tubes to the background flow is extremely strong.
Examination of the storm/substorm relationship using global auroral X-ray images

[1] Global measurements by the Polar Ionospheric X-ray Imaging Experiment (PIXIE) instrument on board NASA's Polar spacecraft of the auroral X-ray emissions associated with substorms show significant differences between isolated substorms and those occurring during geomagnetic storms. During isolated substorms at substorm onset the emissions are initially seen in the premidnight-to-midnight sector and then spread toward dawn. The emissions extend beyond 12 magnetic local time (MLT) with the most intense emissions occurring in the postdawn sector. The timescales for the appearance of X-ray emissions in the various morningside MLT sectors are consistent with the drift times of electrons, of energies that produce the photons observed by PIXIE, under the influence of a magnetospheric electric field inferred from ionospheric ion drift measurements. During substorm recovery, emissions die away gradually at increasing MLT values with the last of the emissions in the noon sector disappearing several hours (∼3–4) after substorm onset. During the stormtime substorms, onset-associated emissions are seen in the premidnight-to-midnight regions and spread toward dawn as in the isolated substorms. However, the emissions do not reach much beyond ∼9–10 MLT and very intense emissions are seen in the predawn MLT sectors. These intense predawn emissions are seen throughout the stormtime periods and are associated with significantly enhanced magnetospheric convection. There are brief reductions in intensity in the morningside emissions shortly after substorm onset consistent with a brief reduction in the cross-tail electric field, followed by intensification again in the predawn sector on a timescale consonant with drifting electrons under the influence of a magnetospheric electric field. We conclude that the differences between the temporal evolution and morphology of the auroral X-ray emissions during isolated and stormtime subtorms are the result of pitch angle scattering mechanisms whose MLT distribution and intensity are dependent on the strength of the magnetospheric electric field.
Photodisintegration of Ultrahigh Energy Cosmic Rays: A New Determination

We present the results of a new calculation of the photodisintegration of ultra-high-energy cosmic-ray (UHCR) nuclei in intergalactic space. The critical interactions for energy loss and photodisintegration of UHCR nuclei occur with photons of the 2.73 K cosmic background radiation (CBR) and with photons of the IR background radiation (IBR). We have reexamined this problem, making use of a new determination of the IBR based on empirical data primarily from IRAS galaxies, which is consistent with direct measurements and upper limits from TeV γ-ray observations. We have also improved the calculation by including the specific threshold energies for the various photodisintegration interactions in our Monte Carlo calculation. With the new smaller IBR flux, the steepness of the Wien side of the now relatively more important CBR makes their inclusion essential for more accurate results. Our results indicate a significant increase in the propagation time of UHCR nuclei of a given energy over previous results. We discuss the possible significance of this for UHCR origin theory.
Stalking the LREE-enriched component in ureilites

The results of an experiment using progressively more aggressive acid leaches on a LREE-enriched whole-rock sample of Kenna show that the vast majority of the leachable LREE-enriched component in this ureilite is removed by weak (0.04 M and 0.2 M) HNO3, and suggest that this component resides principally on grain surfaces of interstitial phases, rather than in a minor, LREE-enriched mineral. Our best estimate of the Sm-Nd composition of this component is 147Sm/144Nd = 0.112, ϵNd = −8.5, [Nd] = 18 ppm, but neodymium isotopes are incompletely equilibrated. Strontium and Ba are also enriched in this component, but other incompatible elements are not. The olivine + pyroxene residue in this experiment is over-leached relative to what is necessary to remove the leachable LREE-enriched component, and has 147Sm/144Nd = ∼0.33, similar to the most LREE-depleted whole-rock samples of Kenna. This result strengthens the argument that the 3.79 Ga 147Sm/144Nd143Nd/144Nd line defined by whole-rock samples and mineral separates of Kenna, Novo Urei, ALHA 77257 and Goalpara is an isochron, because if it were a line of mixing between 4.55 Ga ultramafic rocks and leachable LREE-enriched component then samples devoid of this component would have 147Sm/144Nd = 0.51 (the composition at which the 3.79 Ga line intersects the 4.55 Ga chondritic evolution line). The 3.79 Ga isochron may record the time of reequilibration of highly LREE-depleted (147Sm/144Nd = 0.51) 4.55 Ga proto-ureilite material with LREE-enriched material. The best candidate for this LREE-enriched material is a COCO2 fluid and the most likely time for its generation was during the event that led to formation of reduction rims on ureilite olivine and pyroxene grains. Although this model has serious difficulties which prevent us from embracing it, we suggest that it offers the most promising lines along which to think about the origin of the LREE-enriched component in ureilites. Acid-leaching experiments have failed to fully reveal the nature of this component and some other method of investigation is needed.
Synthesis of R2R′2C4B8H8 tetracarbon carboranes from (η6-cyclooctatriene)iron(dicarbahexaborane) complexes via mixed-ligand thermal fusion

Abstract Reactions of (R2C2B4H4)Fe(η6-C8H10) complexes with Na+R′2C2B4H−5 salts (R = C2H5, n-C4H9, CH2C6H5; R′ = CH3, C2H5, n-C4H9, CH2C6H5) at 150°C in the absence of solvent gave products of the general formula R2R′2C4B8H8, accompanied in each case by R4C4B8H8 carboranes. 11B, 1H, and 13C NMR Studies of the R2R′2C4B8H8 clusters indicated that each consists of two isomers consistent with the “open” and “closed” geometries identified in earlier work on R4C4B8H8 clusters, and that the isomer ratios do not change over time in solution at room temperature.
On the Design of Wire Rope

In recent work, a design methodology for multi-lay wire strands has been developed. The current paper expands on this earlier work to study wire ropes in which the strand is a basic component. Wire ropes with the three types of cores, independent-wire-rope-core (IWRC), fiber-core (FC), and wire-strand-core (WSC), are considered. This work further generalizes the previously developed linearized theory which, through substantiation with experiment, is felt to be reasonably accurate for most wire rope behavior. The theory is then utilized to examine various parameters in the design of wire ropes.
Highly Unsaturated Cyclobutane Derivatives

1 Introduction 2 1,3-Cyclobutadiene 3 Butalene Chemistry 4 Other C4H4 Isomers 5 More Highly Unsaturated C4 Structures 6 Heterocyclic Analogs 7 Conclusions 8 Acknowledgments Keywords: highly unsaturated cyclobutane derivatives; cyclobutadiene role in aromaticity and antiaromaticity theory; isolable 1,3-cyclobutadienes; cyclobutadiene in synthesis; butalene chemistry; REPE (resonance energy per electron) method to butalene; perfluorination and dramatic effects on reaction energetics; cyclobutyne rearrangements
Synthesis of Vinyl Boronates from Aldehydes by a Practical Boron–Wittig Reaction

A highly stereoselective boron-Wittig reaction between stable and readily accessible 1,1-bis(pinacolboronates) and aldehydes furnishes a variety of synthetically useful di- and trisubstituted vinyl boronate esters.
Evidence for oxygen reduction reaction activity of a Ni(OH)2/graphene oxide catalyst

Oxygen reduction reaction catalysis on a microwave synthesized Ni(OH)2/graphene oxide material was investigated via cyclic voltammetry, rotating disk electrode measurements, chronoamperometry, and electrochemical impedance spectroscopy. Cyclic voltammetry in an 0.5 M alkaline solution indicated that the Ni(OH)2/graphene oxide material possesses significant oxygen reduction reaction activity as evidenced by a peak potential of −310 mV vs. Ag/AgCl. This value was a shift of +110 mV as compared to the unsupported Ni(OH)2 nanoparticles and +90 mV as compared to the graphene oxide support alone. Rotating disk electrode studies show that the limiting current density of the Ni(OH)2/GO catalyst is 1.3 mA cm−2 and the electron transfer number is 3.5. Chronoamperometry demonstrates that the current density attributable to the oxygen reduction reaction on the Ni(OH)2/graphene oxide material sustained a steady state value of 60% of its initial value. Electrochemical Impedance spectroscopy showed that the charge transfer resistance of the Ni(OH)2/graphene oxide catalyst was significantly lower than either the Ni(OH)2 nanoparticles or the graphene oxide support. The electrocatalytic properties of the Ni(OH)2/graphene oxide material are discussed in the context of specific chemical interaction between the Ni(OH)2 nanoparticles and the graphene oxide support.
Economic Effects of "Leveling the Playing Field" in International Trade

This paper uses simple economic theory to examine the effects of various policies that are intended to level the playing field in international trade. That is, when foreign producers are given advantages over domestic producers by government subsidies or other interventions that lower their costs, domestic firms may argue that their own governments should either provide comparable assistance or should protect them from competing with the foreign firms on grounds of fairness. Economic analysis easily shows that granting these requests is usually harmful for the domestic economy as a whole, but that may not prevent such policies from being implemented. Therefore this paper examines what the further effects of such policies may be. The main conclusion that emerges is that policies to level the playing field most often overcompensate those who request them, making them better off than if the playing field had not been tilted against them in the first place.
Policy attitudes, ideology and voting behavior in the 2008 Election

This article examines the impact of policy attitudes and ideology on voting behavior in the 2010 U.S. presidential election. The analysis uses data from the 2008 American National Election Study. The empirical results indicate that the 2008 election should not be regarded as a simple referendum on the George W. Bush presidency. At the same time, voting behavior was not particularly aligned along stark policy divisions; the direct effects of issue attitudes were confined largely to the most sophisticated stratum of the electorate. Finally, liberal-conservative orientations did affect citizens' political attitudes and candidate choices in ways that are fairly unique, compared to other recent elections.
Demethylation of crown ethers, aza crown ethers, and cryptands which have inward‐facing anisole units by lithium aluminum hydride in tetrahydrofuran

Lithium aluminum hydride in tetrahydrofuran is an efficient demethylating reagent combination for mono- and bicyclic polyether compounds which bear intra-annular methoxyaryl groups.
Forward Pion Production in Hadron Collisions at STAR

Measurements are reported of the production of high energy π0 mesons at large pseudorapidity, coincident with charged hadrons at mid-rapidity, for proton+proton and deuteron+gold collisions at s N N = 200 GeV . The p+p cross section for inclusive π0 production follows expectations from next-to-leading order perturbative QCD. A suppression of the back-to-back azimuthal correlations was observed in d+Au, qualitatively consistent with the gluon saturation picture. Experimental uncertainties regarding the inclusive measurement are discussed.
Simulation of unsteady hypersonic combustion around projectiles in an expansion tube

The temporal evolution of combustion flowfields established by the interaction between wedge-shaped bodies and explosive hydrogen-oxygen-nitrogen mixtures accelerated to hypersonic speeds in an expansion tube is investigated. The analysis is carried out using a fully implicit, time-accurate, computational fluid dynamics code that we recently developed to solve the Navier-Stokes equations for a chemically reacting gas mixture. The numerical results are compared with experimental data from the Stanford University expansion tube for two different gas mixtures at Mach numbers of 4.2 and 5.2. The experimental work showed that flow unstart occurred for both the Mach 4.2 cases. These results are reproduced by our numerical simulations and, more significantly, the causes for unstart are explained. For the Mach 5.2 mixtures, the experiments and numerical simulations both produced stable combustion. However, the computations indicate that in one case the experimental data were obtained during the transient phase of the flow; that is, before steady state had been attained.
Effect of flux adjustments on temperature variability in climate models

It has been suggested that “flux adjustments” in climate models suppress simulated temperature variability. If true, this might invalidate the conclusion that at least some of observed temperature increases since 1860 are anthropogenic, since this conclusion is based in part on estimates of natural temperature variability derived from flux-adjusted models. We assess variability of surface air temperatures in 17 simulations of internal temperature variability submitted to the Coupled Model Intercomparison Project. By comparing variability in flux-adjusted vs. non-flux adjusted simulations, we find no evidence that flux adjustments suppress temperature variability in climate models; other, largely unknown, factors are much more important in determining simulated temperature variability. Therefore the conclusion that at least some of observed temperature increases are anthropogenic cannot be questioned on the grounds that it is based in part on results of flux-adjusted models. Also, reducing or eliminating flux adjustments would probably do little to improve simulations of temperature variability.
Classical lattice gauge fields with hard thermal loops

Abstract We propose a formulation of the long-distance dynamics of gauge theories at finite temperature on a lattice in Minkowski space, including the effects of hard thermal loops on the dynamics of the long wavelength modes. Our approach is based on the dual classical limits of quantum fields as waves and particles in the infrared and ultraviolet limits, respectively. It exhibits manifest invariance under space-dependent lattice gauge transformations and conserves Gauss' law.
Value Investing: The Use of Historical Financial Statement Information to Separate Winners from Losers

This paper examines whether a simple accounting-based fundamental analysis strategy, when applied to a broad portfolio of high book-to-market firms, can shift the distribution of returns earned by an investor. I show that the mean return earned by a high book-to-market investor can be increased by at least 7.5% annually through the selection of financially strong high BM firms, while the entire distribution of realized returns is shifted to the right. In addition, an investment strategy that buys expected winners and shorts expected losers generates a 23% annual return between 1976 and 1996, and the strategy appears to be robust across time and to controls for alternative investment strategies. Within the portfolio of high BM firms, the benefits to financial statement analysis are concentrated in small and medium-sized firms, companies with low share turnover, and firms with no analyst following, yet this superior performance is not dependent on purchasing firms with low share prices. A positive relationship between the sign of the initial historical information and both future firm performance and subsequent quarterly earnings announcement reactions suggests that the market initially underreacts to the historical information. In particular, one-sixth of the annual return difference between ex ante strong and weak firms is earned over the four three-day periods surrounding
Binding interaction of HMGB4 with cisplatin-modified DNA.

Proteins in the HMG family are important transcription factors. They recognize cisplatin-damaged DNA lesions with a structure-specific preference and account for more than 70% of all proteins that interact with the cisplatin 1,2-intrastrand d(GpG) cross-link. HMGB4, a new member of the mammalian HMGB protein family expressed preferentially in the testis, was generated recombinantly and its interactions with cisplatin-modified DNA were investigated in vitro. The binding affinities of the two individual DNA-binding domains of HMGB4 to DNA carrying a cisplatin 1,2-intrastrand d(GpG) cross-link are weaker than those of the DNA-binding domains of HMGB1. Full-length HMGB4, however, has a 28-fold stronger binding affinity (Kd = 4.35 nM) for the platinated adduct compared to that of HMGB1 (Kd = 120 nM), presumably because the former lacks a C-terminal acidic tail. The residue Phe37 plays a critical role in stabilizing the binding complex of HMGB4 with the cisplatin-modified DNA, as it does for HMGB1. Hydroxyl radical footprinting analysis of the HMGB4/platinated DNA complex reveals a very different footprinting pattern from that of HMGB1, however, revealing very little binding asymmetry with respect to the platinated lesion. An in vitro repair assay revealed that HMGB4, at 1 µM concentration, interferes with repair of cisplatin 1,2-intrastrand cross-link damage by >90% compared to control, whereas HMGB1 at the same concentration inhibits repair by 45% This repair inhibition capability is highly dependent on both the binding affinity and size of the proteins. The putative role of HMGB4 in the mechanism of action of cisplatin, and especially its potential relevance to the hypersensitivity of testicular germ cell tumors to cisplatin, are discussed.
Nonclairvoyantly scheduling power-heterogeneous processors

Abstract We show that a natural nonclairvoyant online algorithm for scheduling jobs on a power-heterogeneous multiprocessor is bounded-speed bounded-competitive for the objective of flow plus energy.
Business groups and their types

We clarify what business groups are and analyze their various types. We first distinguish business groups from other types of firm networks based on the strategic relationships among companies; business groups are defined as those networks that exhibit unrelated diversification under common ownership. We then separate business groups into three types based on their ownership: family-owned, widely-held, and state-owned. We argue that each type has different agency costs and diversification logics. As a result of these differences, their performance varies, with family-owned business groups outperforming widely-held ones, and these in turn outperforming state-owned business groups.
Distinguished tame supercuspidal representations and odd orthogonal periods

We further develop and simplify the general theory of distinguished tame supercuspidal representations of reductive $p$-adic groups due to Hakim and Murnaghan, as well as the analogous theory for finite reductive groups due to Lusztig. We apply our results to study the representations of ${\rm GL}_n(F)$, with $n$ odd and $F$ a nonarchimedean local field, that are distinguished with respect to an orthogonal group in $n$ variables. In particular, we determine precisely when a supercuspidal representation is distinguished with respect to an orthogonal group and, if so, that the space of distinguishing linear forms has dimension one.
ETHYLENE OXIDATION IN A WELL-STIRRED REACTOR

Ethylene is an important intermediate in the combustion of methane, larger aliphatic hydrocarbons, and aromatics. The detailed ethylene oxidation data set of Thornton, obtained for a well-stirred reactor operated fuel-lean at atmospheric pressure and for temperatures of 1,003 K to 1,253 K, is used as a basis for the comparison of chemical kinetic mechanisms reported in the literature and for the development of a new ethylene oxidation mechanism. The mechanisms examined are those of Westbrook and Pitz and Dagaut et al. These mechanisms indicated that unusually large rates for the vinyl decomposition reaction are required to obtain agreement with the Thornton data set. A new ethylene oxidation mechanism is developed in order to overcome some of the drawbacks of the previous mechanisms. The new mechanism closely simulates the overall rate of loss of ethylene, and the concentration of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6} measured for the stirred reactor. Predictions by this mechanism are dependent on a new high temperature vinyl oxidation route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O, with a branching ratio of 1.4 at 1,053 K to 2.05 at 1,253 K.more » The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction. 143 refs., 8 figs., 5 tabs.« less
PREPARATION OF THIOL ACIDS, THIOL ESTERS AND AMIDES BY REACTIONS OF CARBONYL SULFIDE WITH GRIGNARD REAGENTS

(1995). PREPARATION OF THIOL ACIDS, THIOL ESTERS AND AMIDES BY REACTIONS OF CARBONYL SULFIDE WITH GRIGNARD REAGENTS. Organic Preparations and Procedures International: Vol. 27, No. 3, pp. 361-366.