cssi/SciSciGPT-SciSciNet huggingface dataset:
DotStar: breaking the scalability and performance barriers in parsing regular expressions

Regular expressions (shortened as regexp ) are widely used to parse data, detect recurrent patterns and information, and are a common choice for defining configurable rules for a variety of systems. In fact, many data-intensive applications rely on regexp matching as the first line of defense to perform on-line data filtering. Unfortunately, few solutions can keep up with the increasing data rate and complexity of sets containing hundreds of expressions. In this paper we present DotStar (.*), a complete algorithmic solution and a software tool-chain, that can compile large sets of regexp into an automaton that can take advantage of the vector/SIMD extensions available on many commodity multi-core processors. DotStar relies on several algorithmic innovations to transform the user-provided regexp set into a sequence of manageable intermediate representations. The resulting automaton is both space and time efficient, and can search in a single pass without backtracking. The experimental evaluation, performed on a family of state-of-the-art processors, shows that DotStar can efficiently handle both small sets of regexp, used in protocol parsing, and larger sets designed for Network Intrusion Detection Systems (NIDS), achieving a performance between 1 and 5 Gbit/sec per core.
Second generation multinational operations

(1992). Second generation multinational operations. The Washington Quarterly: Vol. 15, No. 3, pp. 113-131.
Hybrid electric chemical propulsion

Abstract : A spacecraft propulsion concept that uses a combination of electrical energy and chemical energy for thrust is explored using thermodynamic modeling calculations. The essence of this concept consists of adding a carefully chosen amount of O2 or F2 oxidizer to the propellant flow of a conventional H2 electrothermal thruster. A general method is given for selecting the Fuel: oxidizer ratio so as to optimize the thruster performance for any set of mission constraints. Auxiliary propulsion, Chemically augmented electrothermal thrusters, Electric propulsion, Spacecraft propulsion. (mjm)
Preparation of Bicyclic 1,2,4-Trioxanes from γ,δ-Unsaturated Ketones

Treatment of γ,δ-unsaturated ketones with hydrogen peroxide and acid provides a rapid entry into the medicinally important 1,2,4-trioxane structure. Alkene substitution that stabilizes carbocationic intermediates proved to be important for the success of this transformation.
Hook Length Polynomials for Plane Forests of a Certain Type

The original motivation for the study of hook length polynomials was to find a combinatorial proof for a hook length formula for binary trees given by Postnikov, as well as a proof for a hook length polynomial formula conjectured by Lascoux. In this paper, we define the hook length polynomial for plane forests of a given degree sequence type and show that it can be factored into a product of linear forms. Some other enumerative results on forests are also given.
Explaining Opposing Compliance Motivations towards Organizational Information Security Policies

Lack of compliance with organizational information security policies (ISPOs) is a widespread organizational issue that increasingly bears very large direct and qualitative costs. The purpose of our study was to explain the causes of tensions within organizations to either comply with new ISPOs or react negatively against them. To do so, we proposed an innovative model, which pits organizational control theory, as a force that explains ISPO compliance, against reactance theory, as a force that explains ISPO noncompliance and anger toward organizations. To test the model, we used a sample of 320 working professionals in a variety of industries to examine the likely organizational outcomes when a new ISPO is delivered to employees in the form of a typical memo sent throughout an organization. We found support for our newly proposed model, which is an important contribution to research on organizational security practices.
Auditor Switches in the Pre‐ and Post‐Enron Eras: Risk or Realignment?

ABSTRACT: Using a comprehensive sample of switches to and from the largest auditors (i.e., the Big N), we examine empirically whether the sensitivity of Big N auditor switches to client risk and misalignment changed between the pre‐ and post‐Enron periods. Although we find an increase in the sensitivity to client misalignment, the sensitivity to client risk generally decreases. The results are consistent with Big N auditors rebalancing their audit client portfolios in response to post‐Enron capacity constraints arising from the supply of former Arthur Andersen clients and the audit demands imposed by Sarbanes‐Oxley rather than increasing their sensitivity to client risk. Additional evidence indicates that the Sarbanes‐Oxley demand shock did not affect Big N auditor switching behavior incremental to the initial Andersen supply shock.
Evolution in Mendelian populations

The frequency of a given gene in a population may be modified by a number of conditions including recurrent mutation to and from it, migration, selection of various sorts and, far from least in importance, were chance variation
School choice through relocation: evidence from the Washington, D.C. area

Abstract In this paper I show how the monetary value parents place on school quality may be inferred from their residential location choice. The method identifies parental valuation of school quality from the differential effect of school quality on residential choices of households with and without children. I implement the method with 1990 Census data for Washington, D.C. For whites, households with children are willing to pay $1800 more per year for schools generating a 100 SAT point advantage. While some evidence indicates African-American choices are negatively associated with school quality, additional evidence suggests African-American households may be constrained in available choices.
New algorithms for generating Conway polynomials over finite fields

Abstract Arithmetic in a finite field of prime characteristic p normally employs an irreducible polynomial in Z p [X] . A particular class of irreducible polynomials, generally known as Conway polynomials, provides a means for representing several finite fields of characteristic p in a compatible manner. Conway polynomials are used in computational algebra systems such as GAP and Magma to represent finite fields. The generation of the Conway polynomial for a particular finite field has previously been done by an often expensive brute force search. We present two new algorithms for generating Conway polynomials that avoid the brute force search. We have implemented one of these algorithms in Magma and present numerous new Conway polynomials generated by our implementation.
Giant low-temperature piezoresistance effect in AlAs two-dimensional electrons

We present piezoresistance measurements in modulation doped AlAs quantum wells where the two-dimensional electron system occupies two conduction band valleys with elliptical Fermi contours. Our data demonstrate that, at low temperatures, the strain gauge factor (the fractional change in resistance divided by the sample’s fractional length change) in this system exceeds 10 000. Moreover, in the presence of a moderate magnetic field perpendicular to the plane of the two-dimensional system, gauge factors up to 56 000 can be achieved. The piezoresistance data can be explained qualitatively by a simple model that takes into account intervalley charge transfer.
Robust PCA With Partial Subspace Knowledge

In recent work, robust Principal Components Analysis (PCA) has been posed as a problem of recovering a low-rank matrix ${\bf L}$ and a sparse matrix ${\bf S}$ from their sum, ${\bf M}:= {\bf L} + {\bf S}$ and a provably exact convex optimization solution called PCP has been proposed. This work studies the following problem. Suppose that we have partial knowledge about the column space of the low rank matrix ${\bf L}$ . Can we use this information to improve the PCP solution, i.e., allow recovery under weaker assumptions? We propose here a simple but useful modification of the PCP idea, called modified-PCP, that allows us to use this knowledge. We derive its correctness result which shows that, when the available subspace knowledge is accurate, modified-PCP indeed requires significantly weaker incoherence assumptions than PCP. Extensive simulations are also used to illustrate this. Comparisons with PCP and other existing work are shown for a stylized real application as well. Finally, we explain how this problem naturally occurs in many applications involving time series data, i.e., in what is called the online or recursive robust PCA problem. A corollary for this case is also given.
Vacuum Choices and the Predictions of Inflation

In the presence of a short-distance cutoff, the choice of a vacuum state in an inflating, non-de Sitter universe is unavoidably ambiguous. The ambiguity is related to the time at which initial conditions for the mode functions are specified and to the way in which the expansion of the universe affects those initial conditions. In this paper we study the imprint of these uncertainties on the predictions of inflation. We parametrize the most general set of possible vacuum initial conditions by two phenomenological variables. We find that the power spectrum generated receives an oscillatory correction, the amplitude of which is proportional to the Hubble parameter over the cutoff scale. In order to further constrain the phenomenological parameters that characterize the vacuum definition, we study gravitational particle production during different cosmological epochs.
A comparison of simulated and analytic major merger counts

We use large volume, high resolution, N-body simulations of 3 different ΛCDM models, with different clustering strengths, to generate dark matter halo merging histories. Over the reliable range of halo masses, roughly galaxy groups to rich clusters of galaxies, we quantify the number density of major mergers for two different time intervals and compare with analytic predictions based on the extended Press-Schechter (1974) theory.
The role of an electromagnetic environment model in spectrum management

The role of an electromagnetic (EM) environment model is spectrum management is developed. Spectrum management is traced from electromagnetic compatibility (EMC) considerations in international agreements through related domestic law to the fundamental spectrum management procedures -- allocation, allotment, and assignment. The need for a model of the EM environment is derived from requirements of allocation, allotment, and assignment proceedings. Data elements required to support an EM environment model for spectrum management purposes are reviewed. An outline and derivation of a general EM environment model is given. The ways systems respond to the EM environment are cataloged and reviewed so that specific applications of an EM environment model are readily apparent. Applications and limitations of current models are discussed.
The thermodynamic properties of quinoline and isoquinoline

Abstract Measurements leading to the calculation of the ideal-gas thermodynamic properties for quinoline and isoquinoline are reported. Thermodynamic and thermophysical properties were determined by adiabatic heat-capacity calorimetry, comparative ebulliometry, densitometry, and combustion calorimetry. Vibrational spectral frequencies for quinoline and isoquinoline were assigned. Entropies and enthalpies for the ideal-gas state from the calorimetric measurements and from the vibrational assignments were derived and compared. Entropies, enthalpies, and Gibbs energies of formation, were derived at selected temperatures between T → 0 and T = 1000 K. New density measurements for benzene are reported.
Bank regulation and international financial stability: A case against the 2006 Basel framework for controlling tail risk in trading books ☆

Abstract In attempting to promote international financial stability, the Basel Committee on Banking Supervision (2006) provided a framework that sought to control the amount of tail risk that large banks around the world would take in their trading books relative to their corresponding minimum capital requirements. However, many of these banks suffered significant trading losses during the recent financial crisis. Our paper examines whether the Basel framework allowed banks to take substantive tail risk in their trading books without a capital requirement penalty. We find that it allowed banks to do so and that its minimum capital requirements can be notably procyclical. Hence, focusing on the way the Basel framework sought to control the amount of tail risk in trading books relative to their corresponding minimum capital requirements, our paper supports the view that it was not properly designed to promote financial stability. We also discuss alternative regulatory frameworks that would potentially be more effective than the Basel framework in preventing banks from taking substantive tail risk in their trading books without a capital requirement penalty.
Pediatric Medical Home: Foundations, Challenges, and Future Directions

The medical home concept has been in existence since the late 1960s and has recently been significantly broadened to encompass comprehensive primary care for all patient populations throughout the lifespan. This article provides (1) a review of the foundations and evolution of the medical home concept; (2) an analysis of patient/family, provider, and systemic challenges to developing an effective pediatric medical home particularly in relation to children's mental health needs; and (3) a discussion of future directions for its further adoption and successful implementation.
Effect of various approximations on predicted progressive failure in plain weave composites

Three-dimensional finite element analysis was used to simulate progressive failure of a plain weave composite subjected to in-plane extension. The loading was parallel to one of the tow directions. The effects of various characteristics of the finite element model on predicted behavior were examined. The predicted behavior was found to be sensitive to quadrature order, mesh refinement and the material degradation model. Also the sensitivity of the predictions to the tow waviness was studied. The predicted strength decreased considerably with increased waviness. More numerical studies and comparisons with experimental data are needed to establish reliable guidelines for accurate progressive failure prediction.
The Host Galaxy and the Extended Emission-Line Region of the Radio Galaxy 3C 79

We present extensive ground-based spectroscopy and HST imaging of 3C 79, an FR II radio galaxy associated with a luminous extended emission-line region (EELR). Surface brightness modeling of an emission-line-free HST R-band image reveals that the host galaxy is a massive elliptical with a compact companion 0.8'' away and 4 mag fainter. The host galaxy spectrum is best described by an intermediate-age (1.3 Gyr) stellar population (4% by mass), superimposed on a 10 Gyr old population and a power law (αλ = − 1.8); the stellar populations are consistent with supersolar metallicities, with the best fit given by the 2.5 Z☉ models. We derive a dynamical mass of 4 × 1011 M☉ within the effective radius from the velocity dispersion. The EELR spectra clearly indicate that the EELR is photoionized by the hidden central engine. Photoionization modeling shows evidence that the gas metallicity in both the EELR and the nuclear narrow-line region is mildly subsolar (0.3-0.7 Z☉), significantly lower than the supersolar metallicities deduced from typical active galactic nuclei in the Sloan Digital Sky Survey. The more luminous filaments in the EELR exhibit a velocity field consistent with a common disk rotation. Fainter clouds, however, show high approaching velocities that are uncoupled from this apparent disk rotation. The striking similarities between this EELR and the EELRs around steep-spectrum radio-loud quasars provide further evidence for the orientation-dependent unification schemes. The metal-poor gas is almost certainly not native to the massive host galaxy. We suggest that the close companion galaxy could be the tidally stripped bulge of a late-type galaxy that is merging with the host galaxy. The interstellar medium of such a galaxy is probably the source for the low-metallicity gas in 3C 79.
Edge-disjoint paths revisited

The approximability of the maximum edge-disjoint paths problem (EDP) in directed graphs was seemingly settled by an Ω(m1/2 - ϵ)-hardness result of Guruswami et al. [2003], and an O(√m) approximation achievable via a natural multicommodity-flow-based LP relaxation as well as a greedy algorithm. Here m is the number of edges in the graph. We observe that the Ω(m1/2 - ϵ)-hardness of approximation applies to sparse graphs, and hence when expressed as a function of n, that is, the number of vertices, only an Ω(n1/2- ϵ)-hardness follows. On the other hand, O(√m)-approximation algorithms do not guarantee a sublinear (in terms of n) approximation algorithm for dense graphs. We note that a similar gap exists in the known results on the integrality gap of the flow-based LP relaxation: an Ω(√n) lower bound and O(√m) upper bound. Motivated by this discrepancy in the upper and lower bounds, we study algorithms for EDP in directed and undirected graphs and obtain improved approximation ratios. We show that the greedy algorithm has an approximation ratio of O(min(n2/3, √m)) in undirected graphs and a ratio of O(min(n4/5, √m)) in directed graphs. For acyclic graphs we give an O(√n ln n) approximation via LP rounding. These are the first sublinear approximation ratios for EDP. The results also extend to EDP with weights and to the uniform-capacity unsplittable flow problem (UCUFP).
Dynamic Correlation Analysis of Asian Stock Markets

This paper examines the stock market linkages within the Asia-Pacific region and between Asian markets and the U.S. market over the period of January 2000 to June 2010, employing the dynamic conditional correlation GARCH model. Our results show that there exist very high correlations among the stock markets during the 2008 financial crisis. Therefore, consistent with the finding in literature, there are no diversification benefits during the financial crisis. However, our results show that there are still substantial opportunities for global investors to improve the risk-return performance between China and other markets during the sample period. In addition, we find evidence that the U.S. market significantly affects the stock markets in the Asia-Pacific region. Using T-GARCH model, there is a strong evidence of an asymmetric effect on conditional variance except stock markets in China and Malaysia.
SN 2006jc: A Wolf-Rayet Star Exploding in a Dense He-rich Circumstellar Medium

We present optical photometry and spectra of the peculiar Type Ib supernova (SN) 2006jc. Strong and relatively narrow He I emission lines indicate the progenitor star exploded inside a dense circumstellar medium (CSM) rich in He. An exceptionally blue apparent continuum persists from our first spectrum obtained 15 days after discovery through our last spectrum ~1 month later. Based on the presence of isolated Fe II emission lines, we interpret the blue "continuum" as blended, perhaps fluorescent, Fe emission. One or two of the reddest He I line profiles in our spectra are double-peaked, suggesting that the CSM has an aspherical geometry. The He I lines that are superposed on the blue continuum show P Cygni profiles, while the redder He I lines do not, implying that the blue continuum also originates from an asymmetric mass distribution. The He-rich CSM, aspherical geometry, and line velocities indicate that the progenitor star was a WNE Wolf-Rayet (W-R) star. A recent (2 years before the SN), coincident, luminous outburst similar to those seen in luminous blue variables (LBVs) is the leading candidate for the dense CSM. Such an eruption associated with a W-R star has not been seen before, indicating that the progenitor star may have recently transitioned from the LBV phase. We also present unpublished spectral and photometric data on SN 2002ao, which, along with SN 1999cq, is very similar to SN 2006jc. We propose that these three objects may represent a new and distinct class of SNe arising from W-R progenitors surrounded by a dense CSM.
Why Do I Hate Thee? Conflict Misperceptions and Intergroup Mistrust

Members of partisan social groups often exaggerate how much their own opinions differ from those of their rivals. In the present two studies, partisans estimated their own and their rivals' attitudes toward different issues related to the social conflict and also made a variety of evaluative judgments about their own and the rival group. The authors found that (a) partisans perceive more disagreement with their rivals about values that are central to their own sides' ideological position than those that are central to their rivals' position and (b) perceptions of disagreement about the partisans' own central values are what predicts partisans' global evaluations of members of the outgroup (e.g., disliking, trait stereotypes, perceived similarity). Furthermore, partisans believed their adversaries were motivated by an opposition to the partisans' own core values rather than by promotion of the adversaries' core values. Discussion concentrates on the theoretical and applied implications of these findings.
Gamma Rays from Single-Lobe Supernova Explosions

Multidimensional simulations of the neutrino-driven mechanism behind core-collapse supernovae have long shown that the explosions from this mechanism would be asymmetric. Recently, detailed core-collapse simulations have shown that the explosion may be strongest in a single direction. We present a suite of simulations modeling these "single-lobe" supernova explosions of a 15 M☉ red supergiant star, focusing on the effect these asymmetries have on the gamma-ray emission and the mixing in the explosion. We discuss how these asymmetries in the explosion mechanism might explain many of the observed "asymmetries" of supernovae, focusing on features of both supernova 1987A and the Cassiopeia A supernova remnant. In particular, we show that single-lobe explosions provide a promising solution to the redshifted iron lines of supernova 1987A. We also show that the extent of mixing for explosive burning products depends sensitively on the angular profile of the velocity asymmetry and may be much more extensive than previously assumed.
A priority assessment multi-criteria decision model for human spaceflight mission planning at NASA

Analog missions are real-life, Earth-based science missions whose purpose is to help understand the operations, techniques, and technologies required to perform similar tasks during future human spaceflight missions. The goal of performing an analog mission is to prepare crewmembers and support teams for future space missions in a low risk, low-cost environment. Vehicle, habitat, and surface terrain simulators are used to test hardware, operations, and tasks repeatedly for analog missions. This study presents a multi-criteria decision making model that was developed for the Integrated Human Exploration Mission Simulation Facility project at Johnson Space Center to assess the priority of a set of human spaceflight mission simulators. The proposed framework integrates subjective judgments derived from the analytic hierarchy process with entropy data into a preference model to prioritize five mission simulators for the human exploration of Mars.
Computational explorations of mechanisms and ligand-directed selectivities of copper-catalyzed Ullmann-type reactions.

Computational investigations of ligand-directed selectivities in Ullmann-type coupling reactions of methanol and methylamine with iodobenzene by β-diketone- and 1,10-phenanthroline-ligated CuI complexes are reported. Density functional theory calculations using several functionals were performed on both the nucleophile formation and aryl halide activation steps of these reactions. The origin of ligand-directed selectivities in N- versus O-arylation reactions as described in a previous publication (J. Am. Chem. Soc. 2007, 129, 3490−3491) were studied and explained. The selectivities observed experimentally are derived not from initial CuI(nucleophile) complex formation but from the subsequent steps involving aryl halide activation. The arylation may occur via single-electron transfer (SET) or iodine atom transfer (IAT), depending on the electron-donating abilities of the ligand and nucleophile. Mechanisms involving either oxidative addition/reductive elimination or σ-bond metathesis are disfavored. SET mec...
Stability analysis of network-based cooperative resource allocation strategies

Resource allocation involves deciding how to divide a resource of limited availability among multiple demands in a way that optimizes current objectives. In this brief paper we focus on one type of distributed resource allocation problem where via an imperfect communication network multiple processors can share the load presented by multiple task types. We introduce asynchronous ''cooperative'' resource allocation strategies, and show that they lead to a bounded cumulative demand.
Heavy Quarkonia — A review of the experimental status

Abstract A review of the present status of the spectroscopy of heavy quarkonia ( b, c ) is presented.
On finite congruence-simple semirings

Abstract In this paper, we describe finite, additively commutative, congruence simple semirings. The main result is that the only such semirings are those of order 2, zero-multiplication rings of prime order, matrix rings over finite fields, ones with trivial addition, and those that are additively idempotent.
Extensions of estimation methods using the EM algorithm

Abstract The EM algorithm described by Dempster, Laid, and Rubin (1977) is reviewed with the purpose of clarifying several misconceptions in the statistical and econometric literature. The clarifications lead to several applications of the algorithm to models that have appeared to be less tractable. The relationship between the EM algorithm and the method of scoring is also explained, providing estimators of the score and the information from the EM algorithm. The EM algorithm is extended to missing-data problems and an estimation method based on simulations.
On the environmental, economic and budgetary impacts of fossil fuel prices: A dynamic general equilibrium analysis of the Portuguese case

Abstract This paper examines the influence of fossil fuel prices on carbon dioxide emissions, economic activity, and the public sector account in Portugal. It uses a dynamic general equilibrium model which highlights the mechanisms of endogenous growth and includes a detailed modeling of the public sector. Fuel price scenarios are based on forecasts by the US Department of Energy (DOE-US), the International Energy Agency (IEA-OECD) and IHS Global Insight Inc. The differences in relative fuel prices among the three scenarios lead to substantially different environmental impacts. Higher fuel prices in the DOE-US scenario lead to a 10.2% reduction in the policy effort required to meet the EU 2020 emission targets, while relative price changes in the IEA-OECD scenario result in a 19.2% increase in the required policy effort and decreasing fuel prices increase the emissions deficit by 95.9% under the IHS scenario. In terms of the long term economic impacts, our results suggest a 2.2% reduction in GDP in the DOE-US scenario and 1.9% in the IEA-OECD scenario and an increase of 1.4% in the IHS scenario. As to the budgetary impact, higher fuel prices lead to lower tax revenues, which, coupled with a reduction in public spending translates to lower public deficits. From a methodological perspective, our results highlight the importance of the mechanisms of endogenous growth. A scenario of higher fuel prices would, under exogenous economic growth assumptions, result in larger baseline emissions growth, substantially smaller economic effects, and rather different budgetary effects. From a policy perspective, our results highlight the importance of fossil fuel prices in defining the level of policy intervention required for compliance with international and domestic climate change legislation.
Metal–metalloporphyrin frameworks: a resurging class of functional materials

This review presents comprehensively recent progress in metal–metalloporphyrin frameworks (MMPFs) with an emphasis on versatile functionalities. Following a brief introduction of basic concepts and the potential virtues of MMPFs, we give a snapshot of the historical perspective of MMPFs since 1991. We then summarize four effective strategies implemented frequently to construct prototypal MMPFs. MMPFs represent a resurging class of promising functional materials, highlighted with diverse applications including guest-molecule adsorption and separation, catalysis, nano-thin films and light-harvesting.
MESOSCOPIC FLUCTUATIONS OF THE GROUND-STATE SPIN OF A SMALL METAL PARTICLE

We study the statistical distribution of the ground-state spin for an ensemble of small metallic grains, using a random-matrix toy model. Using the Hartree-Fock approximation, we find that for interaction strengths well below the Stoner criterion there is already an appreciable probability that the ground state has a spin other than zero or one half. Possible relations to experiments are discussed.
Cleavage of DNA by nickel complexes

Abstract The cleavage of plasmid DNA (pUB110) by several square planar nickel(II) complexes in the presence of either magnesium monoperoxyphthalic acid (MPPA) or iodosylbenzene was investigated. At 25°C and near neutral pH, Ni(salen) (100 μM) or Ni(CR) 2+ (100 μM) promoted complete conversion of supercoiled plasmid to the nicked circular form in 5 min with iodosylbenzene (0.1 g/ml) as oxidant or in 2.5 h with MPPA (1 mM) as oxidant (salen = bis(salicylaldehyde)ethylenediimine, CR = 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca- 1(17),2,11,13,15-pentaene). No cleavage was observed under similar conditions with Ni(cyclam) 2+ , Ni(dioxocyclam), Ni(TPP) or Ni(NO 3 ) 2 (cyclam = 1,4,8,11-tetraazacyclotetradecane, dioxocyclam = 1,4,8,11-tetraazacyclotetradecane- 5,7-dione, TPP=5,10,15,20-tetraphenyl-21 H ,23 H -porphine). Possible roles for the nickel complexes in promoting DNA cleavage are discussed.
On reducing broadcast redundancy in ad hoc wireless networks

Unlike in a wired network, a packet transmitted by a node in an ad hoc wireless network can reach all neighbours. Therefore, the total number of transmissions (forward nodes) is generally used as the cost criterion for broadcasting. The problem of finding the minimum number of forward nodes is NP-complete. Among various approximation approaches, dominant pruning by H. Lim and C. Kim (2001) utilizes 2-hop neighbourhood information to reduce redundant transmissions. In this paper, we analyze some deficiencies of the dominant pruning algorithm and propose two better approximation algorithms: total dominant pruning and partial dominant pruning. Both algorithms utilize 2-hop neighbourhood information more effectively to reduce redundant transmissions. Simulation results of applying these two algorithms show performance improvements compared with the original dominant pruning. In addition, two termination criteria are discussed and compared through simulation.
Stereotactic diagnosis and treatment of pineal region tumours and vascular malformations.

Diagnosis and treatment of tumours and vascular malformations in the region of the pineal gland continue to challenge the neurosurgeon's skill. Due to vital vascular and brain structures in the region, microsurgical removal of such masses is often impossible. During the past nine years, we have managed 47 patients with pineal region mass lesions using stereotactic techniques for diagnosis and treatment. In order to determine further therapeutic options, 15 patients underwent stereotactic biopsy of pineal region tumours. In all patients, the histologic diagnosis obtained served to direct further therapy. Thirty-two patients were treated with stereotactic radiosurgery for pineal region tumours or vascular malformations. During the follow-up period, one patient underwent delayed microsurgical resection of a midbrain angiographically occult vascular malformation. No other patient required microsurgical intervention after a stereotactic procedure. In all 47 patients, no significant morbidity or mortality occurred after stereotactic biopsy or radiosurgery. Empiric treatment of pineal region tumours with fractionated radiation therapy is no longer warranted. Image-guided stereotactic technology provides a safe method to accurately diagnose and effectively treat selected pineal region masses. After definitive histologic diagnosis is established, proper treatment may be instituted. Options for treatment include stereotactic radiosurgery for selected tumours and vascular malformations, microsurgical resection of benign tumours or fractionated external beam radiation therapy for malignant germ cell and glial tumours. Stereotactic surgery should be the first option in the diagnosis and therapy of pineal region masses.
Rational expectations in limited dependent variable models

Abstract The appropriate characterizations of rational expectations solutions in one-limit and two-limit models are derived. We prove the existence and uniqueness of the rational expectations solution for each model. Our analysis is general without imposing serial independence and the parametric distributional assumption.
TiO2 accessory minerals: coarsening, and transformation kinetics in pure and doped synthetic nanocrystalline materials

Abstract In this paper we review the distribution, composition and relationships among the four TiO2 minerals [anatase, brookite, rutile and TiO2 (B)] and discuss the possible importance of a fifth phase, TiO2 II, which has a stability field at high pressure. We also consider the geological application of kinetic data for the anatase to rutile transformation. Previous experimental studies of this reaction were carried out between 610° and 1000°C. Extrapolation using reported rate laws over geologic time results in predicted and natural distribution patterns that are broadly consistent. Experimental data reported here show enhanced anatase-rutile transformation rates if the anatase is very finely crystalline. We attribute the rapid transformation in these materials to a lower activation energy (∼ 60 kcal mol−1 compared to 80–148 kcal mol−1 reported previously). Rapid coarsening accompanies early, rapid transformation. Declining coarsening rates correlate strongly with declining transformation rates and extrapolate to those calculated from published data for coarsely crystalline material. The first-formed crystals of rutile have average volumes approximately eight times greater than those of coexisting anatase, suggesting that anatase must achieve a critical particle size before it transforms to rutile. Dopants can affect both coarsening and transformation rates. Y (1%) retards both coarsening of anatase and its transformation to rutile. However, Cr and Ta have very little effect on coarsening rates but significantly reduce transformation rates. Cr in anatase lowers both the transformation activation energy (∼ 47 kcal mol−1) and the frequency factor (∼ 1011 hr−1). Together these result in comparable transformation rates at temperatures ∼ 50°C higher than in pure anatase; Ta exerts a similar effect. The distribution of the impurities (within particles vs. on the surface) may largely explain differences between Y and Ta or Cr. Results suggest that quantification of the dependence of the transformation kinetics on impurities may allow the interpretation of anatase-rutile distribution patterns to provide time-temperature information in low-grade metasediments.
Stability of Massive Cosmological Gravitons

We analyze the physics of massive spin-2 fields in (A)dS backgrounds and exhibit that: The theory is stable only for masses m2⩾2Λ/3, where the conserved energy associated with the background timelike Killing vector is positive, while the instability for m^2<2Λ/3 is traceable to the helicity 0 energy. The stable, unitary, partially massless theory at m^2=2Λ/3 describes 4 propagating degrees of freedom, corresponding to helicities (±2,±1) but contains no 0 helicity excitation.
Studying melanin and lipofuscin in RPE cell culture models

The retinal pigment epithelium contains three major types of pigment granules; melanosomes, lipofuscin and melanolipofuscin. Melanosomes in the retinal pigment epithelium (RPE) are formed during embryogenesis and mature during early postnatal life while lipofuscin and melanolipofuscin granules accumulate as a function of age. The difficulty in studying the formation and consequences of melanosomes and lipofuscin granules in RPE cell culture is compounded by the fact that these pigment granules do not normally occur in established RPE cell lines and pigment granules are rapidly lost in adult human primary culture. This review will consider options available for overcoming these limitations and permitting the study of melanosomes and lipofuscin in cell culture and will briefly evaluate the advantages and disadvantages of the different protocols.
Motion estimation performance models with application to hardware error tolerance

The progress of VLSI technology towards deep sub-micron feature sizes, e.g., sub-100 nanometer technology, has created a growing impact of hardware defects and fabrication process variability, which lead to reductions in yield rate. To address these problems, a new approach, system-level error tolerance (ET), has been recently introduced. Considering that a significant percentage of the entire chip production is discarded due to minor imperfections, this approach is based on accepting imperfect chips that introduce imperceptible/acceptable system-level degradation; this leads to increases in overall effective yield. In this paper, we investigate the impact of hardware faults on the video compression performance, with a focus on the motion estimation (ME) process. More specifically, we provide an analytical formulation of the impact of single and multiple stuck-at-faults within ME computation. We further present a model for estimating the system-level performance degradation due to such faults, which can be used for the error tolerance based decision strategy of accepting a given faulty chip. We also show how different faults and ME search algorithms compare in terms of error tolerance and define the characteristics of search algorithm that lead to increased error tolerance. Finally, we show that different hardware architectures performing the same metric computation have different error tolerance characteristics and we present the optimal ME hardware architecture in terms of error tolerance. While we focus on ME hardware, our work could also applied to systems (e.g., classifiers, matching pursuits, vector quantization) where a selection is made among several alternatives (e.g., class label, basis function, quantization codeword) based on which choice minimizes an additive metric of interest.
First principles study of carbon monoxide adsorption on zirconia-supported copper

Abstract We have calculated the adsorption energy of carbon monoxide on a monolayer of copper adsorbed on the (1 1 1) face of cubic zirconia. For the bulk oxide, we compute the structural parameters of cubic, tetragonal, and monoclinic ZrO2 and obtain good agreement with experimental parameters. We also analyze the structural relaxation of the stoichiometric, oxidized and reduced (1 1 1) surfaces of cubic zirconia (c-ZrO2). For adsorption of copper on stoichiometric c-ZrO2, we find that the preferred binding site is atop the terminal oxygen atom, favored by 0.4 eV over other high symmetry sites. Charge density rearrangement reveals that adsorption on the oxide support causes a depletion of charge from the Cu dz2 orbitals. Consequently, CO adsorption on zirconia-supported copper is significantly stronger than CO adsorption on clean c-ZrO2 or clean Cu(1 0 0).
Introducing a mixed-valent dirhodium(II,III) catalyst with increased stability in C–H amination

A new mixed-valent Rh2II,III dimer, [Rh2(espn)2Cl] (espn2− = α,α,α′,α′-tetramethyl-1,3-benzenedipropanamidate), is reported. This compound readily dissociates Cl− at low concentrations in solution to form the active [Rh2(espn)2]+ catalyst, which performs intramolecular C–H amination with TONs > 1400. This work expands the scope of Rh2II,III dimers to nitrenoid chemistry.
The twisted top

We describe a new type of top, the twisted top, obtained by appending a cocycle to the Lie–Poisson bracket for the charged heavy top, thus breaking its semidirect product structure. The twisted top has an integrable case that corresponds to the Lagrange (symmetric) top. We give a canonical description of the twisted top in terms of Euler angles. We also show by a numerical calculation of the largest Lyapunov exponent that the Kovalevskaya case of the twisted top is chaotic.
Effects of Finite-Precision Arithmetic on Interior-Point Methods for Nonlinear Programming

We show that the effects of finite-precision arithmetic in forming and solving the linear system that arises at each iteration of primal-dual interior-point algorithms for nonlinear programming are benign, provided that the iterates satisfy centrality and feasibility conditions of the type usually associated with path-following methods. When we replace the standard assumption that the active constraint gradients are independent by the weaker Mangasarian--Fromovitz constraint qualification, rapid convergence usually is attainable, even when cancellation and roundoff errors occur during the calculations. In deriving our main results, we prove a key technical result about the size of the exact primal-dual step. This result can be used to modify existing analysis of primal-dual interior-point methods for convex programming, making it possible to extend the superlinear local convergence results to the nonconvex case.
Comparison of free energy methods for molecular systems

We present a detailed comparison of computational efficiency and precision for several free energy difference (DeltaF) methods. The analysis includes both equilibrium and nonequilibrium approaches, and distinguishes between unidirectional and bidirectional methodologies. We are primarily interested in comparing two recently proposed approaches, adaptive integration, and single-ensemble path sampling to more established methodologies. As test cases, we study relative solvation free energies of large changes to the size or charge of a Lennard-Jones particle in explicit water. The results show that, for the systems used in this study, both adaptive integration and path sampling offer unique advantages over the more traditional approaches. Specifically, adaptive integration is found to provide very precise long-simulation DeltaF estimates as compared to other methods used in this report, while also offering rapid estimation of DeltaF. The results demonstrate that the adaptive integration approach is the best overall method for the systems studied here. The single-ensemble path sampling approach is found to be superior to ordinary Jarzynski averaging for the unidirectional, "fast-growth" nonequilibrium case. Closer examination of the path sampling approach on a two-dimensional system suggests it may be the overall method of choice when conformational sampling barriers are high. However, it appears that the free energy landscapes for the systems used in this study have rather modest configurational sampling barriers.
Equilibration of an Atmosphere by Adiabatic Eddy Fluxes

AbstractA major question for climate studies is to quantify the role of turbulent eddy fluxes in maintaining the observed atmospheric mean state. Both the equator-to-pole temperature gradient and the static stability of the extratropical atmosphere are set by a balance between these eddy fluxes and the radiative forcing. Much attention has been paid to the adjustment of the isentropic slope, which relates the static stability and the meridional temperature gradient. It is often argued that the extratropical atmosphere always equilibrates such that isentropes leaving the surface in the subtropics reach the tropopause near the poles. However, recent work challenged this argument. This paper revisits scaling arguments for the equilibrated mean state of a dry atmosphere, which results from a balance between the radiative forcing and the along-isentropic eddy heat flux. These arguments predict weak sensitivity of the isentropic slope to changes in the radiative forcing, consistent with previous results. Large ...
Astrophysical black holes as natural laboratories for fundamental physics and strong-field gravity

Astrophysical tests of general relativity belong to two categories: 1) “internal”, i.e. consistency tests within the theory (for example, tests that astrophysical black holes are indeed described by the Kerr solution and its perturbations), or 2) “external”, i.e. tests of the many proposed extensions of the theory. I review some ways in which astrophysical black holes can be used as natural laboratories for both “internal” and “external” tests of general relativity. The examples provided here (ringdown tests of the black hole “no-hair” theorem, bosonic superradiant instabilities in rotating black holes and gravitational-wave tests of massive scalar-tensor theories) are shamelessly biased towards recent research by myself and my collaborators. Hopefully this colloquial introduction aimed mainly at astrophysicists will convince skeptics (if there are any) that space-based detectors will be crucial to study fundamental physics through gravitational-wave observations.
Inflation targeting, flexible exchange rates and inflation convergence

Using a disaggregated level Consumer Price Index (CPI) data, this article compares convergence properties of regional inflation rates in a small open economy, Turkey, between pre-inflation-targeting and inflation-targeting periods, where the latter also corresponds to a flexible exchange rate regime. It is found that during the inflation-targeting period, Turkish regional inflation rates have converged to each other in terms of CPI groups with relatively nontradable components, while they have diverged from each other in terms of CPI groups with relatively tradable components. Since a common and sound monetary policy among the regions of a country is supposed to have a convergence effect on regional inflation rates according to the conventional wisdom, the results for CPI groups with relatively tradable components require further attention and have significant policy implications, especially for inflation-targeting countries using flexible exchange rate regimes.
Cause and effects of poison pill adoptions by spinoff units

Abstract We find that units are more likely to adopt poison pills at the time of a spinoff if their parents have anti-takeover provisions in place. In addition, the probability that a spinoff unit adopts a poison pill is negatively related to outside block ownership, but positively related to the size of the unit, institutional ownership, industry takeover activities, and relative industry market-to-book ratio. Units that adopted poison pills elicit a strong negative market response at the time of the spinoff, which implies that investors may believe the pills could prevent the units from being acquired. Despite the initial negative market response, abnormal long-run returns are higher among units that implement poison pills before the spinoff is executed than among units that do not. Moreover, we find that the units’ adoption of poison pills does not reduce their likelihood of being acquired, which suggests that the pills may be intended to increase bargaining power rather than prevent takeovers, and could explain the more favorable long-run abnormal returns.