cssi/SciSciGPT-SciSciNet huggingface dataset:
MODELING SELECTIVE PERCEPTION OF COMPLEX, NATURAL SCENES

Computational modeling of the human visual system is of current interest to developers of artificial vision systems, primarily because a biologically-inspired model can offer solutions to otherwise intractable image understanding problems. The purpose of this study is to present a biologically-inspired model of selective perception that augments a stimulus-driven approach with a high-level algorithm that takes into account particularly informative regions in the scene. The representation is compact and given in the form of a topographic map of relative perceptual conspicuity values. Other recent attempts at compact scene representation consider only low-level information that codes salient features such as color, edge, and luminance values. The previous attempts do not correlate well with subjects' fixation locations during viewing of complex images or natural scenes. This study uses high-level information in the form of figure/ground segmentation, potential object detection, and task-specific location bias. The results correlate well with the fixation densities of human viewers of natural scenes, and can be used as a preprocessing module for image understanding or intelligent surveillance applications.
Three-Dimensional (3D) Microstructure Visualization and Finite Element Modeling of the Mechanical Behavior of Heterogeneous Materials

A serial sectioning process was used to develop a three-dimensional (3D) representation of the microstructure of a SiC particle reinforced Al composite, for visualization and finite-element modeling (FEM). The Young’s modulus and stress-strain behavior of the composite predicted by the 3D model of microstructure correlated very well with experimental results.
Open-Closed Moduli Spaces and Related Algebraic Structures

We set up a Batalin–Vilkovisky Quantum Master Equation (QME) for open-closed string theory and show that the corresponding moduli spaces give rise to a solution, a generating function for their fundamental chains. The equation encodes the topological structure of the compactification of the moduli space of bordered Riemann surfaces. The moduli spaces of bordered J-holomorphic curves are expected to satisfy the same equation, and from this viewpoint, our paper treats the case of the target space equal to a point. We also introduce the notion of a symmetric Open-Closed Topological Conformal Field Theory (OC TCFT) and study the L ∞ and A ∞ algebraic structures associated to it.
SpeX SPECTROSCOPY OF UNRESOLVED VERY LOW MASS BINARIES. I. IDENTIFICATION OF 17 CANDIDATE BINARIES STRADDLING THE L DWARF/T DWARF TRANSITION

We report the identification of 17 candidate brown dwarf binaries whose components straddle the L dwarf/T dwarf transition. These sources were culled from a large near-infrared spectral sample of L and T dwarfs observed with the Infrared Telescope Facility SpeX spectrograph. Candidates were selected on the basis of spectral ratios which segregate known (resolved) L dwarf/T dwarf pairs from presumably single sources. Composite templates, constructed by combining 13,581 pairs of absolute flux-calibrated spectra, are shown to provide statistically superior fits to the spectra of our 17 candidates as compared to single templates. Ten of these candidates appear to have secondary components that are significantly brighter than their primaries over the 1.0-1.3 μm band, indicative of rapid condensate depletion at the L dwarf/T dwarf transition. Our results support prior indications of enhanced multiplicity amongst early-type T dwarfs; 53% ± 7% of the T0-T4 dwarfs in our spectral sample are found to be either resolved or unresolved (candidate) pairs, although this is consistent with an intrinsic (volume complete) brown dwarf binary fraction of only 15%. If verified, this sample of spectral binaries more than doubles the number of known L dwarf/T dwarf transition pairs, enabling a broader exploration of this poorly understood phase of brown dwarf atmospheric evolution.
Uplink capacity and interference avoidance for two-tier femtocell networks

Two-tier femtocell networks- comprising a conventional cellular network plus embedded femtocell hotspots- offer an economically viable solution to achieving high cellular user capacity and improved coverage. With universal frequency reuse and DS-CDMA transmission however, the ensuing cross-tier interference causes unacceptable outage probability. This paper develops an uplink capacity analysis and interference avoidance strategy in such a two-tier CDMA network. We evaluate a network-wide area spectral efficiency metric called the operating contour (OC) defined as the feasible combinations of the average number of active macrocell users and femtocell base stations (BS) per cell-site that satisfy a target outage constraint. The capacity analysis provides an accurate characterization of the uplink outage probability, accounting for power control, path loss and shadowing effects. Considering worst case interference at a corner femtocell, results reveal that interference avoidance through a time-hopped CDMA physical layer and sectorized antennas allows about a 7x higher femtocell density, relative to a split spectrum two-tier network with omnidirectional femtocell antennas. A femtocell exclusion region and a tier selection based handoff policy offers modest improvements in the OCs. These results provide guidelines for the design of robust shared spectrum two-tier networks.
Status of MARS Electromagnetic Physics

New modules for simulating electromagnetic showers at energies from 1 keV to a multi-TeV region have been developed and implemented into the MARS code. The entire shower and several “non-standard” processes essential at high energies are treated either exclusively or inclusively, according to the user’s choice. Results of calculations are in a good agreement with data.
Self-targeted subsidies - the distributional impact of the Egyptian food subsidy system

By gradually reducing the number of subsidized foods, and by focusing subsidies on foods consumed more by the poor than by the rich - like coarse baladi bread - Egyptian policymakers have found a way to self-target food subsidies to the urban poor. Yet because the rural poor do not consume as much baladi bread, this system is not as well-targeted to the rural poor. The Egyptian food subsidy system is an untargeted system that is essentially open to all Egyptians. For this reason, the budgetary costs of this system have been high and the ability of this system to improve the welfare status of the poor has been questioned. Since the food riots of 1977, Egyptian policymakers have been reluctant to make large changes in their food subsidy system. Rather, their strategy has been to reduce the costs and coverage of this system gradually. For example, since 1980 policymakers have reduced the number of subsidized foods from 20 to just four. Despite these cutbacks, Adams uses new 1997 household survey data to show that the Egyptian food subsidy system is self-targeted to the poor, because it subsidizes inferior goods. In urban Egypt, for instance, the main subsidized food - coarse baladi bread - is consumed more by the poor (the lowest quintile group of the population) than by the rich (the highest quintile). So subsidizing baladi bread is a good way of improving the welfare status of the urban poor. But in rural Egypt where the poor do not consume so much baladi bread, the poor receive less in income transfers than the rich. In many countries, administrative targeting of food subsidies can do a better job of targeting the poor than self-targeting systems. In Jamaica, for example, poor people get food stamps at health clinics, so the Jamaican poor receive double the income transfers from food subsidies that the Egyptian poor receive. But starting a comparable system in Egypt would be costly both in financial and political terms, because many nonpoor households currently receiving food subsidies would have to be excluded. For these reasons, it is likely that the government will continue to refine the present food subsidy system, perhaps by eliminating current subsidies on sugar or edible oil. Neither of these foods is an inferior good, so eliminating these subsidies will have only a minimal impact on the welfare status of the poor. This paper - a product of the Poverty Division, Poverty Reduction and Economic Management Network - is part of a larger effort in the network to identify the impact of transfer programs on the urban and rural poor.
An empirical investigation of the link between market orientation and church performance

Will the same marketing tools and strategies used in the for-profit world of business work in a church environment? George Barna, America's most well recognized and respected authority on business and religion has spent the last 20 years writing over a dozen books attempting to convince church leaders to adopt a market-oriented philosophy. Yet, to date, there has been no scientific inquiry aimed at testing this assumption. This research provides the first known scholarly study of the church sector which empirically examines the relationship between market orientation and performance. Gray et al.'s (1998) five-dimension market orientation scale was adapted to the church sector and was found to be both valid and reliable. Using a sample of 230 church leaders from the five largest Christian denominational families in the United States, the authors found tentative evidence to suggest market orientation is correlated with improved overall church performance. Increases in market orientation were effective in garnering higher levels of visitors to the various church service offerings. However, it was also discovered that the majority of market-oriented churches struggle to transition these visitors into long-term, financially committed members. Finally, the results indicate that a fairly large percentage of modern churches in the U.S. have adopted a market-oriented culture. Directions for future research, limitations of the study and managerial implications of the findings are subsequently identified and discussed. Copyright © 2007 John Wiley & Sons, Ltd.
An Empirical Analysis of the Revival of Fiscal Activism in the 2000s

An empirical review of the three fiscal stimulus packages of the 2000s shows that they had little if any direct impact on consumption or government purchases. Households largely saved the transfers and tax rebates. The federal government only increased purchases by a small amount. State and local governments saved their stimulus grants and shifted spending away from purchases to transfers. Counterfactual simulations show that the stimulus-induced decrease in state and local government purchases was larger than the increase in federal purchases. Simulations also show that a larger stimulus package with the same design as the 2009 stimulus would not have increased government purchases or consumption by a larger amount. These results raise doubts about the efficacy of such packages adding weight to similar assessments reached more than thirty years ago. (JEL E21, E23, E32, E62, H50)
Asymptotics of Height Change on Toroidal Temperleyan Dimer Models

The dimer model is an exactly solvable model of planar statistical mechanics. In its critical phase, various aspects of its scaling limit are known to be described by the Gaussian free field. For periodic graphs, criticality is an algebraic condition on the spectral curve of the model, determined by the edge weights (Kenyon et al. in Ann Math (2) 163(3):1019–1056, 2006); isoradial graphs provide another class of critical dimer models, in which the edge weights are determined by the local geometry. In the present article, we consider another class of graphs: general Temperleyan graphs, i.e. graphs arising in the (generalized) Temperley bijection between spanning trees and dimer models. Building in particular on Forman’s formula and representations of Laplacian determinants in terms of Poisson operators, and under a minimal assumption—viz. that the underlying random walk converges to Brownian motion—we show that the natural topological observable on macroscopic tori converges in law to its universal limit, i.e. the law of the periods of the dimer height function converges to that of the periods of a compactified free field.
Trend shocks and the countercyclical U.S. current account

From 1960{2009, the U.S. current account balance has tended to decline during expansions and improve in recessions. We argue that trend shocks to productivity can help explain the countercyclical U.S. current account. Our framework is a two-country, two-good real business cycle (RBC) model in which cross-border asset trade is limited to an international bond. We identify trend and transitory shocks to U.S. productivity using generalized method of moments (GMM) estimation. The specication that best matches the data assigns a large role to trend shocks. The estimated model generates a countercyclical current account without excessive consumption volatility.
Planning Among Movable Obstacles with Artificial Constraints

This paper presents artificial constraints as a method for guiding heuristic search in the computationally challenging domain of motion planning among movable obstacles. The robot is permitted to manipulate unspecified obstacles in order to create space for a path. A plan is an ordered sequence of paths for robot motion and object manipulation. We show that under monotone assumptions, anticipating future manipulation paths results in constraints on both the choice of objects and their placements at earlier stages in the plan. We present an algorithm that uses this observation to incrementally reduce the search space and quickly find solutions to previously unsolved classes of movable obstacle problems. Our planner is developed for arbitrary robot geometry and kinematics. It is presented with an implementation for the domain of navigation among movable obstacles.
LHC Symposium 2003: Summary Talk

Received: Abstract. This summary talk reviews the LHC 2003 Symposium, focusing on expec- tations as we prepare to leap over the current energy frontier into new territory. We may learn from what happened in the two most recent examples of leaping into new energy territory. Quite dierent scenarios appeared in those two cases. In addition, we review the status of the machine and experiments as reported at the Symposium. Finally, I suggest an attitude which may be most appropriate as we look forward to the opportunities anticipated for the rst data from the LHC.
Role of scattering in nanotransistors

We model the influence of scattering along the channel and extension regions of dual gate nanotransistors. It is found that the reduction in drain current due to scattering in the right half of the channel is comparable to the reduction in drain current due to scattering in the left half of the channel, when the channel length is comparable to the scattering length. This is in contrast to a popular belief that scattering in the source end of a nanotransistor is significantly more detrimental to the drive current than scattering elsewhere. As the channel length becomes much larger than the scattering length, scattering in the drain-end is less detrimental to the drive current than scattering near the source-end of the channel. Finally, we show that for nanotransistors, the classical picture of modeling the extension regions as simple series resistances is not valid.
Some New Perspectives on India's Approach to Capital Account Liberalization

In this paper, I analyze India's approach to capital account liberalization through the lens of the new literature on financial globalization. India's authorities have taken a cautious and calibrated path to capital account opening, which has served the economy well in terms of reducing its vulnerability to crises. By now, the capital account has become quite open and reversing this is not a viable option. Moreover, the remaining capital controls are rapidly becoming ineffective, making the debate about capital controls rather moot. Managing de facto financial integration into international capital markets and aligning domestic macroeconomic policies in a manner that maximizes the indirect benefits and reduces the risks is the key challenge now facing India's policymakers on this front.
Notes on decoherence at absolute zero

Abstract The problem of electron decoherence at low-temperature is analyzed from the perspective of recent experiments on decoherence rate measurement and on related localization phenomena in low-dimensional systems. The importance of decoherence at zero temperature, perhaps induced by quantum fluctuations, is put in a broader context.
A SPACE LOWER BOUND FOR NAME-INDEPENDENT COMPACT ROUTING IN TREES

Given a rooted n-node tree with arbitrary positive edge weights, and arbitrarily assigned node names, what is the minimum amount of space that a single-source compact routing algorithm could use in...
Demography, urbanization and development: Rural push, urban pull and … urban push?

Developing countries have urbanized rapidly since 1950. To explain urbanization, standard models emphasize rural-urban migration, focusing on rural push factors (agricultural modernization and rural poverty) and urban pull factors (industrialization and urban-biased policies). Using new historical data on urban birth and death rates for seven countries from Industrial Europe (1800–1910) and thirty-five developing countries (1960–2010), this paper argues that a non-negligible part of developing countries’ rapid urban growth and urbanization may also be linked to demographic factors, such as rapid internal urban population growth, or an urban push. High urban natural increase in today’s developing countries follows from lower urban mortality, relative to Industrial Europe, where higher urban deaths offset urban births. This compounds the effects of migration and displays strong associations with urban congestion, providing additional insight into the phenomenon of urbanization without growth.
Galactic Evolution of Silicon Isotopes: Application to Presolar SiC Grains from Meteorites

We calculate and discuss the chemical evolution of the isotopic silicon abundances in the interstellar medium (ISM) at distances and times appropriate to the birth of the solar system. This has several objectives, some of which are related to anomalous silicon isotope ratios within presolar grains extracted from meteorites; namely: (1) What is the relative importance for silicon isotopic compositions in the bulk ISM of Type II supernovae, Type Ia supernovae, and AGB stars? (2) Are 29Si and 30Si primary or secondary nucleosynthesis products? (3) In what isotopic direction in a three-isotope plot do core-collapse supernovae of different mass move the silicon isotopic composition? (4) Why do present calcu-lations not reproduce the solar ratios for silicon isotopes, and what does that impose upon studies of anomalous Si isotopes in meteoritic silicon carbide grains? (5) Are chemical-evolution features recorded in the anomalous SiC grains? Our answers are formulated on the basis of the Woosley & Weaver super-nova yield survey. Renormalization with the calculated interstellar medium silicon isotopic composition and solar composition is as an important and recurring concept of this paper. Possible interpretations of the silicon isotope anomalies measured in single SiC grains extracted from carbonaceous meteorites are then presented. The calculations suggest that the temporal evolution of the isotopic silicon abundances in the interstellar medium may be recorded in these grains.
A block-tridiagonal solver with two-level parallelization for finite element-spectral codes

Abstract Two-level parallelization is introduced to solve a massive block-tridiagonal matrix system. One-level is used for distributing blocks whose size is as large as the number of block rows due to the spectral basis, and the other level is used for parallelizing in the block row dimension. The purpose of the added parallelization dimension is to retard the saturation of the scaling due to communication overhead and inefficiencies in the single-level parallelization only distributing blocks. As a technique for parallelizing the tridiagonal matrix, the combined method of “Partitioned Thomas method” and “Cyclic Odd–Even Reduction” is implemented in an MPI-Fortran90 based finite element-spectral code (TORIC) that calculates the propagation of electromagnetic waves in a tokamak. The two-level parallel solver using thousands of processors shows more than 5 times improved computation speed with the optimized processor grid compared to the single-level parallel solver under the same conditions. Three-dimensional RF field reconstructions in a tokamak are shown as examples of the physics simulations that have been enabled by this algorithmic advance.
Planar graph coloring with an uncooperative partner

We show that the game chromatic number of a planar graph is at most 33. More generally, there exists a function f: f\l --+ f\l so that for each n E f\l. if a graph does not contain a homeomorph of Kn• then its game chromatic number is at most f(n). In particular, the game chromatic number of a graph is bounded in terms of its genus. Our proof is motivated by the concept of p-arrangeability, which was first introduced by Guantao and Schelp in a Ramsey theoretic setting. © 1994 John Wiley & Sons, Inc.
Exploring Bis(cyclometalated) Ruthenium(II) Complexes as Active Catalyst Precursors: Room‐Temperature Alkene–Alkyne Coupling for 1,3‐Diene Synthesis

Described is the development of a new class of bis(cyclometalated) ruthenium(II) catalyst precursors for CC coupling reactions between alkene and alkyne substrates. The complex [(cod)Ru(3-methallyl)2] reacts with benzophenone imine or benzophenone in a 1:2 ratio to form bis(cyclometalated) ruthenium(II) complexes (1). The imine-ligated complex 1 a promoted room-temperature coupling between acrylic esters and amides with internal alkynes to form 1,3-diene products. A proposed catalytic cycle involves CC bond formation by oxidative cyclization, β-hydride elimination, and CH bond reductive elimination. This RuII/RuIV pathway is consistent with the observed catalytic reactivity of 1 a for mild tail-to-tail methyl acrylate dimerization and for cyclobutene formation by [2+2] norbornene/alkyne cycloaddition.
Edge reconstruction in armchair phosphorene nanoribbons revealed by discontinuous Galerkin density functional theory

With the help of our recently developed massively parallel DGDFT (Discontinuous Galerkin Density Functional Theory) methodology, we perform large-scale Kohn–Sham density functional theory calculations on phosphorene nanoribbons with armchair edges (ACPNRs) containing a few thousands to ten thousand atoms. The use of DGDFT allows us to systematically achieve a conventional plane wave basis set type of accuracy, but with a much smaller number (about 15) of adaptive local basis (ALB) functions per atom for this system. The relatively small number of degrees of freedom required to represent the Kohn–Sham Hamiltonian, together with the use of the pole expansion the selected inversion (PEXSI) technique that circumvents the need to diagonalize the Hamiltonian, results in a highly efficient and scalable computational scheme for analyzing the electronic structures of ACPNRs as well as their dynamics. The total wall clock time for calculating the electronic structures of large-scale ACPNRs containing 1080–10 800 atoms is only 10–25 s per self-consistent field (SCF) iteration, with accuracy fully comparable to that obtained from conventional planewave DFT calculations. For the ACPNR system, we observe that the DGDFT methodology can scale to 5000–50 000 processors. We use DGDFT based ab initio molecular dynamics (AIMD) calculations to study the thermodynamic stability of ACPNRs. Our calculations reveal that a 2 × 1 edge reconstruction appears in ACPNRs at room temperature.
New trialkylsilyl enol ether chemistry: Direct 1,2-bis-azidonation of triisopropylsilyl enol ethers: An azido-radical addition process promoted by TEMPO

Treatment of triisopropylsilyl enol ethers with PhIO/TMSN3/TEMPO (cat.)–45 °C results in 1,2-bis-azidonation, which appears to occur through a radical addition process; the 1-azido group can be replaced by carbon nucleophiles such as allyl, methyl, cyano, acetylene and acetonyl.
Fixing Numbers of Graphs and Groups

The fixing number of a graph $G$ is the smallest cardinality of a set of vertices $S$ such that only the trivial automorphism of $G$ fixes every vertex in $S$. The fixing set of a group $\Gamma$ is the set of all fixing numbers of finite graphs with automorphism group $\Gamma$. Several authors have studied the distinguishing number of a graph, the smallest number of labels needed to label $G$ so that the automorphism group of the labeled graph is trivial. The fixing number can be thought of as a variation of the distinguishing number in which every label may be used only once, and not every vertex need be labeled. We characterize the fixing sets of finite abelian groups, and investigate the fixing sets of symmetric groups.
The Fibonacci model and the Temperley-Lieb algebra

We give an elementary construction of the Fibonacci model, a unitary braid group representation that is universal for quantum computation.
Computational Properties of Environment-based Disambiguation

The standard pipeline approach to semantic processing, in which sentences are morphologically and syntactically resolved to a single tree before they are interpreted, is a poor fit for applications such as natural language interfaces. This is because the environment information, in the form of the objects and events in the application's runtime environment, cannot be used to inform parsing decisions unless the input sentence is semantically analyzed, but this does not occur until after parsing in the single-tree semantic architecture. This paper describes the computational properties of an alternative architecture, in which semantic analysis is performed on all possible interpretations during parsing, in polynomial time.
The Adjusted Earnings Yield

The earnings yield, determined by the ratio of reported earnings to price, is frequently used to predict real return. Complications characterize the predictions, however, because reported earnings are not real. This research identifies an adjusted earnings yield that ensures that real return can be determined as a ratio of current-period prices. From freely accessible and publicly disseminated data, an adjusted-earnings-yield series is created for the U.S. equity market. Statistical tests indicate that this measure is a much better predictor of future real returns than are other popular valuation measures.
How Cold Dark Matter Theory Explains Milgrom's Law

Milgrom noticed the remarkable fact that the gravitational effect of dark matter in galaxies only becomes important where accelerations are less than about 10-8 cm s-2 ~ cH0 ("Milgrom's law"). This forms the basis for modified Newtonian dynamics, an alternative to particle dark matter. However, any successful theory of galactic dynamics must account for Milgrom's law. We show how Milgrom's law comes about in the cold dark matter theory of structure formation.
INFERENCE ON REGRESSIONS WITH INTERVAL DATA ON A REGRESSOR OR OUTCOME

This paper examines inference on regressions when interval data are available on one variable, the other variables being measured precisely. Let a population be characterized by a distribution P(y,x, v, v 0 , v 1 ), where y ∈ R 1 , x ∈ R k , and the real variables (v, v 0 , v 1 ) satisfy v 0 ≤ v ≤ v 1 . Let a random sample be drawn from P and the realizations of (y, x, v 0 , v 1 ) be observed, but not those of v. The problem of interest may be to infer E(y|x, v) or E(v|x). This analysis maintains Interval (I), Monotonicity (M), and Mean Independence (MI) assumptions: (I) P(v 0 ≤ v ≤ v 1 ) = 1; (M) E(y|x, v) is monotone in v; (MI) E(y|x, v, v 0 , v 1 ) = E(y|x, v). No restrictions are imposed on the distribution of the unobserved values of v within the observed intervals [v 0 , v 1 ]. It is found that the IMMI Assumptions alone imply simple nonparametric bounds on E(y|x, v) and E(v|x). These assumptions invoked when y is binary and combined with a semiparametric binary regression model yield an identification region for the parameters that may be estimated consistently by a modified maximum score (MMS) method. The IMMI assumptions combined with a parametric model for E(y|x, v) or E(v|x) yield an identification region that may be estimated consistently by a modified minimum-distance (MMD) method. Monte Carlo methods are used to characterize the finite-sample performance of these estimators. Empirical case studies are performed using interval wealth data in the Health and Retirement Study and interval income data in the Current Population Survey.
Carbon dating the web: estimating the age of web resources

In the course of web research it is often necessary to estimate the creation datetime for web resources (in the general case, this value can only be estimated). While it is feasible to manually establish likely datetime values for small numbers of resources, this becomes infeasible if the collection is large. We present "carbon date", a simple web application that estimates the creation date for a URI by polling a number of sources of evidence and returning a machine-readable structure with their respective values. To establish a likely datetime, we poll bitly for the first time someone shortened the URI, topsy for the first time someone tweeted the URI, a Memento aggregator for the first time it appeared in a public web archive, Google's time of last crawl, and the Last-Modified HTTP response header of the resource itself. We also examine the backlinks of the URI as reported by Google and apply the same techniques for the resources that link to the URI. We evaluated our tool on a gold standard data set of 1200 URIs in which the creation date was manually verified. We were able to estimate a creation date for 75.90% of the resources, with 32.78% having the correct value. Given the different nature of the URIs, the union of the various methods produces the best results. While the Google last crawl date and topsy account for nearly 66% of the closest answers, eliminating the web archives or Last-Modified from the results produces the largest overall negative impact on the results. The carbon date application is available for download or use via a web API.
Price-Based Spectrum Management in Cognitive Radio Networks

Cognitive radios (CRs) have a great potential to improve spectrum utilization by enabling users to access the spectrum dynamically without disturbing licensed primary radios (PRs). A key challenge in operating these radios as a network is how to implement an efficient medium access control (MAC) mechanism that can adaptively and efficiently allocate transmission powers and spectrum among CRs according to the surrounding environment. Most existing works address this issue via suboptimal heuristic approaches or centralized solutions. In this paper, we propose a novel joint power/channel allocation scheme that improves the performance through a distributed pricing approach. In this scheme, the spectrum allocation problem is modeled as a noncooperative game, with each CR pair acting as a player. A price-based iterative water-filling (PIWF) algorithm is proposed, which enables CR users to reach a good Nash equilibrium (NE). This PIWF algorithm can be implemented distributively with CRs repeatedly negotiating their best transmission powers and spectrum. Simulation results show that the social optimality of the NE solution is dramatically improved through pricing. Depending on the different orders according to which CRs take actions, we study sequential and parallel versions of the PIWF algorithm. We show that the parallel version converges faster than the sequential version. We then propose a corresponding MAC protocol to implement our resource management schemes. The proposed MAC allows multiple CR pairs to be first involved in an admission phase, then iteratively negotiate their transmission powers and spectrum via control-packet exchanges. Following the negotiation phase, CRs proceed concurrently with their data transmissions. Simulations are used to study the performance of our protocol and demonstrate its effectiveness in terms of improving the overall network throughput and reducing the average power consumption.
Area and length preserving geometric invariant scale-spaces

In this paper, area preserving multi-scale representations of planar curves are described. This allows smoothing without shrinkage at the same time preserving all the scale-space properties. The representations are obtained deforming the curve via geometric heat flows while simultaneously magnifying the plane by a homethety which keeps the enclosed area constant. When the Euclidean geometric heat flow is used, the resulting representation is Euclidean invariant, and similarly it is affine invariant when the affine one is used. The flows are geometrically intrinsic to the curve, and exactly satisfy all the basic requirements of scale-space representations. In the case of the Euclidean heat flow, it is completely local as well. The same approach is used to define length preserving geometric flows. A similarity (scale) invariant geometric heat flow is studied as well in this work. >
AIR TRANSPORTATION SERVICES: BOTH A TRADED COMMODITY AND A TRANSACTIONS COST IN INTERNATIONAL TRADE

Air transportation is a major facilitator of international trade in terms of the value of goods and services involved, and is important to specific industries, such as tourism, that are being developed by many lower income countries. High air transportation costs can pose a major impediment to the economic growth of countries, or to regions within them. But international air transportation is also an industry in its own right that can earn profits and foreign exchange for the parenting country. The newer international trade models treat transportation as a transactions cost, reductions of which confer in most cases, a gain to trading partners. Reducing air transportation costs, if resulting from rent seeking activities in protected markets, can, however reduce income for the air transportation-providing country and may impact on its foreign exchange earnings. This can reduce the incentive for a country to participate in Open Skies type situations where international air services are offered in a competitive market. Furthermore liberal trade in air transportation services can, in some cases lead to potentially less efficient provision of these services.
Decomposing solution sets of polynomial systems: a new parallel monodromy breakup algorithm

Our problem is to decompose a positive dimensional solution set of a polynomial system into irreducible components. This solution set is represented by a witness set, which can be partitioned into irreducible subsets according to the action of monodromy. Our straightforward parallel version of the original monodromy breakup algorithm suffers from synchronisation issues. The new approach not only resolves these issues, but also, according to accumulated statistics, reduces the expected number of homotopy continuation paths tracked. The latter property gives a faster serial algorithm.
A new development in camera calibration: calibrating a pair of mobile cameras

A new method of camera calibration is proposed for active visual sensing for use in three-dimensional (3D) scene analysis. The method permits calibration of a mobile camera as a function of the position and orientation of the camera. The algorithm for identification of the calibration matrices is divided into two steps: first, calibration for a fixed position of the camera (i. e. , the transformation between the real-world coordinates and the coordinates of the corresponding points in the image plane of the camera); second, calibration as a function of the position and orientation of the camera, which uses the prior information of the calibration for a fixed position. The method can be used for any mobile camera as long as the movement of the camera support is known.
Toward a General Theory of Strategic Action Fields

In recent years there has been an outpouring of work at the intersection of social movement studies and organizational theory. While we are generally in sympathy with this work, we think it implies a far more radical rethinking of structure and agency in modern society than has been realized to date. In this article, we offer a brief sketch of a general theory of strategic action fields (SAFs). We begin with a discussion of the main elements of the theory, describe the broader environment in which any SAF is embedded, consider the dynamics of stability and change in SAFs, and end with a respectful critique of other contemporary perspectives on social structure and agency.
Direct numerical simulation of stationary homogeneous stratified sheared turbulence

Using direct numerical simulation, we investigate stationary and homogeneous shear-driven turbulence in various stratifications, ranging from neutral to very stable. To attain and maintain a stationary flow, we throttle the mean shear so that the net production stays constant for all times. This results in a flow that is characterized solely by its mean shear and its mean buoyancy gradient, independent of initial conditions. The method of throttling is validated by comparison with experimental spectra in the case of neutral stratification. With increasing stratification comes the emergence of vertically sheared large-scale horizontal motions that preclude a straightforward interpretation of flow statistics. However, once these motions are excluded, simply by subtracting the horizontal average, the underlying flow appears amenable to the standard methods of turbulence analysis. It is shown that a direct acknowledgement of the confining influence of the periodic simulation box can lead to a meaningful physical interpretation of the large scales. Once an appropriate confinement scale is identified, many features, including horizontal spectra, flux-gradient relationships and length scales, of stratified sheared turbulence can be readily understood, both qualitatively and quantitatively, in terms of Monin-Obukhov similarity theory. Finally, the similarity-theory framework is used to interpret the scaling of the vertical diapycnal diffusivity in stratified turbulence. © 2012 Cambridge University Press.
Carbonylation of heterocycles by homogeneous catalysts

This article summarizes the recent developments (particularly the uses of homogeneous organometallic catalysts) in ring-opening carbonylations, ring-opening carbonylative polymerizations and ring-expansion carbonylations of heterocycles such as epoxides, aziridines, lactones and oxazolines.
Analyzing integrated optical waveguides: a comparison of two new methods

We present a comparison of two recently developed methods of analyzing optical waveguides. One of them is numerical, and the other is an approximate analytical method.
Contribution to Unresolved Infrared Fluctuations from Dwarf Galaxies at Redshifts of 2-3

In order to understand the origin of clustered anisotropies detected in Spitzer images between 3.6 and 8 μm, we stack the Spitzer IRAC/Great Observatories Origins Deep Survey (GOODS) images at pixel locations corresponding to faint, z_(AB) ~ 27 mag, optical sources with no obvious IR counterparts. We obtain a strong detection of the sources with a stacked median flux at 3.6 μm of 130 ± 5 nJy above the background. The wealth of multiwavelength imaging data in GOODS enables a similar stacking analysis to be undertaken at various wavelengths between the ultraviolet and near-infrared bands. We obtain strong stacked detections of these optically faint sources over the entire wavelength range, which places constraints on the average properties of these sources. We find that the flux spectrum of the median, stacked source is consistent with a L less than or similar to 0.03L_*, _(UV) galaxy with a 90% confidence interval for the redshift of 1.9-2.7. These sources produce a 3.6 μm absolute background intensity between 0.1 and 0.35 nW m^(−2) sr^(−1), and the clustered IR light could account for ~30%-50% of fluctuation power in the IR background at 4' angular scales. Although the exact redshift distribution of these sources is unknown, these galaxies appear to contain 5%-20% of the comoving stellar mass density at z ~ 2.5.
Integrated optical receivers using MSM detectors

The performance of a metal-semiconductor-metal (MSM) detector when combined with preamplifier electronics is discussed, and it is noted that certain advantages due to its horizontal surface can result in receivers with fundamentally higher performance than that possible with vertical p-i-n detector designs. The sensitivity of optical receivers using a MSM detector is analyzed, and a set of scaling rules is used to compare a MSM receiver's sensitivity with that of a similar receiver using a vertical p-i-n photodiode structure. Assuming identical preamplifier designs it is shown that the MSM-based receiver, except at very high bit rates, can in principle consistently outperform its p-i-n counterpart with as much as a 6-dB improvement in sensitivity. >
Faster ray packets - triangle intersection through vertex culling

To eliminate unnecessary ray packet-triangle intersection tests, we check for separation of two convex objects: a triangle and a frustum containing intersections of rays with a leaf node of an acceleration structure. We show a performance improvement that is proportional to the ratio of lengths of average leaf edge to triangle edge, which opens new possibilities for creation of better acceleration structures.
Synthesis of Stereoisomeric Medium-Ring α,α‘-Dihydroxy Cycloalkanones

The stereochemical course of the epoxidation of the silyl enol ethers of 2-tert-butyldimethylsilyloxycycloheptanone and -cyclooctanone has been investigated and shown to proceed exclusively anti to the existing α-substituent. 2-(Benzyloxy)cyclooctanone behaves similarly, and the presence of a transannular double bond does not alter the outcome. α-Ketol rearrangements are seen to operate during ensuing fluoride ion-induced removal of the silyl protecting groups in select examples. The preferred means for generating the cis isomers of the α,α‘-dihydroxy cycloalkanones involves methylenation of the monoprotected trans-dihydroxy ketones with the Nysted reagent, followed by oxidation and subsequent reduction with sodium borohydride. Ozonolysis and fluoride ion-induced desilylation complete the route.
Antitumor agents. Part 226: synthesis and cytotoxicity of 2-phenyl-4-quinolone acetic acids and their esters.

Abstract 2-Phenyl-4-quinolone acetic acids and their esters were synthesized and evaluated for interaction with tubulin and for cytotoxicity against a panel of human tumor cell lines. 2-Phenyl- and 2-(2′-fluorophenyl)-4-quinolone-8-acetic acids (11 and 12) displayed potent cytotoxicity with ED50 values at nanomolar concentrations, but had minimal activity against tubulin polymerization. 2-(2′-Fluorophenyl)-4-quinolone-6-acetic acid (3) and 2-(2′-fluorophenyl)-4-quinolone-8-acetic acid methyl ester (10) moderately inhibited tubulin polymerization.
Nanoporous Copper Silicates with One‐Dimensional 12‐Ring Channel Systems

O species fill these channels,presumablyactingastemplatesduringthesynthesis.CrystalsoftheCuSH-1Aphasesweresynthesizedaspale-blue plates with maximum dimensions of about 0.4mm.CuSH-1Na was prepared as a single phase in high yield(greaterthan80%basedonCu).CuSH-1KandCuSH-1RbcouldbesynthesizedonlyasminorphaseswhileCuSH-1Csisobtained as major phase (greater than 50% based on Cu).Compositions of CuSH-1Na and CuSH-1Cs were measuredby elemental analysis.
Fastest Mixing Markov Chain on Graphs with Symmetries

We show how to exploit symmetries of a graph to efficiently compute the fastest mixing Markov chain on the graph (, find the transition probabilities on the edges to minimize the second-largest eigenvalue modulus of the transition probability matrix). Exploiting symmetry can lead to significant reduction in both the number of variables and the size of matrices in the corresponding semidefinite program, and thus enable numerical solution of large-scale instances that are otherwise computationally infeasible. We obtain analytic or semianalytic results for particular classes of graphs, such as edge-transitive and distance-transitive graphs. We describe two general approaches for symmetry exploitation, based on orbit theory and block-diagonalization, respectively, and establish a formal connection between them.
Framework for Measuring Corporate Safety Culture and Its Impact on Construction Safety Performance

This paper presents the results of a structural equation model SEM that describes and quantifies the relationships between corporate culture and safety performance. The SEM is estimated using 196 individual questionnaire responses from three companies with better than average safety records. A multiattribute analysis of corporate safety culture characteristics resulted in a hierarchical description of corporate safety culture comprised of three major categories—people, process, and value. These three major categories were decom- posed into 54 measurable questions and used to develop a questionnaire to quantify corporate safety culture. The SEM identified five latent variables that describe corporate safety culture: 1 a company's safety commitment; 2 the safety incentives that are offered to field personal for safe performance; 3 the subcontractor involvement in the company culture; 4 the field safety accountability and dedica- tion; and 5 the disincentives for unsafe behaviors. These characteristics of company safety culture serve as indicators for a company's safety performance. Based on the findings from this limited sample of three companies, this paper proposes a list of practices that companies may consider to improve corporate safety culture and safety performance. A more comprehensive study based on a larger sample is recommended to corroborate the findings of this study.
Comparisons Between the Extended Kalman Filter and the State-Dependent Riccati Estimator

The state-dependent Riccati equation-based estimator is becoming a popular estimation tool for nonlinear systems since it does not use system linearization. In this paper, the state-dependent Riccati equation-based estimator is compared with the widely used extended Kalman filter for three simple examples that appear in the open literature. It is demonstrated that, by simulation, the state-dependent Riccati equation-based estimator at best has comparable results to the extended Kalman filter but is often worse than the extended Kalman filter. In some cases, the state-dependent Riccati equation-based estimator does not converge, even though the system considered satisfies all the mathematical constraints on controllability and observability. Sufficient detail is presented in the paper so that the interested reader cannot only duplicate the results but perhaps make suggestions on how to get the state-dependent Riccati equation-based estimator to perform better.
Photonic band gap resonators for high energy accelerators

We have proposed that a new type of microwave resonator, based on photonic band gap (PBG) structures, may be particularly useful for high energy accelerators. We provide an explanation of the PBG concept and present data which illustrate some of the special properties associated with such structures. Further evaluation of the utility of PBG resonators requires laboratory testing of model structures at cryogenic temperatures, and at high fields. We provide a brief discussion of our test program, which is currently in progress. >