cssi/SciSciGPT-SciSciNet huggingface dataset:
Bypassing UGC from some optimal geometric inapproximability results

The Unique Games Conjecture (UGC) has emerged in recent years as the starting point for several optimal inapproximability results. While for none of these results a reverse reduction to Unique Games is known, the assumption of bijective projections in the Label Cover instance nevertheless seems critical in these proofs. In this work, we bypass the need for UGC assumption in inapproximability results for two geometric problems, obtaining a tight NP-hardness result in each case.The first problem, known as Lp Subspace Approximation, is a generalization of the classic least squares regression problem. Here, the input consists of a set of points X = lα1, … , αmr ⊆ Rn and a parameter k (possibly depending on n). The goal is to find a subspace H of Rn of dimension k that minimizes the ep norm of the Euclidean distances to the points in X. For p = 2, k = n − 1, this reduces to the least squares regression problem, while for p = ∞, k = 0 it reduces to the problem of finding a ball of minimum radius enclosing all the points. We show that for any fixed p ∈ (2, ∞), and for k = n − 1, it is NP-hard to approximate this problem to within a factor of γp − e for constant e > 0, where γp is the pth norm of a standard Gaussian random variable. This matches the γp approximation algorithm obtained by Deshpande, Tulsiani, and Vishnoi who also showed the same hardness result under the UGC.The second problem we study is the related Lp Quadratic Grothendieck Maximization Problem, considered by Kindler, Naor, and Schechtman. Here, the input is a multilinear quadratic form ∑ni, j = 1aijxixj and the goal is to maximize the quadratic form over the ep unit ball, namely, all x with ∑ni = 1vxivp l 1. The problem is polynomial time solvable for p = 2. We show that for any constant p ∈ (2, ∞), it is NP-hard to approximate the quadratic form to within a factor of γ2p − e for any e > 0. The same hardness factor was shown under the UGC by Kindler et al. We also obtain a γ2p-approximation algorithm for the problem using the convex relaxation of the problem defined by Kindler et al. A γ2p approximation algorithm has also been independently obtained by Naor and Schechtman.These are the first approximation thresholds, proven under P ≠ NP, that involve the Gaussian random variable in a fundamental way. Note that the problem statements themselves do not explicitly involve the Gaussian distribution.
An improved variable step-size affine projection sign algorithm for echo cancellation

This paper proposes an improved variable step-size (VSS) algorithm for the recently introduced affine projection sign algorithm (APSA) based on the recovery of the near-end signal energy in the error signal. Simulation results demonstrate that, compared to the previous VSS for APSA, the proposed approach provides both more robustness to impulse interference and better tracking ability of echo path change.
Protecting the poor in Vietnam's emerging market economy

All households see some fluctuation in their incomes over time. Many have access to consumption-smoothing devices such as savings and borrowing that allow them to maintain relatively stable living standards. But the poor tend to have fewer reserves beyond what is needed to survive lean periods during normal years and also less access to credit. An unfavorable turn of events, particularly an unexpected one or even a series of small shocks, can be catastrophic. Poor people's exposure to downside risk in their living standards can also bring adverse long-term consequences from the depletion of their productive assets at times of distress and the adoption of costly risk avoidance strategies. This paper uses Vietnam as a case study in rapidly assessing the strengths and weaknesses of an existing system of transfers and safety nets. Data are taken to be weak; in particular, rigorous ex-post evaluations of the components of the existing social security system are not available in time to inform policy choices. So the aim is instead to provide a broad qualitative assessment, also pointing to key issues on which knowledge needs to improve. The paper provides a critical overview of the existing public poverty and safety net programs in Vietnam that aim to help and protect those outside the formal employment sectors, notably those in the rural economy and urban informal sector. It begins with a brief examination of the principal sources of vulnerability for Vietnamese households and what is known about household coping strategies.
Accelerate single-shot data acquisitions using compressed sensing and FRONSAC imaging

Nonlinear spatial encoding magnetic (SEM) fields have been studied to complement multichannel RF encoding and accelerate MRI scans. Published schemes include PatLoc, O-Space, Null Space, 4D-RIO, and others, but the large variety of possible approaches to exploiting nonlinear SEMs remains mostly unexplored. Before, we have presented a new approach, Fast ROtary Nonlinear Spatial ACquisition (FRONSAC) imaging, where the nonlinear fields provide a small rotating perturbation to standard linear trajectories. While FRONSAC encoding greatly improves image quality, at the highest accelerations or weakest FRONSAC fields, some undersampling artifacts remain. However, the under-sampling artifacts that occur with FRONSAC encoding are relatively incoherent and well suited to the compressed sensing (CS) reconstruction. CS provides a sparsity-promoting convex strategy to reconstruct images from highly undersampled datasets. The work presented here combines the benefits of FRONSAC and CS. Simulations illustrate that this combination can further improve image reconstruction with FRONSAC gradients of low amplitudes and frequencies.
Universal Rigidity of Complete Bipartite Graphs

We describe a very simple condition that is necessary for the universal rigidity of a complete bipartite framework $$(K(n,m),\mathbf{p},\mathbf{q})$$(K(n,m),p,q). This condition is also sufficient for universal rigidity under a variety of weak assumptions, such as general position. Even without any of these assumptions, in complete generality, we extend these ideas to obtain an efficient algorithm, based on a sequence of linear programs, that determines whether an input framework of a complete bipartite graph is universally rigid or not.
Logarithmic derivatives of solutions to linear differential equations

Given an ordinary differential field K of characteristic zero, it is known that if y and 1/y satisfy linear differential equations with coefficients in K, then y'/y is algebraic over K. We present a new short proof of this fact using Grobner basis techniques and give a direct method for finding a polynomial over K that y'/y satisfies. Moreover, we provide explicit degree bounds and extend the result to fields with positive characteristic. Finally, we give an application of our method to a class of nonlinear differential equations.
The Formation Histories of Metal-Rich and Metal-Poor Globular Clusters

This review presents the results of ongoing studies of the formation histories of metal-poor and metal-rich globular clusters and their host galaxies. I first discuss the strong observational evidence that the globular cluster systems of most elliptical galaxies have bimodal metallicity distributions. I then focus on new results for metal-poor and metal-rich globular cluster systems. Metal-poor globular clusters are often associated with early structure formation, and I review new constraints on their formation epoch based on the “bias” of the number of metal-poor clusters with host galaxy mass. For metal-rich globular clusters, I discuss new results from ongoing optical to near-infrared photometric studies which both confirm an intermediate-age population in NGC 4365 and generally reveal a variety of formation histories for now quiescent ellipticals.
The Enterohepatic Circulation of Bile Acids in Man

Steady-state and dynamic descriptions of the enterohepatic circulation of bile acids in healthy man are given. Methods for characterizing the enterohepatic circulation of bile acids in health and disease are summarized.
Mixing of quantum walk on circulant bunkbeds

This paper give new observations on the mixing dynamics of a continuous-time quantumwalk on circulants and their bunkbed extensions. These bunkbeds are defined throughtwo standard graph operators: the join G + H and the Cartesian product G × H ofgraphs G and H. Our results include the following: (i) The quantum walk is average uniform mixing oncirculants with bounded eigenvalue multiplicity. This extends a known fact about thecycles Cn. (ii) Explicit analysis of the probability distribution of the quantum walk onthe join of circulants. This explains why complete partite graphs are not averageuniform mixing, using the fact Kn = K1 + Kn-1 and Kn....,n = Kn + ... + Kn.(iii)The quantum walk on the Cartesian product of a m-vertex path Pm and a circulantG, namely, Pm × G, is average uniform mixing if G is. This highlights a differencebetween circulants and the hypercubes Qn = P2 × Qn-1.Our proofs employ purely elementary arguments based on the spectra of the graphs.
Integrating model construction and evaluation

To date, most probabilistic reasoning systems have relied on a fixed belief network constructed at design time. The network is used by an application program as a representation of (in)dependencies in the domain. Probabilistic inference algorithms operate over the network to answer queries. Recognizing the inflexibility of fixed models has led researchers to develop automated network construction procedures that use an expressive knowledge base to generate a network that can answer a query. Although more flexible than fixed model approaches, these construction procedures separate construction and evaluation into distinct phases. In this paper we develop an approach to combining incremental construction and evaluation of a partial probability model. The combined method holds promise for improved methods for control of model construction based on a trade-off between fidelity of results and cost of construction.
Mean Paleomagnetic Poles for the Major Continents and the Pacific Plate

Apparent polar wander is the motion of Earth’s spin axis relative to a reference frame that is usually fixed relative to a tectonic plate or stable interior of a continent. The main method for estimating the past position of Earth’s spin axis is through paleomagnetism, the investigation of the magnetic memory of rocks. Mean paleomagnetic poles, which average poles over about half a geologic period and typically differ in mean age by -20 to 30 millions of years, are presented for the major cratons over Phanerozoic time and are presented for more closely spaced ages for the Pacific plate since Late Jurassic time.
Policy-Specific Information and Informal Agenda Power

In Gilligan and Krehbiel's models of procedural choice in legislatures, a committee exerts costly effort to acquire private information about an unknown state of the world. Subsequent work on expertise, delegation, and lobbying has largely followed this approach. In contrast, we develop a model of information as policy valence. We use our model to analyze a procedural choice game, focusing on the effect of transferability, i.e., the extent to which information acquired to implement one policy option can be used to implement a different policy option. We find that when information is transferable, as in Gilligan and Krehbiel's models, closed rules can induce committee specialization. However, when information is policy-specific, open rules are actually superior for inducing specialization. The reason for this surprising result is that a committee lacking formal agenda power has a greater incentive to exercise informal agenda power by exerting costly effort to generate high-valence legislation.
Leveraging Personalization To Facilitate Privacy.

Online social networks have enabled new methods and modalities of collaboration and sharing. These advances bring privacy concerns: online social data is more accessible and persistent and simultaneously less contextualized than traditional social interactions. To allay these concerns, many web services allow users to configure their privacy settings based on a set of multiple-choice questions. We suggest a new paradigm for privacy options. Instead of suggesting the same defaults to each user, services can leverage knowledge of users' traits to recommend a machine-learned prediction of their privacy preferences for Facebook. As a case study, we build and evaluate MyPrivacy, a publicly available web application that suggests personalized privacy settings. An evaluation with 199 users shows that users find the suggestions to be appropriate and private; furthermore, they express intent to implement the recommendations made by MyPrivacy. This supports the proposal to put personalization to work in online communities to promote privacy and security.
Integrated Yet Marginalized: Implications of Globalization for African Development

This article discusses Africa’s deepening marginalization in the globalization of production, finance, and labor. It underscores critical development issues that result from, and are exacerbated by, globalization in the context of unequal global distribution of economic and political power: illicit financial flows and tax evasion, the brain drain, an increasing incidence of noncommunicable diseases, and the disproportionate burden of environmental degradation that is shouldered by the African continent. It also offers some policy suggestions to address these issues at national and regional levels. Resume: Cet article traite de la marginalisation croissante de l’Afrique face a la mondialisation de la production, des finances et du monde du travail. Il met en evidence des questions critiques de developpement qui non seulement resultent de la mondialisation mais sont aussi exacerbes par elle notamment dans le contexte de repartition mondiale inegale du pouvoir economique et politique: les flux financiers illicites et l’evasion fiscale, la fuite des cerveaux, une incidence croissante des maladies non transmissibles et la charge disproportionnee de la degradation de l’environnement qui est assumee par le continent africain. Il propose egalement quelques suggestions de programmes politiques pour traiter ces questions aux niveaux national et regional.
Estimating the fiscal costs of implementing Ghana's single pay spine reform

Public sector pay policy is one of the main decisions facing a government, as it determines the ability to attract, retain, and motivate staff needed to fulfill its service delivery objectives. One option usually considered is relying on a single pay spine for all services into which jobs would be slotted, thus ensuring greater comparability of similar jobs across the public sector. This paper examines the single spine pay reform currently being considered in Ghana, highlighting the differences between the Ghanaian proposal and similarly named proposals elsewhere, and underscoring the potential cost of implementing the proposal -- which is expected to be significant. There are three main findings: (i) the implementation of the single spine pay reform would raise the base pay wage bill (salaries plus category one allowances) in Ghana to GHC2.8 billion by January 1, 2010 -- an almost 50 percent increase compared with an equivalent figures of GHC1.9 billion at end-2008; (ii) because these estimates focus narrowly on the base pay wage bill, they should be regarded as a lower bound estimate of the overall increase in the wage bill; and (iii) because these estimates are derived from assumptions regarding (1) the distribution of public sector employees across public sector services and institutions; (2) the minimum public sector wage; and the (3) the relativity of all other public sector wages with respect to this minimum wage, they are subject to changes any time these assumptions also change.
Damping estimates for oscillatory integral operators with finite type singularities

We derive damping estimates and asymptotics of L p operator norms for oscillatory integral operators with finite type singularities. The methods are based on incorporating finite type conditions into L 2 almost orthogonality technique of Cotlar-Stein.
Astrophysical Evidence for Black Hole Event Horizons

Astronomers have identified potential black holes in a variety of astrophysical objects. In binary star systems, consisting of two stars revolving around each other under the influence of their mutual gravitational attraction, black holes with masses of order several solar masses (M ~ 5 – 20M⊙) are thought to exist as the dead remnant of the initially more massive of the two stars.
A Dichotomy on the Complexity of Consistent Query Answering for Atoms with Simple Keys

We study the problem of consistent query answering under primary key violations. In this setting, the relations in a database violate the key constraints and we are interested in maximal subsets of the database that satisfy the constraints, which we call repairs. For a boolean query Q, the problem CERTAINTY(Q) asks whether every such repair satisfies the query or not; the problem is known to be always in coNP for conjunctive queries. However, there are queries for which it can be solved in polynomial time. It has been conjectured that there exists a dichotomy on the complexity of CERTAINTY(Q) for conjunctive queries: it is either in PTIME or coNPcomplete. In this paper, we prove that the conjecture is indeed true for the case of conjunctive queries without self-joins, where each atom has as a key either a single attribute (simple key) or all attributes of the atom.
Documentation of Concurrent Programs

This research explores the usefulness of control-flow versus interprocess communications information in documentation of concurrent processing programs. Programmer performance was examined on a modification task where modifications were made to either the data structure or the control flow of a program. The results suggest that for simple programs and simple modifications, it is not crucial whether interprocess communications or control-flow information is highlighted in the documentation format. For more complex problems, it would appear that detailed control-flow information is not necessary, and, in fact, may interfere with making the modification.
Finding network motifs using MCMC sampling

Scientists have shown that network motifs are key building block of various biological networks. Most of the existing exact methods for finding network motifs are inefficient simply due to the inherent complexity of this task. In recent years, researchers are considering approximate methods that save computation by sacrificing exact counting of the frequency of potential motifs. However, these methods are also slow when one considers the motifs of larger size. In this work, we propose two methods for approximate motif finding, namely SRW-rw, and MHRW based on Markov Chain Monte Carlo (MCMC) sampling. Both the methods are significantly faster than the best of the existing methods, with comparable or better accuracy. Further, as the motif size grows the complexity of the proposed methods grows linearly.
Prospects for Star Formation Studies with Mid-Infrared Instruments on Large Telescopes

Imaging and spectroscopic observations in the mid-infrared wavelength range (5μm–30μm) offer valuable insight into the origins of stars and planets. Sensitive new array detectors on 8-meter class telescopes make it possible to study a wide range of phenomena, from protoplanetary disks to starburst galaxies, in unprecedented detail. I review the capabilities of ground-based mid-infrared instruments (e.g., high spatial resolution) and their limitations (e.g., poor sensitivity, small field of view) using several examples in the field of star formation, and discuss prospects for the near future.
Traveling wave parametric amplifier with Josephson junctions using minimal resonator phase matching

Josephson parametric amplifiers have become a critical tool in superconducting device physics due to their high gain and quantum-limited noise. Traveling wave parametric amplifiers (TWPAs) promise similar noise performance, while allowing for significant increases in both bandwidth and dynamic range. We present a TWPA device based on an LC-ladder transmission line of Josephson junctions and parallel plate capacitors using low-loss amorphous silicon dielectric. Crucially, we have inserted λ/4 resonators at regular intervals along the transmission line in order to maintain the phase matching condition between pump, signal, and idler and increase gain. We achieve an average gain of 12 dB across a 4 GHz span, along with an average saturation power of −92 dBm with noise approaching the quantum limit.
Existence of global weak solutions for 3D degenerate compressible Navier–Stokes equations

In this paper, we prove the existence of global weak solutions for 3D compressible Navier–Stokes equations with degenerate viscosity. The method is based on the Bresch and Desjardins (Commun Math Phys 238:211–223 2003) entropy conservation. The main contribution of this paper is to derive the Mellet and Vasseur (Commun Partial Differ Equ 32:431–452, 2007) type inequality for weak solutions, even if it is not verified by the first level of approximation. This provides existence of global solutions in time, for the compressible barotropic Navier–Stokes equations. The result holds for any $$\gamma >1$$ in two dimensional space, and for $$1<\gamma <3$$ in three dimensional space, in both case with large initial data possibly vanishing on the vacuum. This solves an open problem proposed by Lions (Mathematical topics in fluid mechanics. Vol. 2. Compressible models, 1998).
The Inelastic Maxwell Model

Dynamics of inelastic gases are studied within the framework of random collision processes. The corresponding Boltzmann equation with uniform collision rates is solved analytically for gases, impurities, and mixtures. Generally, the energy dissipation leads to a significant departure from the elastic case. Specifically, the velocity distributions have overpopulated high energy tails and different velocity components are correlated. In the freely cooling case, the velocity distribution develops an algebraic high-energy tail, with an exponent that depends sensitively on the dimension and the degree of dissipation. Moments of the velocity distribution exhibit multiscaling asymptotic behavior, and the autocorrelation function decays algebraically with time. In the forced case, the steady state velocity distribution decays exponentially at large velocities. An impurity immersed in a uniform inelastic gas may or may not mimic the behavior of the background, and the departure from the background behavior is characterized by a series of phase transitions.
Exotic Differential Operators on Complex Minimal Nilpotent Orbits

The orbit\(\mathcal{O}\)of highest weight vectors in a complex simple Lie algebra g is the smallest non-zero adjoint orbit that is conical, i.e., stable under the Euler dilation action of\(\mathbb{C}\) *on g.\(\mathcal{O}\)is a smooth quasi-affine variety and its closure Cl(\(\mathcal{O}\)) is a singular quadratic cone in g. The varieties\(\mathcal{O}\)and C1(\(\mathcal{O}\)) have the same algebra of regular functions, i.e., R(\(\mathcal{O}\)) = R(Cl(\(\mathcal{O}\))), and hence the same algebra of algebraic differential operators, i.e., D(\(\mathcal{O}\)) = D(Cl(\(\mathcal{O} \))).
The Long Swing: Comparisons and Interactions Between British and American Balance of Payments, 1820–1913

In the past decade there has been an extremely active interest in the evidence and importance of the twenty-year building cycle, or Kuznets cycle as Lewis suggests we call it, in both American nineteenth-century development and British development after 1870.2 The evidence of building cycles in the United States is perhaps more extensive and seems clearly, in the research accumulated by Kuznets, Burns and Abramovitz, to indicate a long swing in the general process of growth, not just long swings isolated to the building trades.3 Whereas American long swings pervade all domestic series of output, income and investment, British experience seems somewhat different. After 1870 long swings in British capital exports alternated with long swings in domestic investment in a fashion which eliminated excess fluctuations in income and output, which would have been due mainly to fluctuations in aggregate demand.1
Scaling Properties of Pure Random Walk on Random 3-SAT

Experimental results are given on the scaling of the Pure Random Walk version (PRWSAT) ofWalkSAT. PRWSAT is very simple because of the absence of heuristics: not only the clause is selected at random, but also the literal within that clause. The main result is that, despite the simplicity and absence of heuristics, it has non-trivial behavior on Random 3-SAT. There appears to be a threshold at a clause/variable ratio of about 2.65. Below the threshold, problems are solved in a tightly-distributed and linear number of flips. Above the threshold scaling appears to be non-polynomial. The simplicity and the nontrivial threshold make it a good candidate for theoretical analysis.
Fast Algorithms for the Maximum Clique Problem on Massive Sparse Graphs

The maximum clique problem is a well known NP-Hard problem with applications in data mining, network analysis, information retrieval and many other areas related to the World Wide Web. There exist several algorithms for the problem with acceptable runtimes for certain classes of graphs, but many of them are infeasible for massive graphs. We present a new exact algorithm that employs novel pruning techniques and is able to quickly find maximum cliques in large sparse graphs. Extensive experiments on different kinds of synthetic and real-world graphs show that our new algorithm can be orders of magnitude faster than existing algorithms. We also present a heuristic that runs orders of magnitude faster than the exact algorithm while providing optimal or near-optimal solutions.
Analysis of Mixed Interior Penalty Discontinuous Galerkin Methods for the Cahn–Hilliard Equation and the Hele–Shaw Flow

This paper proposes and analyzes two fully discrete mixed interior penalty discontinuous Galerkin (DG) methods for the fourth order nonlinear Cahn--Hilliard equation. Both methods use the backward Euler method for time discretization and interior penalty DG methods for spatial discretization. They differ from each other on how the nonlinear term is treated; one of them is based on fully implicit time-stepping and the other uses energy-splitting time-stepping. The primary goal of the paper is to prove the convergence of the numerical interfaces of the DG methods to the interface of the Hele--Shaw flow. This is achieved by establishing error estimates that depend on $\epsilon^{-1}$ only in some low polynomial orders, instead of exponential orders. Similar to [X. Feng and A. Prohl, Numer. Math., 74 (2004), pp. 47--84], the crux is to prove a discrete spectrum estimate in the discontinuous Galerkin finite element space. However, the validity of such a result is not obvious because the DG space is not a subspa...
Reasoning, metareasoning, and mathematical truth: studies of theorem proving under limited resources

In earlier work, we introduced flexible inference and decision-theoretic metareasoning to address the intractability of normative inference. Here, rather than pursuing the task of computing beliefs and actions with decision models composed of distinctions about uncertain events, we examine methods for inferring beliefs about mathematical truth before an automated theorem prover completes a proof. We employ a Bayesian analysis to update belief in truth, given theorem-proving progress, and show how decision-theoretic methods can be used to determine the value of continuing to deliberate versus taking immediate action in time-critical situations.
Robust mechanism design and dominant strategy voting rules

We develop an analysis of voting rules that is robust in the sense that we do not make any assumption regarding voters’ knowledge about each other. In dominant strategy voting rules, voters’ behavior can be predicted uniquely without making any such assumption. However, on full domains, the only dominant strategy voting rules are random dictatorships. We show that the designer of a voting rule can achieve Pareto improvements over random dictatorship by choosing rules in which voters’ behavior can depend on their beliefs. The Pareto improvement is achieved for all possible beliefs. The mechanism that we use to demonstrate this result is simple and intuitive, and the Pareto improvement result extends to all equilibria of the mechanism that satisfy a mild refinement. We also show that the result only holds for voters’ interim expected utilities, not for their ex post expected utilities.
Gene expression associated with white syndromes in a reef building coral, Acropora hyacinthus

Corals are capable of launching diverse immune defenses at the site of direct contact with pathogens, but the molecular mechanisms of this activity and the colony-wide effects of such stressors remain poorly understood. Here we compared gene expression profiles in eight healthy Acropora hyacinthus colonies against eight colonies exhibiting tissue loss commonly associated with white syndromes, all collected from a natural reef environment near Palau. Two types of tissues were sampled from diseased corals: visibly affected and apparently healthy. Tag-based RNA-Seq followed by weighted gene co-expression network analysis identified groups of co-regulated differentially expressed genes between all health states (disease lesion, apparently healthy tissues of diseased colonies, and fully healthy). Differences between healthy and diseased tissues indicate activation of several innate immunity and tissue repair pathways accompanied by reduced calcification and the switch towards metabolic reliance on stored lipids. Unaffected parts of diseased colonies, although displaying a trend towards these changes, were not significantly different from fully healthy samples. Still, network analysis identified a group of genes, suggestive of altered immunity state, that were specifically up-regulated in unaffected parts of diseased colonies. Similarity of fully healthy samples to apparently healthy parts of diseased colonies indicates that systemic effects of white syndromes on A. hyacinthus are weak, which implies that the coral colony is largely able to sustain its physiological performance despite disease. The genes specifically up-regulated in unaffected parts of diseased colonies, instead of being the consequence of disease, might be related to the originally higher susceptibility of these colonies to naturally occurring white syndromes.
Witten diagrams revisited: the AdS geometry of conformal blocks

We develop a new method for decomposing Witten diagrams into conformal blocks. The steps involved are elementary, requiring no explicit integration, and operate directly in position space. Central to this construction is an appealingly simple answer to the question: what object in AdS computes a conformal block? The answer is a “geodesic Witten diagram”, which is essentially an ordinary exchange Witten diagram, except that the cubic vertices are not integrated over all of AdS, but only over bulk geodesics connecting the boundary operators. In particular, we consider the case of four-point functions of scalar operators, and show how to easily reproduce existing results for the relevant conformal blocks in arbitrary dimension.
On the free boundary min-max geodesics

Given a Riemannian manifold and a closed submanifold, we find a geodesic segment with free boundary on the given submanifold. This is a corollary of the min-max theory which we develop in this article for the free boundary variational problem. In particular, we develop a modified Birkhoff curve shortening process to achieve a strong "Colding-Minicozzi" type min-max approximation result.
Minimum cost constrained input-output and control configuration co-design problem: A structural systems approach

In this paper, we study the minimal cost constrained input-output (I/O) and control configuration co-design problem. Given a linear time-invariant plant, where a collection of possible inputs and outputs is known a priori, we aim to determine the collection of inputs, outputs and communication among them incurring in the minimum cost, such that desired control performance, measured in terms of arbitrary pole-placement capability of the closed-loop system, is ensured. We show that this problem is NP-hard in general (in the size of the state space). However, the subclass of problems, in which the dynamic matrix is irreducible, is shown to be polynomially solvable and the corresponding algorithm is presented. In addition, under the same assumption, the same algorithm can be used to solve the minimal cost constrained I/O selection problem, and the minimal cost control configuration selection problem, individually. In order to illustrate the main results of this paper, some simulations are also provided.
Fiscal decentralization in developing and transition economies: progress, problems, and the promise

Shah discusses the revolution in public sector thinking that is transforming the public sectors of developing and transition countries. Countries are reconsidering their fiscal systems and searching for the right balance between central government control and decentralized governance. Political decentralization has advanced in most countries. Subnational expenditures in developing countries as a percentage of total public expenditures have also increased over the past two decades. However, the process is far from complete. In many countries, the central government is still involved in the delivery of local services, local governments have few sources of own-revenues, local governments have limited access to borrowing for capital projects, and the design of intergovernmental transfers does neither address regional fiscal equity nor convey appropriate incentives for fiscal discipline, improved service delivery performance, and accountability to citizens. Decentralized public governance can help realign public sector incentives through greater accountability to citizens, and attenuate the "democracy deficit" caused by globalization and the role of supranational institutions and regimes. However, this requires careful examination of the entire fiscal system. Elements of a comprehensive package of fiscal system reforms would include: - Clarifying roles of various levels of government in public service delivery. - Reassigning taxing responsibilities to ensure local revenue autonomy, accountability, and efficiency without endangering an internal common market. - Designing fiscal transfers to ensure regional fiscal equity and to create an enabling environment for innovative and competitive service delivery. - Facilitating responsible credit market access to subnational governments. - Designing institutional arrangements for intergovernmental fiscal relations to better coordinate policies. - Aligning operational capacity with the authorizing environment through the "accountability for results" framework of public management. This paper - a product of the Poverty Reduction and Economic Management Division, World Bank Institute - is part of a larger effort in the institute to disseminate ideas in strengthening responsive, responsible, and accountable public governance.
Evolutionary dynamics of shared niche construction

Many species engage in niche construction that ultimately leads to an increase in the carrying capacity of the population. We have investigated how the specificity of this behaviour affects evolutionary dynamics using a set of coupled logistic equations, where the carrying capacity of each genotype consists of two components: an intrinsic part and a contribution from all genotypes present in the population. The relative contribution of the two components is controlled by a specificity parameter γ, and we show that the ability of a mutant to invade a resident population depends strongly on this parameter. When the carrying capacity is intrinsic, selection is almost exclusively for mutants with higher carrying capacity, while a shared carrying capacity yields selection purely on growth rate. This result has important implications for our understanding of niche construction, in particular the evolutionary dynamics of tumor growth.
The globalization of consulting engineering

After discussing the globalization of the world's economy in general, the author considers the globalization of consulting engineering in particular. Attention is given to the engineering roadway to globalization, forms of foreign market presence, the US market, and the projected future of globalization in the balance of the 1990s. >
Protection of Infrastructure

Critical infrastructure consists of the basic mechanisms and services essential for a society to function. It must be protected against natural and deliberate damage. These protective efforts should be selected according to careful risk analysis, with consideration of opportunity costs and the interactions between different kinds of investment. For natural threats, there is a large literature that often focuses on the extreme events; for deliberate threats, one must also consider game theory. Keywords: elicitation; epistemic probability; extreme events; game theory; portfolio analysis
Economic implications of reducing carbon emissions from energy use and industrial processes in Brazil

The overall impacts on the Brazilian economy of reducing CO2 emissions from energy use and industrial processes can be assessed using a recursive dynamic general equilibrium model and a hypothetical carbon tax. The study projects that in 2040 under a business-as-usual scenario, CO2 emissions from energy use and industrial processes would be almost three times as high as in 2010 and would account for more than half of total national CO2 emissions. Current policy aims to reduce deforestation by 70 percent by 2017 and emissions intensity of the overall economy by 36-39 percent by 2020. If policy is implemented as planned and continued to 2040, CO2 emissions from energy use and industrial processes would not have to be cut until 2035 as reductions of emissions through controlling deforestation would be enough to meet emission targets. The study also finds evidence that supports the double dividend hypothesis: using revenue from a hypothetical carbon tax to finance a cut in labor income tax significantly lowers the gross domestic product impacts of the carbon tax. Using carbon tax revenue to subsidize wind power can effectively increase the output of wind power in the country, although the impact of the tax on gross domestic product would be somewhat increased.
The Banach envelope of Paley-Wiener type spaces

We give an explicit computation of the Banach envelope for the Paley-Wiener type spaces E p , 0 < p < 1. This answers a question by Joel Shapiro.
Financial development in Asia : beyond aggregate indicators

This paper documents the major trends in financial development in Asia since the early 1990s and the spillovers to firms. It compares Asia with advanced and emerging countries and uses both aggregate and disaggregate indicators. Financial systems in Asia remain less developed than in advanced countries but more developed than in Eastern Europe and Latin America. Bond and stock markets play a larger role and institutional investors have gained importance. Nonetheless, capital-raising activity has not expanded. A few large companies capture most of the issuances. Many secondary markets remain illiquid. The public sector captures a significant share of bond markets. The largest advancements in Asia occurred in China and India. But still in these countries, few large companies use capital markets to expand and grow, becoming much larger than nonuser firms. In sum, Asia's financial systems remain less developed than aggregate measures suggest, with few spillovers to many firms.
Local versus Global Search in Channel Graphs

Previous studies of search in channel graphs have assumed global search, for which the status of any link can be probed by the search algorithm at any time. We consider for the first time local search, for which only links to which an idle path from the source has already been established may be probed. We show that some well-known channel graphs may require exponentially more probes, on average, when search must be local than when it may be global. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2013
PRODUCT VARIETY AND COMPETITION IN THE RETAIL MARKET FOR EYEGLASSES

I use original data on eyewear retailers in a cross-section of U.S. markets to study how firms' product range choices vary with the degree of local competition. Market level regressions show average per firm variety declining in the number of rivals. In regressions at the firm level, taking account of spatial differentiation within each market, a non-monotonic relationship between product ranges and competition is apparent. As the number of nearby rivals increases, per firm variety may first rise before eventually declining. Explanations for this pattern are offered, in terms of a tradeoff between business stealing and clustering effects.
A noncommutative version of the John-Nirenberg theorem

We prove a noncommutative version of the John-Nirenberg theorem for nontracial filtrations of von Neumann algebras. As an application, we obtain an analogue of the classical large deviation inequality for elements of the associated BMO space.
Municipal vulnerability to climate change and climate related events in Mexico

A climate change vulnerability index in agriculture is presented at the municipal level in Mexico. Because the index is built with a multidimensional approach to vulnerability (exposure, sensitivity and adaptive capacity), it represents a tool for policy makers, academics and government alike to inform decisions about climate change resilience and regional variations within the country. The index entails baseline (2005) and prediction (2045) levels based on historic climate data and future-climate modeling. The results of the analysis suggest a wide variation in municipal vulnerability across the country at baseline and prediction points. The vulnerability index shows that highly vulnerable municipalities demonstrate higher climate extremes, which increases uncertainty for harvest periods, and for agricultural yields and outputs. The index shows at baseline that coastal areas host some of the most vulnerable municipalities to climate change in Mexico. However, it also shows that the Northwest and Central regions will likely experience the largest shifts in vulnerability between 2005 and 2045. Finally, vulnerability is found to vary according to specific variables: municipalities with higher vulnerability have more adverse socio-demographic conditions. With the vast municipal data available in Mexico, further sub-index estimations can lead to answers for specific policy and research questions.
Throughput of multiprocessors with replicated shared memories

Multiprocessors with replicated shared memory use a memory structure consisting of a set of memories, one for each processor, with identical contents. This minimizes read interference since each processor simply accesses its own private copy of the shared memory. To ensure shared-memory integrity, write requests transfer data to all copies in parallel. Compared to traditional shared memories, multiprocessors with replicated shared memories may achieve a speed-up which approaches O(N), with N equal to the number of processors. This speed-up occurs for systems with large N, a small number of shared memories, and large shared-memory use and fractions of read requests.
Modeling the effect of finite size gratings on scatterometry measurements

The interpretation of scatterometry measurements generally assumes that the grating extends over an area large enough to intercept all the illumination provided by an incident beam. However, in practice, the gratings used in scatterometry are relatively small. Thus, the detected light also includes both that scattered by the grating as well as that from a region surrounding the grating because, generally, the incident beam illuminates both the grating and the surrounding region. To model the effects of such real structures, simulations of the effective reflectance were performed whereby the reflection from the grating was considered to be the sum of the diffraction by the grating and the diffraction of the surrounding region, taking into account the beam profile. To demonstrate the model, the illumination field was assumed to be Gaussian. Results are shown for a specific target design consisting of a 50 μm square measured by normal incidence reflectometry. Significant errors occur when the incident profile has wings that fall outside of the profile and when the scattered light is partially apertured.
A self-stabilized algorithm for enforcing constraints in multibody systems

A new algorithm is developed for the enforcement of constraints within the framework of nonlinear, flexible multibody system modeled with the finite element approach. The proposed algorithm exactly satisfies the constraints at the displacement and velocity levels, and furthermore, it achieves nonlinear unconditional stability by imposing the vanishing of the work done by the constraint forces when combined with specific discretizations of the inertial and elastic forces. Identical convergence rates are observed for the displacements, velocities, and Lagrange multipliers. The proposed algorithm is closely related to the stabilized index-2 or GGL method, although no additional multipliers are introduced in the present approach. These desirable characteristics are obtained without resorting to numerically dissipative algorithms. If high frequencies are present in the system, i.e. the system is physically stiff, dissipative schemes become necessary; the proposed algorithm is extended to deal with this situation.
Stochastic prediction techniques for wind shear hazard assessment

The threat of low-altitude wind shear has prompted development of aircraft-based sensors that measure winds directly on the aircraft's intended flight path. Measurements from these devices are subject to turbulence inputs and measurement error, as well as to the underlying wind profile. Stochastic estimators are developed to process on-board Doppler sensor measurements, producing optimal estimates of the winds along the path. A stochastic prediction technique is described to predict the hazard to the aircraft from the estimates as well as the level of uncertainty of the hazard prediction. The stochastic prediction technique is demonstrated in a simulated microburst wind shear environment. Use of the technique in a decision-making process is discussed. >
Under a cloud of suspicion: trust, distrust, and their interactive effect in interorganizational contracting

Although considerable research has examined the role of trust in interorganizational relationship (IOR) contracting, scholars have devoted less attention to how trust and distrust jointly influence this process. We propose and test a model wherein trust, based on partner reliability, is constrained to the IOR exchange context where it develops and does not generalize to other contexts. Distrust, rooted in value incongruence, more readily generalizes across exchange contexts. Results support these predictions. In addition, our analysis shows that trust and distrust combine such that managers decrease their preferences for highly specific focal-context contracts only when in-context trust is high and distrust is low. We discuss how these findings may provide a more nuanced understanding of the relationship between trust-based and contract-based IOR governance. Copyright © 2011 John Wiley & Sons, Ltd.