cssi/SciSciGPT-SciSciNet huggingface dataset:
I/O-Efficient Algorithms for Sparse Graphs

Massive graphs arise naturally in many applications. Recent web crawls, for example, produce graphs with on the order of 200 million nodes and 2 billion edges. Recent research in web modelling uses depth-first search, breadth-first search, and the computation of shortest paths and connected components as primitive routines for investigating the structure of the web [158]. Massive graphs are also often manipulated in Geographic Information Systems (GIS), where many problems can be formulated as fundamental graph problems. When working with such massive data sets, only a fraction of the data can be held in the main memory of a state-of-the-art computer. Thus, the transfer of data between main memory and secondary, disk-based memory, and not the internal memory computation, is often the bottleneck. A number of models have been developed for the purpose of analyzing this bottleneck and designing algorithms that minimize the traffic between main memory and disk. The algorithms discussed in this chapter are designed and analyzed in the parallel disk model (PDM) of Vitter and Shriver [755]. For a definition and discussion of this model, the reader may refer to Chapter 1.
Expanding social mobile games beyond the device screen

Emerging pervasive games use sensors, graphics and networking technologies to provide immersive game experiences integrated with the real world. Existing pervasive games commonly rely on a device screen for providing game-related information, while overlooking opportunities to include new types of contextual interactions like jumping, a punching gesture, or even voice to be used as game inputs. We present the design of Spellbound, a physical mobile team-based game, to help contribute to our understanding of how we can design pervasive games that aim to nurture a spirit of togetherness. We also briefly touch upon how togetherness and playfulness can transform physical movement into a desirable activity in the user evaluation section. Spellbound is an outdoor pervasive team-based physical game. It takes advantage of the above-mentioned opportunities and integrates real-world actions like jumping and spinning with a virtual world. It also replaces touch-based input with voice interaction and provides glanceable and haptic feedback using custom hardware in the true spirit of social play characteristic of traditional children's games. We believe Spellbound is a form of digital outdoor gaming that anchors enjoyment on physical action, social interaction, and tangible feedback. Spellbound was well received in user evaluation playtests which confirmed that the main design objective of enhancing a sense of togetherness was largely met.
Reasonable Value and the Role of Negotiation in Agriculture's Use of the Environment

General environmental policy and restrictions specifically targeted at agriculture will continue to influence agricultural policy. Agricultural and environmental communities can react to these events in many ways, but the most promising way to resolve agricultural and environmental disputes lies in negotiated regulations mediated by governmental agencies. This approach should attract the agricultural community because it provides an opportunity to educate environmental groups about the complexities facing modern agriculture. It also ensures that regulators consider private business interests during policy development. While not a panacea, a negotiated regulations approach is the best hope for flexibly satisfying the dual objectives of a clean environment and an economically viable agricultural sector.
Incomplete contracts and investment : a study of land tenancy in Pakistan

When contracts are incomplete, relationship-specific investments may be underprovided due to the threat of opportunistic expropriation or holdup. The authors find evidence of such underinvestment on tenanted land in rural Pakistan. Using data from households cultivating multiple plots under different tenure arrangements, they show that land-specific investment is lower on leased plots. This result is robust to the possible effects of asymmetric information in the leasing market. Greater tenure security also increases land-specific investment on leased plots. Moreover, variation in tenure security appears to be driven largely by heterogeneity across landlords, suggesting that reputation may be important in mitigating the holdup problem.
Stiefel-Whitney classes and the conormal cycle of a singular variety

A geometric construction of Sullivan's Stiefel-Whitney homology classes of a real analytic variety X is given by means of the conormal cycle of an embedding of X in a smooth variety. We prove that the Stiefel-Whitney classes define additive natural transformations from certain constructible functions to homology. We also show that, for a complex analytic variety, these classes are the mod 2 reductions of the Chern-MacPherson classes. We present a new definition of the Stiefel-Whitney homology classes of a possibly singular real analytic variety X. The original definition, due to Sullivan [S], involves a triangulation of X; its geometric meaning is unclear. Our definition uses the conormal cycle of an embedding of X in a smooth variety. The conormal cycle of a subanalytic subset X of an analytic manifold M was defined by the first author [F4] using geometric measure theory. The conormal cycle is an integral current representing (up to sign) Kashiwara's characteristic cycle of the sheaf DMRX [F4, 4.7]. Our construction of the Stiefel-Whitney classes is based on the fundamental observation that the conormal cycle of a real analytic variety is antipodally symmetric mod 2. We use this observation to give a definition of Stiefel-Whitney classes which is parallel to the first author's definition of the Chern-Schwartz-MacPherson classes of a complex analytic variety [F5]. (This definition of Chern classes is related to earlier work of Brylinski-Dubson-Kashiwara [BDK] and Sabbah [Sa].) In fact we show that the Stiefel-Whitney homology classes of a complex analytic variety are the mod 2 reductions of the Chern classes. We prove that our Stiefel-Whitney classes satisfy axioms similar to the Deligne-Grothendieck axioms for Chern classes, and we prove a specialization formula for the Stiefel-Whitney classes of a family of varieties. We show that the Stiefel-Whitney classes of an affine real analytic variety X are represented by the polar cycles of X, introduced for simplicial spaces by Banchoff [B] and McCrory [Mc], and we give a new proof of the combinatorial formula for Stiefel-Whitney classes of manifolds. Our central result is a specialization formula for the conormal cycle (Theorem 3.7). We use this formula to prove the basic results of Kashiwara and Schapira's calculus of subanalytically constructible functions [Sc], [KS, 9.7], as well as the pushforward and specialization formulas for Stiefel-Whitney classes. Received by the editors October 2, 1995. 1991 Mathematics Subject Classification. Primary 14P25, 57R20; Secondary 14P15, 49Q15.
Reduced space-time and time costs using dislocation codes and arbitrary Ancillas

We propose two distinct methods of improving quantum computing protocols based on surface codes. First, we analyze the use of dislocations instead of holes to produce logical qubits, potentially reducing spacetime volume required. Dislocations[8, 9] induce defects which, in many respects, behave like Majorana quasi-particles. We construct circuits to implement these codes and present fault-tolerant measurement methods for these and other defects which may reduce spatial overhead. One advantage of these codes is that Hadamard gates take exactly 0 time to implement. We numerically study the performance of these codes using a minimum weight and a greedy decoder using finite-size scaling. Second, we consider state injection of arbitrary ancillas to produce arbitrary rotations. This avoids the logarithmic (in precision) overhead in online cost required if T gates are used to synthesize arbitrary rotations. While this has been considered before[4], we consider also the parallel performance of this protocol. Arbitrary ancilla injection leads to a probabilistic protocol in which there is a constant chance of success on each round; we use an amortized analysis to show that even in a parallel setting this leads to only a constant factor slowdown as opposed to the logarithmic slowdown that might be expected naively.
Case–Control Study, Prevalent

Case–control studies based on incident cases are well suited to studies of etiologic factors that affect disease onset. A prevalent case–control study includes subjects who have survived to the time of the study and had a previous history of disease onset. Associations with prevalent disease may therefore reflect not only disease onset but also influences on survival following disease onset. In a steady state population, the prevalence odds ratio for an exposure equals the incidence odds ratio times the ratio of mean survival times following disease onset. We discuss the interpretation of prevalent case–control studies, with examples of nosocomial infection and of neural tube defects. Keywords: prevalent case–control study; incident case–control study; prevalence odds ratio; cross-sectional study; incidence–prevalence relationships; etiologic studies; steady state population
Uncertainties in the Age Scale for Young Open Clusters and Moving Groups

Young open clusters provide the template data for calibrating nearly all methods of age-dating field stars. Despite the potential for open cluster ages to be quite precise – and despite a large amount of observational effort – the age scale for young open clusters is still controversial, with correction factors of a factor of 2 or more proposed. I will discuss some of the causes for this uncertainty, and touch on the role of future large surveys in helping to resolve the issue.
An evaluation of the initial impact of the medical assistance program for the poor in Georgia

As part of the recent health reform effort, the government of Georgia launched a Medical Assistance Program in June 2006 to provide health insurance to its poor population. So far the program covers slightly over 50 percent of the poor and provides benefit coverage for outpatient and inpatient care. This paper estimates initial impact of the Medical Assistance Program and assesses whether the benefits have reached the poorest among those eligible, using utilization data from June 2006 to December 2006. Based on the analysis using a regression discontinuity design and a three-part model, the paper presents two main findings. First, the Medical Assistance Program has significantly increased utilization of acute surgeries/inpatient services by the poor. Second, the benefits have successfully reached the poorest among the poor. These two findings indicate that government efforts to improve the poor's access to and utilization of health services are yielding results. The paper emphasizes that the initial dramatic increase in surgeries must be interpreted with caution, given the possible misclassification or misreporting of acute surgeries in the data. The paper also stresses the need to continue monitoring implementation of the Medical Assistance Program and further improve program design, particularly the targeting mechanism, to achieve better efficiency, effectiveness and overall equity in access to health care services.
Transitions in climate and energy discourse between Hurricanes Katrina and Sandy

Although climate change and energy are intricately linked, their explicit connection is not always prominent in public discourse and the media. Disruptive extreme weather events, including hurricanes, focus public attention in new and different ways offering a unique window of opportunity to analyze how a focusing event influences public discourse. Media coverage of extreme weather events simultaneously shapes and reflects public discourse on climate issues. Here, we analyze climate and energy newspaper coverage of Hurricanes Katrina (2005) and Sandy (2012) using topic models, mathematical techniques used to discover abstract topics within a set of documents. Our results demonstrate that post-Katrina media coverage does not contain a climate change topic, and the energy topic is limited to discussion of energy prices, markets, and the economy with almost no explicit linkages made between energy and climate change. In contrast, post-Sandy media coverage does contain a prominent climate change topic, a distinct energy topic, as well as integrated representation of climate change and energy, indicating a shift in climate and energy reporting between Hurricane Katrina and Hurricane Sandy.
Non-Big 4 Local Market Leadership and its Effect on Competition

ABSTRACT: This study examines local characteristics associated with non-Big 4 local market leadership and the impact of non-Big 4 local market leadership on competition. We identify non-Big 4 local market leaders by collecting accounting firm rankings from business publications for 46 of the largest metropolitan statistical areas from 2005–2010. These rankings are based on the number of local office employees and provide a more holistic measure of office size than measures based on public company audit fees. We find local supply and demand factors are significantly associated with non-Big 4 local market leadership and that non-Big 4 leadership is associated with lower overall audit fees in the local market. We also find that non-Big 4 leaders earn a fee premium over other non-Big 4 auditors. Our results imply that non-Big 4 leaders increase local market competition. Data Availability: All data are publicly available from sources identified in the study.
Length of Incubation for Enumerating Nitrifying Bacteria Present in Various Environments

The effect of incubation time on most-probable-number estimates of autotrophic nitrifying bacteria was investigated by using waters, rooted aquatic plants, sediments, and slimes as inoculum sources. Maximum most probable numbers of the NH4+-oxidizing group were attained in 20 to 55 days (median, 25). Estimates of NO2- oxidizers were highest at termination (103 to 113) days.
Econometric Methods in Health Services

The purpose of this article is to provide a brief summary of prominent econometric applications in modern health economics, by providing a broad overview of problems to which econometric methods have been applied. These methods typically are used to address problems in health, health care delivery, and health care costs from a cross-section of observations at a given time. The chapter considers methods for analyzing continuous outcomes, such as cost; continuous, nonnormally distributed outcomes; simultaneous equation methods; and methods for count data, such as utilization data. Keywords: costs; methods; identification; bias; heteroscedasticity
Economy of description by parsers, DPDA's, and PDA's

Abstract It is shown that there is a sequence of languages E 1 , E 2 ,… such that every correct prefix parser (one which detects errors at the earliest possible moment, e.g., LR or LL parsers) for E n has size 2 cn , yet a deterministic PDA recognizing E n exists and has size O( n 2 ). There is another easily described sequence of languages N 1 , N 2 ,… for which N has a nondeterministic PDA of size O( n 2 ), but no deterministic PDA of size less than 2 cn . It is shown moreover, that this latter gap can be made arbitrarily large for different sequences of languages.
Risk factors for umbilical venous catheter-associated thrombosis in very low birth weight infants.

Background Thrombosis in neonates is a rare but serious occurrence, usually associated with central catheterization. The objective of this study was to investigate the risk factors associated with catheter related thrombosis in very low birth weight (VLBW) infants. Procedure The present retrospective study was performed using data from a randomized trial of duration of umbilical venous catheters (UVC) placement among infants <1,250 g birth weight. Twenty-two cases of UVC-associated thrombosis were identified in this sample. The remaining study sample (n = 188) served as the comparison group. Data on thrombosis, platelets, gestational age, birth weight, hematocrit, serum sodium, maternal preeclampsia, blood group, infant of diabetic mother (IDM) and demographic factors were collected using database and record review. Results Among the total subjects (n = 210), 112 (53%) were males and 126 (60%) were Caucasians, with mean gestational age of 27.7 ± 2.1 weeks (standard deviation) and mean birth weight of 923 ± 195 g. Bivariate analysis revealed significant association of thrombosis with hematocrit >55% in the first week (odds ratio [OR] 5.4; 95% confidence interval [CI] 2.0–14.6; P = 0.0003), being small for gestational age (SGA) (OR, 2.9; 95% CI, 1.2–7.4; P = 0.02) and maternal preeclampsia (OR, 3.97; 95% CI, 1.6–9.84; P = 0.0017). In multivariate logistic regression analysis, only hematocrit >55% was independently associated with thrombus (OR, 3.7; 95% CI 1.1–11.8; P = 0.03). Conclusions This study demonstrates a significant, independent association between elevated hematocrit and development of UVC-associated thrombosis. Careful monitoring for catheter-associated thrombosis may be indicated in VLBW infants who have hematocrit >55% in the first week of life. Pediatr Blood Cancer 2009;52:75–79. © 2008 Wiley-Liss, Inc.
Maximally stabilizing task release control policy for a dynamical queue

In this paper, we consider the following stability problem for a novel dynamical queue. Independent and identical tasks arrive for a queue at a deterministic rate. The server spends deterministic state-dependent times to service these tasks, where the server state is governed by its utilization history through a simple dynamical model. Inspired by empirical laws for human performance as a function of mental arousal, we let the service time be related to the server state by a continuous convex function. We consider a task release control architecture which regulates task entry into service. The objective in this paper is to design such task release control policies that can stabilize the dynamical queue for the maximum possible arrival rate, where the queue is said to be stable if the number of tasks awaiting service does not grow unbounded over time. First, we prove an upper bound on the maximum stabilizable arrival rate for any task release control policy by postulating a notion of one-task equilibrium for the dynamical queue and exploiting its optimality. Then, we propose a simple threshold policy that allocates a task to the server only if its state is below a certain fixed value. We prove that this task release control policy ensures stability of the queue for the maximum possible arrival rate.
The Wittig reaction in the generation of organometallic compounds containing alkenes as side groups

Abstract The Wittig reaction has been identified as a viable route to transition metal monomers. It has been used to synthesize {η 5 -C 5 [C(CH 3 )CHR]}Mn(CO) 3 [R  H (68% yield), -CH 3 (60%), -CH 2 CH 3 (51%), -CH 2 CH 2 CH 3 (40%), -C 6 H 5 (46%)] from acetylcymantrene and the appropriate phosphorane at room temperature. {η 5 C 5 H 4 [C(CH 3 )CHR]}(η 5 -C 5 H 5 )Fe [R  -H (81%), -CH 3 (77%). -CH 2 CH 3 (36%), -CH 2 CH 2 CH 3 (27%) have been prepared from acetylferrocene and phosphorane at room temperature. [η 5 -C 5 (CHCRR′)H 4 ](η 5 -C 5 -H 5 )Fe [R,R′ -H,H (79%); -CH 3 ,H (69%); -CH 2 CH 3 ,H (48%); -CH 2 CH 2 CH 3 ,H (49%); -C 6 H 5 ,H (80%); -C(CH 3 ) 2 H,H (73%); -CH 3 ,CH 3 (67%)] have been produced from formylferrocene and phosphorane in refluxing benzene. E / Z isomeric ratios were identified for alkenylcymantrenes and are consistent with past Wittig studies. The aldol reaction has been identified as a side route in the Wittig reactions of acetylferrocene and phosphoranes. Carbomethoxyphosphoranes did not produce alkenes at room temperature with nonpolar solvents.
The Rise in the Disability Rolls and the Decline in Unemployment

Between 1984 and 2001, the share of nonelderly adults receiving Social Security Disability Insurance income (DI) rose by 60 percent to 5.3 million beneficiaries. Rapid program growth despite improving aggregate health appears to be explained by reduced screening stringency, declining demand for less skilled workers, and an unforeseen increase in the earnings replacement rate. We estimate that the sum of these forces doubled the labor force exit propensity of displaced high school dropouts after 1984, lowering measured U. S. unemployment by one-half a percentage point. Steady state calculations augur a further 40 percent increase in the rate of DI receipt.
The Levy-Gromov Isoperimetric Inequality in Convex Manifolds with Boundary

We observe after Bayle and Rosales that the Levy-Gromov isoperimetric inequality generalizes to convex manifolds with boundary and certain singularities.
Collective Choice and Voluntary Provision of Public Goods

Some public goods are provided entirely with private contributions, others with a mixture of public and private funding, and still others are entirely publicly funded. In order to study this variation, a model of dual provision is developed that endogenizes public and private funding. Households vote over an income tax that finances public supply of the good and on whether to permit private contributions. While permitting private contributions may lead to a reduction in total provision, a majority always favors permitting private contributions. Results are developed for small and large economies, and the relevance of nonexcludability and noncongestion are investigated.
Understanding the Effects of a Shock to Government Purchases

Abstract This paper investigates the consequences of an exogenous increase in U.S. government purchases. We find that in response to such a shock, employment, output, and nonresidential investment rise, while real wages, residential investment, and consumption expenditures fall. The paper argues that a simple variant of the neoclassical growth model which distinguishes between nonresidential and residential investment is consistent with this evidence.Journal of Economic LiteratureClassification Numbers: E1, E6.
Biosynthesis of aminocyclitol-aminoglycoside antibiotics and related compounds

Covering: 1978 to June 2006This review covers the biosynthesis of aminocyclitol-aminoglycoside antibiotics and related compounds, particularly from the molecular genetic perspectives. 195 references are cited.
HOW DO DISKS SURVIVE MERGERS

We develop a general physical model for how galactic disks survive and/or are destroyed in mergers and interactions. Based on simple dynamical arguments, we show that gas primarily loses angular momentum to internal torques in a merger, induced by the gravity of the secondary. Gas within some characteristic radius, determined by the efficiency of this angular momentum loss (itself a function of the orbital parameters, mass ratio, and gas fraction of the merging galaxies), will quickly lose angular momentum to the stars sharing the perturbed host disk, fall to the center, and be consumed in a starburst. We use a similar analysis to determine where violent relaxation of the premerger stellar disks is efficient on final coalescence. Our model describes both the dissipational and dissipationless components of the merger, and allows us to predict, for a given arbitrary encounter, the stellar and gas content of the material that will survive (without significant angular momentum loss or violent relaxation) to re-form a disk in the merger remnant, versus being dissipationlessly and violently relaxed or dissipationally losing angular momentum and forming a compact central starburst. We test these predictions with a large library of hydrodynamic merger simulations, and show that they agree well (with small scatter) with the properties of simulated merger remnants as a function of merger mass ratio, orbital parameters, and gas distributions in simulations which span a wide range of parameter space in these properties as well as prescriptions for gas physics, stellar and active galactic nucleus (AGN) feedback, halo and initial disk structural properties, redshift, and galaxy masses. We show that, in an immediate (short-term) sense, the amount of stellar or gaseous disk that survives or re-forms following a given interaction can be understood purely in terms of simple, well understood gravitational physics, independent of the details of the interstellar medium gas physics or stellar and AGN feedback. This allows us to demonstrate and quantify how these physics are in fact important, in an indirect sense, to enable disks to survive mergers by lowering star formation efficiencies in low-mass systems (allowing them to retain large gas fractions) and distributing the gas to large radii. The efficiency of disk destruction in mergers is a strong function of gas content—our model allows us to explicitly predict and demonstrate how, in sufficiently gas-rich mergers (with quite general orbital parameters), even 1:1 mass-ratio mergers can yield disk-dominated remnants, and more realistic 1:3-1:4 mass-ratio major mergers can yield systems with <20% of their mass in bulges. We discuss a number of implications of this modeling for the abundance and morphology of bulges as a function of mass and redshift, and provide simple prescriptions for the implementation of our results in analytic or semianalytic models of galaxy formation.
A divergent synthesis of d- and l-carbocyclic 4′-fluoro-2′,3′-dideoxynucleosides as potential antiviral agents

Abstract d - and l -Carbocyclic 4′-fluoro-2′,3′-dideoxynucleosides have been synthesized from 2 , which can be conveniently prepared from 1,2:5,6-di- O -isopropylidene- d -mannitol 1 in eight steps. Ruthenium-catalyzed ring-closing metathesis has been employed in the synthesis of d -nucleosides, whereas the l -series have been obtained through an intramolecular nucleophilic substitution reaction. The Mitsunobu condensation was used as a general tool for the synthesis of both purine and pyrimidine nucleosides.
AdS / CFT duality and the black hole information paradox

Abstract Near-extremal black holes are obtained by exciting the Ramond sector of the D1-D5 CFT, where the ground state is highly degenerate. We find that the dual geometries for these ground states have throats that end in a way that is characterized by the CFT state. Below the black hole threshold we find a detailed agreement between propagation in the throat and excitations of the CFT. We study the breakdown of the semiclassical approximation and relate the results to the proposal of gr-qc/0007011 for resolving the information paradox: semiclassical evolution breaks down if hypersurfaces stretch too much during an evolution. We find that a volume V stretches to a maximum throat depth of V /2G .
Bézier representation for cubic surface patches

Abstract The paper describes a new method for creating rectangular Bezier surface patches on an implicit cubic surface. Traditional techniques for representing surfaces have relied on parametric representations of surfaces, which, in general, generate surfaces of implicit degree 8 in the case of rectangular Bezier surfaces with rational biquadratic parameterization. The method constructs low-degree algebraic surface patches by reducing the implicit degree from 8 to 3. The construction uses a rectangular biquadratic Bezier control polyhedron that is embedded within a tetrahedron and satisfies a projective constraint. The control polyhedron and the resulting cubic surface patch satisfy all of the standard properties of parametric Bezier surfaces, including interpolation of the corners of the control polyhedron and the convex-hull property.
Evaluation of High-Order Spectral Volume Method for Benchmark Computational Aeroacoustic Problems

A time-accurate, high-order finite volume method named spectral volume (SV) method has been developed recently for conservation laws on unstructured grids and successfully demonstrated for Euler equations. In this paper, the SV method is evaluated for several benchmark problems in computational aeroacoustics (CAA) to demonstrate its potential for CAA applications. Both one-dimensional and two-dimensional problems are tested in the evaluation. It is shown that the higher-order SV schemes can achieve the same accuracy at a much lower cost than the lower-order ones.
The Constitutionality of the Individual Mandate for Health Insurance

If President Barack Obama and Democrats in Congress pass a health care reform bill, conservative groups are likely to challenge parts of it as unconstitutional. Jack Balkin explains why a constitutional challenge is unlikely to succeed.
Absolute extreme-ultraviolet metrology

NIST has a long-standing program for the calibration of extreme ultraviolet optical components. Early activities, which began with the advent of the Synchrotron Ultraviolet Radiation Facility (SURF) almost 40 years ago, centered on the development and characterization of detectors for extreme ultraviolet (EUV) radiation. About a decade ago the program was expanded to include reflectometry of normal- incidence EUV multilayer optics. Both calibrated detectors and EUV optics are used by researchers in private industry, academia, and government, in such diverse fields as EUV lithography, astronomy, and plasma physics. Since the inception of SURF, nearly 800 transfer standard photodiodes have been issued to customers, and over 500 measurements of other EUV optical components have been made. NIST researchers, in collaboration with U.S. companies, have developed new, high-quality radiometric detectors for use throughout the EUV spectral range. We will discuss the history of NIST's involvement in EUV metrology and offer examples of our recent work.
Welfare-domination under preference-replacement: A survey and open questions

The objective of this paper is to describe various applications of a requirement of solidarity pertaining to situations in which the preferences of some of the agents may change. It says that the welfares of all agents whose preferences are fixed should be affected in the same direction: they should all weakly gain, or they should all weakly lose. We show how this condition, which we name “welfare-domination under preference-replacement”, can help in evaluating allocation rules. We discuss it in several contexts: private good allocation in classical economies, public good decision, binary choice with quasi-linear preferences, economies with indivisible goods, economies with single-peaked preferences, both in the private good case and in the public good case, and economies with time. For some of these models the implications of the property are well understood. For others, we state a number of open problems.
Invariant-Based Recognition of Complex Curved 3D Objects from Image Contours

This paper addresses the problem of recognizing three-dimensional objects bounded by smooth curved surfaces from image contours found in a single photograph. The proposed approach is based on a viewpoint-invariant relationship between object geometry and certain image features under weak perspective projection. The image features themselves are viewpoint-dependent. Concretely, the set of all possible silhouette bitangents, along with the contour points sharing the same tangent direction, is the projection of a one-dimensional set of surface points where each point lies on the occluding contour for a five-parameter family of viewpoints. These image features form a one-parameter family of equivalence classes, and it is shown that each class can be characterized by a set of numerical attributes that remain constant across the corresponding five-dimensional set of viewpoints. This is the basis for describing objects by “invariant” curves embedded in high-dimensional spaces. Modeling is achieved by moving an object in front of a camera and does not require knowing the object-to-camera transformation; nor does it involve implicit or explicit three-dimensional shape reconstruction. At recognition time, attributes computed from a single image are used to index the model database, and both qualitative and quantitative verification procedures eliminate potential false matches. The approach has been implemented and examples are presented.
Synthesis of alkylidenephthalans through fluoride-induced cyclization of electron-deficient 2-siloxymethylphenylacetylene derivatives

Fluoride-based deprotection of silylated 2-alkynylbenzyl alcohol derivatives featuring carbonyl-substituted alkynes results in the direct synthesis of alkylidenephthalan vinylogous esters. The reaction is selective for the Z alkylidenephthalans in a thermodynamically controlled process. Similar compounds are also produced in the coupling of Fischer carbene complexes with 2-alkynylbenzoyl derivatives in an aqueous solvent system. Subsequent acid-catalyzed inter- or intramolecular Diels-Alder reactions lead to hydronaphthalene or hydrophenanthrene derivatives.
Anomalies in instanton calculus

I develop a formalism for solving topological field theories explicitly, in the case when the explicit expression of the instantons is known. I solve topological Yang-Mills theory with the k = 1 instanton of Belavin et al. and topological gravity with the Eguchi-Hanson instanton. It turns out that naively empty theories are indeed nontrivial. Many unexpected interesting hidden quantities (punctures, contact terms, nonperturbative anomalies with or without gravity) are revealed. Topological Yang-Mills theory with G = SU(2) is not just Donaldson theory, but contains a certain link theory. Indeed, local and non-local observables have the property of marking cycles. Moreover, from topological gravity one learns that an object can be considered BRST exact only if it is so all over the moduli space M, boundary included. Being BRST exact in any interior point of M is not sufficient to make an amplitude vanish. Presumably, recursion relations and hierarchies can be found to solve topological field theories in four dimensions, in particular topological Yang-Mills theory with G = SU(2) on R4 and topological gravity with the full set of asymptotically locally Euclidean manifolds.
Towards a Theory of Quark and Lepton Masses

Has any progress been made on understanding and predicting the 13 parameters which describe the observed masses and mixing angles of the quarks and leptons? Arguments are given in favor of pursuing schemes in which grand unified and family symmetries provide many relations among these 13 parameters. A sequence of simple assumptions leads to a supersymmetric SO(10) theory with 8 predictions: tan β, mt, Vcb, ms, ms/md, mu/md, Vub and the amount of CP violation J. These predictions are presented, together with experiments which will test them.
Experimental Investigation of Lift Enhancement and Roll Control Using Plasma Actuators

An experimental investigation into the use of trailing-edge-mounted plasma actuators for lift enhancement and roll control is described. Data are presented showing the effect that the actuators have on lift, pitch, and roll moment coefficients as a function of angle of attack and wind speed. The results indicate that the performance of the actuators is strongly influenced by Reynolds number effects. The implications of the findings on the utility of plasma actuators as lift and roll-control devices are discussed.
Discrete space-time symmetries

Symmetries have always fascinated human beings; they are found in nature, art, and architecture. Physicists, like other scientists have often used symmetries as a basis of their understanding of nature. When the dynamics is unknown, symmetries serve to delineate and define it. When the dynamics is known, symmetries are used to study structure. These two lectures review the theory and present understanding and status of two discrete space-time symmetries,, namely parity (P) and time reversal (T).
Enforcement strategies for computer use violations at a public university

Crafting appropriate use policies (AUP), is only the first step in addressing issues of inappropriate use of electronic resources on our college and university campuses. Many AUP's are intentionally general in order to cover as many contingencies as possible. Older AUP's may not have addressed many of the violations that have become more common with the advent of World Wide Web servers. The proliferation of computing activities and expanded body of users unfortunately has spawned an equally growing number of questionable activities. When confronted with these perceived inappropriate uses, computer resource managers must organize rational enforcement responses which assure due process and the protection of constitutional rights and privileges for all individuals.
The addition of alkylzinc iodides to 1-(phenoxycarbonyl)pyridinium salts

Abstract Several 1-(phenoxycarbonyl)-1,2-dihydropyridines were prepared by the addition of alkylzinc iodides to 1-(phenoxycarbonyl)pyridinium salts.
Lowering social security's duration-of-marriage requirement: distributional effects for future female retirees.

A number of alternatives to Social Security's auxiliary benefit system have been proposed in the context of changes in American family and work patterns. This article focuses on one modification therein—lowering the 10-year duration-of-marriage requirement for divorced spouses. Using a powerful microsimulation model (MINT), we examine the distributional effects of extending spouse and survivor benefit eligibility to 5- and 7-year marriages ending in divorce among female retirees in 2030, a population largely comprised of baby boomers. Results show that the options would increase benefits for a small share of female retirees, around 2 to 4%, and would not affect the vast majority of low-income divorced older women. However, of those affected, the options would substantially increase benefits and lower incidence of poverty and near poor. Low-income divorced retirees with marriages between 5 and 9 years in length and a deceased former spouse face the greatest potential gains.
Inducing Approximately Optimal Flow Using Truthful Mediators

We revisit a classic coordination problem from the perspective of mechanism design: how can we coordinate a social welfare maximizing flow in a network congestion game with selfish players? The classical approach, which computes tolls as a function of known demands, fails when the demands are unknown to the mechanism designer, and naively eliciting them does not necessarily yield a truthful mechanism. Instead, we introduce a weak mediator that can provide suggested routes to players and set tolls as a function of reported demands. However, players can choose to ignore or misreport their type to this mediator. Using techniques from differential privacy, we show how to design a weak mediator such that it is an asymptotic ex-post Nash equilibrium for all players to truthfully report their types to the mediator and faithfully follow its suggestion, and that when they do, they end up playing a nearly optimal flow. Notably, our solution works in settings of incomplete information even in the absence of a prior distribution on player types. Along the way, we develop new techniques for privately solving convex programs which may be of independent interest.
Sudden Radiative Braking in Colliding Hot-Star Winds

Hot, massive stars have strong stellar winds, and in hot-star binaries these winds can undergo violent collision. Because such winds are thought to be radiatively driven, radiative forces may also play an important role in moderating the wind collision. However, previous studies have been limited to considering how such forces may inhibit the initial acceleration of the companion stellar wind. In this paper we analyze the role of an even stronger radiative braking effect, whereby the primary wind is rather suddenly decelerated by the radiative momentum flux it encounters as it approaches a bright companion. We further show that the braking location and velocity law along the line of centers between the stars can be approximated analytically using a simple one-dimensional analysis. The results of this analysis agree well with a detailed two-dimensional hydrodynamical simulation of the wind collision in the WR + O binary V444 Cygni and demonstrate that radiative braking can significantly alter the bow-shock geometry and reduce the strength of the wind collision. We then apply the derived analytic theory to a set of 14 hot-star binary systems, and conclude that radiative braking is likely to be of widespread importance for wind-wind collisions in WR + O binaries with close to medium separation, D 100 R?. It may also be important in other types of hot-star binaries that exhibit a large imbalance between the component wind strengths.
Recent Theoretical Work on the Soft Budget Constraint

The soft budget constraint is a syndrome that was identified and studied by Janos Kornai in his analysis of centrally planned economies ( see, Kornai, 1980 ) . The syndrome is said to arise when a seemingly unprofitable enterprise is bailed out by the government or the enterprise’s creditors. In other words, the enterprise is not held to a fixed budget, but finds its budget constraint ‘‘softened’’ by the infusion of additional credit when it is on the verge of failure. Kornai viewed the soft budget constraint as a crucial ingredient for explaining the salient features of socialist economic performance, in particular, the pervasiveness of shortages. One interesting puzzle is why centrally planned economies have been particularly susceptible to the influence of the soft budget constraint; the capitalist world is hardly immune, as the recent financial crisis in Asia attests, but on the whole it has proved less vulnerable. Indeed, the very origin of the soft budget constraint and the mechanism by which it gives rise to shortages and other undesirable effects are also obviously important questions. Although Kornai’s work has long been well known and appreciated, answers to these associated theoretical questions have been hazarded only recently. In Maskin ( 1996 ) , I surveyed some of the initial efforts in this direction, including Mathias Dewatripont and Maskin (1995), which argues that centralization of credit can give rise to soft budget constraints because it facilitates the refinancing of
Physical properties of single crystalline BaSn5

We present a comprehensive study of the binary intermetallic superconductor, BaSn5. High-quality single crystalline BaSn5 was grown out of a Sn flux. Detailed thermodynamic and transport measurements were performed to study BaSn5's normal and superconducting state properties. This material appears to be a strongly coupled, multiband superconductor. H c2(T) is almost isotropic. De Haas–van Alphen oscillations were observed and two effective masses were estimated from the FFT spectra. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of ≈−0.053 ± 0.001 K/kbar.
Neutral helium lines and departures from LTE in hot stars

LTE departure calculated for He I in hot star model atmospheres for effects on populations of singlet and triplet states
The Edge of the Solar System

We have surveyed for Kuiper Belt objects (KBOs) in six fields of the ecliptic (total sky area 1.5 deg2) to limiting magnitudes between R = 24.9 and R = 25.9. This is deep enough to detect KBOs of diameter 160 km at a distance of 65 AU. We detected 24 objects. None of these objects, however, is beyond 53 AU. Our survey places a 95% CL upper limit of Σ 160 km KBOs in the 55-65 AU region is, at greater than 95% confidence, less than the mean density in the 30-50 AU region, and at most two-thirds of the mean density from 40 to 50 AU. Thus, a substantial density increase beyond 50 AU is excluded in this model-independent estimate. A dense primordial disk could be present beyond 50 AU if it contains only smaller objects or is sufficiently thin and inclined to have escaped detection in our six survey fields.
Pancreatic Ductal Adenocarcinoma Radiology Reporting Template: Consensus Statement of the Society of Abdominal Radiology and the American Pancreatic Association

Pancreatic ductal adenocarcinoma is an aggressive malignancy with a high mortality rate. Proper determination of the extent of disease on imaging studies at the time of staging is one of the most important steps in optimal patient management. Given the variability in expertise and definition of disease extent among different practitioners as well as frequent lack of complete reporting of pertinent imaging findings at radiologic examinations, adoption of a standardized template for radiology reporting, using universally accepted and agreed on terminology for solid pancreatic neoplasms, is needed. A consensus statement describing a standardized reporting template authored by a multi-institutional group of experts in pancreatic ductal adenocarcinoma that included radiologists, gastroenterologists, and hepatopancreatobiliary surgeons was developed under the joint sponsorship of the Society of Abdominal Radiologists and the American Pancreatic Association. Adoption of this standardized imaging reporting template should improve the decision-making process for the management of patients with pancreatic ductal adenocarcinoma by providing a complete, pertinent, and accurate reporting of disease staging to optimize treatment recommendations that can be offered to the patient. Standardization can also help to facilitate research and clinical trial design by using appropriate and consistent staging by means of resectability status, thus allowing for comparison of results among different institutions.
Why is the Divorce Rate Declining in Indonesia

This article examines trends in marital dissolution in Indonesia. Analysis considers the impact of educational expansion delayed marriage urbanization increasing employment before marriage legislative change and increased free choice in marriage on the decline in marital disruption. Trends such as delayed marriage and educational expansion account for about one-third of the decline in marital dissolution. Moreover factors associated with marital disruption are shifting in importance. In particular age at marriage and marital duration are becoming less reliable predictors of marital stability whereas education is becoming more important. The authors conclude that the shifting forces governing marital formation and dissolution in Indonesia have modified the linkages between the conjugal couple broader kinship systems and modes of economic support such that traditional patterns sustaining high levels of marital instability are no longer in effect. (authors)
The competitive market paradox

Abstract The competitive market model is paradoxical. In perfect competition, agents cannot influence price: they only select an output quantity. Such passive behavior does not conform to the intuitive notion of competition. This paper describes an experiment which demonstrates that near or even at a competitive equilibrium price, competition is undiminished. A substantial difference between the performance of sellers and buyers frequently results from this vigorous competition, even with low price variability and approximate efficiency. In double auction experiment sessions conducted with both automated and human agents, exogenous variation of the pace of asks and bids of automated agents demonstrates that the performance difference between sellers and buyers results primarily from a difference between the pace of asks and bids. If the buyers’ pace is slower than sellers’ pace, buyers make price concessions less frequently than sellers so that prices move below the equilibrium price. Then more buyers become active and fewer sellers remain active. Prices stabilize when changes to the numbers of active buyers and sellers offset the superior bargaining capability of one side or the other. In competitive equilibrium, to a first approximation agents are price takers, but that does not preclude vigorous competition: competitive behavior moves to the dimension of bargaining pace.