cssi/SciSciGPT-SciSciNet huggingface dataset:
Apparatus for In Vivo Knee Laxity Assessment Using High-Speed Stereo Radiography

Computational modeling is of growing importance in orthopedics and biomechanics as a tool to understand differences in pathology and predict outcomes from surgical interventions. However, the computational models of the knee have historically relied on in vitro data to create and calibrate model material properties due to the unavailability of accurate in vivo data. This work demonstrates the design and use of a custom device to quantify anterior-posterior (AP) and internal-external (IE) in vivo knee laxity, with an accuracy similar to existing in vitro methods. The device uses high-speed stereo radiography (HSSR) tracking techniques to accurately measure the resulting displacements of the femur, tibia, and patella bones during knee laxity assessment at multiple loads and knee flexion angles. The accuracy of the knee laxity apparatus was determined by comparing laxity data from two cadaveric specimens between the knee laxity apparatus and an existing in vitro robotic knee joint simulator. The accuracy of the knee laxity apparatus was within 1 mm (0.04 in.) for AP and 2.5 deg for IE. Additionally, two living subjects completed knee laxity testing to confirm the laboratory use of the novel apparatus. This work demonstrates the ability to use custom devices in HSSR to collect accurate data, in vivo, for calibration of computational models.
Improved 3D real‐time MRI of speech production

PURPOSE To provide 3D real-time MRI of speech production with improved spatio-temporal sharpness using randomized, variable-density, stack-of-spiral sampling combined with a 3D spatio-temporally constrained reconstruction. METHODS We evaluated five candidate (k, t) sampling strategies using a previously proposed gradient-echo stack-of-spiral sequence and a 3D constrained reconstruction with spatial and temporal penalties. Regularization parameters were chosen by expert readers based on qualitative assessment. We experimentally determined the effect of spiral angle increment and kz temporal order. The strategy yielding highest image quality was chosen as the proposed method. We evaluated the proposed and original 3D real-time MRI methods in 2 healthy subjects performing speech production tasks that invoke rapid movements of articulators seen in multiple planes, using interleaved 2D real-time MRI as the reference. We quantitatively evaluated tongue boundary sharpness in three locations at two speech rates. RESULTS The proposed data-sampling scheme uses a golden-angle spiral increment in the kx -ky plane and variable-density, randomized encoding along kz . It provided a statistically significant improvement in tongue boundary sharpness score (P < .001) in the blade, body, and root of the tongue during normal and 1.5-times speeded speech. Qualitative improvements were substantial during natural speech tasks of alternating high, low tongue postures during vowels. The proposed method was also able to capture complex tongue shapes during fast alveolar consonant segments. Furthermore, the proposed scheme allows flexible retrospective selection of temporal resolution. CONCLUSION We have demonstrated improved 3D real-time MRI of speech production using randomized, variable-density, stack-of-spiral sampling with a 3D spatio-temporally constrained reconstruction.
Definitions, Religion, and Free Exercise Guarantees

The First Amendment protects free exercise. Because non-religious practices do not receive those same protections, it may be important in particular cases to determine whether particular practices qualify as religious. Regrettably, members of the Court have been unable to agree about the criteria in light of which such a determination should be made, virtually guaranteeing an incoherent jurisprudence. This article examines some of the differing approaches to defining religious practice that have been suggested, concluding that many, although not all, of these approaches are reconcilable, although in a way that doubtless will leave both the religious and the non-religious somewhat dissatisfied.
Iterative packing for demand and hypergraph matching

Iterative rounding has enjoyed tremendous success in elegantly resolving open questions regarding the approximability of problems dominated by covering constraints. Although iterative rounding methods have been applied to packing problems, no single method has emerged that matches the effectiveness and simplicity afforded by the covering case. We offer a simple iterative packing technique that retains features of Jain's seminal approach, including the property that the magnitude of the fractional value of the element rounded during each iteration has a direct impact on the approximation guarantee. We apply iterative packing to generalized matching problems including demand matching and k-column-sparse column-restricted packing (k-CS-PIP) and obtain approximation algorithms that essentially settle the integrality gap for these problems. We present a simple deterministic 2k-approximation for k-CSPIP, where an 8k-approximation was the best deterministic algorithm previously known. The integrality gap in this case is at least 2(k-1+1/k). We also give a deterministic 3-approximation for a generalization of demand matching, settling its natural integrality gap.
Positron Emission Tomography (PET)

Positron emission tomography (PET) is a technique for physiological imaging of the brain, which employs the physical properties of radioactive atoms that decay by emission of positrons, negatively charged electrons. A PET scanner produces an image representing regional radioactivity within the scanner. Positron-emitting radionuclides such as 15 O, 11 C, and 18 F can be used to label a wide variety of molecules, thus providing PET with the capability to measure a wide variety of biological processes in vivo in the human brain.
Adaptation of a Six-legged Walking Robot to Its Local Environment

Walking in rough and unstructured terrain with a legged robot remains to be a challenging task, not only regarding the construction of a robust walking machine, but also looking at the control of such a complex system. Walking robots have the ability to climb over obstacles and can also walk fast in flat terrain. This is possible because the control parameters are adapted to the surrounding terrain. For example, the swing height has to correspond with the obstacle height, elsewise the robot cannot walk over these obstacles. An adaptation of the control parameters according to the environment can be realised in different ways. If there is no environment model present, the robot can only rely on its sensor systems trying to react to influences from the environment. Only the use of an environment model can enable the robot to interact more intelligently with the environment and adapt its parameters in advance. In this way, the robot can avoid many collisions, which speeds up the walking process. In the example, this would mean to increase the swing height and therefore modify the footpoint trajectory with the aim to overstep the obstacle. Because the swing height is only one parameter among many others, it is obvious how expedient an environment model is for a complex walking robot like LAURON.
Optimal verification of operations on dynamic sets

We study the design of protocols for set-operation verification, namely the problem of cryptographically checking the correctness of outsourced set operations performed by an untrusted server over a dynamic collection of sets that are owned (and updated) by a trusted source. We present new authenticated data structures that allow any entity to publicly verify a proof attesting the correctness of primitive set operations such as intersection, union, subset and set difference. Based on a novel extension of the security properties of bilinear-map accumulators as well as on a primitive called accumulation tree, our protocols achieve optimal verification and proof complexity (i.e., only proportional to the size of the query parameters and the answer), as well as optimal update complexity (i.e., constant), while incurring no extra asymptotic space overhead. The proof construction is also efficient, adding a logarithmic overhead to the computation of the answer of a set-operation query. In contrast, existing schemes entail high communication and verification costs or high storage costs. Applications of interest include efficient verification of keyword search and database queries. The security of our protocols is based on the bilinear q-strong Diffie-Hellman assumption.
Leflunomide in solid organ transplantation and polyoma virus infection.

Leflunomide, trade name Arava® (Aventis Pharmaceuticals Incorporation, Bridgewater, New Jersey, U.S.A.), belongs to a family of drugs called the malonitrilamides. Some, like leflunomide, have substantial immune suppressive activity in experimental allograft models. In addition to experimental data suggesting leflunomide’s value in preventing1, 2, 3, 4, 5 and reversing acute1,5 and chronic rejection,6,7 it has been shown to inhibit human cytomegalovirus (CMV) and herpes simplex virus (HSV) in vitro.8, 9, 10 Because it is a drug with a variety of biologic activities, it has been investigated for diseases as disparate as cancer and autoimmunity. Leflunomide was approved for the treatment of rheumatoid arthritis and has been used in more than 300,000 patients worldwide with efficacy and a favorable side effect profile. In this chapter, we will discuss the immunemodulatory effects of leflunomide and its metabolite A77 1726 that prevent organ rejection. We will also share our experience in the treatment of polyomavirus infections.
Large devaluations, foreign direct investment and exports : a speculative note

One side-effect of the Global Financial Crisis of 2008-09 was the resurgence of a debate over exchange rates. The conventional wisdom dictates that real-exchange rate adjustments are needed in order to bring about changes in trade balances across countries. However, the literature on the effect of exchange rate fluctuations and currency under-valuations on exports is surprisingly ambiguous. This note explores for the first time the potential role of foreign direct investment as an intermediate variable in the process of trade adjustment after large real-exchange rate changes. Real-exchange rate devaluations might result in increases in foreign direct investment inflows, as investors can take advantage of changes in the foreign-currency value of domestic assets. If so, the response of exports will depend to some extent on the nature of such foreign direct investment inflows, with inflows motivated by"horizontal"foreign direct investment associated with negligible changes in export growth after devaluation. The author utilizes quarterly data on real effective exchange rates, foreign direct investment inflows and exports to explore the effects of large devaluations (defined as the largest observed quarterly real effective exchange rate devaluation) on foreign direct investment and exports from 1990 to 2010. The admittedly speculative evidence suggests that there were heterogeneous experiences regarding the timing and magnitude of subsequent changes in foreign direct investment and exports, but on average foreign direct investment inflows tended to precede export surges within two year horizons.
Sufficiency for optimal control problems involving parameters

The optimal control problem is extended to the case where the performance index, the differential constraints, and the prescribed final conditions contain parameters. The sufficient condition for a minimum is derived for nonsingular problems using the sweep method. As expected, it involves the finiteness of a matrix or the location of the conjugate point. The minimum-time navigation problem is solved as a fixed final time problem to illustrate the application of the theory.
An agent-based information foraging model of scientific knowledge creation and spillover in open science communities

Motivation and problem-domain preferences of scientists can affect aggregate level emergence and growth of problem domains in science. In this study, we introduce an agent-based model that is based on information foraging and expectancy theory to examine the impact of rationality and openness on the growth and evolution of scientific domains. We simulate a virtual socio-technical system, in which scientists with different preferences search for problem domains to contribute knowledge, while considering their motivational gains. Problem domains become mature and knowledge spills occur over time to facilitate creation of new problem domains. We conduct experiments to examine emergence and growth of clusters of domains based on local interactions and preferences of scientists and present preliminary qualitative observations.
Public key exchange using semidirect product of (semi)groups

In this paper, we describe a brand new key exchange protocol based on a semidirect product of (semi)groups (more specifically, on extension of a (semi)group by automorphisms), and then focus on practical instances of this general idea. Our protocol can be based on any group, in particular on any non-commutative group. One of its special cases is the standard Diffie-Hellman protocol, which is based on a cyclic group. However, when our protocol is used with a non-commutative (semi)group, it acquires several useful features that make it compare favorably to the Diffie-Hellman protocol. Here we also suggest a particular non-commutative semigroup (of matrices) as the platform and show that security of the relevant protocol is based on a quite different assumption compared to that of the standard Diffie-Hellman protocol.
Synthesis of mixed-valent α- and β-NaFe2O3 polymorphs under controlled partial oxygen pressure

Abstract Synthesis of mixed valent compounds, especially when multiple polymorphs exist, requires careful control of the preparation conditions. α- and β-NaFe2O3 polymorphs were synthesized under controlled partial oxygen pressure (pO2). pO2 regions of stability at 850 °C were determined for both phases for the first time. A modified oxygen buffer method was developed for the facile preparation of mixed valent oxides under controlled pO2. β-NaFe2O3 is the only known n=2 member of the AMnOn+1 (A=alkali metal, M=3d metal) rock-salt related homolog series with layered cation ordering. The possibility of new members of the homolog series with other 3d metals is considered.
Are risk attitudes fixed factors or fleeting feelings

We investigate the stability of measured risk attitudes over time, using a 13-year longitudinal sample of individuals in the National Longitudinal Survey of Youth 1979. We find that an individual’s risk aversion changes systematically in response to personal economic circumstances. Risk aversion increases with lengthening spells of employment and time out of labor force, and decreases with lengthening unemployment spells. However, the most important result is that the majority of the variation in risk aversion is due to changes in measured individual tastes over time and not to variation across individuals. These findings that measured risk preferences are endogenous and subject to substantial measurement errors suggest caution in interpreting coefficients in models relying on contemporaneous, one-time measures of risk preferences.
HISTORY OF WEAK INTERACTIONS.

In 1898 Lord Rutherford1 discovered that the so-called Becquerel ray actually consisted of two distinct components: one that is readily absorbed, which he called alpha radiation, and another of a more penetrating character, which he called beta radiation. With that began the history of the weak interaction. Then, in 19002, the Curies measured the electric charge of the β particle and found it to be negative.
A General Conditional Large Deviation Principle

Given a sequence of Borel probability measures on a Hausdorff space which satisfy a large deviation principle (LDP), we consider the corresponding sequence of measures formed by conditioning on a set B. If the large deviation rate function I is good and effectively continuous, and the conditioning set has the property that (1) $$\overline{B^{\circ }} = \overline{B}$$ and (2) $$I(x) < \infty $$ for all $$x \in \overline{B}$$ , then the sequence of conditional measures satisfies a LDP with the good, effectively continuous rate function $$I_B$$ , where $$I_B(x) = I(x)-\inf I(B)$$ if $$x\in \overline{B}$$ and $$I_B(x) = \infty $$ otherwise.
Potomac Horse Fever

E. risticii, the cause of classic Potomac horse fever, is now known to produce two disease syndromes: EEC and EEA. The pathogen appears to commonly infect horses based on seroepidemiologic studies; however, the method of transmission remains unknown. The most common clinical disease is EEC, commonly called Potomac horse fever, which presents a wide spectrum of clinical signs. Diagnosis is currently dependent on serology, which frequently does not lead to a definitive diagnosis and at best results in a retrospective diagnosis. A new diagnostic approach, polymerase chain reaction, may offer a rapid and accurate diagnostic test but is yet to be proven. Antimicrobials found to be highly effective in treating EEC include intravenous oxytetracycline and the oral combination of erythromycin and rifampin. Without an understanding of the mode of transmission, prevention of EEC will remain impossible. Although two commercial bacterins are available, vaccination does not result in complete protection. EEA is a recently recognized clinical syndrome caused by E. risticii. After recovery from EEC, pregnant mares may abort. Based on histologic examination, the aborted fetus appears to be a victim of an ehrlichial colitis as well as placentitis. The effect of antimicrobials and vaccination on the occurrence of EEA has yet to be investigated.
An Integrated Dynamic Market Mechanism for Real-Time Markets and Frequency Regulation

The intermittent and uncertain nature of renewables represents a major challenge for large scale adoption of sustainable energy resources. Of particular concern is the need to maintain both quality of grid frequency and low costs of regulation reserves in the face of increasing fluctuations in renewables. To this end, we propose an integrated dynamic market mechanism (DMM), which combines real-time market and frequency regulation allowing market players, including renewable generators and flexible consumers, to iteratively negotiate electricity prices at the wholesale level while using the most recent information on the available wind power and the quality of grid frequency. Main features of the integrated DMM are as follows: 1) a Newton-Raphson-based method, which leads to fast convergence to the optimal dispatch; and 2) use of an aggregated frequency error as a feedback signal for the negotiation process, which leads to reduced regulation capacity requirements. The benefits of this DMM are illustrated via simulations on the IEEE 118 bus system.
Microeconomic Sources of Real Exchange Rate Variability

Abstract We provide a series of variance decompositions based on a panel data set of international goods prices. The panel spans 301 goods and services across 123 cities from 78 countries over the years 1990-2015. We analyze good-by-good deviations from the Law of One Price (LOP) for all bilateral city pairs and time periods. Our main finding is that variation within the LOP distribution is large relative to how the distribution itself moves over time. More specifically, we find that (i) long term deviations from LOP account for just as much of the overall price distribution as does time series variation around the long term LOP deviations, (ii) the cross good variance of the price distribution dwarfs movement in its mean, the equally-weighted real exchange rate, (iii) common variation in LOP deviations — such as that imparted by variation in nominal exchange rates — is small relative to good-specific variation, (iv) time series variation is larger for traded goods than for non-traded goods, whereas the opposite is true for cross-sectional variation, and (v) city and good-specific ‘fixed effects’ play an important role in describing how the moments of the price distribution vary in the cross section. We argue that these findings should inform research at the intersection of international macroeconomics and international trade.
Optimal commodity taxation with moral hazard and unobservable outcomes.

The optimal public insurance-taxation scheme is derived for a model with unobservable outcomes. If the government can only observe aggregate commodity expenditures, reimbursement insurance is constrained-efficient. However, two distortions accompany the reimbursement scheme. First, consumers are induced to take (forego) actions which increase (decrease) the likelihood of adverse outcomes (i.e., ex ante moral hazard). Second, reimbursement insurance creates a subsidy distortion (i.e., ex post moral hazard). Ex ante moral hazard calls for taxation (subsidization) of commodities which increase (decrease) the probability of adverse outcomes. The second distortion calls for taxation (subsidization) of commodities which are sufficiently strong complements to (substitutes for) the insured commodity. An example centered on cigarettes and medical insurance is presented.
Polarities, axiallities and marketability of items

We apply polarities, axiallities and the notion of entropy to the task of identifying marketable items and the customers that should be approached in a marketing campaign. An algorithm that computes the criteria for identifying marketable items and the corresponding experimental work is also included.
Map Learning with Indistinguishable Locations

Abstract Nearly all spatial reasoning problems involve uncertainty of one sort or another. Uncertainty arises due to the inaccuracies of sensors used in measuring distances and angles. We refer to this as directional uncertainty. Uncertainty also arises in combining spatial information when one location is mistakenly identified with another. We refer to this as recognition uncertainty. Most problems in constructing spatial representations ( maps ) for the purpose of navigation involve both directional and recognition uncertainty. In this paper, we show that a particular class of spatial reasoning problems involving the construction of representations of large-scale space can be solved efficiently even in the presence of directional and recognition uncertainty. We pay particular attention to the problems that arise due to recognition uncertainty.
Evolution of swarming behavior is shaped by how predators attack

Animal grouping behaviors have been widely studied due to their implications for understanding social intelligence, collective cognition, and potential applications in engineering, artificial intelligence, and robotics. An important biological aspect of these studies is discerning which selection pressures favor the evolution of grouping behavior. In the past decade, researchers have begun using evolutionary computation to study the evolutionary effects of these selection pressures in predator-prey models. The selfish herd hypothesis states that concentrated groups arise because prey selfishly attempt to place their conspecifics between themselves and the predator, thus causing an endless cycle of movement toward the center of the group. Using an evolutionary model of a predator-prey system, we show that how predators attack is critical to the evolution of the selfish herd. Following this discovery, we show that density-dependent predation provides an abstraction of Hamilton's original formulation of domains of danger. Finally, we verify that density-dependent predation provides a sufficient selective advantage for prey to evolve the selfish herd in response to predation by coevolving predators. Thus, our work corroborates Hamilton's selfish herd hypothesis in a digital evolutionary model, refines the assumptions of the selfish herd hypothesis, and generalizes the domain of danger concept to density-dependent predation.
A New Sufficient Condition for Sum-Rate Tightness in Quadratic Gaussian Multiterminal Source Coding

This paper considers the quadratic Gaussian multiterminal (MT) source coding problem and provides a new sufficient condition for the Berger-Tung (BT) sum-rate bound to be tight. The converse proof utilizes a set of virtual remote sources given which the observed sources are block independent with a maximum block size of 2. The given MT source coding problem is then related to a set of two-terminal problems with matrix-distortion constraints, for which a new lower bound on the sum-rate is given. By formulating a convex optimization problem over all distortion matrices, a sufficient condition is derived for the optimal BT scheme to satisfy the subgradient-based Karush-Kuhn-Tucker condition. The subset of the quadratic Gaussian MT problem satisfying our new sufficient condition subsumes all previously known tight cases, and our proof technique opens a new direction for more general partial solutions.
Distribution Free Decomposition of Multivariate Data

We present a practical approach to nonparametric cluster analysis of large data sets. The number of clusters and the cluster centres are automatically derived by mode seeking with the mean shift procedure on a reduced set of points randomly selected from the data. The cluster boundaries are delineated using a k-nearest neighbour technique. The proposed algorithm is stable and efficient, a 10,000 point data set being decomposed in only a few seconds. Complex clustering examples and applications are discussed, and convergence of the gradient ascent mean shift procedure is demonstrated for arbitrary distribution and cardinality of the data.
Entrepreneurs, legal institutions and firm dynamics

This paper assesses the impact of legal institutions on firm dynamics in a model where entrepreneurs have heterogeneous risk aversion, credit constraints and may default. Entrepreneurs choose firm size, capital structure, consumption, default and whether to incorporate. We find that less risk-averse entrepreneurs tend to incorporate while more risk-averse entrepreneurs do not; this occurs because leaving some personal assets exposed by not incorporating allows more risk-averse borrowers to credibly commit to lower default rates. We show that incorporation is determined by two effects: the standard effect that bankruptcy insures low firm returns and a new “scale effect”—more risk-averse entrepreneurs run smaller firms and default more often. The more risk-averse choose to leave some personal assets unshielded in bankruptcy due to a commitment problem that dominates the value of insurance. The less risk-averse run larger firms, default less and incorporate.
Relative generic computational forensic techniques

Computational forensic engineering is the process of identification of the tool or algorithm that was used to produce a particular output or solution by examining the structural properties of the output. We introduce a new Relative Generic Forensic Engineering (RGFE) technique that has several advantages over the previously proposed approaches. The new RGFE technique not only performs more accurate identification of the tool used but also provides the identification with a level of confidence. Additionally, we introduce a generic formulation (integer linear programming formulation) which enables rapid application of the RGFE approach to a variety of problems that can be formulated as 0-1 integer linear programs. The key innovations of the RGFE technique include the development of a simulated annealing-based (SA) CART classification technique and a generic property formulation technique that facilitates property reuse. We introduce instance properties which enable an enhanced classification of problem instances leading to a higher accuracy of algorithm identification. Finally, the single most important innovation, property calibration, interprets the value for a given algorithm for a given property relative to the values for other algorithms. We demonstrated the effectiveness of the RGFE technique on the boolean satisfiability (SAT) and graph coloring (GC) problems.
An examination of distributed planning in the world of air traffic control

A Distributed Planning System is a network whose nodes represent distinct processors, each cooperating with a selected set of others to achieve a common set of goals. We address two important issues in this paper: (i) How individual processors should be interconnected so that their capacities are fully utilized and their goals can be accomplished effectively and efficiently, (ii) What kind of planning activity the individual processors should engage in. We have chosen the Air Traffic Control (ATC) environment, an intellectually challenging domain of much practical importance, to study different ideas in distributed planning systems. Here we show the results obtained with one type of possible organizational architecture, Location-Centered Cooperative mode of operation. We describe and demonstrate algorithmically a simulation-based planning process based on this architecture. The work described in this paper is part of our continuing effort in examining ways in which greater responsibilities can be delegated to computers in ATC. © 1986 Academic Press, Inc.
A Robustly Efficient Auction

We study the problem of efficient auction design in environments with interdependent values, under arbitrary common knowledge assumptions. We propose a simple mechanism and show that, under a rather mild condition, it "robustly" achieves efficiency. Our mechanism consists in a standard Vickrey auction, preceded by one round of communication, where agents report their private signals and receive transfers from the designer. We interpret the transfers as the cost for the designer to robustly achieve efficiency. We introduce a notion of robust informational size and show that the transfers are small if agents are informationally small in our sense. Furthermore, the transfers are decreasing in the amount of information available to the designer and in the strength of the common knowledge assumptions. In other words, the more robust the efficient implementation result, the higher the cost of achieving efficiency. We thus formalize the intuitive idea of a trade-off between robustness and efficient implementation and analyze the determinants of the "cost of robustness".
THE PHYSIOLOGIC SIGNIFICANCE OF GRUNTING RESPIRATION

The effect of grunting respiration before and after induction of pneumonia was studied in 14 experiments on five dogs artificially ventilated with a modified piston respirator. An end-inspiratory pause was produced which was exactly the same duration as the pause that usually occurs after normal expiration. Only the respiratory pattern was changed; frequency, tidal volume, and flow rates remained constant. Before pneumonia, grunting produced a mean increase in PaO2 of 10.5% (± 7.0%), a mean decrease in PaCO2 of 11.0% (± 5.1%), and a mean increase in VA of 21.8% (± 9.5%). The results after pneumonia were not significantly different. Intrapulmonary gas distribution was somewhat improved by grunting in normal lungs, but the ellect was not as pronounced after pneumonia.
The Marginal Worker and the Aggregate Elasticity of Labor Supply

This paper attempts to reconcile the large volatility of aggregate employment with small micro estimates of the elasticity of labor supply. Our model of indivisible labor with complete markets shows that the aggregate intertemporal elasticity of labor supply depends on the homogeneity of the workforce at the margin. Hence, the shape of the distribution of reservation wages is the key determinant of the elasticity of aggregate labor supply. Even if most workers are wage-inelastic, the aggregate elasticity can be large if sufficiently many agents are close to their reservation wage. These agents are indeed likely to enter or exit the labor market upon a small change in their wage. To evaluate this hypothesis, we estimate the model using monthly panel data drawn from the NLSY. This allows us to measure the aggregate elasticity implied by realistic heterogeneity. We estimate a Frisch elasticity around 1.5. Our model also has a natural cross-sectional implication: workers who are nearly indifferent between working or not are more sensitive to aggregate fluctuations. We find empirical support for this prediction: on average, the group of marginal workers, which makes up 22% of the population, accounts for 49% of aggregate fluctuations in employment.
Radical Cation/Anion and Neutral Radicals: A Comparison

This article examines similarities between radical and radical ion reactions. Radicals and radical ions have worked there way into almost every facet of mainstream chemistry over the past 60 years. The importance as well as usefulness now associated with the reactions of radicals is in stark contrast to their prior role as poorly understood scapegoat molecules often blamed for failed reactions. The processes discussed herein demonstrate two critically important concepts to the radical chemist: (i) kinetic studies are an excellent and versatility applicable tool to determine mechanistic data for chemical reactions and (ii) published mechanistic data for more thoroughly studied radical processes have provided and continue to provide key insight into the factors governing reactivity and mechanism of their charge bearing counterparts. Keywords: kinetics; mechanism; radical rearrangement; hydrogen atom transfer; intramolecular radical cyclization; cyclopropane ring opening; deprotonation
Interaction of Dioxygen Species and Metal Ions—Equilibrium Aspects

Proprietes des intermediaires dans la reduction de O 2 . Affinites de O 2 − et O 2 2− pour les ions metalliques
Fruit Consumption: Dietary Health and Policy Implications

Health benefits of a diet rich in fruit and vegetables has been emphasized in the U.S. However, consumption of fruits more than for vegetables has remained well below recommended amounts. Efforts to influence eating habits will be enhanced if socio-demographic factors and the nature of their interaction are better understood. This study uses logistic regression to determine the role of age, sex, race and place of residency to investigate this question. The analysis identifies that sex, social class and place of residence influence optimal fruit consumption. Particularly, this study finds that young adult males of modest means living in rural areas are less likely to incorporate the recommended amount of fruit in their diet.
Error Estimation in the Histogram Monte Carlo Method

We examine the sources of error in the histogram reweighting method for Monte Carlo data analysis. We demonstrate that, in addition to the standard statistical error which has been studied elsewhere, there are two other sources of error, one arising through correlations in the reweighted samples, and one arising from the finite range of energies sampled by a simulation of finite length. We demonstrate that while the former correction is usually negligible by comparison with statistical fluctuations, the latter may not be, and give criteria for judging the range of validity of histogram extrapolations based on the size of this latter correction.
Intertemporal excess burden, bequest motives, and the budget deficit

The author aims to empirically determine the significant factors that affect the levels of budget deficits of central governments across time and across countries. He empirically tests two prominent theories of budget deficits-the Barro (1979) tax-smoothing approach, and the still-untested theory of negative bequest motives advocated by Cukierman and Meltzer (1989). The author uses econometric techniques including fixed-effects (both country and time) panel regressions spanning 87 countries over the period 1975 to 1992, and the Griliches treatment of missing data. The author finds relatively stronger statistical support for the tax-smoothing approach among developing countries but not in industrial countries. The existence of empirical evidence supporting the theory of negative bequest motives is indeterminate. The author also conducted post-regression analyses to assess the proportion of observed differences in budget deficits the factors were actually able to explain. These reveal that both theories are generally weak in accounting for inter-temporal changes in budget deficit shares for both industrial and developing countries. The theories performed significantly better in accounting for cross-section differences. The author has many contributions to the literature. First, he analyzes the question of what determines the size of central government budget deficits using cross-country time series data leading into the 1990s. Second, he provides empirical tests of the still-untested Cukierman-Meltzer (1989) negative bequest motive theory of budget deficits. By using the panel data, the author attempts to determine the factors that influence not only the inter-temporal differences in budget deficits but also those factors that lead to cross-country differences. Last but not least, he provides some preliminary evidence that poverty reduction is necessary for long-term government budget deficit reduction.
Radical Moderation: Recapturing Power in Two-Party Parliamentary Systems

We estimate the parameters of a reputational game of political competition using data from five two-party parliamentary systems. We find that latent party preferences (and party reputations) persist with high probability across election periods, with one exception: parties with extreme preferences who find themselves out of power switch to moderation with higher probability than the equivalent estimated likelihood for parties in government (extreme or moderate) or for moderate parties in opposition. We find evidence for the presence of significant country-specific differences. We subject the model to a battery of goodness-of-fit tests and contrast model predictions with survey and vote margin data not used for estimation. Finally, according to the estimated model parameters, Australia is less than half as likely to experience extreme policies and Australian governments can expect to win more consecutive elections in the long run as compared to their counterparts in Greece, Malta, New Zealand, and the United Kingdom.
Formula-based probabilistic inference

Computing the probability of a formula given the probabilities or weights associated with other formulas is a natural extension of logical inference to the probabilistic setting. Surprisingly, this problem has received little attention in the literature to date, particularly considering that it includes many standard inference problems as special cases. In this paper, we propose two algorithms for this problem: formula decomposition and conditioning, which is an exact method, and formula importance sampling, which is an approximate method. The latter is, to our knowledge, the first application of model counting to approximate probabilistic inference. Unlike conventional variable-based algorithms, our algorithms work in the dual realm of logical formulas. Theoretically, we show that our algorithms can greatly improve efficiency by exploiting the structural information in the formulas. Empirically, we show that they are indeed quite powerful, often achieving substantial performance gains over state-of-the-art schemes.
A system performance and economics analysis of IGCC with supercritical steam bottom cycle supplied with varying blends of coal and biomass feedstock

In recent years, Integrated Gasification Combined Cycle Technology (IGCC) has been gaining steady popularity for use in clean coal power operations with carbon capture and sequestration. Great efforts have been continuously spent on investigating various ways to improve the efficiency and further reduce the greenhouse gas (GHG) emissions of such plants. This study focuses on investigating two approaches to achieve these goals. First, replace the traditional subcritical Rankine steam cycle portion of the overall plant with a supercritical steam cycle. Second, add different amounts of biomass as co-feedstock to reduce carbon footprint as well as SOx and NOx emissions. Employing biomass as a feedstock to generate fuels or power has the advantage of being carbon neutral or even becoming carbon negative if carbon is captured and sequestered. Due to a limited supply of feedstock, biomass plants are usually small, which results in higher capital and production costs. In addition, biomass can only be obtained at specific times in the year, meaning the plant cannot feasibly operate year-round, resulting in fairly low capacity factors. Considering these challenges, it is more economically attractive and less technically challenging to co-combust or co-gasify biomass wastes with coal. The results show that supercritical IGCC the net plant efficiency increases with increased biomass blending in the all cases. For both subcritical and supercritical cases, the efficiency increases initially from 0% to 10% (wt.) biomass, and decreases thereafter. However, the efficiency of the blended cases always remains higher than that of the pure coal baseline cases. The emissions (NOx, SOx, and effective CO2) and the capital cost all decrease as biomass ratio increases, but the cost of electricity increases with biomass ratio due to the high cost of the biomass used. Finally, implementing a supercritical steam cycle is shown to increase the net plant output power by 13% and the thermal efficiency by about 1.6 percentage points (or 4.56%) with a 6.7% reduction in capital cost, and a 3.5% decrease in cost of electricity.
Carcerands and Hemicarcerands

Carcerands and hemicarcerands are spherical, hollow host molecules with inner cavities that are large enough to accommodate smaller organic guest molecules. Since the first synthesis of a carcerand in the mid-1980s, a large variety of different hemicarcerands and carcerands have been prepared and their properties investigated. In this review, mechanism and scope of (hemi)carcerand synthesis, which is a templated reaction, is discussed. This includes recent work on dynamic hemicarcerands, in which building blocks are connected via dynamic covalent bonds, and gated hemicarcerands, which open and/or close in response to an external trigger such as irradiation or the addition of acid, base, or thiols. In the second part of this chapter, the molecular recognition properties of hemicarcerands are reviewed. As part of this, binding properties of chiral hemicarcerands and water-soluble hosts are discussed. In the last part, applications of hemicarcerands as molecular reaction flasks are reviewed. Through-shell reactions between an encapsulated reactant and a bulk-phase reactant include amine protonation, oxidation/reduction, H/D exchange, and nucleophilic substitutions and additions. In most of these reactions, bond formation/breaking takes place in a size-restricted portal in the host shell. Thus, scope and reaction rate depend on guest orientation in the inner phase as well as size and shape of the bulk-phase reactant relative to those of the hemicarcerand's portal. Hemicarcerands have also been used extensively for the inner-phase stabilization of reactive intermediates. If a reactive intermediate is generated photochemically or thermally in the inner phase of the hemicarcerand, the surrounding host prevents dimerization of the intermediate or reactions with bulk-phase reactants that cannot pass through an opening in the host shell. Many otherwise fleeting intermediates gain longevity through this extrinsic stabilization, making possible their observation, for example, by NMR spectroscopy. Examples that are discussed include cyclobutadiene, benzyne, anti-Bredt olefins, cyclic allenes and ketenimines, carbenes, and nitrenes. Furthermore, investigations of photoelectron transfer and energy transfer across the shell of hemicarcerands have improved our understanding of these important photophysical processes. Recent advances in this area are discussed. Keywords: host–guest chemistry; molecular container chemistry; encapsulation; supramolecular chemistry; hemicarcerands; carcerands; molecular recognition; reactive intermediates
Boundary rigidity with partial data

We study the boundary rigidity problem with partial data consisting of determining locally the Riemannian metric of a Riemannian manifold with boundary from the distance function measured at pairs of points near a fixed point on the boundary. We show that one can recover uniquely and in a stable way a conformal factor near a strictly convex point where we have the information. In particular, this implies that we can determine locally the isotropic sound speed of a medium by measuring the travel times of waves joining points close to a convex point on the boundary. The local results lead to a global lens rigidity uniqueness and stability result assuming that the manifold is foliated by strictly convex hypersurfaces.
Approximation of a polyline with a sequence of geometric primitives

The problem of recognition of a polyline as a sequence of geometric primitives is important for the resolution of applied tasks such as post-processing of lines obtained as a result of vectorization; polygonal line compression; recognition of characteristic features; noise filtering; and text, symbol, and shape recognition. Here, a method is proposed for the approximation of polylines with straight segments, circular arcs, and free curves.
Sums of Consecutive Integers.

Wai Yan Pong (wpong@csudh.edu) received his B.Sc. from the Chinese University of Hong Kong and his M.Sc. and Ph.D. from the University of Illinois at Chicago. He was a Doob Research Assistant Professor at the University of Illinois at Urbana-Champaign for three years. He then moved to California and is now teaching at California State University, Dominguez Hills. His research interests are in model theory and number theory.
EFFICACY VS. EQUITY: WHAT HAPPENS WHEN STATES TINKER WITH COLLEGE ADMISSIONS IN A RACE-BLIND ERA?

We investigate the efficacy and equity of college admissions criteria by estimating the effect of multiple measures of college readiness on college performance in the context of race-blind automatic admissions policies. We take advantage of a unique institutional feature of the Texas higher education system to control for selection into admissions. We find that SAT/ACT scores, high school exit exams, and advanced coursework are all predictors of student success in college. However, when we simulate changes in college enrollment and outcomes with additional admissions criteria, we find that adding SAT/ACT or exit exam criteria to an existing rank-based admissions policy significantly decreases enrollment among minorities, low-income students, and students who attend low socioeconomic status high schools, with the most negative effects generated by the SAT/ACT, while inducing only minimal gains in college grade point average and 4-year graduation rates.
Estimating Welfare in Insurance Markets Using Variation in Prices

We provide a graphical illustration of how standard consumer and producer theory can be used to quantify the welfare loss associated with inefficient pricing in insurance markets with selection. We then show how this welfare loss can be estimated empirically using identifying variation in the price of insurance. Such variation, together with quantity data, allows us to estimate the demand for insurance. The same variation, together with cost data, allows us to estimate how insurers’ costs vary as market participants endogenously respond to price. The slope of this estimated cost curve provides a direct test for both the existence and the nature of selection, and the combination of demand and cost curves can be used to estimate welfare. We illustrate our approach by applying it to data on employerprovided health insurance from one specific company. We detect adverse selection but estimate that the quantitative welfare implications associated with inefficient pricing in our particular application are small, in both absolute and relative terms.