cssi/SciSciGPT-SciSciNet huggingface dataset:
GENERATING INFINITE SYMMETRIC GROUPS

Let S = Sym(Ω) be the group of all permutations of an infinite set Ω. Extending an argument of Macpherson and Neumann, it is shown that if U is a generating set for S as a group, then there exists a positive integer n such that every element of S may be written as a group word of length at most n in the elements of U . Likewise, if U is a generating set for S as a monoid, then there exists a positive integer n such that every element of S may be written as a monoid word of length at most n in the elements of U . Some related questions and recent results are noted, and a brief proof is given of a result of Ore’s on commutators, which is used in the proof of the above result. 1. Introduction, notation, and some lemmas on full moieties In [14, Theorem 1.1], Macpherson and Neumann show that if Ω is an infinite set, then the group S = Sym(Ω) is not the union of a chain of |Ω| or fewer proper subgroups. We will repeat the beautiful proof of that result, with modifications that will allow us to obtain, along with it, the result stated in the abstract. The present section is devoted to obtaining strengthened versions of the lemmas used in that proof. Following the notation of [14], for Ω an infinite set, Sym(Ω), generally abbreviated to S, will denote the group of all permutations of Ω, and such permutations will be written to the right of their arguments. For subsets Σ ⊆ Ωa ndU ⊆ S ,t he symbol U(Σ) will denote the set of elements of U that stabilize Σ pointwise, and U{Σ} is the set {f ∈ U :Σ f =Σ } .( In [14] this notation is used only for U a subgroup.) A subset Σ ⊆ Ω will be called full with respect to U ⊆ S if the set of permutations of Σ induced by members of U{Σ} is all of Sym(Σ). The cardinality of a set X will be written |X|, and a subset Σ ⊆ Ω will be called a moiety if |Σ| = |Ω| = |Ω − Σ|. Suppose that Σ1 and Σ2 are moieties of Ω whose intersection is also a moiety, and whose union is all of Ω. Then [14, Lemma 2.3] says that if G is a subgroup of S = Sym(Ω) such that Σ1 and Σ2 are both full with respect to G, then G = S. To strengthen this result, we will consider subsets U, V ⊆ S, closed under inverses, such that Σ1 is full with respect to U and Σ2 with respect to V . By the lemma cited, � U ∪ V � = S; our version of this result will bound the number of factors from U and V needed to obtain the general element of S. Our proof will use the following fact, first proved by Ore [18]. Much stronger results have been proved since. In § 4 we will give a self-contained proof of a statement of intermediate strength.
Metal‐Organic Frameworks as Single‐Site Solid Catalysts for Asymmetric Reactions

This review documents the evolution of chiral MOF catalysts from simple Lewis acid and Lewis base catalysts that afford limited selectivity to more recent advancements that exhibit high stereo- and regioselectivities. MOF-based catalysts provide unprecedented opportunities for interrogating structure-activity relationships at high structural precision and for controlling catalytic activity by using external stimuli. The most notable disadvantage of MOF-based catalysts has been the inherent instability of the materials. This hurdle, which effectively limits the reaction scope of MOF catalysts, is slowly being overcome by the advent of new binding moieties and secondary building units.
A new class of symmetric error correcting/unidirectional error detecting codes

Abstract A new class of symmetric error correcting/unidirectional error detecting codes are developed. They provide protection against both transient and permanent faults. The codes are systematic in nature and, hence, the information bits are easy to retrieve. The encoding/decoding methods for these codes are discussed.
Strength of Recommendation Taxonomy (SORT): A Patient-Centered Approach to Grading Evidence in the Medical Literature

A large number of taxonomies are used to rate the quality of an individual study and the strength of a recommendation based on a body of evidence. We have developed a new grading scale that will be used by several family medicine and primary care journals (required or optional), with the goal of allowing readers to learn one taxonomy that will apply to many sources of evidence. Our scale is called the Strength of Recommendation Taxonomy. It addresses the quality, quantity, and consistency of evidence and allows authors to rate individual studies or bodies of evidence. The taxonomy is built around the information mastery framework, which emphasizes the use of patient-oriented outcomes that measure changes in morbidity or mortality. An A-level recommendation is based on consistent and good quality patient-oriented evidence; a B-level recommendation is based on inconsistent or limited quality patient-oriented evidence; and a C-level recommendation is based on consensus, usual practice, opinion, disease-oriented evidence, or case series for studies of diagnosis, treatment, prevention, or screening. Levels of evidence from 1 to 3 for individual studies also are defined. We hope that consistent use of this taxonomy will improve the ability of authors and readers to communicate about the translation of research into practice.
Superdense stars of large size

We avoid the recently asserted (1) destruction of matter by postulating that under extreme pressures it behaves like a gas of particles much heavier than nucleons, namely with masses up to the natural unit defined by gravity.
Full field measurements of curvature using coherent gradient sensing: application to thin film characterization

This paper introduces coherent gradient sensing (CGS) as an optical, full-field, real-time, non-intrusive and non-contact technique for measurement of curvature and curvature changes in thin film and micro-mechanical structures. The technique is applied to determine components of the curvature tensor field in multilayered thin films deposited on silicon wafers. Curvature field measurements using CGS are compared with average curvatures obtained using high-resolution X-ray diffraction. Finally, examples are presented to demonstrate the capability of CGS in measuring curvature in a variety of thin film and micro-mechanical structures.
Capital raising, underwriting and the certification hypothesis

Abstract This paper develops a theory of the role of the underwriter in certifying that risky issue prices reflect potentially adverse inside information. The theory derives from the literature on the use of reputational capital to guarantee product quality. An underwriting cost/benefit paradigm is employed to generate testable implications related to announcement effects, issue underpricing, the choice of competitive versus negotiated underwriting, and the level of underwriter compensation as a function of firm-specific information. Existing empirical literature is reviewed in the context of the certification hypothesis and several new tests are conducted. All of the findings are supportive of the hypothesis.
MATCHING FINANCIAL AND REAL INVESTMENT OPTIONS: EVIDENCE FROM WARRANT CALLS

We provide new evidence on the sequential financing explanation for the use of warrants. Consistent with sequential financing, capital spending starts increasing in the year of the call and peaks three years after the call. In addition, both equity and debt financing increase significantly in the year of the call and remain at high levels. Warrant contract features—the exercise price and the presence or absence of a price condition for callable warrants—are also consistent with the sequential financing hypothesis.
Standard Monomial Theory for Bott-Samelson Varieties of GL(n)

We construct an explicit basis for the coordinate ring of the Bott-Samelson variety Z{ associated to G=GL(n) and an arbitrary sequence of simple reflections i. Our basis is parametrized by certain standard tableaux and generalizes the Standard Monomial basis for Schubert varieties. In this paper, we prove the results announced in [LkMg] for the case of Type An-i (the groups GL (n) and SL (n) ). That is we construct an explicit basis for certain "generalized Demazure modules", natural finite-dimensional representations of the group B of upper triangular matrices. These modules can be constructed in an elementary way as flagged Schur modules [Mgl, Mg2, RSI, RS2]. They include as special cases almost all natural examples of jB-modules, and their characters include most of the known generalizations of Schur polynomials. We view these representations geometrically via Borel~Weil theory as the space of global sections of a line bundle over a Bott-Samelson variety. Thus, our theory also describes the coordinate ring of this variety. Notations: G — GL(n, IF) or SL(n, F), where IF is an algebraically closed field of arbitrary characteristic; B is the Borel subgroup consisting of upper triangular matrices; T is the maximal torus consisting of diagonal matrices; W is the symmetric group Sn generated by the adjacent transpositions (simple reflections) s, = (i, i + 1); Pt ^ B is the minimal parabolic subgroup of G associated to st, namely P1={(xlJ) ^G x tj — 0 if i>/ and (i,j] =£ (i + 1, i)}.
On the secondary bifurcation of three-dimensional standing waves

This paper contains an analysis of the complex set of periodic solutions that may occur in a fluid filled vessel of rectangular cross-section. A previous analysis by Verma and Kelley [Phys. Fluids, 5 (1962), pp. 52–56] found only simple eigenvalues for the linearized problem. It is shown herein that at critical values of the vessel aspect ratio double eigenvalues occur. Eight nonlinear solution branches are emitted from these double eigenvalues. The solutions along the various branches are derived and the results displayed graphically. It is shown that irregular waves occur along some of these branches.In an interesting development, Bauer, Keller and Reiss [SIAM Rev., 17 (1975), pp. 101–122], in their analysis of shell buckling, showed that the splitting of multiple eigenvalues may lead to secondary bifurcation. This theory is applied to the nonlinear standing wave problem herein, and it is shown that secondary bifurcation does occur in the neighborhood of the double eigenvalue. A perturbation method is u...
Michael Akam and the rise of evolutionary developmental biology

Michael Akam has been awarded the 2007 Kowalevsky medal for his many research accomplishments in the area of evolutionary developmental biology. We highlight three tributaries of Michael’s contribution to evolutionary developmental biology. First, he has made major contributions to our understanding of development of the fruit fly, Drosophila melanogaster. Second, he has maintained a consistent focus on several key problems in evolutionary developmental biology, including the evolving role of Hox genes in arthropods and, more recently, the evolution of segmentation mechanisms. Third, Michael has written a series of influential reviews that have integrated progress in developmental biology into an evolutionary perspective. Michael has also made a large impact on the field through his effective mentorship style, his selfless promotion of younger colleagues, and his leadership of the University Museum of Zoology at Cambridge and the European community of evolutionary developmental biologists.
Observations of supersonic free shear layers

Visual spreading rates of turbulent shear layers with at least one stream supersonic were measured using Schlieren photography. The experiments were done at a variety of Mach number-gas combinations. The spreading rates are correlated with a compressibility-effect parameter called the convective Mach number. It is found that for supersonic values of the convective Mach number, the spreading rate is about one quarter that of an incompressible layer at the same velocity and density ratio. The results are compared with other experimental and theoretical results.
Synthesis of endo-12-aminotricyclo[6.3.2.02,7]trideca-2(7), 3,5-triene-12-exo-carboxylic acid: A novel, conformationally restricted phenylalanine analogue

A seven step synthesis of the conformationally restricted phenylalanine analogue 9 from cycloheptadiene (1) is described.
Automating the price discovery process: Some international comparisons and regulatory implications

Automated trade execution systems are examined with respect to the degree to which they automate the price discovery process. Seven levels of automation of price discovery are identified, and 47 systems are classified according to these criteria. Systems operating at various levels of automation are compared with respect to age, geographical location, and type of securities traded. Information provided to market participants and asymmetries of information between traders with direct access to the automated market and outside investors also are examined. It is found, for example, that the degree of asymmetric information increases with the level of automation of price discovery. The potential for trading abuses related to prearranged trading, noncompetitive execution, and trading ahead of customers is analyzed for each level of automation. Certain levels of automation widen the opportunities for trading abuses in some respects, but may narrow them in others.
Magnetic excitations of undoped iron oxypnictides

We study the magnetic excitations of undoped iron oxypnictides using a three-dimensional Heisenberg model with single-ion anisotropy. Analytic forms of the spin-wave dispersion, velocities, and structure factor are given. Aside from quantitative comparisons that can be made to inelastic neutron scattering experiments, we also give qualitative criteria that can distinguish various regimens of coupling strength. The magnetization reduction due to quantum zero point fluctuations shows clear dependence on the c-axis coupling.
Resonance Capture of Neutrons by Uranium

The resonance capture of slow neutrons by ${\mathrm{U}}^{238}$ has been studied by absorption methods with "good" geometry and thin detectors using the cyclotron as an intense source of neutrons. The experimental cross section for self-absorption for slow neutrons transmitted by cadmium was measured with thin absorbers and found to be 4600\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$/atom\ifmmode\pm\else\textpm\fi{}40 percent. Evidence is given for the existence of more than one level. The predominant level has an energy somewhat under 11 ev, a total natural width somewhat less than 0.20 ev and a neutron width somewhat less than 0.0086 ev. The value $\ensuremath{\int}\frac{\ensuremath{\sigma}\mathrm{dE}}{E}$ in the resonance region was found to be 290\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$/atom\ifmmode\pm\else\textpm\fi{}40 percent.
Interpretive structural modeling—A useful tool for technology assessment?

Abstract Interpretive Structural Modeling (ISM) is a computer based technique for helping small groups develop graphical representations of complex systems. In this paper, the rationale for the use of Interpretative Structural Modeling in activities such as technology assessment is developed and the basic concepts underlying the technique are explored. Several applications of ISM are described and from these experiences some observations are made about the nature and effectiveness of the ISM process and product. ISM was found to provide its users with a systematic and comprehensive method for integrating group judgments in the development of “first-cut‘ structural models. At the same time, however, the technique was found to be relatively inflexible and may, in some instances, inhibit group processes. Possible directions for the development of less rigid methods are suggested.
The NGO's Dilemma: How to Influence Firms to Replace a Potentially Hazardous Substance

We study a nongovernmental organization's NGO's decisions when it attempts to remove a potentially hazardous substance from commercial use in a market with competing firms. Specifically, we determine under what market and regulatory conditions an NGO should target the industry versus the regulatory body to influence firms to replace the substance. We examine how the NGO's strategy changes as the NGO's pragmatism i.e., the extent to which the NGO incorporates firms' profits into its decision making increases. Our results demonstrate that when the NGO is less pragmatic, it should examine the existing market structure to determine whether to target the industry or the regulatory body. However, as the pragmatism of the NGO increases, the NGO should increasingly leverage the competition between firms to ensure that a replacement is available to consumers. We examine multiple extensions including varying the competition dynamics, the NGO targeting both the industry and the regulatory body, the time discounting of replacement costs, and a firm potentially lobbying to counteract an NGO's activism. We show that the potential for a firm to lobby can benefit consumers by motivating the NGO to exert more effort and increase the market sensitivity to a substance, thereby forcing the firm to replace.
A provably time-efficient parallel implementation of full speculation

Speculative evaluation, including leniency and futures, is often used to produce high degrees of parallelism. Understanding the performance characteristics of such evaluation, however, requires having a detailed understanding of the implementation. For example, the particular implementaion technique used to suspend and reactivate threads can have an asymptotic effect on performance. With the goal of giving the users some understanding of performance without requiring them to understand the implementation, we present a provable implementation bound for a language based on speculative evaluation. The idea is (1) to supply the users with a semantics for a language that defines abstract costs for measuring or analyzing the performance of computations, (2) to supply the users with a mapping of these costs onto runtimes on various machine models, and (3) to describe an implementation strategy of the language and prove that it meets these mappings. For this purpose we consider a simple language based on speculative evaluation. For every computation, the semantics of the language returns a directed acyclic graph (DAG) in which each node represents a unit of computation, and each edge represents a dependence. We then describe an implementation strategy of the language and show that any computation with w work (the number of nodes in the DAG) and d depth (the length of the longest path in the DAG) will run on a p-processor PRAM in O(w/p + d log p) time. The bounds are work efficient (within a constant factor of linear speedup) when there is sufficient parallelism, w/d ≥ p log p. These are the first time bounds we know of for languages with speculative evaluation. The main challenge is in parallelizing the necessary queuing operations on suspended threads.
Simultaneous heat and mass transfer in absorption of gases in turbulent liquid films

Abstract This paper describes a theoretical analysis of the combined heat and mass transfer process taking place in the absorption of a gas or vapor in a turbulent liquid film. Eddy diffusivity correlations have been used to describe the transport near the wall and the interface and in the bulk of the film. The energy and diffusion equations are solved simultaneously to give the temperature and concentration variations in the film. Two cases of interest are considered: a constant-temperature and an adiabatic wall. The Nusselt and Sherwood numbers are expressed in terms of the operating parameters, from which heat and mass transfer coefficients are determined.
Series in the Spectra of Aluminum and Magnesium in the Extreme Ultra-Violet

PASCHEN (Ann. d. Phy. 71, p. 152, 1923), in his investigation of the spectrum of doubly ionised aluminum (Al. III.), and Fowler (“Series in Line Spectra,” p. 120), in his study of ionised magnesium (Mg. II.), have pointed out the type of series relations which exist in these substances, and have arranged many lines to conform to them. In a study 01 the spectra of both aluminum and magnesium in the extreme ultra-violet, under various forms of excitation, I have recently observed certain lines which appear to be higher members of some of the series discovered by Paschen and by Fowler ; Millikan has already identified the two strongest, but the remainder seem to have escaped observation. The wave-lengths and the series to which these lines belong are given in the following tables.
Synthesis of Single-Molecule Nanocars

The drive to miniaturize devices has led to a variety of molecular machines inspired by macroscopic counterparts such as molecular motors, switches, shuttles, turnstiles, barrows, elevators, and nanovehicles. Such nanomachines are designed for controlled mechanical motion and the transport of nanocargo. As researchers miniaturize devices, they can consider two complementary approaches: (1) the “top-down” approach, which reduces the size of macroscopic objects to reach an equivalent microscopic entity using photolithography and related techniques and (2) the “bottom-up” approach, which builds functional microscopic or nanoscopic entities from molecular building blocks. The top-down approach, extensively used by the semiconductor industry, is nearing its scaling limits. On the other hand, the bottom-up approach takes advantage of the self-assembly of smaller molecules into larger networks by exploiting typically weak molecular interactions. But self-assembly alone will not permit complex assembly. Using nan...
Low-frequency fluctuations in plasma magnetic fields.

It is shown that even a non-magnetized plasma with temperature T sustains zero-frequency magnetic fluctuations in thermal equilibrium. Fluctuations in electric and magnetic fields, as well as in densities, are computed. Four cases are studied: a cold, gaseous, isotropic, non-magnetized plasma; a cold, gaseous plasma in a uniform magnetic field; a warm, gaseous plasma described by kinetic theory; and a degenerate electron plasma. For the simple gaseous plasma, the fluctuation strength of the magnetic field as a function of frequency and wavenumber is calculated with the aid of the fluctuation-dissipation theorem. This calculation is done for both collisional and collisionless plasmas. The magnetic field fluctuation spectrum of each plasma has a large zero-frequency peak. The peak is a Dirac {delta}-function in the collisionless plasma; it is broadened into a Lorentzian curve in the collisional plasma. The plasma causes a low frequency cutoff in the typical black-body radiation spectrum, and the energy under the discovered peak approximates the energy lost in this cutoff. When the imposed magnetic field is weak, the magnetic field were vector fluctuation spectra of the two lowest modes are independent of the strength of the imposed field. Further, these modes contain finite energy even when the imposedmore » field is zero. It is the energy of these modes which forms the non-magnetized zero-frequency peak of the isotropic plasma. In deriving these results, a simple relationship between the dispersion relation and the fluctuation power spectrum of electromagnetic waves if found. The warm plasma is shown, by kinetic theory, to exhibit a zero-frequency peak in its magnetic field fluctuation spectrum as well. For the degenerate plasma, we find that electric field fluctuations and number density fluctuations vanish at zero frequency; however, the magnetic field power spectrum diverges at zero frequency.« less
Total synthesis of (-)-aurantioclavine.

The concise total synthesis of (−)-aurantioclavine has been achieved by taking advantage of strategies for the asymmetric alkenylation of N-tert-butanesulfinyl imines. The enantiomerically pure natural product was prepared in 6 steps and 27% overall yield by using Rh-catalyzed addition of a N-methyliminodiacetic acid (MIDA) boronate and in 5 steps and 29% yield by employing a Grignard reagent addition sequence.
Analytic model of aurorally coupled magnetospheric and ionospheric electrostatic potentials

This paper describes modest but significant improvements on earlier studies of electrostatic potential structure in the auroral region using the adiabatic auroral arc model. This model has crucial nonlinearities (connected, for example. with aurorally produced ionization) which have hampered analysis; earlier work has either been linear, which I will show is a poor approximation or, if nonlinear, either numerical or too specialized to study parametric dependencies. With certain simplifying assumptions I find new analytic nonlinear solutions fully exhibiting the parametric dependence of potentials on magnetospheric (e.g.. cross-tail potential) and ionospheric (e.g., recombination rate) parameters. No purely phenomenological parameters are introduced. The results are in reasonable agreement with observed average auroral potential drops, inverted-V scale sizes, and dissipation rates. The dissipation rate is quite comparable to tail energization and transport rates and should have a major effect on tail and magnetospheric dynamics. This paper gives various relations between the cross-tail potential and auroral parameters (e.g., total parallel currents and potential drops) which can be studied with existing data sets.
Examining School Security Measures as Moderators of the Association between Homophobic Victimization and School Avoidance.

Homophobic victimization is a pervasive problem in U.S. schools that leads to negative outcomes for students. Those who experience homophobic victimization are at greater risk for avoiding particular spaces in school because they feel unsafe or afraid. Visible school security measures (e.g., security guards, metal detectors, and cameras) offer spatial guardianship that may reduce students’ place-specific avoidance behaviors. To test this moderating effect of school security, we analyzed data from six panels of the School Crime Supplement to the National Crime Victimization Survey (N = 41,229). Logistic regression models were used to examine the moderating effect of three types of school security measures on the association between homophobic victimization and avoidance of six specific locations in school and overall fear of victimization at school. Results suggest that visible security measures did not meaningfully moderate the association between homophobic victimization and school avoidance.
A Human Expert-Based Approach to Electrical Peak Demand Management

The objective of this paper is to propose a human expert-based approach to electrical peak demand management. The proposed approach helps to allocate demand curtailments (MW) among distribution substations (DS) or feeders in an electric utility service area based on requirements of the central load dispatch center. Demand curtailment allocation is quantified by taking into account demand response (DR) potential and load curtailment priority of each DS, which can be determined using DS loading level, capacity of each DS, customer types (residential/commercial), and load categories (deployable, interruptible, or critical). The analytic hierarchy process is used to model a complex decision-making process according to both expert inputs and objective parameters. Simulation case studies are conducted to demonstrate how the proposed approach can be implemented to perform DR using real-world data from an electric utility. Simulation results demonstrate that the proposed approach is capable of achieving realistic demand curtailment allocations among different DSs to meet the peak load reduction requirements at the utility level.
Mild and General Cross-Coupling of (α-Alkoxyvinyl)silanols and -silyl Hydrides

(α-Alkoxyvinyl)silanols and (α-alkoxyvinyl)silyl hydrides are efficiently converted to aryl vinyl ethers by a palladium(0)-catalyzed cross-coupling reaction with aryl halides in the presence of tetrabutylammonium fluoride or hydroxide. Yields are generally high, and the reaction is compatible with a wide range of functional groups.
Computer Simulation for Program Evaluation.

Computer simulations in evaluation research are useful for (1) improving student understanding of basic research principles and analytic techniques; (2) investigating the effects of problems that arise in the implementation of research; and (3) exploring the accuracy and utility of novel analytic techniques applied to problematic data structures. This article describes these uses of microcomputer simulations for the context of human service program evaluation. Simple mathematical models are described for the three most commonly used human service outcome evaluation designs: the pretest-posttest random ized experiment, the pretest posttest nonequivalent groups design; and the regression- discontinuity design. The models are translated into a single microcomputer program that can be used to conduct the simulations. Examples of the use of this program on an IBM PC microcomputer are provided to illustrate the three uses of the simulations described. The article concludes by arguing that simulations need to ut...
Catalytic C–H functionalization by metalloporphyrins: recent developments and future directions

Metalloporphyrins are a class of versatile catalysts with the capability to functionalize saturated C–H bonds via several well-defined atom/group transfer processes, including oxene, nitrene, and carbene C–H insertions. The corresponding hydroxylation, amination, and alkylation reactions provide direct approaches for the catalytic conversion of abundant hydrocarbons into value-added functional molecules through C–O, C–N, and C–C bond formations, respectively. This tutorial review describes metalloporphyrin-based catalytic systems for the functionalization of different types of sp3 C–H bonds, both inter- and intramolecularly, including challenging primary C–H bonds. Additional features of metalloporphyrin-catalyzed C–H functionalization include unusual selectivities and high turnover numbers.
Chiral limit of QCD

This talk contains an analysis of quenched chiral perturbation theory and its consequences. The chiral behavior of a number of quantities such as the pion mass m{sub pi}{sup 2}, the Bernard-Golterman ratios R and {sub X}, the masses of nucleons, and the kaon B-parameter are examined to see if the singular terms induced by the additional Goldstone boson, {eta}{prime}, are visible in present data. The overall conclusion (different from that presented at the lattice meeting) of this analysis is that even though there are some caveats attached to the indications of the extra terms induced by {eta}{prime} loops, the standard expressions break down when extrapolating the quenched data with m{sub q} < m{sub s}/2 to physical light quarks. I then show that due to the single and double poles in the quenched {eta}{prime}, the axial charge of the proton cannot be calculated using the Adler-Bell-Jackiw anomaly condition. I conclude with a review of the status of the calculation of light quark masses from lattice QCD.
Electromagnetic self-forces and generalized Killing fields

Building upon previous results in scalar field theory, a formalism is developed that uses generalized Killing fields to understand the behavior of extended charges interacting with their own electromagnetic fields. New notions of effective linear and angular momenta are identified, and their evolution equations are derived exactly in arbitrary (but fixed) curved spacetimes. A slightly modified form of the Detweiler–Whiting axiom that a charge's motion should only be influenced by the so-called regular component of its self-field is shown to follow very easily. It is exact in some interesting cases and approximate in most others. Explicit equations describing the center-of-mass motion, spin angular momentum and changes in mass of a small charge are also derived in a particular limit. The chosen approximations—although standard—incorporate dipole and spin forces that do not appear in the traditional Abraham–Lorentz–Dirac or Dewitt–Brehme equations. They have, however, been previously identified in the test body limit.
The Negative Income Tax and the Evolution of U.S. Welfare Policy

The negative income tax proposed by Milton Friedman represents one of the fundamental ideas of modern welfare policy. However, the academic literature has raised two difficulties with it, one challenging its purported work incentives and the other suggesting the possible superiority of work requirements. In addition, work requirement approaches have gained ground in actual U.S. welfare policy over the last 30 years and the number of different programs has proliferated, another development counter to the negative income tax. On the other hand, the Earned Income Tax Credit has produced a negative-income-tax-like program on a vast scale.
Competitive collaborative learning

Intuitively, it is clear that trust or shared taste enables a community of users to make better decisions over time, by learning cooperatively and avoiding one another's mistakes. However, it is also clear that the presence of malicious, dishonest users in the community threatens the usefulness of such collaborative learning processes. We investigate this issue by developing algorithms for a multi-user online learning problem in which each user makes a sequence of decisions about selecting products or resources. Our model, which generalizes the adversarial multi-armed bandit problem, is characterized by two key features:(1)The quality of the products or resources may vary over time. (2)Some of the users in the system may be dishonest, Byzantine agents. Decision problems with these features underlie applications such as reputation and recommendation systems in e-commerce, and resource location systems in peer-to-peer networks. Assuming the number of honest users is at least a constant fraction of the number of resources, and that the honest users can be partitioned into groups such that individuals in a group make identical assessments of resources, we present an algorithm whose expected regret per user is linear in the number of groups and only logarithmic in the number of resources. This bound compares favorably with the naive approach in which each user ignores feedback from peers and chooses resources using a multi-armed bandit algorithm; in this case the expected regret per user would be polynomial in the number of resources.
Chronic rhinitis in children

Children are not small adults, and although many features of chronic rhinitis in children are similar to those in adults, there are significant differences in etiologic factors, manner of presentation, and therapy. The fact that children are growing and developing also has special therapeutic implications in the management of rhinitis.
Pharmacokinetics and pharmacodynamics of piperacillin/tazobactam when administered by continuous infusion and intermittent dosing.

Abstract Background: Although intermittent bolus dosing is currently the standard of practice for many antimicrobial agents, beta-lactams exhibit time-dependent bacterial killing. Maximizing the time above the minimum inhibitory concentration (MIC) for a pathogen is the best pharmacodynamic predictor of efficacy. Use of a continuous infusion has been advocated for maximizing the time above the MIC compared with intermittent bolus dosing. Objective: This study compared the pharmacokinetics and pharmacodynamics of piperacillin/tazobactam when administered as an intermittent bolus versus a continuous infusion against clinical isolates of Pseudomonas aeruginosa and Klebsiella pneumoniae . Methods: Healthy volunteers were randomly assigned to receive piperacillin 3 g/ tazobactam 0.375 g q6h for 24 hours, piperacillin 6 g/tazobactam 0.75 g continuous infusion over 24 hours, and piperacillin 12 g/tazobactam 1.5 g continuous infusion over 24 hours. Five clinical isolates each of P aeruginosa and K pneumoniae were used for pharmacodynamic analyses. Results: Eleven healthy subjects (7 men, 4 women; mean ± SD age, 28 ± 4.7 years) were enrolled. Mean steady-state serum concentrations of piperacillin were 16.0 ± 5.0 and 37.2 ± 6.8 μg/mL with piperacillin 6 and 12 g, respectively. Piperacillin/tazobactam 13.5 g continuous infusion (piperacillin 12 g/tazobactam 1.5 g) was significantly more likely to produce a serum inhibitory titer ≥1:2 against P aeruginosa at 24 hours than either the 6.75 g continuous infusion (piperacillin 6 g/tazobactam 0.75 g) or 3.375 g q6h (piperacillin 3 g/ tazobactam 0.375 g). There were no statistical differences against K pneumoniae between regimens. The median area under the inhibitory activity-time curve (AUIC) for the 13.5 g continuous infusion was higher than that for 3.375 g q6h and the 6.75 g continuous infusion against both P aeruginosa and K pneumoniae ( P ≤ 0.007, 13.5 g continuous infusion and 3.375 g q6h vs 6.75 g continuous infusion against K pneumoniae ). The percentage of subjects with an AUIC ≥ 125 was higher with both 3.375 g q6h and the 13.5 g continuous infusion than with the 6.75 g continuous infusion against P aeruginosa and K pneumoniae (both, P K pneumoniae ). Conclusions: Piperacillin 12 g/tazobactam 1.5 g continuous infusion consistently resulted in serum concentrations above the breakpoint for Enterobacteriaceae and many of the susceptible strains of P aeruginosa in this study in 11 healthy subjects. Randomized controlled clinical trials are warranted to determine the appropriate dose of piperacillin/tazobactam.
Income, Environmental Disamenity, and Toxic Releases

The literature argues that income growth leads to increased demand for environmental quality and thus reduction in pollution. Using a utility theoretic model, we hypothesize that the income‐pollution relationship should depend on the level of disamenity of the pollutant. We proxy for disamenity using the toxicity of releases. For counties in the United States, the functional relationship between income and releases depends on the level of disamenity: the form is more concave for more toxic releases. We find that environmental improvements occur at lower levels of per capita income for more toxic pollutants. (JEL Q25, Q28, O13)
Learning about Social Learning in MOOCs: From Statistical Analysis to Generative Model

We study user behavior in the courses offered by a major massive online open course (MOOC) provider during the summer of 2013. Since social learning is a key element of scalable education on MOOC and is done via online discussion forums, our main focus is on understanding forum activities. Two salient features of these activities drive our research: (1) high decline rate : for each course studied, the volume of discussion declined continuously throughout the duration of the course; (2) high-volume, noisy discussions : at least 30 percent of the courses produced new threads at rates that are infeasible for students or teaching staff to read through. Further, a substantial portion of these discussions are not directly course-related. In our analysis, we investigate factors that are associated with the decline of activity on MOOC forums, and we find effective strategies to classify threads and rank their relevance. Specifically, we first use linear regression models to analyze the forum activity count data over time, and make a number of observations; for instance, the teaching staff’s active participation in the discussions is correlated with an increase in the discussion volume but does not slow down the decline rate. We then propose a unified generative model for the discussion threads, which allows us both to choose efficient thread classifiers and to design an effective algorithm for ranking thread relevance. Further, our algorithm is compared against two baselines using human evaluation from Amazon Mechanical Turk.
Who enjoys ‘TRIPs’ abroad? An empirical analysis of intellectual property rights in the Uruguay Round

. Analysis of the Uruguay Round is extended by quantifying the impact of the TRIPs agreement. The static costs of raising the standards of patent protection are captured by the transfers of income between countries, with the majority of countries estimated to make net payments abroad, the United States being a major beneficiary. To offset these transfers the model provides estimates of the dynamic benefits from the greater incentive to innovate, revealing that there is potential for all countries to benefit from the TRIPs agreement in the long run. However, the distribution of these benefits is highly skewed towards developed countries. JEL classification: O34, F43 Qui tire profit des ADPICs a l’etranger? Une analyse empirique des droits de propriete intellectuelle dans la Ronde de l’Uruguay. On analyse les decisions de la Ronde de l’Uruguay en vue de quantifier l’impact de l’accord sur les droits de propriete intellectuelle qui touchent au commerce. Les couts statiques de normes plus elevees pour la protection des brevets sont mesures par les transferts de revenus entre pays. On estime que la majorite des pays effectuent des transferts nets vers l’exterieur, et que les Etats-Unis sont un beneficiaire important de ces transferts. Pour compenser ces transferts, le modele cherche a determiner les avantages dynamiques qu’il y a a encourager ainsi l’innovation, et montre qu’il y a un potentiel de gains pour tous les pays decoulant des accords sur les ADPICs a plus long terme. Cependant, la repartition de ces avantages est fortement biaisee en faveur des pays developpes.
The Pisgah Automated Survey: A Photometric Search for Low-Mass Detached Eclipsing Binaries and Other Variable Stars

The Pisgah Survey, located at the facilities of the Pisgah Astronomical Research Institute in Rosman, North Carolina, is a low-cost project to acquire fully automated I-band photometry of selected areas of the sky. The survey collects multiple images of ~16.5 deg2 of sky per night, searching for variability in stars with apparent magnitudes brighter than I ~ 15. The main scientific goal of this project is to discover new low-mass detached eclipsing binaries in order to provide precise constraints to the mass-radius relation for the lower main sequence. In this paper we present a technical description of the project, including the software routines used to automate the collection and analysis of the data, and a description of our variable identification strategy. We prove the feasibility of our technique by showing the successful detection of the previously known M dwarf detached eclipsing binary GJ 2069A, and we present the results of the analysis of the first set of fields imaged by the survey, in which 15 new variables have been discovered among 8201 stars monitored. The paper concludes with an outline of the project's prospects.
The Astromag Superconducting Magnet Facility Configured for a Free Flying Satellite

The magnet parameters of a free-flying version of Astromag and the parameters of the space cryogenic system for the magnet are presented. Consideration is given to the free-flyer version of the Astromag magnet. The diameter of the magnet, its cryostat, the satellite and the two instruments is limited by the 4.27-m shroud diameter of the Atlas IIa. The magnet coil must use a stable reliable superconductor which can carry the full magnet current at 4.2 K at a peak induction in the coil of 7.5 T. The magnet must operate in the persistent mode. The changes in the overall design and operating requirements for the free-flying-design Astromag suggest that the coils, the cryogenic system, and the charging system can be simplified without a loss of required magnet function. Attention is given to switches, trim coils, and plumbing in the low field region between the coils; the magnet charging system and the quench protection system; and cooled helium supply to the magnet gas-cooled electrical leads.
Production of Dimuons from High-Energy Polarized Proton Proton Collisions

Abstract The high-energy process p+p→μ++μ−+X for dimuons with large invariant mass is studied in the case that the protons are polarized. In general, the cross section d σ/ d Q 2 d y d Ω is determined by nine structure functions, and several interesting correlations between the polarization direction and the observed cross section are possible. In the Drell-Yan parton model for the process, the structure of the cross section is much simpler: there are six linear relations among the structure functions. An experimental test of these relations would provide a stringent test of the Drell-Yan model.
Platelet glycoprotein IIb/IIIa receptor antagonists derived from isoxazolidines

A series of isoxazolidines has been synthesized as mimetics of the RGD sequence and was evaluated as antagonists of the platelet glycoprotein IIb/IIIa receptor. These compounds were shown to be highly potent GPIIb/IIIa antagonists, exhibiting submicromolar potencies.
Bias-free time-integrating optical correlator using a photorefractive crystal.

An acoustooptic time-integrating correlator is demonstrated using a photorefractive crystal as the time-integrating detector.
The truth, the myths and the possible in freight road pricing in congested urban areas

Abstract This paper discusses a number of myths related to the trucking industry, its economics, and the industry response to pricing and what the author considers a fundamental truth and a possible course of action. The paper analyzes the empirical and econometric evidence about the behavioural impacts of freight road pricing, complements it with game theoretic analyses, and concludes that moving trucks to the off-hours require comprehensive policies targeting key components of the supply chain (i.e., receivers and carriers). The paper discusses the role of agent interactions and their role in determining freight mode choice, and the carrier industry response to time of day pricing. The paper shows that shipper-carrier interactions are part of a cooperative game in which both agents interact to find the overall optimal. The paper also shows the decision about delivery times is jointly made between carriers and receivers, as part of the “Battle of the Sexes” game. This suggests that moving truck traffic to the off-hours requires a change in the behaviour of receivers, so that they accept off-hour deliveries. This could be accomplished by a combination of financial incentives to receivers in conjunction with freight road pricing. Due to the fact that transporting during the off-hours is more efficient than during regular hours, it is likely that, should a sufficient number of receivers be willing to accept off-hour deliveries, the carriers will follow suit. The paper suggests a toll surcharge to finance the incentives to receivers.
Persistent Inequality in Educational Attainment and its Institutional Context

has repeatedly shown that educational opportunities are distributed unevenly in all countries. Therefore, the question is not whether family background and educational outcomes are related but to what degree they are related. This latter question then invites a comparative perspective. That is, does social inequality in education differ across time and countries? If yes, which institutional characteristics can explain differences in educational inequality? Educational inequality is conceptualized as the association between individuals' and their parents' highest educational level attained. Intergenerational educational mobility processes are analysed for 20 industrialized nations by means of log-linear and log-multiplicative models. The results show that the degree of educational mobility has remained stable across the second half of the 20th century in virtually all countries. However, nations differ widely in the extent to which parents' education influences their children's educational attainment. The degree of educational inequality is associated with the institutional structure of national education systems. Rigid systems with dead-end educational pathways appear to be a hindrance to the equalization of educational opportunities, especially if the sorting of students occurs early in the educational career. This association is not mediated by other institutional characteristics included in this analysis that do not exert notable influences on educational mobility.