cssi/SciSciGPT-SciSciNet huggingface dataset:
Designing the Payout Phase of Pension Systems : Policy Issues, Constraints and Options

This paper examines the policy issues, constraints and options facing policymakers in promoting the development of sound markets for retirement products. It discusses the various risks faced by pensioners and the risk characteristics of alternative retirement products and also reviews the risks faced by providers of retirement products and the management and regulatory challenges of dealing with these risks. The paper focuses on policies that could be adopted by developing and transitioning countries where financial and insurance markets are not well developed. It argues for promoting an adequate level of annuitization but avoiding excessive annuitization. It also argues for favoring combinations of payout options, covering different products at a particular point in time as well as different payout options over time. The paper also discusses the choice between centralized and decentralized markets and highlights the basic elements of an effective regulation of risk management.
Broadband Spread Spectrum Multiple Access For Personal And Cellular Communications

Bandwidth is the most important parameter of a code division multiple access (CDMA) system. It is governed by the system chip rate and affects capacity, fade margin, data rate, voice quality, performance in indoor and outdoor environments, transition plan, frequency management, overlay capability, and adaptive power control. The author discusses how each of these parameters is affected by the choice of bandwidth. A comparison is made between the capacity of a B-CDMA system in the cellular and PCS bands.
CANCER: Computer Analysis of Nonlinear Circuits Excluding Radiation

Cancer is a program designed for the complete simulation of integrated electronic circuits, possessing the following features:
Correlated electrons in δ-plutonium within a dynamical mean-field picture

Given the practical importance of metallic plutonium, there is considerable interest1,2,3 in understanding its fundamental properties. Plutonium undergoes a 25 per cent increase in volume4 when transformed from its α-phase (which is stable below 400 K) to the δ-phase (stable at around 600 K), an effect that is crucial for issues of long-term storage and disposal. It has long been suspected that this unique property is a consequence of the special location of plutonium in the periodic table, on the border between the light and heavy actinides—here, electron wave–particle duality (or itinerant versus localized behaviour) is important5. This situation has resisted previous theoretical treatment. Here we report an electronic structure method, based on dynamical mean-field theory, that enables interpolation between the band-like and atomic-like behaviour of the electron. Our approach enables us to study the phase diagram of plutonium, by providing access to the energetics and one-electron spectra of strongly correlated systems. We explain the origin of the volume expansion between the α- and δ-phases, predict the existence of a strong quasiparticle peak near the Fermi level and give a new viewpoint on the physics of plutonium, in which the α- and δ-phases are on opposite sides of the interaction-driven localization–delocalization transition.
Kalman Filter and its Economic Applications

This paper is an eclectic study of the uses of the Kalman filter in existing econometric literature. An effort is made to introduce the various extensions to the linear filter first developed by Kalman(1960) through examples of their uses in economics. The basic filter is first derived and then some applications are reviewed.
A Pieri-type formula for the K-theory of a flag manifold

We derive explicit Pieri-type multiplication formulas in the Grothendieck ring of a flag variety. These expand the product of an arbitrary Schubert class and a special Schubert class in the basis of Schubert classes. These special Schubert classes are indexed by a cycle which has either the form (k-p+1, k-p+2,..., k+1) or the form (k+p, k+p-1,..., k), and are pulled back from a Grassmannian projection. Our formulas are in terms of certain labeled chains in the k-Bruhat order on the symmetric group and are combinatorial in that they involve no cancellations. We also show that the multiplicities in the Pieri formula are naturally certain binomial coefficients.
A new model for the width of the broad emission lines in AGN: The role of the accretion rate

Abstract We present a model which relates the Broad Emission Line Regions of AGN to the accretion mechanism. Based on the Keplerian assumption for the high velocity clouds of the gas responsible for the production of the Broad Emission Lines, we identify that gas with an outflowing disk/coronal wind from a stabilized Shakura–Sunyaev accretion disk. We show that in the framework of this picture the observed range of H β FWHM from Broad Line to Narrow Line type 1 AGN, is well reproduced as a function of the accretion rate.
Terrestrial dominance of organic matter in north temperate lakes

[1] Aquatic ecosystems are hotspots of decomposition and sources of carbon dioxide to the atmosphere that are globally significant. Carbon exported from land (allochthonous) also supplements the carbon fixed by photosynthesis in aquatic ecosystems (autochthonous), contributing to the organic matter (OM) that supports aquatic consumers. Although the presence of terrestrial compounds in aquatic OM is well known, the contribution of terrestrial versus aquatic sources to the composition of OM has been quantified for only a handful of systems. Here we use stable isotopes of hydrogen and carbon to demonstrate that the terrestrial contribution (ΦTerr) to particulate organic matter (POM) is as large or larger (mean = 54.6% terrestrial) than the algal contribution in 39 lakes of the northern highlands region of Wisconsin and Michigan. Further, the largest carbon pool, dissolved organic matter (DOM), is strongly dominated by allochthonous material (mean for the same set of lakes approximately 100% terrestrial). Among lakes, increases in terrestrial contribution to POM are significantly correlated with more acidic pH. Extrapolating this relationship using a survey of pH in 1692 lakes in the region reveals that, with the exception of eutrophic lakes, most of the OM in lakes is of terrestrial origin. These results are consistent with the growing evidence that lakes are significant conduits for returning degraded terrestrial carbon to the atmosphere.
Entropy for Symbolic Dynamics with Overlapping Alphabets

We consider shift spaces in which elements of the alphabet may overlap nontransitively. We define a notion of entropy for such spaces and show that it is equal to a limit of entropies of standard (non-overlapping) shifts when the underlying shift is of finite type. When a shift space with overlaps arises as a model for a discrete dynamical system with a finite set of overlapping neighborhoods, the entropy gives a lower bound for the topological entropy of the dynamical system.
Optimistic fair exchange with multiple arbiters

Fair exchange is one of the most fundamental problems in secure distributed computation. Alice has something that Bob wants, and Bob has something that Alice wants. A fair exchange protocol would guarantee that, even if one of them maliciously deviates from the protocol, either both of them get the desired content, or neither of them do. It is known that no two-party protocol can guarantee fairness in general; therefore the presence of a trusted arbiter is necessary. In optimistic fair exchange, the arbiter only gets involved in case of faults, but needs to be trusted. To reduce the trust put in the arbiter, it is natural to consider employing multiple arbiters. Expensive techniques like byzantine agreement or secure multi-party computation with Ω(n2) communication can be applied to distribute arbiters in a nonautonomous way. Yet we are interested in efficient protocols that can be achieved by keeping the arbiters autonomous (non-communicating), especially for p2p settings in which the arbiters do not even know each other. Avoine and Vaudenay [6] employ multiple autonomous arbiters in their optimistic fair exchange protocol which uses global timeout mechanisms; all arbiters have access to -loosely- synchronized clocks. They left two open questions regarding the use of distributed autonomous arbiters: (1) Can an optimistic fair exchange protocol without timeouts provide fairness (since it is hard to achieve synchronization in a p2p setting) when employing multiple autonomous arbiters? (2) Can any other optimistic fair exchange protocol with timeouts achieve better bounds on the number of honest arbiters required? In this paper, we answer both questions negatively. To answer these questions, we define a general class of optimistic fair exchange protocols with multiple arbiters, called "distributed arbiter fair exchange" (DAFE) protocols. Informally, in a DAFE protocol, if a participant fails to send a correctly formed message, the other party must contact some subset of the arbiters and get correctly formed responses from them. The arbiters do not communicate with each other, but only to Alice and Bob.We prove that no DAFE protocol can meaningfully exist.
Identifying mislabeled training data

This paper presents a new approach to identifying and eliminating mislabeled training instances for supervised learning. The goal of this approach is to improve classification accuracies produced by learning algorithms by improving the quality of the training data. Our approach uses a set of learning algorithms to create classifiers that serve as noise filters for the training data. We evaluate single algorithm, majority vote and consensus filters on five datasets that are prone to labeling errors. Our experiments illustrate that filtering significantly improves classification accuracy for noise levels up to 30%. An analytical and empirical evaluation of the precision of our approach shows that consensus filters are conservative at throwing away good data at the expense of retaining bad data and that majority filters are better at detecting bad data at the expense of throwing away good data. This suggests that for situations in which there is a paucity of data, consensus filters are preferable, whereas majority vote filters are preferable for situations with an abundance of data.
Quench energies of potted magnets, III

Several different formulas have been proposed for estimating quench energies of potted magnets.1–3 These formulas, although based on plausible approximations, disagree with one another by factors of 2 to 6. By the use of maximum and minimum principles for the heat balance equation, it has been possible to determine whether each estimate is an upper or lower bound.
Classical kinematics and Finsler structures for nonminimal Lorentz-violating fermions

In the current paper the Lagrangian of a classical, relativistic point particle is obtained whose conjugate momentum satisfies the dispersion relation of a quantum wave packet that is subject to Lorentz violation based on a particular coefficient of the nonminimal standard-model extension (SME). The properties of this Lagrangian are analyzed and two corresponding Finsler structures are obtained. One structure describes a scaled Euclidean geometry, whereas the other is neither a Riemann nor a Randers or Kropina structure. The results of the article provide some initial understanding of classical Lagrangians of the nonminimal SME fermion sector.
Orbital Parameters of the PSR B1620-26 Triple System

Previous timing data for PSR~B1620$-$26 were consistent with a second companion mass $m_2$ anywhere in the range $\sim10^{-3}-1\,M_\odot$, i.e., from a Jupiter-type planet to a star. We present the latest timing parameters for the system, including a significant change in the projected semi-major axis of the inner binary, a marginal detection of the fourth time derivative of the pulse frequency, and the pulsar proper motion (which is in agreement with published values for the proper motion of M4), and use them to further constrain the mass $m_2$ and the orbital parameters. Using the observed value of $\stackrel{\ldots.}{f}$, we obtain a one-parameter family of solutions, all with $m_2 \lo 10^{-2}\,M_\odot$, i.e., excluding stellar masses. Varying $\stackrel{\ldots.}{f}$ within its formal $1\sigma$ error bar does not affect the mass range significantly. However, if we vary $\stackrel{\ldots.}{f}$ within a $4\sigma$ error bar, we find that stellar-mass solutions are still possible. We also calculate the predicted rate of change of the projected semi-major axis of the inner binary and show that it agrees with the measured value.
The Cosmic Star-Formation History: The UV Finds Most

The assigned subtitle of this talk was “The UV Takes it All!” The absurdity of that subtitle must have been obvious to many conference participants when they first read the program, and now, after four days of talks, I hope it is obvious to everyone here. The UV cannot possibly “take all” of the cosmic star-formation history. Data from low and high redshift alike overwhelmingly show that rapidly star-forming galaxies emit the bulk of their bolometric luminosities in the far-infrared, not the UV. Some extremely luminous high-redshift galaxies have not been detected in the UV at all (see, e.g., Hughes’ and Blain’s contributions to these proceedings); many others dominate relatively short 850 μm exposures but are barely detected in even the deepest (rest-frame) UV images. I was asked by the organizers to make a case for studying the distant universe in the restframe UV, and I will; but I cannot pretend that UV surveys are the best way to study all star-forming galaxies at high redshift. Some fraction of the stars in the universe formed in extremely dusty galaxies that are best studied in the infrared. Nevertheless the available data—even IR data!—suggest that most stars formed in objects that are easiest to detect in the rest-frame ultraviolet, and so I have modified the subtitle of this talk to a statement I am prepared to defend.
Persistent Private Information

This paper studies the design of optimal contracts in dynamic environments where agents have private information that is persistent. In particular, I focus on a continuous-time version of a benchmark insurance problem where a risk-averse agent would like to borrow from a risk-neutral lender to stabilize his utility. The agent privately observes a persistent state variable, typically either income or a taste shock, and he makes reports to the principal. I give verifiable sufficient conditions showing that incentive-compatible contracts can be written recursively, conditioning on the report and two additional state variables: the agent's promised utility and promised marginal utility of the private state. I then study two examples where the optimal contracts can be solved in closed form, showing how persistence alters the nature of the contract. Unlike the previous discrete-time models with independent and identically distributed (i.i.d.) private information, the agent's consumption under the contract may grow over time. Furthermore, in my setting the efficiency losses due to private information increase with the persistence of the private information, and the distortions vanish as I approximate an i.i.d. environment.
Activized learning: transforming passive to active with improved label complexity

We study the theoretical advantages of active learning over passive learning. Specifically, we prove that, in noise-free classifier learning for VC classes, any passive learning algorithm can be transformed into an active learning algorithm with asymptotically strictly superior label complexity for all nontrivial target functions and distributions. We further provide a general characterization of the magnitudes of these improvements in terms of a novel generalization of the disagreement coefficient. We also extend these results to active learning in the presence of label noise, and find that even under broad classes of noise distributions, we can typically guarantee strict improvements over the known results for passive learning.
Optimal Taxation with Behavioral Agents

This paper develops a theory of optimal taxation with behavioral agents. We use a general framework that encompasses a wide range of biases such as misperceptions and internalities. We revisit the three pillars of optimal taxation: Ramsey (linear commodity taxation to raise revenues and redistribute), Pigou (linear commodity taxation to correct externalities) and Mirrlees (nonlinear income taxation). We show how the canonical optimal tax formulas are modified and lead to novel economic insights. We also show how to incorporate nudges in the optimal taxation framework, and jointly characterize optimal taxes and nudges.
A spectral algorithm for learning Hidden Markov Models

Hidden Markov Models (HMMs) are one of the most fundamental and widely used statistical tools for modeling discrete time series. In general, learning HMMs from data is computationally hard (under cryptographic assumptions), and practitioners typically resort to search heuristics which suffer from the usual local optima issues. We prove that under a natural separation condition (bounds on the smallest singular value of the HMM parameters), there is an efficient and provably correct algorithm for learning HMMs. The sample complexity of the algorithm does not explicitly depend on the number of distinct (discrete) observations-it implicitly depends on this quantity through spectral properties of the underlying HMM. This makes the algorithm particularly applicable to settings with a large number of observations, such as those in natural language processing where the space of observation is sometimes the words in a language. The algorithm is also simple, employing only a singular value decomposition and matrix multiplications.
Gas‐Phase Positive and Negative Ion Chemistry of Organophosphorus Compounds via Mass Spectrometric Techniques

1 Introduction 2 Thermochemistry and Kinetics 3 Ion—Molecule Reactions 4 Mass Spectrometric Analysis of Organophosphorus Species 5 Conclusions 6 Acknowledgements Keywords: mass spectroscopy developments; thermochemistry and kinetics; ion–molecule reactions; mass spectrometric analysis of organophosphorus species; alkyl phosphine reactions; phosphorus–carbon bond formation reactions; neutralization–reionization reactions; positive and negative ions
A sharp Schwarz inequality on the boundary

A number of classical results reflect the fact that if a holomorphic function maps the unit disk into itself, taking the origin into the origin, and if some boundary point b maps to the boundary, then the map is a magnification at b. We prove a sharp quantitative version of this result which also sharpens a classical result of Loewner. A recent paper of the author and Min Ru [OR] makes use of a new Schwarztype lemma on surfaces (Lemma 2.1 of that paper.) An effort to understand the geometry underlying the proof of that lemma led the author to a much more general Ahlfors-Schwarz Lemma on surfaces, and to an apparently new link between lemmas of that sort and the standard comparison theorems of Riemannian geometry [0]. Looking back at the comparable situation in the classical case, one finds the following: The standard Schwarz Lemma states that an analytic function f (z) mapping the unit disk into itself, with f(O) = 0, must map each smaller disk IzI 1. It is also true that one again has strict inequality unless f is a rotation, but that does not follow from the standard Schwarz inequality; one needs a stronger form where one has a quantitative bound on how much each disk IzI < r < 1 is shrunk if f is not a rotation. These facts are well known. (See, for example, Caratheodory [C2], ??296-301.) However, what does not seem to have been observed, at least in print, is that there is a sharp boundary inequality (Lemma 1 below) from which the above facts follow. Although the components of the proof can all be found in the literature (in particular, the sections of Caratheodory's book cited above), it seems worth presenting the sharp inequalities of Lemmas 1 and 3 below together with direct elementary proofs. Received by the editors June 15, 1998 and, in revised form, January 26, 1999. 2000 Mathematics Subject Classification. Primary 30C80.
Models of Foreign Policy Decisions: Rivals or Partners?

Decisionmaking on War and Peace: The Cognitive-Rational Debate edited by Nehemia Geva and Alex Mintz
Simulation-efficient shortest probability intervals

Bayesian highest posterior density (HPD) intervals can be estimated directly from simulations via empirical shortest intervals. Unfortunately, these can be noisy (that is, have a high Monte Carlo error). We derive an optimal weighting strategy using bootstrap and quadratic programming to obtain a more computationally stable HPD, or in general, shortest probability interval (Spin). We prove the consistency of our method. Simulation studies on a range of theoretical and real-data examples, some with symmetric and some with asymmetric posterior densities, show that intervals constructed using Spin have better coverage (relative to the posterior distribution) and lower Monte Carlo error than empirical shortest intervals. We implement the new method in an R package (SPIn) so it can be routinely used in post-processing of Bayesian simulations.
Separations, Sorting and Cyclical Unemployment

Abstract This paper establishes a new fact about the compositional changes in the pool of unemployed over the US business cycle. Using microdata from the Current Population Survey for the years 1962–2012, it documents that in recessions the pool of unemployed shifts toward workers with high wages in their previous job and that these shifts are driven by the high cyclicality of separations for high-wage workers. The paper finds that standard theories of wage setting and unemployment have difficulty in explaining these patterns and evaluates a number of alternative theories that do better in accounting for the new fact. (JEL E24, E32, J31, J63, J64)
Sort-Invariant Non-Messing-Up

A poset has the non-messing-up property if it has two covering sets of disjoint saturated chains so that for any labeling of the poset, sorting the labels along one set of chains and then sorting the labels along the other set yields a linear extension of the poset. The linear extension yielded by thus twice sorting a labeled non-messing-up poset may be independent of which sort was performed first. Here we characterize such sort-invariant labelings for convex subposets of a cylinder. They are completely determined by avoidance of a particular subpattern: a diamond of four elements whose smallest two labels appear at opposite points.
IMMIGRANT HOUSEHOLD INVESTMENT BEHAVIOR AND COUNTRY OF ORIGIN: A STUDY OF IMMIGRANTS TO THE UNITED STATES

Previous literature concerning immigrant financial market participation has typically treated the immigrant population as a homogeneous collective. However, the immigrant population in the United States is incredibly diverse, particularly in regards to country of origin. Using panel data, we test the hypothesis that differing information costs generate differences in U.S. immigrant asset market participation rates. We find significant variations (by country of origin) in the immigrant rates of holding stock, mutual funds, U.S. Savings Bonds, and other fixed income securities do exist. Our results provide support for the theory that information costs drive these differences. (JEL: G11)Keywords: Household investment decision making; immigrants ©2010. All rights reserved. Work in progress. All errors are our own. Copyright © 2012 John Wiley & Sons, Ltd.
Equilibrium cluster fluids: pair interactions via inverse design

Inverse methods of statistical mechanics are becoming productive tools in the design of materials with specific microstructures or properties. While initial studies have focused on solid-state design targets (e.g., assembly of colloidal superlattices), one can alternatively design fluid states with desired morphologies. This work addresses the latter and demonstrates how a simple iterative Boltzmann inversion strategy can be used to determine the isotropic pair potential that reproduces the radial distribution function of a fluid of amorphous clusters with prescribed size. The inverse designed pair potential of this “ideal” cluster fluid, with its broad attractive well and narrow repulsive barrier at larger separations, is qualitatively different from the so-called SALR form most commonly associated with equilibrium cluster formation in colloids, which features short-range attractive (SA) and long-range repulsive (LR) contributions. These differences reflect alternative mechanisms for promoting cluster formation with an isotropic pair potential, and they in turn produce structured fluids with qualitatively different static and dynamic properties. Specifically, equilibrium simulations show that the amorphous clusters resulting from the inverse designed potentials display more uniformity in size and shape, and they also show greater spatial and temporal resolution than those resulting from SALR interactions.
Investment in learning capital: enhancing the rate of learning by doing in semiconductor manufacturing

Summary form only given. Learning by doing occurs in the semiconductor industry through manufacturing yield improvements that result in cost reductions. While all semiconductor firms learn through engineering analysis of production volume to improve yields, firms differ substantially in the level and rate of improvement of yields. In this paper, a set of physical and human capital factors is identified that influences the rate of learning by doing.
Computing Stable Coalitions: Approximation Algorithms for Reward Sharing

Consider a setting where selfish agents are to be assigned to coalitions or projects from a set $$\mathcal {P}$$. Each project $$k\in \mathcal {P}$$ is characterized by a valuation function; $$v_kS$$ is the value generated by a set S of agents working on project k. We study the following classic problem in this setting: "how should the agents divide the value that they collectively create?". One traditional approach in cooperative game theory is to study core stability with the implicit assumption that there are infinite copies of one project, and agents can partition themselves into any number of coalitions. In contrast, we consider a model with a finite number of non-identical projects; this makes computing both high-welfare solutions and core payments highly non-trivial. The main contribution of this paper is a black-box mechanism that reduces the problem of computing a near-optimal core stable solution to the well-studied algorithmic problem of welfare maximization; we apply this to compute an approximately core stable solution that extracts one-fourth of the optimal social welfare for the class of subadditive valuations. We also show much stronger results for several popular sub-classes: anonymous, fractionally subadditive, and submodular valuations, as well as provide new approximation algorithms for welfare maximization with anonymous functions. Finally, we establish a connection between our setting and simultaneous auctions with item bidding; we adapt our results to compute approximate pure Nash equilibria for these auctions.
Regulating Financial Markets: Protecting Us from Ourselves and Others

The current global financial and economic crisis highlights the ongoing tug-of-war between those who pull toward free markets and those who pull toward strict regulation of markets—between those who pull toward libertarianism and those who pull toward paternalism. Rising stock markets and economic prosperity empower those who favor free markets and libertarianism; stock market crashes and economic recessions empower those who favor strict regulation and paternalism. This article discusses the current crisis against the backdrop of earlier crises and focuses on margin regulations, which limit leverage; suitability regulations, which require providers of financial products to act in the interests of their clients; blue-sky laws, which prohibit securities deemed unfair or unduly risky; and mandatory-disclosure regulations, which require providers of financial products to disclose pertinent information even if potential buyers do not ask for it.
Public Expenditure and Growth

Given that public spending will have a positive impact on GDP if the benefits exceed the marginal cost of public funds, the present paper deals with measuring costs and benefits of public spending. The paper discusses one cost seldom considered in the literature and in policy debates, namely, the volatility derived from additional public spending. The paper identifies a relationship between public spending volatility and consumption volatility, which implies a direct welfare loss to society. This loss is substantial in developing countries, estimated at 8 percent of consumption. If welfare losses due to volatility are this sizeable, then measuring the benefits of public spending is critical. Gauging benefits based on macro aggregate data requires three caveats: a) considering of the impact of the funding (taxation) required for the additional public spending; b) differentiating between investment and capital formation; c) allowing for heterogeneous response of output to different types of capital and differences in network development. It is essential to go beyond country-specificity to project-level evaluation of the benefits and costs of public projects. From the micro viewpoint, the rate of return of a project must exceed the marginal cost of public funds, determined by tax levels and structure. Credible evaluations require microeconomic evidence and careful specification of counterfactuals. On this, the impact evaluation literature and methods play a critical role. From individual project evaluation, the analyst must contemplate the general equilibrium impacts. In general, the paper advocates for project evaluation as a central piece of any development platform. By increasing the efficiency of public spending, the government can permanently increase the rate of productivity growth and, hence, affect the growth rate of GDP.
Iron-Catalyzed Allylic C–H Amination of Substituted 1,3-Dienes

A catalytic method for the selective allylic C–H amination of dienes and trienes using arylhydroxylamines has been developed. This iron-catalyzed approach involves the in situ generation of activated nitrosoarenes, which in turn react with dienes or trienes to give the corresponding aminomethyl dienes or trienes as the major products, and hetero-Diels–Alder adducts as minor products. The selectivity depends on the structures of both the catalyst and the substrate. We have also studied substituent effects using p-substituted phenylhydroxylamines.
The Burst and Transient Source Experiment Earth Occultation Technique

An Earth orbiting detector sensitive to gamma-ray photons will see step-like occultation features in its count rate when a gamma-ray point source crosses the Earth's limb. This is due to the change in atmospheric attenuation of the gamma rays along the line of sight. In an uncollimated detector, these occultation features can be used to locate and monitor astrophysical sources provided their signals can be individually separated from the detector background. We show that the Earth occultation technique applied to the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) is a viable and flexible all-sky monitor in the low-energy gamma-ray and hard X-ray energy range (20 keV-1 MeV). The method is an alternative to more sophisticated photon imaging devices for astronomy and can serve well as a cost-effective science capability for monitoring the high energy sky. Here we describe the Earth occultation technique for locating new sources and for measuring source intensity and spectra without the use of complex background models. Examples of transform imaging, step searches, spectra, and light curves are presented. Systematic uncertainties due to source confusion, detector response, and contamination from rapid background fluctuations are discussed and analyzed for their effect on intensity measurements. A sky location-dependent average systematic error is derived as a function of Galactic coordinates. The sensitivity of the technique is derived as a function of incident photon energy and also as a function of angle between the source and the normal to the detector entrance window. Occultations of the Crab Nebula by the Moon are used to calibrate Earth occultation flux measurements independent of possible atmospheric scattering effects.
Regiocontrol in an Intramolecular Schmidt Reaction: Total Synthesis of (+)-Aspidospermidine

A total synthesis of (+)-aspidospermidine (1) is described, featuring an intramolecular Schmidt reaction as the key step. The effects of stereochemistry and protecting group status on the regio- an...
Heating and Acceleration of Intracluster Medium Electrons by Turbulence

We investigate the feasibility of bremsstrahlung radiation from "nonthermal" electrons as a source of hard X-rays from the intracluster medium of clusters of galaxies. With an exact treatment of the Coulomb collisions in a Fokker-Planck analysis of the electron distribution, we find that the severe difficulties with lifetimes of nonthermal particles found earlier by Petrosian in 2001 using a cold-target model remain problematic. We then address the possible acceleration of background electrons into a nonthermal tail. We assume a simplified but generic acceleration rate and determine the expected evolution of an initially Maxwellian distribution of electrons. We find that strong nonthermal components arise only for a rapid rate of acceleration, which also heats up the entire plasma. These results confirm the conclusion that if the observed nonthermal excesses are due to some process accelerating the background thermal electrons, then this process must be short lived.
Separation of Singing Voice From Music Accompaniment for Monaural Recordings

Separating singing voice from music accompaniment is very useful in many applications, such as lyrics recognition and alignment, singer identification, and music information retrieval. Although speech separation has been extensively studied for decades, singing voice separation has been little investigated. We propose a system to separate singing voice from music accompaniment for monaural recordings. Our system consists of three stages. The singing voice detection stage partitions and classifies an input into vocal and nonvocal portions. For vocal portions, the predominant pitch detection stage detects the pitch of the singing voice and then the separation stage uses the detected pitch to group the time-frequency segments of the singing voice. Quantitative results show that the system performs the separation task successfully
A lattice construction of chiral gauge theories

Abstract We formulate chiral gauge theories non-perturbatively, using two different cutoffs for the fermions and gauge bosons. We use a lattice with spacing b to regulate the gauge fields in standard fashion, while computing the chiral fermion determinant on a finer lattice with spacing f ⪡ b. This determinant is computed in the background of f-lattice gauge fields, obtained by gauge-covariantly interpolating b-lattice gauge fields. The notorious doublers that plague lattice theories containing fermions are decoupled by the addition of a Wilson term. In chiral theories such a term breaks gauge invariance explicitly. However, the advantage of the two-cutoff regulator is that gauge invariance can be restored to O(f2/b2) by a one-loop subtraction of calculable local gauge field counterterms. We show that the only obstruction to this procedure is the presence of an uncancelled gauge anomaly among the fermion representations. We conclude that for practical purposes, it suffices to choose f/b ∼ b/L, where L is the physical volume of the system. In our construction it is simple to prove the Adler-Bardeen theorem for anomalies in global currents to all orders. The related subject of fermion-number violation is also studied. Finally, we discuss the prospects for improving the efficiency of our algorithm.
New experimental system for measuring composite delayed-neutron spectra following fission

Abstract We describe a new experimental approach for measuring composite delayed-neutron spectra as a function of delay time following fission. Fission fragments are transported from the fission chamber to a low background counting room by helium jet and tape transport systems. A β-neutron time-of-flight spectrometer incorporating both 6Li-glass and Pilot U scintillators is used to measure the spectra in the neutron energy range 10–2000 keV. Delay times can be varied from 0.17 s to several minutes. Fission is induced with either thermal or fast neutrons.
Hydrogermylation of 5-ethynyluracil nucleosides: formation of 5-(2-germylvinyl)uracil and 5-(2-germylacetyl)uracil nucleosides.

A stereoselective radical-mediated hydrogermy- lation of the protected 5-ethynyluracil nucleosides with trialkyl-, triaryl,- or tris(trimethylsilyl)germanes gave (Z)-5-(2- germylvinyl)uridine, 2'-deoxyuridine, or ara-uridine as major products. Reaction of the β-triphenylgermyl vinyl radical intermediate with oxygen and fragmentation of the resulting peroxyradical provided also 5-(2-(triphenylgermyl)acetyl)- pyrimidine nucleosides in low to moderate yields. Thermal isomerization of the latter in MeOH occurred via a four-centered activated complex, and subsequent hydrolysis of the resulting O-germyl substituted enol yielded 5-acetyluracil nucleosides in quantitative yield.
Epidemiology of alcohol-associated cancers

Alcohol, especially in combination with smoking, is a well-established risk factor for cancers of the oral cavity and pharynx, esophagus, and larynx, with 25% to 80% of these cancers being attributable to alcohol. Rates of these cancers in the United States have been decreasing in recent years, possibly because of reductions in cigarette smoking and alcohol use. Chronic alcohol consumption has been linked with increased risk of liver cancer in epidemiologic studies. However, the rising rates of this cancer in the United States are most likely due to the increasing prevalence of chronic hepatitis B and C infections. Epidemiologic evidence has linked light to moderate intake of alcohol to cancers of the colorectum and female breast. These cancers are common in developed countries, so even small increases in risk can have important public health implications. Although results of most epidemiologic studies have provided little or no support for a causal relation between light and moderate alcohol use and risk of pancreatic cancer, a possible role of heavy alcohol consumption cannot be ruled out. Further studies of these cancers are needed to clarify the role of type of alcoholic beverage, the role of alcohol concentration, and the dose-response curve at low concentrations of alcohol. Future research also should be designed to promote the use of uniform ways to report alcohol intake and uniform measures for analysis, to include the investigation of alcohol-associated cancer risks in U.S. minority populations, to enhance experimental work to better understand the underlying mechanisms through which alcohol promotes carcinogenesis, and to develop preventive strategies.
Quarkonium formation in statistical and kinetic models

I review the present status of two related models addressing scenarios in which the formation of heavy quarkonium states in high energy heavy ion collisions proceed via “off-diagonal” combinations of a quark and an antiquark. The physical process involved belongs to a general class of quark “recombination”, although technically the recombining quarks here were never previously bound in a quarkonium state. Features of these processes relevant as a signature of color deconfinement are discussed.
Static test of an ultralight airplane

This paper describes all of the work necessary to perform the static test of an ultralight airplane. A steel reaction gantry was designed first, then all of the loading whiffletrees, the hydraulic actuation system, and instrumentation systems were designed. Loads and stress analyses were performed on the airplane and the gantry and whiffletrees. Components tested to date are: tubing samples, cables, and two-by-four whiffletrees. A hydraulic system consisting of a 3000-psi hand pump, 10,000-pound actuator, pressure gage and lines, and a Barksdale valve are described. Load cell calibration and pressure indicator calibration procedures are also described. A description of the strain and deflection measurement system is included. Preliminary data obtained to date are compared to the analytical predictions.
Farm size, household size and composition, and women's contribution to agricultural production: evidence from Zaire.

This article examines a unique data set on peasant farms in Zaire, focusing on several of the propositions regarding land‐abundant tropical agriculture recently set forth by Binswanger and McIntire. In an environment fairly comparable to their base case, we find empirical support for their contentions concerning the virtual universality of self‐cultivation, the limited extent of hiring of labour, and the importance for farm size of the household's age‐sex composition. Women's contribution to farm size at the margin is larger than that of men, although this difference is apparent only among larger households. Our results differ somewhat from the Binswanger‐McIntire proposition that area cultivated per working household member will be largely invariant to household size or wealth. There is a decline in cultivated area per worker as household size increases that may reflect incentive problems as well as a tendency toward greater diversification of household activities as household size increases. Wealthy hou...
AN EXPERT SYSTEM FOR INTERPRETING MESOSCALE FEATURES IN OCEANOGRAPHIC SATELLITE IMAGES

Thermal infrared images of the ocean obtained from satellite sensors are widely used for the study of ocean dynamics. The derivation of mesoscale ocean information from satellite data depends to a large extent on the correct interpretation of infrared oceanographic images. The difficulty of the image analysis and understanding problem for oceanographic images is due in large part to the lack of precise mathematical descriptions of the ocean features, coupled with the time varying nature of these features and the complication that the view of the ocean surface is typically obscured by clouds, sometimes almost completely. Towards this objective, the present paper describes a hybrid technique that utilizes a nonlinear probabilistic relaxation method and an expert system for the oceanographic image interpretation problem. This paper highlights the advantages of using the contextual information in the feature labeling algorithm. The need for an expert system and its feedback in automatic interpretation of oceanic features is discussed. The paper presents some important results of the series of experiments conducted at the Remote Sensing Branch, of the Naval Oceanographic and Atmospheric Research Laboratory, on the National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer (AVHRR) imagery data. The results clearly indicate the drastic improvement in labeling due to the oceanographic expert system.
A Contemplated Magnetic Survey of the North Pacific ocean by the Carnegie Institution

A PROJECT for a magnetic survey of the North Pacific Ocean by the Department of International Research in Terrestrial Magnetism has been favourably acted upon by the executive committee of the Carnegie Institution of Washington, and authorisation has been given to begin the work this year. An initial allotment of 20,000 dollars has been made to cover the expenses for the current year.
Active visualization in a multidisplay immersive environment

Abstract Building a system to actively visualize extremely large data sets on large tiled displays in a real-time immersive environment involves a number of challenges. First, the system must be completely scalable to support the rendering of large data sets. Second, it must provide fast, constant frame rates regardless of user viewpoint or model orientation. Third, it must output the highest resolution imagery where it is needed. Fourth, it must have a flexible user interface to control interaction with the display. This paper presents the prototype for a system which meets all four of these criteria. It details the design of a wireless user interface in conjunction with two different multiresolution techniques—foveated vision and progressive image composition—to generate images on a tiled display wall. The system emphasizes the parallel, multidisplay, and multiresolution features of the Metabuffer image composition hardware architecture to produce interactive renderings of large data streams with fast, constant frame rates.
Resonance-averaged photoionization cross sections for astrophysical models

We present ground-state photoionization cross sections of atoms and ions averaged over resonance structures for photoionization modeling of astrophysical sources. The detailed cross sections calculated in the close-coupling approximation using the R-matrix method, with resonances delineated at thousands of energies, are taken from the Opacity Project database TOPbase and the Iron Project, including new data for the low ionization stages of iron Fe I-Fe V. The resonance-averaged cross sections are obtained by convolving the detailed cross sections with a Gaussian distribution over the autoionizing resonances. This procedure is expected to minimize errors in the derived ionization rates that could result from small uncertainties in computed positions of resonances while preserving the overall resonant contribution to the cross sections in the important near-threshold regions. The detailed photoionization cross sections at low photon energies are complemented by new relativistic distorted-wave calculations for Z ≤ 12 and from central-field calculations for Z > 12 at high energies, including inner shell ionization. The effective cross sections are then represented by a small number of points that can be readily interpolated linearly for practical applications; a FORTRAN subroutine and data are available. The present numerically averaged cross sections are compared with analytic fits that do not accurately represent the effective cross sections in regions dominated by resonances.
Life-Cycle Engineering Design

Life-cycle engineering seeks to incorporate various product life-cycle values into the early stages of design. These values include functional performance, manufacturability, serviceability, and environmental impact. We start with a survey of life-cycle engineering research focusing on methodologies and tools. Further, the paper addresses critical research issues in life-cycle design tools : design representation and measures for life-cycle evaluation. The paper describes our design representation scheme based on a semantic network that is effective for evaluating the structural layout. Evaluation measures for serviceability and recyclability illustrate the practical use of these representation schemes.
On the Baryonic Density and Susceptibilities in a Holographic Model of QCD

In this paper, we calculate analytically the baryonic density and susceptibilities, which are sensitive probes to the fermionic degrees of freedom, in a holographic model of QCD both in its hot QGP phase and in its cold dense phase. Interesting patterns due to strong coupling dynamics will be shown and valuable lessons for QCD will be discussed.
Creating an inquiry-learning environment using the World Wide Web

The University of Michigan Digital Library (UMDL) Project provides guidelines and design standards for teaching and learning materials and methods to support science inquiry using on-line resources. In this paper, we present an initial report of our experiences using on-line resources to promote sustained inquiry in science classrooms. We examine the challenges faced by teachers and students as well as the challenges posed in creating or finding useful content and in designing the technological tools for students to investigate meaningful questions on-line.