cssi/SciSciGPT-SciSciNet huggingface dataset:
Rule by example: an example-based approach to knowledge base management

An example-based approach to knowledge base management involves capturing all rules as example data. Such an approach has many advantages since data have been studied extensively, and a variety of techniques for effective management have been developed. Expressing all rules as stereotypical data allowed in the system provides a comprehensive solution to the three basic problems of a knowledge base system. It provides a simple end-user language by reducing rules to data which have simpler semantics; it allows the storage of rules as data and hence the use of database technology to store, retrieve, and maintain rules; and it simplifies execution of rules by reducing it to data comparison. >
The effects of the Food Reserve Agency on maize market prices in Zambia

Over the last decade, governments throughout eastern and southern Africa have increasingly used strategic reserves and/or marketing boards to influence grain market outcomes, yet little is known about how these activities are affecting grain markets. This article estimates the effects of the Food Reserve Agency (FRA) on maize market prices in production and consumption regions in Zambia using a vector autoregression model and monthly data from July 1996 through December 2008. In recent years, FRA has become the dominant buyer of smallholder maize in Zambia. Simulations show that FRA activities stabilized market prices throughout the July 1996–December 2008 study period and raised mean prices between July 2003 and December 2008 by 17–19%. The price raising effects of FRA policies have assisted surplus maize producers but adversely affected net buyers of maize in Zambia, namely urban consumers and the majority of the rural poor. The increase in maize price stability is unlikely to have had substantial welfare effects on poor households. In contrast, relatively wealthy producers are likely to have benefited from the higher average and more stable maize prices resulting from FRA policies.
High Resolution Near-Infrared Spectroscopy of FUors and FUor-like stars

We present new high-resolution (R 18, 000) near-infrared spectroscopic observations of a sample of classical FU Orionis stars (FUors) and other young stars with FUor characteristics that are sources of Herbig-Haro (HH) flows. Spectra are presented for the region λ = 2.203-2.236 μm which is rich in absorption lines sensitive to both effective temperatures and surface gravities of stars. Both FUors and FUor-like stars show numerous broad and weak-unidentified spectral features in this region. Spectra of the 2.280-2.300 μm region are also presented, with the 2.2935 μm v = 2-0 CO absorption bandhead being clearly the strongest feature seen in the spectra of all FUors and FUor-like stars. A cross-correlation analysis shows that FUor and FUor-like spectra in the 2.203-2.236 μm region are not consistent with late-type dwarfs, giants, nor embedded protostars. The cross-correlations also show that the observed FUor-like HH energy sources have spectra that are substantively similar to those of FUors. Both object groups also have similar near-infrared colors. The large line widths and double-peaked nature of the spectra of the FUor-like stars are consistent with the established accretion disk model for FUors, also consistent with their near-infrared colors. It appears that young stars with FUor-like characteristics may be more common than projected from the relatively few known classical FUors.
Results from the Ariel 5 All-Sky Monitor

A summary of results obtained from the first year of Ariel-5 All-Sky Monitor operation is presented. Transient source observations, as well as the results of long-term studies of Sco X-1, Cyg X-3 and Cyg X-1 are described. By example, the included results are indicative of the temporal effects to which the All-Sky Monitor remains sensitive as it begins its second year of observation.
Bandwidth partitioning in decentralized wireless networks

This paper addresses the following question, which is of interest in the design of a multiuser decentralized network. Given a total system bandwidth of W Hz and a fixed data rate constraint of R bps for each transmission, how many frequency slots N of size W/N should the band be partitioned into in order to maximize the number of simultaneous links in the network? Dividing the available spectrum results in two competing effects. On the positive side, a larger N allows for more parallel, non- interfering communications to take place in the same area. On the negative side, a larger N increases the SINR requirement for each link because the same information rate must be achieved over less bandwidth. Exploring this tradeoff and determining the optimum value of N in terms of the system parameters is the focus of the paper. Using stochastic geometry, the optimal SINR threshold - which directly corresponds to the optimal spectral efficiency - is derived for both the low SNR (power-limited) and high SNR (interference-limited) regimes. This leads to the optimum choice of the number of frequency bands N in terms of the path loss exponent, power and noise spectral density, desired rate, and total bandwidth.
Chemical Synthesis of the Cardiotonic Steroid Glycosides and Related Natural Products

The active components from the extracts of Digitalis, cardiotonic steroid glycosides, have been ingested by humans for more than 200 years as a medicinal therapy for heart failure and abnormal heart rhythms. The positive inotropic activity of the cardiotonic steroids that mediates clinically useful physiological effects in patients has been attributed largely to a high affinity inhibitory interaction with the extracellular surface of the membrane-bound sodium pump (Na(+)/K(+)-ATPase). However, previously unrecognized intracellular signaling pathways continue to be uncovered. This Review examines both partial and de novo synthetic approaches to the medicinally important and structurally captivating cardenolide and bufadienolide steroid families, with an emphasis on the stereocontrolled construction of the pharmacophoric aglycone (genin) framework.
A Bayes Net Approach to Argumentation

Argumentation-based negotiation approaches have been proposed to capture realistic negotiation contexts where all issues being negotiated are not fixed a priori and the negotiatorýs beliefs may be influenced during the negotiation process. We have proposed a novel Bayesian network based argumentation and decision making framework that allows agents to utilize models of other agents. We discuss a decision mechanism for generating the most effective argument to convince the opponent to accept favorable contracts.
Limit theorems for free multiplicative convolutions

We determine the distributional behavior for products of free random variables in a general infinitesimal triangular array. The main theorems in this paper extend a result for measures supported on the positive half-line, and provide a new limit theorem for measures on the unit circle with nonzero first moment.
Continuous functors as a model for the equivariant stable homotopy category

It is a classical observation that a based continuous functor X from the category of finite CW‐complexes to the category of based spaces that takes homotopy pushouts to homotopy pullbacks “represents” a homology theory—the collection of spaces fX.S n /g obtained by evaluating X on spheres yields an ‐prespectrum. Such functors are sometimes referred to as linear or excisive. The main theorem of this paper provides an equivariant analogue of this result. We show that a based continuous functor from finite G ‐CW‐complexes to based G ‐spaces represents a genuine equivariant homology theory if and only if it takes G ‐homotopy pushouts to G ‐homotopy pullbacks and satisfies an additional condition requiring compatibility with Atiyah duality for orbit spaces G=H . Our motivation for this work is the development of a recognition principle for equivariant infinite loop spaces. In order to make the connection to infinite loop space theory precise, we reinterpret the main theorem as providing a fibrancy condition in an appropriate model category of spectra. Specifically, we situate this result in the context of the study of equivariant diagram spectra indexed on the category WG of based G ‐spaces homeomorphic to finite G ‐CW‐complexes for a compact Lie group G . Using the machinery of Mandell‐May‐Schwede‐Shipley, we show that there is a stable model structure on this category of diagram spectra which admits a monoidal Quillen equivalence to the category of orthogonal G ‐spectra. We construct a second “absolute” stable model structure which is Quillen equivalent to the stable model structure. There is a model-theoretic identification of the fibrant continuous functors in the absolute stable model structure as functors Z such that for A2 WG the collectionfZ.A^ S W /g forms an ‐G ‐prespectrum as W varies over the universe U . Thus, our main result provides a concrete identification of the fibrant objects in the absolute stable model structure. This description of fibrant objects in the absolute stable model structure makes it clear that in the equivariant setting we cannot hope for a comparison between the category of equivariant continuous functors and equivariant A ‐spaces, except when G is finite. We provide an explicit analysis of the failure of the category of equivariant A ‐spaces to model connective G ‐spectra, even for GD S 1 .
Learning in time: new institutionalism and the Central and Eastern European economic reform experience

The article explores the conceptual dynamics set into motion by the encounter between the policy prescriptions inspired by the mainstream economics and the very concrete reform experience after 1989. The raise of the new institutionalism is discussed as one of the most significant reactions and epistemic outcomes of the reform experience. The article investigates how the limits of the mainstream approaches to reform policies invited a challenge from new perspectives and theories. It likewise traces and overviews the most critical areas in which intuitive and practical conclusions derived from the experience of transition converged with and supported the theoretical conclusions of the institutionalist approach. The article also outlines several key elements of the new institutionalist vision and its theoretical underpinning. The conclusion points the potential of the new approach to challenge at a foundational level the economics mainstream.
Optimization Methods for Sparse Pseudo-Likelihood Graphical Model Selection

Sparse high dimensional graphical model selection is a popular topic in contemporary machine learning. To this end, various useful approaches have been proposed in the context of l1-penalized estimation in the Gaussian framework. Though many of these inverse covariance estimation approaches are demonstrably scalable and have leveraged recent advances in convex optimization, they still depend on the Gaussian functional form. To address this gap, a convex pseudo-likelihood based partial correlation graph estimation method (CONCORD) has been recently proposed. This method uses coordinate-wise minimization of a regression based pseudo-likelihood, and has been shown to have robust model selection properties in comparison with the Gaussian approach. In direct contrast to the parallel work in the Gaussian setting however, this new convex pseudo-likelihood framework has not leveraged the extensive array of methods that have been proposed in the machine learning literature for convex optimization. In this paper, we address this crucial gap by proposing two proximal gradient methods (CONCORD-ISTA and CONCORD-FISTA) for performing l1-regularized inverse covariance matrix estimation in the pseudo-likelihood framework. We present timing comparisons with coordinate-wise minimization and demonstrate that our approach yields tremendous payoffs for l1-penalized partial correlation graph estimation outside the Gaussian setting, thus yielding the fastest and most scalable approach for such problems. We undertake a theoretical analysis of our approach and rigorously demonstrate convergence, and also derive rates thereof.
FINDING DISCONTINUITIES OF PIECEWISE-SMOOTH FUNCTIONS

Formulas for stable differentiation of piecewise-smooth functions are given. The data are noisy values of these functions. The locations of discontinuity points and the sizes of the jumps across these points are not assumed known, but found stably from the noisy data.
Million Atom Electronic Structure and Device Calculations on Peta-Scale Computers

Semiconductor devices are scaled down to the level which constituent materials are no longer considered continuous. To account for atomistic randomness, surface effects and quantum mechanical effects, an atomistic modeling approach needs to be pursued. The Nanoelectronic Modeling Tool (NEMO 3-D) has satisfied the requirement by including empirical sp 3 s* and sp 3 d 5 s* tight binding models and considering strain to successfully simulate various semiconductor material systems. Computationally, however, NEMO 3-D needs significant improvements to utilize increasing supply of processors. This paper introduces the new modeling tool, OMEN 3-D, and discusses the major computational improvements, the 3-D domain decomposition and the multi-level parallelism. As a featured application, a full 3-D parallelized Schrodinger-Poisson solver and its application to calculate the bandstructure of delta doped phosphorus(P) layer in silicon is demonstrated. Impurity bands due to the donor ion potentials are computed.
On the evidence for low-dimensional chaos in an epileptic electroencephalogram

Abstract A variant of the method of surrogate data is applied to a single time series from an electroencephalogram (EEG) recording of a patient undergoing an epileptic seizure. The time series is a nearly periodic pattern of spike-and-wave complexes. The surrogate data sets are generated by shuffling the individual spike-and-wave cycles, and correspond to a null hypothesis that there is no deterministic structure in the cycle-to-cycle variability of the original data. Using estimates of autocorrelation, correlation dimension, and Lyapunov exponent as discriminating statistics, the evidence for dynamical correlations between successive spike-and-wave patterns is evaluated both formally and informally.
Testing For Threshold Nonlinearity in Short-Term Interest Rates

This article addresses some empirical problems in the term structure of interest rates using a threshold autoregressive framework with GARCH errors. This framework provides a parsimonious representation of some stylized features of interest rate data and facilitates statistical inference in the presence of high persistence and conditional heteroskedasticity. We propose a bootstrap-based LM test for linearity in the conditional mean and variance functions. The empirical results indicate a presence of threshold nonlinearities in the AR and GARCH representations of the conditional moments of short-term rate. The explicit modeling of these nonlinearities appears to improve the stability properties of the process for spot rate. The article also reports that allowing for threshold nonlinearities in conditional mean and variance leadsto significantforecastimprovements. The economic significance of these findings is evaluated by the term structure implications of the estimated TAR-GARCH model.
"Token" equilibria in sensor networks with multiple sponsors

When two sponsoring organizations, working towards separate goals, can employ wireless sensor networks for a finite period of time, it can be efficiency-enhancing for the sponsors to program their sensors to cooperate. But if each sensor privately knows whether it can provide a favor in any particular period, and the sponsors cannot contract on ex post payments, then no favors are performed in any Nash equilibrium. Allowing the sponsors to contract on ex post payments, we construct equilibria based on the exchange of "tokens" that yield significant cooperation and increase expected sponsor payoffs. Increasing the sponsors' liability is beneficial because it enables them to use more tokens
Predicting unseen triphones with senones

In large-vocabulary speech recognition, we often encounter triphones that are not covered in the training data. These unseen triphones are usually backed off to their corresponding diphones or context-independent phones, which contain less context yet have plenty of training examples. We propose to use decision-tree-based senones to generate needed senonic baseforms for these unseen triphones. A decision tree is built for each Markov state of each base phone; the leaves of the trees constitute the senone pool. To find the senone associated with a Markov state of any triphone, the corresponding tree is traversed until a leaf node is reached. The effectiveness of the proposed approach was demonstrated in the ARPA 5000-word speaker-independent Wall Street Journal dictation task. The word error rate was reduced by 11% when unseen triphones were modeled by the decision-tree-based senones instead of context-independent phones. When there were more than five unseen triphones in each test utterance, the error rate reduction was more than 20%.
On the evolution of star forming galaxies

The evolution in the comoving space density of the global average galaxy star formation rate (SFR) out to a redshift around unity is well established. Beyond z ≈ 1 there is growing evidence that this evolution is flat or even increasing, contrary to early indications of a turnover. Some recent analyses of z ≈ 6 photometric dropouts are suggestive of a decline from z = 3 to z ≈ 6, but there is still very little constraint on the extent of dust obscuration at such high redshifts. In less than a decade, numerous measurements of galaxy SFR density spanning z = 0 to as high as z ≈ 6 have rapidly broadened our understanding of galaxy evolution, and a summary of existing SFR density measurements is presented here. This global star formation history compilation is found to be consistent to within factors of about 3 over essentially the entire range 0 < z 6, and it can be used to constrain the evolution of the luminosity function (LF) for star-forming galaxies. The LF evolution for star-forming galaxies has been previously explored using optical source counts, as well as radio source counts at 1.4 GHz, and a well-known degeneracy between luminosity evolution [L (1 + z)Q] and density evolution [ (1 + z)P] is found. Combining the constraints from the global SFR density evolution with those from the 1.4 GHz radio source counts at submillijansky levels allows this degeneracy to be broken and a best-fitting evolutionary form to be established. The preferred evolution in a H0 = 70, ΩM = 0.3, ΩΛ = 0.7 cosmology from these combined constraints is Q = 2.70 ± 0.60, P = 0.15 ± 0.60.
Product Theorems Via Semidefinite Programming

The tendency of semidefinite programs to compose perfectly under product has been exploited many times in complexity theory: for example, by Lovasz to determine the Shannon capacity of the pentagon; to show a direct sum theorem for non-deterministic communication complexity and direct product theorems for discrepancy; and in interactive proof systems to show parallel repetition theorems for restricted classes of games. Despite all these examples of product theorems--some going back nearly thirty years--it was only recently that Mittal and Szegedy began to develop a general theory to explain when and why semidefinite programs behave perfectly under product. This theory captured many examples in the literature, but there were also some notable exceptions which it could not explain--namely, an early parallel repetition result of Feige and Lovasz, and a direct product theorem for the discrepancy method of communication complexity by Lee, Shraibman, and Spalek. We extend the theory of Mittal and Szegedy to explain these cases as well. Indeed, to the best of our knowledge, our theory captures all examples of semidefinite product theorems in the literature.
Eighty-Eight Year Periodicity in Solar-Terrestrial Phenomena Confirmed

The existence of a 60–100 year periodic variation in solar and/or solar-terrestrial phenomena has been a matter of dispute for many years. A wide variety of data sets previously have been analyzed, and the results of the analyses have been interpreted as showing evidence either for or against such a variation. However, all data sets that are proxy for solar wind in the ecliptic at 1 AU show variations consistent with a period of about 88 years. Here we report that a maximum entropy spectral analysis of the number of aurora reported per decade in Europe and the Orient from 450 A.D. to 1450 A.D. shows a strong stable line at a 88.4±0.7 years. Since the data set contains 11 cycles, this analysis establishes the reality of the “long cycle” for 1000 years. The mean amplitude and phase are then estimated from a superposed epoch analysis. The mean amplitude was 2.2 auroral reports per decade and the last minimum phase in these data occurred between 1403 A.D. and 1413 A.D.
An integrated, CMOS, constant-fraction timing discriminator for multichannel detector systems

An integrated, CMOS, constant-fraction timing discriminator (CFD) designed to accommodate the special requirements of large, multichannel detector systems is described. This CFD features on-chip, zero-crossing shaping and an automatic walk setting to limit the number of user adjustments. The circuit is realized in the Orbit 1.2 micron, N-well, CMOS process and operates with a 5 V power supply. The time walk in a 100:1 dynamic range (-15 mV to -1.5 V) is less than /spl plusmn/250 ps for a 10 ns rise time/10 ns fall time signal, yet the power dissipation is about 2 mW/channel. The discriminator has a 170 micron pitch, is 800 microns long, and is structured for arraying multiple channels on a single die. >
Single-Electron Transfer and Single-Electron Transfer Degenerative Chain Transfer Living Radical Polymerization

The special of Chemical Review informs about studies conducted on single-electron transfer and single-electron transfer degenerative chain transfer living radical polymerization. Researchers have demonstrated that living radical polymerization (LRP) can be significantly effective for the synthesis of tailored polymers. The special issue aims at covering the latest progress in two related polymerization methodologies that rely on single-electron transfer (SET), single-electron transfer degenerative chain transfer living radical polymerization (SET-DTLRP), and single-electron transfer living radical polymerization (SET-LRP). It is demonstrated that SET-DTLRP proceeds through SET initiation and competition of SET activation, deactivation, and degenerative transfer (DT). SET-LRP proceeds exclusively through a SET initiation, activation, and deactivation. It is also revealed that the two techniques have arose from investigations into Cu-catalyzed LRP initiated with sulfonyl halides.
Contingency planning: emergency preparedness for terrorist attacks

The terrorist attack is one type of tragedy caused by humans. Although rare, it has catastrophic effects. In the aftermath of 9-11, it is the responsibility of security personnel to help every employee get back to business as normal, while being prepared for possible future terrorist attacks. An up-to-date contingency plan is expected to help security managers fulfill this role. Security managers should reassess or develop this contingency plan using FEMA's guidebook. They are encouraged to adopt the Homeland Security Advisory System, or to develop alternative, simple colour-coded systems to respond to the threat of terrorist attack. They are also encouraged to consider three factors in planning: top management's commitment; adequate training; and coordination with public agencies.
Some Novel Techniques for Size Reduction of Microstrip Patch Antennas

In this article, we detail the design of a size-reduced antenna that can be conveniently fabricated by using the LTCC process, and present some examples of a modified design that enables us to further reduce the size of the antenna than that achievable by using the side-loading approach alone. The additional size-reduction is realized by routing the current distribution on the patch along a circuitous path to effectively increase its resonant length.
Is Sometimes Ever Better Than Always

The “intermittent assertion” method for proving programs correct is explained and compared with the conventional method. Simple conventional proofs of iterative algorithms that compute recursively defined functions, including Ackermann's function, are given.
Impact of cognitive theory on the practice of courseware authoring

The cognitive revolution has yielded unprecedented progress in our understanding of higher cognitive processes such as remembering and learning. It is natural to expect this scientific breakthrough to inform and guide the design of instruction in general and computer-based instruction in particular. In this paper I survey the different ways in which recent advances in cognitive theory might influence the design of computer-based instruction and spell out their implications for the design of authoring tools and tutoring system shells. The discussion will be divided into four main sections. The first two sections deal with the design and the delivery of instruction. The third section analyzes the consequences for authoring systems. In the last section I propose a different way of thinking about this topic.
The Rise and Fall of the Environmental Kuznets Curve

Summary. — This paper presents a critical history of the environmental Kuznets curve (EKC). The EKC proposes that indicators of environmental degradation first rise, and then fall with increasing income per capita. Recent evidence shows however, that developing countries are addressing environmental issues, sometimes adopting developed country standards with a short time lag and sometimes performing better than some wealthy countries, and that the EKC results have a very flimsy statistical foundation. A new generation of decomposition and efficient frontier models can help disentangle the true relations between development and the environment and may lead to the demise of the classic EKC. � 2004 Elsevier Ltd. All rights reserved.
Domain-specificity and gender differences in decision making

This paper examines the effect of characteristics of the decision situation and of the decision maker on decision processes and outcomes in the context of risky choice. Male and female undergraduate students were presented with decisions from different domains of life. For each decision they indicated the likelihood with which they would use each of five decision modes (i.e., ways of making the decision): by following someone's advice, by weighing pros and cons, by following their intuition, etc. They also chose between two courses of action described for each decision and rated the perceived riskiness of both alternatives. We found that the content domain of the decision and/or the gender (or the interaction of both) of the decision maker influenced decision mode usage, and risk perception, behavior, and preference (derived within a risk-return model of risky choice). These results have implications for educational interventions and decision aids that attempt to influence or change the risky decisions of target populations.
Persons and the metaphysics of resurrection

Theories of the human person differ greatly in their ability to underwrite a metaphysics of resurrection. This paper compares and contrasts a number of such views in light of the Christian doctrine of resurrection. In a Christian framework, resurrection requires that the same person who exists on earth also exists in an afterlife, that a post-mortem person be embodied, and that the existence of a post-mortem person is brought about by a miracle. According to my view of persons (the constitution view), a human person is constituted by- but not identical to - a human organism. A person has a first-person perspective essentially, and an organism has interrelated biological functions essentially. I shall argue for the superiority the constitution view as a metaphysical basis for resurrection. 'But what, then, ami?', Descartes famously asked. Although many of us today reject Descartes's equally famous answer- 'I am an immaterial mind' - Descartes was right, I believe, to identify himself with a thinking thing, a thing who ' doubts, understands, affirms, denies, wills, refuses, and which also imagines and senses '-1 But neither an immaterial mind nor a material brain is the thing that thinks. The thing that thinks is the person. Just as your legs and feet are the limbs by means of which you walk, you the person - not your legs and feet - are the walker; so too the brain is the organ by means of which you think, but you the person - not your brain - are the thinker.
Glass Transitions in Lubricants: Its Relation to Elastohydrodynamic Lubrication (EHD)

A preliminary investigation into the possible role of glass transition and glassy state behavior of lubricants in EHD contacts is reported. Measurements of the glass transition of lubricants as a function of pressure by two methods are presented along with a discussion indicating possible implications of the results to EHD lubrication.
Efficient at-most-once messages based on synchronized clocks

This paper describes a new at-most-once message passing protocol that provides guaranteed detection of duplicate messages even when the receiver has no state stored for the sender. It also discusses how to use at-most-once messages to implement higher-level primitives such as at-once-remote procedure calls and sequenced bytestream protocols. Our performance measurements indicate that at-most-once RPCs can provide at the same cost as less desirable forms of RPCs that do not guarantee at-most-once execution. Our method is based on the assumption that clocks throughout the system are loosely synchronized. Modern clock synchronization protocols provide good bounds on clock skew with high probability; our method depends on the bound for performance but not for correctness.
Metamorphic chemical geodynamics of subduction zones

Study of metamorphic suites directly representing the deep subduction of altered oceanic crust and sediments can help elucidate the geochemical evolution of the forearc-to-subarc slab–mantle interface, the nature of slab-derived fluids added to arc lava source regions, and the chemical changes in subducting rocks potentially contributing to the geochemical heterogeneity of the deeper mantle. The stage is set for more focused geochemical study of high-pressure (HP) and ultrahigh-pressure (UHP) metamorphic suites incorporating knowledge of mineral chemistry and reactions, kinetics and disequilibrium, prograde and exhumation-related P–T paths, fluid flow and fluid–rock interactions, and experimental evidence for the physical and chemical properties of fluids at the pressures and temperatures experienced by subducting slabs. Detailed studies of HP and UHP metamorphism published thus far provide some insight regarding the geochemical effects of devolatilization and the element transport capabilities of metamorphic fluids in forearc regions of subduction zones (b 100 km). Future research in this rapidly developing field should prioritize study of UHP suites metamorphosed at depths N 100 km, which have potentially experienced partial melting, with the goal of better characterizing fluid additions to arcs from subducting slabs and sediments and the compositions of dehydration and melting residues that could impact geochemical compositions of the mantle including source regions for ocean island basalts. © 2007 Published by Elsevier B.V.
Randomization in robot tasks

This article explores the role of randomization in the solution of robot manipulation tasks. Randomization refers to the ran dom selection and execution of an action from a collection of possible actions. The intention is that this collection contains some actions that are useful for making progress toward ac complishing a task, but that the precise identity of these useful actions is unknown. Randomization offers one approach for ensuring progress in a probabilistic sense.An example of randomization is given by the strategy of shaking a bin containing a part in order to orient the part in a desired stable state with some high probability. Another exam ple consists of using reliable sensory information to bring two parts close together, then relying on short random motions to actually mate the two parts once the part motions lie below the available sensing resolution. Further examples include tapping parts that are tightly wedged, twirling gears before trying to mesh them, and vibrating parts to facilitat...
Unemployment and the "Labour-Management Conspiracy"

We study a model in which management and a union bargain sequentially, first choosing a rule that will later determine the level of employment, and then choosing a wage. The government then chooses an output or an employment subsidy. An exogenous natural turnover rate in the unionized sector creates unemployment whenever the union wage exceeds the competitive wage. Government intervention can increase both the equilibrium amount of unemployment and worsen the intersectoral allocation of labour, because of the induced change in the endogenous wage. Unemployment weakens but does not eliminate the possibility of a "labour-management conspiracy".
Assessing statistical significance in causal graphs

Causal graphs are an increasingly popular tool for the analysis of biological datasets. In particular, signed causal graphs--directed graphs whose edges additionally have a sign denoting upregulation or downregulation--can be used to model regulatory networks within a cell. Such models allow prediction of downstream effects of regulation of biological entities; conversely, they also enable inference of causative agents behind observed expression changes. However, due to their complex nature, signed causal graph models present special challenges with respect to assessing statistical significance. In this paper we frame and solve two fundamental computational problems that arise in practice when computing appropriate null distributions for hypothesis testing. First, we show how to compute a p-value for agreement between observed and model-predicted classifications of gene transcripts as upregulated, downregulated, or neither. Specifically, how likely are the classifications to agree to the same extent under the null distribution of the observed classification being randomized? This problem, which we call "Ternary Dot Product Distribution" owing to its mathematical form, can be viewed as a generalization of Fisher's exact test to ternary variables. We present two computationally efficient algorithms for computing the Ternary Dot Product Distribution and investigate its combinatorial structure analytically and numerically to establish computational complexity bounds. Second, we develop an algorithm for efficiently performing random sampling of causal graphs. This enables p-value computation under a different, equally important null distribution obtained by randomizing the graph topology but keeping fixed its basic structure: connectedness and the positive and negative in- and out-degrees of each vertex. We provide an algorithm for sampling a graph from this distribution uniformly at random. We also highlight theoretical challenges unique to signed causal graphs; previous work on graph randomization has studied undirected graphs and directed but unsigned graphs. We present algorithmic solutions to two statistical significance questions necessary to apply the causal graph methodology, a powerful tool for biological network analysis. The algorithms we present are both fast and provably correct. Our work may be of independent interest in non-biological contexts as well, as it generalizes mathematical results that have been studied extensively in other fields.
Highly thermally conductive and mechanically strong graphene fibers

Graphene, a single layer of carbon atoms bonded in a hexagonal lattice, is the thinnest, strongest, and stiffest known material and an excellent conductor of heat and electricity. However, these superior properties have yet to be realized for graphene-derived macroscopic structures such as graphene fibers. We report the fabrication of graphene fibers with high thermal and electrical conductivity and enhanced mechanical strength. The inner fiber structure consists of large-sized graphene sheets forming a highly ordered arrangement intercalated with small-sized graphene sheets filling the space and microvoids. The graphene fibers exhibit a submicrometer crystallite domain size through high-temperature treatment, achieving an enhanced thermal conductivity up to 1290 watts per meter per kelvin. The tensile strength of the graphene fiber reaches 1080 megapascals.
Fiber Bundles, Yang-Mills Theory, and General Relativity

I articulate and discuss a geometrical interpretation of Yang–Mills theory. Analogies and disanalogies between Yang–Mills theory and general relativity are also considered.
Contests to become CEO: incentives, selection and handicaps

Should a firm favor insiders (handicap outsiders) when selecting a CEO? One reason to do so is to take advantage of the contest to become CEO as a device for providing current incentives to employees. An important reason not to do so is that this can reduce the ability of future CEOs and, hence, future profits. The trade-off between providing current incentives and selecting the most able individual to become CEO is the focus of this paper. If insiders are good enough (better or nearly as good as outsiders), incentive provision to insiders typically dominates and it is optimal to handicap outsiders, sometimes so severely that they have no chance to win the contest. However, if outsiders are sufficiently better than insiders, selection dominates and it is the insiders who are severely handicapped. This finding is in sharp contrast to the existing literature which has so far ignored this trade-off. In all, our model provides useful insight into contests to become CEO and rationalizes empirical regularities in the source of CEOs chosen by firms. In particular, our analysis helps to explain the lower tendency of firms in more heterogeneous industries and firms with a product or line of business organizational structure to select an outsider as CEO.
Gaussian Fluctuations of Eigenvalues in Wigner Random Matrices

We study the fluctuations of eigenvalues from a class of Wigner random matrices that generalize the Gaussian orthogonal ensemble. We begin by considering an n × n matrix from the Gaussian orthogonal ensemble (GOE) or Gaussian symplectic ensemble (GSE) and let xk denote eigenvalue number k. Under the condition that both k and n − k tend to infinity as n →∞ ,w e show thatxk is normally distributed in the limit. We also consider the joint limit distribution of eigenvalues (xk1 ,...,x km ) from the GOE or GSE where k1, n − km and ki+1 − ki ,1 ≤ i ≤ m − 1, tend to infinity with n. The result in each case is an m-dimensional normal distribution. Using a recent universality result by Tao and Vu, we extend our results to a class of Wigner real symmetric matrices with non-Gaussian entries that have an exponentially de- caying distribution and whose first four moments match the Gaussian moments.
Technological discontinuities and flexible production networks: The case of Switzerland and the world watch industry *

Abstract The twentieth-century history of the Swiss watch industry illustrates how cultures and industrial production systems experience great difficulty adapting to external change at different points in time. The current emphasis on production networks - unique reservoirs of potential technological innovation realized through cooperation rather than competition among firms - lacks a detailed appreciation of historic networks, and in particular their fragile character in times of economic turmoil. While networks can and do promote innovation within an existing technological framework, historical experience suggests their fragmented, atomistic structure is subject to disorganization and disintegration during periods of technological change. An exclusive focus on “production” ignores other constraints that are powerful forces governing the reaction abilities of regions. Previous research has largely relied on a model of oligopolistic competition to explain how the Swiss lost control of the world watch industry. I conclude, on the contrary, that the Swiss experience must be understood from the standpoint of how technological change challenges previous ways of organizing production, industry, culture, and society. Technology shifts present a series of strategic turning points that industrial leaders must navigate during a period of technological change.
Identifying Small Mean Reverting Portfolios

Given multivariate time series, we study the problem of forming portfolios with maximum mean reversion while constraining the number of assets in these portfolios. We show that it can be formulated as a sparse canonical correlation analysis and study various algorithms to solve the corresponding sparse generalized eigenvalue problems. After discussing penalized parameter estimation procedures, we study the sparsity versus predictability trade-off and the significance of predictability in various markets.
Identifying the Reionization Redshift from the Cosmic Star Formation Rate

We show that the cosmic star formation rate per comoving volume should exhibit a distinct drop around the reionization redshift, when the H II regions in the intergalactic medium around individual ionizing sources first overlapped. The drop results from the increase in the temperature of the intergalactic medium as it was photoionized, and the consequent suppression of the formation of low-mass galaxies. We show quantitatively that the detection of this drop, which is marked by a corresponding fall in the number counts of faint galaxies, should become feasible over the coming decade with the Next Generation Space Telescope.
Randomized Sensor Selection in Sequential Hypothesis Testing

We consider the problem of sensor selection for time-optimal detection of a hypothesis. We consider a group of sensors transmitting their observations to a fusion center. The fusion center considers the output of only one randomly chosen sensor at the time, and performs a sequential hypothesis test. We study a sequential multiple hypothesis test with randomized sensor selection strategy. We incorporate the random processing times of the sensors to determine the asymptotic performance characteristics of this test. For three distinct performance metrics, we show that, for a generic set of sensors and binary hypothesis, the time-optimal policy requires the fusion center to consider at most two sensors. We also show that for the case of multiple hypothesis, the time-optimal policy needs at most as many sensors to be observed as the number of underlying hypotheses.
An experiment in musical composition

The high-order probabilities of element sequences can be determined from a sample of linear structures and can be used for synthesis of new structures. From theoretical considerations one can identify the qualitative conditions for satisfactory output. The theoretical concepts can be tested and quantitative parameters determined by experiment. Such an experiment has been performed by analyzing written music and by testing the analysis through the synthesis of new musical compositions, using a digital computer. A sample of 37 melodies was analyzed for the probabilities of the elements, element pairs (digrams), trigrams, and so on to the eighth order. The tables derived were used for the synthesis of original melodies by a random process. The theory and the experimental verification are considered in detail. The experimental results presented include comparative statistics of the successful syntheses using each of the eight orders of analysis, examples of melodies generated by low, medium, and high-order synthesis, and confirmation of degeneracy and other effects predicted by the theory.
ON THE SPECTRUM AND NATURE OF THE PECULIAR TYPE IA SUPERNOVA 1991T

A parametrized supernova synthetic-spectrum code is used to study line identifications in the photospheric-phase spectra of the peculiar Type Ia SN 1991T, and to extract some constraints on the composition structure of the ejected matter. The inferred composition structure is not like that of any hydrodynamical model for Type Ia supernovae. Evidence that SN 1991T was overluminous for a SN Ia is presented, and it is suggested that this peculiar event was probably a substantially super-Chandrasekhar explosion that resulted from the merger of two white dwarfs.
Fatalistically Flawed: A Review Essay on Fragile by Design, by Charles W. Calomiris and Stephen H. Haber

Not long ago a colleague of mine, who works regularly with legislators, attended a conference at which the lunch speaker, a famous economist, began by telling everyone why governments regulate financial institutions. The reasons the economist gave consisted of various (supposed) financial-market failures. Said the colleague International Finance 18:1, 2015: pp. 109–128 DOI: 10.1111/1468-2362.12060
Origin of crack tip instabilities

Abstract This paper demonstrates that rapid fracture of ideal brittle lattices naturally involves phenomena long seen in experiment, but which have been hard to understand from a continuum point of view. These idealized models do not mimic realistic microstructure, but can be solved exactly and understood completely. First it is shown that constant velocity crack solutions do not exist at all for a range of velocities starting at zero and ranging up to about one quarter of the shear wave speed. Next it is shown that above this speed cracks are by and large linearly stable, but that at sufficiently high velocity they become unstable with respect to a nonlinear microcracking instability. The way this instability works itself out is related to the scenario known as intermittency, and the basic time scale which governs it is the inverse of the amount of dissipation in the model. Finally, we compare the theoretical framework with some new experiments in Plexiglas, and show that all qualitative features of the theory are mirrored in our experimental results.
Moduli of twisted sheaves

We study moduli of semistable twisted sheaves on smooth proper algebraic spaces. In the case of a relative curve or surface, we prove results on the structure of these spaces. For curves, they are essentially isomorphic to spaces of semistable vector bundles. In the case of surfaces, we show (under a mild hypothesis on the twisting class) that the spaces are asymptotically geometrically irreducible, normal, generically smooth, and locally complete intersections (l.c.i.'s) over the base. We also develop general tools necessary for these results: the theory of associated points and purity of sheaves on Artin stacks, twisted Bogomolov inequalities, semistability and boundedness results, and basic results on twisted Quot-schemes on a surface
Head and Neck Ultrasound in the Pediatric Population

Ultrasound, as a diagnostic modality, has been developing rapidly. High-resolution ultrasound machines have been reduced to the size of a laptop computer. Ultrasound can be adopted by otolaryngologists for use within the clinic and the operating room. Ultrasound offers several advantages to the pediatric patient population. It is well tolerated and adds a degree of precision to the physical examination. It can be done repeatedly as lesions evolve and treatment is performed. It is valuable for guidance and therapeutic treatment of lesions in the operating room. It is likely that ultrasound use will continue to rapidly grow and evolve as a tool within the field of otolaryngology.
Incidence of federal and state gasoline taxes

The federal specific gasoline tax falls equally on consumers and wholesalers; whereas state specific taxes fall almost entirely on consumers. The consumer incidence of state taxes is greater in states that use relatively little gasoline.