cssi/SciSciGPT-SciSciNet huggingface dataset:
The shape of things to come: Structural and synthetic studies of taxol and related compounds

The history of the development of Taxol (paclitaxel) as an anticancer drug is reviewed, and some aspects of the phytochemistry of Taxus species and of the medicinal chemistry of taxol are discussed. The nature of the taxol-tubulin interaction is then described, with an emphasis on studies that led to the discovery and experimental proof of the T-taxol conformation as the tubulin-binding conformation of taxol. The implications of this conformation for future drug development are also briefly covered.
Sporadic fuzzy temporal associations

The objective of data mining is to discover useful and interesting relationships among the data in a database. Temporal information can be used to provide a linear ordering on the occurrence of events, to determine inter-event relevance, and to link events in a data stream. Events may be linked by the source of the information or by shared attributes. Event linking permits the discovery of relationships that occur among groups of events, rather than restricting the relationships to those that occur within a single event and extends the type of relationships that can be represented and analyzed in a temporal event stream. In this paper, we examine modifications to standard data mining algorithms suitable for identifying sporadic relationships in temporal data defined using event linking and fuzzy relevance constraints.
Evidence of new nucleon resonances from electromagnetic meson production

The study of nucleon resonances in electromagnetic meson production with the CLAS detector is discussed. The electromagnetic interaction is complementary to pion scattering in the exploration of the nucleon excitation spectrum. Higher mass states often decouple from the N{pi} channel and are not seen in {pi} N --> {pi} N. Photoproduction of mesons, such as K {Lambda}, {omega} p and {eta}' p may be more sensitive to many of these states. The CLAS detector, combined with the use of energy-tagged polarized photons and polarized electrons, as well as po- larized targets and the measurement of recoil polarization, are the tools needed for a comprehensive nucleon resonance program. Some of the recently published high statistics data sets had significant impact on further clarifying the nucleon excitation spectrum.
Discovery and Diffusion of Knowledge in an Endogenous Social Network

The authors explore the evolution of the structure and performance of a social network in a population of individuals who search for local optima in diverse and dynamic environments. Individuals choose whether to innovate or imitate, and in the latter case, from whom to learn. The probabilities of these possible actions respond to an individual’s past experiences using reinforcement learning. Among some of the authors’ more interesting findings is that a population’s performance is not monotonically increasing in either the reliability of the communication network or the productivity of innovation.
Airborne Gravity Is Here

The achievement of practical and useful airborne gravity exploration for petroleum is a major culmination of more than twenty years of research and development. Commercial surveys have now been conducted for three years. The precision and anomaly resolution attainable are twice as good as that of current shipborne gravity data. This paper presents data to demonstrate the precision of airborne gravity and discusses its usefulness (with simultaneous magnetics and topography). Industrial acceptance of the method portends a new era in geophysical exploration for oil and gas which gives promise to double the effectiveness of explorations on land in both time and cost.
Bifunctional binding and catalysis in host-guest chemistry

Some dimers of cyclodextrin have been prepared that can bind appropriate substrates in water with binding constants as strong as those of strong antigen/antibody complexes. Doubly linking two cyclodextrins with connections at neighboring glucose units produces a hinged molecule that resembles a clamshell. Another isomer is also produced, in the so-called loveseat configuration, in which the two cyclodextrin units cannot cooperate in binding a single substrate. When the two links are of different length, the clamshell dimer preferentially binds a non-linear substrate with an affinity exceeding 1011 M−1, at least 103 better than the binding of a linear substrate isomer. Binding of substrates occurs by induced fit, in which the host closes around and engulfs the substrate. Mechanistic studies on models for the enzyme ribonuclease have led to a proposed mechanism different from that normally suggested for the enzyme. This mechanism has guided the synthesis of a new enzyme mimic with improved properties. Isotope studies show that this enzyme mimic uses a simultaneous bifunctional mechanism, as does the enzyme. The double binding of the transition state by the two imidazole units of the enzyme mimic occurs because of their linkage. The geometric preference for this binding reflects anon-linear transition state.
The role of electrical and thermal contact resistance for Joule breakdown of single-wall carbon nanotubes.

Several data sets for the electrical breakdown in air of single-wall carbon nanotubes (SWNTs) on insulating substrates are collected and analyzed. A universal scaling of the Joule breakdown power with nanotube length is found, which appears to be independent of the substrate thermal properties of their thickness. This suggests that the thermal resistances at SWNT–insulator and at SWNT–electrode interfaces govern heat sinking from the nanotube. Analytical models for the breakdown power scaling are presented, providing an intuitive, physical understanding of the breakdown process. The electrical and thermal resistances at the electrode contacts limit the breakdown behavior for sub-micron SWNTs; the breakdown power scales linearly with length for tubes that are microns long, and a minimum breakdown power (~0.05 mW) is observed for the intermediate (~0.5 µm) length range.
Performance limitations of adaptive parameter estimation and system identification algorithms in the absence of excitation

We address the problem of fundamental performance limitations in adaptive parameter estimation and system identification, occurring in environments where perturbations are present but there is lack of sufficient excitation. We construct a simple yet general bursting scenario to derive an analytical lower bound on the worst-case peak steady-state error for a wide class of parameter estimation and system identification algorithms. Our results show that in the absence of any input constraints, arbitrarily small perturbations impose a serious performance limitation, in the sense that the worst-case performance deteriorates proportionally with the size of the parametric uncertainty set.
HOW RESPONSIVE ARE PRIVATE TRANSFERS TO INCOME? EVIDENCE FROM A LAISSEZ-FAIRE ECONOMY

Abstract In recent years there has been burgeoning interest in how private transfers respond to household income, or “transfer derivatives”. Much of it is fueled by the specter of “crowding out”: the more responsive are private transfers, the more likely they could be supplanted by expansions in public transfers, weakening or destroying the latter's distributive impact. Yet there is also an emerging consensus that actual transfer derivatives are trivial, at least for the United States, suggesting that crowding out might loom larger in the minds of some economists than in the data. But perhaps crowding out is a fait accompli in the United States. Accordingly, we focus on the Philippines, which has a much smaller public sector. We also pursue a novel theoretical angle, which generates a sharp, non-linear relationship between private transfer receipts and income, in the form of a spline. Our empirical work applies recently developed estimation techniques that treat the spline's threshold as an unknown parameter, and they uncover transfer derivatives much larger than conventional methods reveal. Notably, private transfers patterns are consistent with altruistic preferences, effective risk sharing, or both. In accord with theoretical predictions, however, strong transfer derivatives prevail only among low-income households. Our findings suggest that attempts to aid the poor could be thwarted by private responses, which leak benefits to richer households in the form of lighter burdens of support for less fortunate kin. So the problems that operative private transfers create for public redistribution policy, first pointed out by Becker and Barro over 25-years-ago, do indeed matter empirically.
A conceptual framework and belief-function approach to assessing overall information quality

We develop an information quality model based on a user-centric view adapted from Financial Accounting Standards Board1, Wang et al.2, and Wang and Strong3. The model consists of four essential attributes (or assertions): ‘Accessibility,’ ‘Interpretability,’ ‘Relevance,’ and ‘Integrity.’ Four sub-attributes lead to an evaluation of Integrity: ‘Accuracy,’ ‘Completeness,’ ‘Consistency,’ and ‘Existence.’ These sub-attributes relating to 'Integrity' are intrinsic in nature and relate to the process of how the information was created while the first three attributes: ‘Accessibility,’ ‘Interpretability,’ and ‘Relevance’ are extrinsic in nature. We present our model as an evidential network under the belief-function framework to permit user assessment of quality parameters. Two algorithms for combining assessments into an overall IQ measure are explored, and examples in the domain of medical information are used to illustrate key concepts. We discuss two scenarios, ‘online-user’ and ‘assurance-provider,’ which reflect two likely and important aspects of IQ evaluation currently facing information users – concerns about the impact of poor quality online information, and the need for information quality assurance.
Failure correlation in software reliability models

Perhaps the most stringent restriction in most software reliability models is the assumption of statistical independence among successive software failures. The authors research was motivated by the fact that although there are practical situations in which this assumption could be easily violated, much of the published literature on software reliability modeling does not seriously address this issue. The research work in this paper is devoted to developing the software reliability modeling framework that can consider the phenomena of failure correlation and to study its effects on the software reliability measures. The important property of the developed Markov renewal modeling approach is its flexibility. It allows construction of the software reliability model in both discrete time and continuous time, and (depending on the goals) to base the analysis either on Markov chain theory or on renewal process theory. Thus, their modeling approach is an important step toward more consistent and realistic modeling of software reliability. It can be related to existing software reliability growth models. Many input-domain and time-domain models can be derived as special cases under the assumption of failure s-independence. This paper aims at showing that the classical software reliability theory can be extended to consider a sequence of possibly s-dependent software runs, viz, failure correlation. It does not deal with inference nor with predictions, per se. For the model to be fully specified and applied to estimations and predictions in real software development projects, we need to address many research issues, e.g., the detailed assumptions about the nature of the overall reliability growth, way modeling-parameters change as a result of the fault-removal attempts.
Shear modes, criticality and extremal black holes

We consider a (2+1)-dimensional field theory, assumed to be holographically dual to the extremal Reissner-Nordstrom AdS4 black hole background, and calculate the retarded correlators of charge (vector) current and energy-momentum (tensor) operators at finite momentum and frequency. We show that, similar to what was observed previously for the correlators of scalar and spinor operators, these correlators exhibit emergent scaling behavior at low frequency. We numerically compute the electromagnetic and gravitational quasinormal frequencies (in the shear channel) of the extremal Reissner-Nordstrom AdS4 black hole corresponding to the spectrum of poles in the retarded correlators. The picture that emerges is quite simple: there is a branch cut along the negative imaginary frequency axis, and a series of isolated poles corresponding to damped excitations. All of these poles are always in the lower half complex frequency plane, indicating stability. We show that this analytic structure can be understood as the proper limit of finite temperature results as T is taken to zero holding the chemical potential μ fixed.
Accurate masses for dispersion-supported galaxies

We derive an accurate mass estimator for dispersion-supported stellar systems and demonstrate its validity by analysing resolved line-of-sight velocity data for globular clusters, dwarf galaxies and elliptical galaxies. Specifically, by manipulating the spherical Jeans equation we show that the mass enclosed within the 3D deprojected half-light radius r 1/2 can be determined with only mild assumptions about the spatial variation of the stellar velocity dispersion anisotropy as long as the projected velocity dispersion profile is fairly flat near the half-light radius, as is typically observed. We find M 1/2 = 3G -1 (σ 2 los )r 1/2 ≃ 4G -1 (σ 2 los )R e , where (σ 2 los ) is the luminosity-weighted square of the line-of-sight velocity dispersion and R e is the 2D projected half-light radius. While deceptively familiar in form, this formula is not the virial theorem, which cannot be used to determine accurate masses unless the radial profile of the total mass is known a priori. We utilize this finding to show that all of the Milky Way dwarf spheroidal galaxies (MW dSphs) are consistent with having formed within a halo of a mass of approximately 3 x 10 9 M ⊙ . assuming a A cold dark matter cosmology. The faintest MW dSphs seem to have formed in dark matter haloes that are at least as massive as those of the brightest MW dSphs, despite the almost five orders of magnitude spread in luminosity between them. We expand our analysis to the full range of observed dispersion-supported stellar systems and examine their dynamical I-band mass-to-light ratios Υ I 1/2 . The Υ I 1/2 versus M 1/2 relation for dispersion-supported galaxies follows a U shape, with a broad minimum near Υ I 1/2 ≃ 3 that spans dwarf elliptical galaxies to normal ellipticals, a steep rise to Υ I 1/2 ≃ 3200 for ultra-faint dSphs and a more shallow rise to Υ I 1/2 ≃ 800 for galaxy cluster spheroids.
A backwards view for assessment

Publisher Summary This chapter describes knowledge in the direction opposite to the direction of usage. Much artificial intelligence research focuses on the problem of deducing the validity of unobservable propositions or hypotheses from observable evidence. Many of the knowledge representation techniques designed for this problem encode the relationship between evidence and hypothesis in a directed manner. The direction in which evidence is stored is typically from evidence to hypothesis. Models, which capture the richness of the interactions among their variables, can become impossible to assess in the usage direction even though they can be simple and natural to think about and assess in the opposite direction. Various methods for reasoning with uncertainty are impractical because of the complexity of knowledge assessment and belief revision. The desired simplicity can be found by constructing models in the direction opposite that of usage without having to sacrifice fundamentals.
Effect of change in the time of charging voltage on spark discharge from a metal disk

Electrostatic discharge (ESD) is a source of electromagnetic disturbance. For an ESD immunity test, IEC 61000-4-2 is standardized. In the standard, the air discharge and contact discharge method are described for the application of ESD to equipment under test. Air discharge, which is most common in the field, is a more severe test than contact discharge. Air discharge is dependent on the humidity, the speed of approach to grounded material, the structure of the ESD generator, and so on. An ESD event while charged material approaches grounded material has a more significant effect on electronic equipment than an ESD event from stationary charged material with the same charge potential. This peculiar phenomenon is considered because the rise time becomes faster and the peak spark current becomes larger, but is not well understood for reasons such as the difficulty of reproducibility. To promote an understanding of the spark discharge that occurs while a charged material is approaching a grounded material, the effect of change in the time of the charging voltage on the spark discharge from a stationary metal disk was measured. The experiment showed that the spark voltage and peak spark current increased with a change in the time of the charging voltage, and that the amplitude of the spark current spectra also increased with a change in the time of the charging voltage. The experimental results are considered in terms of the sparking resistance formula, and can be explained qualitatively in terms of the increase of spark voltage. 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(3): 1–9, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20991
Rural‐urban disparity and sectoral labour allocation in China

This study examines China's rural‐urban segmentation and its causes in the context of economic reforms. Household survey and aggregate data indicate a V‐shaped process in which rural‐urban consumption and income differentials decreased between 1978 and 1985, but then have continually increased to historically high levels. This sectoral division is consistent with production function estimates based on provincial data that reveal higher labour productivity in urban/state‐owned industries than in rural industries and agriculture. To explain the V‐shaped change, we argue that the precedent of successful rural reforms raised farmers’ relative earnings, but the remaining obstacles to an efficient sectoral allocation of labour have prevented China from eliminating dualism. Recent financial policies consisting of urban price subsidies and increased investment credits have also had influential distribution effects that are biased against the rural sector.
On the Robin problem in fractal domains

Research partially supported by National Science Foundation (NSF) grants DMS-0244737 and DMS-0303310.
Resonant mode controllers for launch vehicle applications

Electromechanical actuator (EMA) systems are currently being investigated for the National Launch System as a replacement for hydraulic actuators due to the large amount of manpower and support hardware required to maintain the hydraulic systems. EMA systems in weight-sensitive applications, such as launch vehicles, have been limited to around 5 HP due to system size, controller efficiency, thermal management, and battery size. The authors present design and test data for an EMA system that competed favorably in weight and is superior in maintainability to the hydraulic system. The EMA system uses DC power provided by a high-energy-density bipolar lithium thionyl chloride battery, with power conversion performed by low-loss resonant topologies, and a high-efficiency induction motor controlled with a high-performance field-oriented controller to drive a linear actuator. >
A Two Stage Matching Pursuit Based Algorithm for DOA Estimation in Fast Time-Varying Environments

We propose a new directions of arrival (DOA) algorithm which provides very reliable estimates in fast time-varying environments. Popular DOA methods such as MUSIC and ESPRIT cannot be used in these environments because of their reliance on the estimation of a covariance matrix. The algorithm uses a two stage approach. The first stage uses a matching pursuit based algorithm to process each snapshot and determine DOA. These DOA estimates are aggregated at regular intervals and a subset of the DOA are selected and fed to a second processing stage. This stage consists of a bank of least squares estimators which are used to determine the final DOA estimate. The performance of the algorithm is evaluated for closely and widely spaced DOA over a range of SNR values.
Veiling Glare Of A Linear Multichannel Si(Li) Detector

The effective veiling glare has been measured in a linear, 64 element Si(Li) detector of 5 mm thickness and 0.5 mm center-to-center spacing between adjacent sensitive areas. Each elemental contact was 6 mm high and 0.4 mm wide. The measurement was made in two different ways, both employing a 33 keV beam of synchrotron x-rays at the Stanford Synchrotron Radiation Laboratory. In one method, a lead phantom in the shape of an isosceles triangle was illuminated across its width with a fan beam of 33 keV x-rays 0.5 mm high by 20 mm wide. The x-ray flux passing by the phantom was measured in each channel of the Si(Li) detector. In the second method, a highly collimated beam of 33 keV x-rays (0.5 mm high by 0.025 mm wide) was scanned across 15 channels of the detector in 0.01 mm steps. The measured intensity in each channel of the detector was recorded at each position of the beam. The photon flux fell to less than 0.1% at a distance of 3 mm from the edge of the beam. The results of both measurements were in agreement. They were also compared to calculated results based on the known total x-ray cross sections for Compton scattering and photoelectric absorption. To within the experimental error, the observed and calculated results were found to be in good agreement.
The glueing construction and double categories

Abstract We introduce Artin–Wraith glueing and locally closed inclusions in double categories. Examples include locales, toposes, topological spaces, categories, and posets. With appropriate assumptions, we show that locally closed inclusions are exponentiable, and the exponentials are constructed via Artin–Wraith glueing. Thus, we obtain a single theorem establishing the exponentiability of locally closed inclusions in these five cases.
Input Substitution and Pollution Control under Uncertainty and Firm Heterogeneity

Much research has focused on emission-based instruments for pollution control, but indirect approaches that control input use or production technologies are often used. This article derives a simple rule for evaluating the relative efficiency of input-use taxes and standards in the presence of input substitution, firm heterogeneity, and uncertainty. The importance of input substitution is demonstrated and the key parameters that determine the relative efficiency are identified.
Ultrasound in the diagnosis of noninflammatory musculoskeletal conditions

Ultrasonography is a growing technique for the evaluation of superficial structures, such as tendons, ligaments, muscles, joints, nerves, masses, and cysts. Attractive features, including lower cost in comparison with MRI, lack of ionizing radiation, ability to dynamically assess structures, reliable use of unaffected side as an internal control, as well as safety in patients with contraindications to magnetic resonance imaging further expand its application. Power Doppler can determine the extent of target tissue perfusion. In this article, the applications of ultrasound are discussed in traumatic, degenerative, and infectious conditions. Quantitative ultrasound in osteoporosis diagnosis and ultrasound use in detection of foreign bodies, synovial pathology, and crystalline arthropathies is also discussed.
Bootstrap current in quasi-symmetric stellarators

This work examines bootstrap current in quasi-symmetric stellarators with a focus on the impact of bootstrap current on the equilibrium properties of stellarator configurations. In the design of th...
A systematic and effective supervised learning mechanism based on Jacobian rank deficiency

Most neural network applications rely on the fundamental approximation property of feedforward networks. Supervised learning is a means of implementing this approximate mapping. In a realistic problem setting, a mechanism is needed to devise this learning process based on available data, which encompasses choosing an appropriate set of parameters in order to avoid overfitting, using an efficient learning algorithm measured by computation and memory complexities, ensuring the accuracy of the training procedures as measured by the training error, and testing and cross-validation for generalization. We develop a comprehensive supervised learning algorithm to address these issues. The algorithm combines training and pruning into one procedure by utilizing a common observation of Jacobian rank deficiency in feedforward networks. The algorithm not only reduces the training time and overall complexity but also achieves training accuracy and generalization capabilities comparable to more standard approaches. Extensive simulation results are provided to demonstrate the effectiveness of the algorithm.
Security analysis of KEA authenticated key exchange protocol

KEA is a Diffie-Hellman based key-exchange protocol developed by NSA which provides mutual authentication for the parties. It became publicly available in 1998 and since then it was neither attacked nor proved to be secure. We analyze the security of KEA and find that the original protocol is susceptible to a class of attacks. On the positive side, we present a simple modification of the protocol which makes KEA secure. We prove that the modified protocol, called KEA+, satisfies the strongest security requirements for authenticated key-exchange and that it retains some security even if a secret key of a party is leaked. Our security proof is in the random oracle model and uses the Gap Diffie-Hellman assumption. Finally, we show how to add a key confirmation feature to KEA+ (we call the version with key confirmation KEA+C) and discuss the security properties of KEA+C.
Regular and chaotic dynamics of triaxial stellar systems

We use Laskar's frequency mapping technique to study the dynamics of triaxial galaxies with central density cusps and nuclear black holes. For ensembles of ~104 orbits, we numerically compute the three fundamental frequencies of the motion, allowing us to map out the Arnold web. We also compute diffusion rates of stochastic orbits in frequency space. The objects of greatest importance in structuring phase space are found to be the three-dimensional resonant tori, regions where the fundamental frequencies satisfy a relation of the form 0 = lω1 + mω2 + nω3 with integer (l, m, n). When stable, resonant tori generate phase-space regions in which the motion is regular; these regions are not necessarily associated with a stable periodic orbit as in systems with only 2 degrees of freedom. Boxlike orbits are generically stochastic, but some tube orbits are stochastic as well. The spectrum of diffusion rates for boxlike orbits at a given energy is well approximated as a power law over at least 6 decades. Models with high central concentrations—steep central cusps or massive black holes—exhibit the most stochasticity. Even a modest black hole, with a mass of ~0.5% the mass of the galaxy, is as effective as the steepest central density cusp at inducing stochastic diffusion. There is a transition to global stochasticity in boxlike phase space when the mass of the central black hole exceeds ~2% of the galaxy mass. We estimate the dependence of orbital evolution rates on galaxy structural parameters. We predict a greater average degree of dynamical evolution in faint elliptical galaxies because of their high central densities and short crossing times. The evolution time is estimated to be shorter than a galaxy lifetime for absolute magnitudes fainter than about -19 or -20, consistent with the observed change in many elliptical galaxy properties at this luminosity.
Atomic classification of 6D SCFTs

Author(s): Heckman, JJ; Morrison, DR; Rudelius, T; Vafa, C | Abstract: We use F-theory to classify possibly all six-dimensional superconformal field theories (SCFTs). This involves a two step process: We first classify all possible tensor branches allowed in F-theory (which correspond to allowed collections of contractible spheres) and then classify all possible configurations of seven-branes wrapped over them. We describe the first step in terms of "atoms" joined into "radicals" and "molecules," using an analogy from chemistry. The second step has an interpretation via quiver-type gauge theories constrained by anomaly cancellation. A very surprising outcome of our analysis is that all of these tensor branches have the structure of a linear chain of intersecting spheres with a small amount of possible decoration at the two ends. The resulting structure of these SCFTs takes the form of a generalized quiver consisting of ADE-type nodes joined by conformal matter. A collection of highly non-trivial examples involving E8 small instantons probing an ADE singularity is shown to have an F-theory realization. This yields a classification of homomorphisms from ADE subgroups of SU(2) into E8 in purely geometric terms, matching results obtained in the mathematics literature from an intricate group theory analysis.
Charge-based interactions of mammalian sperm with oocytes: inhibition of fertilization of mouse oocytes by ligands of macrophage scavenger receptor(s).

Abstract Objective: To determine whether anionic ligands for the macrophage scavenger receptor inhibit the fertilization of mouse oocytes by mouse spermatozoa. Design: In vitro study of sperm binding and two-cell embryo formation in the presence of scavenger receptor ligands. Sperm-oocyte interaction may be mediated by sulfated sugars. In this study, we tested other nonsulfated anionic ligands for the scavenger receptor for their ability to affect fertilization. The only common feature of these ligands is their anionic nature. Setting: Oocytes and sperm from mice were used. Main Outcome Measure(s): Binding of sperm to oocytes and subsequent formation of two cell embryos were determined. Result(s): Fucoidin, polyinosinic acid, oxidized low-density lipoprotein, acetyl low-density lipoprotein, and malondialdehyde-modified LDL inhibited the binding and fertilization of mouse sperm to mouse oocytes. Addition of fresh sperm to oocytes previously treated with sperm in the presence of these agents restored the binding and fertilization. Conclusion(s): These results show that charge-based interactions analogous to the interactions of the scavenger receptor with its ligands may play an important role in mammalian fertilization.
Efficient Semantic Communication via Compatible Beliefs

In previous works, Juba and Sudan (1) and Goldreich, Juba and Sudan (2) considered the idea of \semantic communication", wherein two players, a user and a server, attempt to communicate with each other without any prior common language (or communication protocol). They showed that if communication was goal-oriented and the user could sense progress towards the goal (or verify when it has been achieved), then meaningful communication is possible, in that the user's goal can be achieved whenever the server is helpful. A principal criticism of their result has been that it is ine-cient: in order to determine the \right" protocol to communicate with the server, the user enumerates protocols and tries them out with the server until it flnds one that allows it to achieve its goal. They also show settings in which such enumeration is essentially the best possible solution. In this work we introduce deflnitions which allow for e-cient behavior in practice. Roughly, we measure the performance of users and servers against their own \beliefs" about natural protocols. We show that if user and server are e-cient with respect to their own beliefs and their beliefs are (even just slightly) compatible with each other, then they can achieve their goals very e-ciently. We show that this model allows su-ciently \broad-minded" servers to talk with \exponentially" many difierent users in polynomial time, while dismissing the \counterexamples" in the previous work as being \narrow-minded," or based on \incompatible beliefs."
Wet surface and dense atmosphere on early Mars suggested by the bomb sag at Home Plate, Mars

[1] We use the Mars Exploration Rover Spirit observation of a bomb sag produced by an explosive volcanic eruption to infer the atmospheric density at the time of eruption. We performed analogue experiments to determine the relationship between the wetness of the substrate and the velocity and density of impacting clasts and 1) the formation (or not) of bomb sags, 2) the morphology of the impact crater, and 3) the penetration depth of the clast. The downward deflection of beds seen on Mars is consistent with water-saturated sediment in the laboratory experiments. Collision angles <20 degrees from vertical are needed to produce bomb sags. From the experiments we infer an impact velocity up to 4 × 101 m/s, lower than ejection velocities during phreatic and phreatomagmatic eruptions on Earth. If this velocity represents the terminal subaerial impact velocity, atmospheric density exceeded 0.4 kg/m3 at the time of eruption, much higher than at present.
Galaxy Morphologies in the Hubble Ultra Deep Field: Dominance of Linear Structures at the Detection Limit

Galaxies in the Hubble Ultra Deep Field (UDF) larger than 10 pixels (03) have been classified according to morphology, and their photometric properties are presented. There are 269 spiral, 100 elliptical, 114 chain, 126 double-clump, 97 tadpole, and 178 clump-cluster galaxies. We also cataloged 30 B-band and 13 V-band dropouts and calculated their star formation rates. Chains, doubles, and tadpoles dominate the other types at faint magnitudes. The fraction of obvious bars among spirals is ~10%, a factor of 2-3 lower than in other deep surveys. The distribution function of axial ratios for elliptical galaxies is similar to that seen locally, suggesting that ellipticals relaxed quickly to a standardized shape. The distribution of axial ratios for spiral galaxies is significantly different than locally, having a clear peak at ~0.55 instead of a nearly flat distribution. The falloff at small axial ratio occurs at a higher value than locally, indicating thicker disks by a factor of ~2. The falloff at high axial ratio could be from intrinsic triaxial shapes or selection effects. Inclined disks should be more highly sampled than face-on disks near the surface brightness limit of a survey. Simple models and data distributions demonstrate these effects. The decreased numbers of obvious spiral galaxies at high redshifts could be partly the result of surface brightness selection.
Dihadron correlations at high pT

Jet quenching in the matter created in high energy nucleus/nucleus collisions provides a tomographic tool to probe the medium properties. Recent experimental results from the Relativistic Heavy-Ion Collider (RHIC) on characterization of jet production via dihadron correlations at high transverse momentum are reviewed. Expectations from the dihadron measurements for the lower energy {radical}s{sub NN} = 62.4 GeV RHIC run are discussed.
On the Irrelevance of Risk Attitudes in Repeated Two-Outcome Games

Abstract We study equilibrium and maximin play in supergames consisting of the sequential play of a finite collection of stage games, where each stage game has two outcomes for each player. We show that for two-player supergames in which each stage game is strictly competitive, in any Nash equilibrium of the supergame, play at each stage is a Nash equilibrium of the stage game provided preferences over certain supergame outcomes satisfy a natural monotonicity condition. In particular, equilibrium play does not depend on risk attitudes. We establish an invariance result for games with more than two players when the solution concept is subgame perfection. Journal of Economic Literature Classification Numbers: C72, C9.
Computing the transmission zeros of large space structures

The transmission zeros of a large space structure are frequently computed by means of the general-purpose algorithm of A. Emami-Naeini and P. Van Dooren (1982). It is shown that careful exploitation of the special form of the equations of motion of structural dynamics leads to an algorithm that is at least 60 times as fast as this when applied to an undamped structure, and 15 times as fast for a lightly damped one. >
Neighborhoods, cars, and commuting in New York City: A discrete choice approach

Cities around the world are trying out a multitude of transportation policy and investment alternatives with the aim of reducing car-induced externalities. However, without a solid understanding of how people make their transportation and residential location choices, it is hard to tell which of these policies and investments are really doing the job and which are wasting precious city resources. The focus of this paper is the determinants of car ownership and car use for commuting. Using survey data from 1997 to 1998 collected in New York City, this paper uses discrete choice econometrics to estimate a model of the choices of car ownership and commute mode while also modeling the related choice of residential location. The main story told by this analysis is that New Yorkers are more sensitive to changes in travel time than they are to changes in travel cost. The model predicts that the most effective ways to reduce both auto ownership and car commuting involve changing the relative travel times for cars and transit, making transit trips faster by increasing both the frequency and the speed of service and making auto trips slower – perhaps simply by allowing traffic congestion. Population density also appears to have a substantial effect on car ownership in New York.
Dependence of Betti Numbers on Characteristic

We study the dependence of graded Betti numbers of monomial ideals on the characteristic of the base field. The examples we describe include bipartite ideals and Stanley–Reisner ideals of vertex-decomposable complexes. We give a description of bipartite graphs and, using discrete Morse theory, provide a way of looking at the homology of arbitrary simplicial complexes through bipartite ideals.
Performance Analysis of the SNA Virtual Route Pacing Control

In this paper we provide a model and analysis of the IBM SNA virtual route pacing control used to control congestion in SNA networks. The model is appropriate to single virtual routes only. The analysis uses a Norton equivalent of the virtual route queueing model. Similar analyses of two other end-to-end window control mechanisms are carried out; one a sliding window with each message individually acknowledged, the other a fixed window control with the final message in the window only producing an acknowledgment, enabling comparisons to be made between all three. The SNA pacing control procedure, in which the first message in a given window induces an acknowledgment, is found to perform within 4 percent of the sliding window mechanism. Simulation results validate the analysis and performance curves obtained. The third window scheme, with the final message in the window generating an acknowledgment, is found to result in considerable reduction in throughput, as expected. As a by-product of the analysis the Norton equivalent is found to be a useful tool in obtaining approximate solutions to rather complex queueing networks.
Quantum phases and phase transitions of Mott insulators

This article contains a theoretical overview of the physical properties of antiferromagnetic Mott insulators in spatial dimensions greater than one. Many such materials have been experimentally studied in the past decade and a half, and we make contact with these studies. Mott insulators in the simplest class have an even number of S=1/2 spins per unit cell, and these can be described with quantitative accuracy by the bond operator method: we discuss their spin gap and magnetically ordered states, and the transitions between them driven by pressure or an applied magnetic field. The case of an odd number of S=1/2 spins per unit cell is more subtle: here the spin gap state can spontaneously develop bond order (so the ground state again has an even number of S=1/2 spins per unit cell), and/or acquire topological order and fractionalized excitations. We describe the conditions under which such spin gap states can form, and survey recent theories of the quantum phase transitions among these states and magnetically ordered states. We describe the breakdown of the Landau-Ginzburg-Wilson paradigm at these quantum critical points, accompanied by the appearance of emergent gauge excitations.
A cross-level process theory of trust development in interorganizational relationships

Most research on trust in interorganizational relationships focuses on a single level of analysis, typically the individual or organizational level, and treats trust as a fairly static phenomenon. ...
The relationship between seismicity and fault structure on the Discovery transform fault, East Pacific Rise

There is a global seismic moment deficit on mid-ocean ridge transform faults, and the largest earthquakes on these faults do not rupture the full fault area. We explore the influence of physical fault structure, including step-overs in the fault trace, on the seismic behavior of the Discovery transform fault, 4S on the East Pacific Rise. One year of microseismicity recorded during a 2008 ocean bottom seismograph deployment (24,377 0 ≤ ML ≤ 4.6 earthquakes) and 24 years of Mw ≥ 5.4 earthquakes obtained from the Global Centroid Moment Tensor catalog, are correlated with surface fault structure delineated from high-resolution multibeam bathymetry. Each of the 15 5.4 ≤ Mw ≤ 6.0 earthquakes that occurred on Discovery between 1 January 1990 and 1 April 2014 was relocated into one of five distinct rupture patches using a teleseismic surface wave cross-correlation technique. Microseismicity was relocated using the HypoDD relocation algorithm. The western fault segment of Discovery (DW) is composed of three zones of varying structure and seismic behavior: a zone with no large events and abundant microseismicity, a fully coupled zone with large earthquakes, and a complex zone with multiple fault strands and abundant seismicity. In general, microseismicity is reduced within the patches defined by the large, repeating earthquakes. While the extent of the large rupture patches on DW correlates with physical features in the bathymetry, step-overs in the primary fault trace are not observed at patch boundaries, suggesting along-strike heterogeneity in fault zone properties controls the size and location of the large events.
Lost and Found: The Sociological Ambivalence Toward Childhood

AbstractRecent social scientific research on childhood is oddly ambivalent. Despite much theoretically creative and empirically innovative work, the sociology of childhood, as a subfield, is often uncomfortable with its own object of inquiry. I identify three possible sources of this sociological ambivalence. First, much work does not fully differentiate children from childhood. Second, much of the literature conflates the notion of childhood as a social construct with childhood as a social good. And third, the construction of childhood in some of the literature is incommensurate with the social policies designed to protect or empower children. This review further illuminates this threefold equivocation with a schematic review of the sociological literature on childhood written since the 1980s. I conclude by briefly suggesting how recent insights from historical and poststructural approaches have begun to alleviate this ambivalence.
Monitoring technical managers: theory, evidence, and prescriptions

Agency relationships—where one party (the principal) delegates authority to another (the agent)—are well studied in financial settings but less so in technical settings. The asymmetry of information between the general manager and the technical manager is likely to create the possibility of misdirected effort, an overuse of the agent’s human capital, whether the agent is opportunistic or not. Analyzing a dataset of information technology hardware and staff spending by larger multidivisional firms during a growth phase of US IT spending, 1989-1993, results suggest that technical managers significantly overspent on hardware, with deleterious consequences for performance. Chief executive experience significantly altered the effects of overspending. Analysis of the results suggest a solution, a model termed “staged commitment,” that can be used to monitor technical agents in many areas of business.
Multilayer optical elements for generation and analysis of circularly polarized X-rays

Abstract Calculations of the relative phase changes of σ and π electric field components on Bragg reflection from and transmission through multilayers are presented. Large relative phase changes can be calculated in certain cases, which may lead to utility of multilayers as quarter-wave plates for generation and analysis of circularly polarized soft X-radiation. Similar behavior may be expected for perfect crystals in the hard X-ray range.
The Emergence of Fiduciary Capitalism

The twentieth century has seen a sea change in the concentration of ownership of U.S. corporations. Early in the century Berle and Means identified the divorce of ownership from control as the central corporate governance problem, but since the 1970’s ownership has been re’rating into the hands of fiduciary institutions – most notably pension funds and mutual funds. By the 1990s fiduciaries collectively owned over 50% of the outstanding equity of the 1,000 largest corporations. This new pattern of ownership, fiduciary capitalism, has begun to raise important policy questions including: How can agents (fiduciaries) effectively monitor other agents (boards of directors)? What are the social implications of universal ownership where fiduciaries own substantial stakes in virtually all of the corporations in a country, and, finally, What does it mean to maximize shareholder wealth when fiduciaries are universal owners?
Hydrodynamic modeling of leachate recirculating landfills

Leachate recirculation is an emerging technology for the on-site management of leachate. The benefits of leachate recirculation have been well-documented by a variety of researchers. However, little work has been done to address the hydrodynamic behavior of the landfill, i.e. the effect of recirculation system and waste characteristics on leachate routing. A modified form of SUTRA - a United States Geological Survey (USGS) saturated-unsaturated flow and transport model - was used to simulate the forces driving liquid movement through a landfill. The variables evaluated included leachate input rates, the permeability of intermediate cover materials, waste permeability, and waste heterogeneity. The model was verified using data from operating landfills in Delaware, California, New York, and Florida.
Are Credit Unions Too Small

Abstract U.S. credit unions serve 93 million members, hold 10% of U.S. savings deposits, and make 13.2% of all nonrevolving consumer loans. Since 1985, the share of U.S. depository institution asse...
A polynomial-time algorithm for global value numbering

We describe a polynomial-time algorithm for global value numbering, which is the problem of discovering equivalences among program sub-expressions. We treat all conditionals as non-deterministic and all program operators as uninterpreted. We show that there are programs for which the set of all equivalences contains terms whose value graph representation requires exponential size. Our algorithm discovers all equivalences among terms of size at most s in time that grows linearly with s. For global value numbering, it suffices to choose s to be the size of the program. Earlier deterministic algorithms for the same problem are either incomplete or take exponential time. We provide a detailed analytical comparison of some of these algorithms.