cssi/SciSciGPT-SciSciNet huggingface dataset:
Discrete Time q-TASEPs

We introduce two new exactly solvable (stochastic) interacting particle systems which are discrete time versions of q-TASEP. We call these geometric and Bernoulli discrete time q-TASEP. We obtain concise formulas for expectations of a large enough class of observables of the systems to completely characterize their fixed time distributions when started from step initial condition. We then extract Fredholm determinant formulas for the marginal distribution of the location of any given particle. Underlying this work is the fact that these expectations solve closed systems of difference equations which can be rewritten as free evolution equations with k − 1t wobody boundary conditions—discrete q-deformed versions of the quantum delta Bose gas. These can be solved via a nested contour integral ansatz. The same solutions also arise in the study of Macdonald processes, and we show how the systems of equations our expectations solve are equivalent to certain commutation relations involving the Macdonald first difference operator.
Assessing allocation concealment and blinding in randomised controlled trials: why bother?

The scientific community's quest for unbiased research received a strong boost from a recent policy amendment on randomised controlled trials (RCTs) in this journal. Henceforth, the status of allocation concealment will be clearly indicated in the abstracts along with that of blinding. Thus, readers will have additional information by which to judge the internal validity of trials. In this editorial I address the background and rationale for these enhancements. Random allocation to intervention groups remains the only method of ensuring that the groups being compared are on an equivalent footing at the outset of the study, thus eliminating selection and confounding biases. This has allowed RCTs to play a key part in advancing medical science. The success of randomisation depends on 2 interrelated processes.1, 2 The first entails generating a sequence by which the participants in a trial are allocated to intervention groups. To ensure unpredictability of that allocation sequence, investigators should generate it by a random process. The second process, allocation concealment, shields those involved in a trial from knowing upcoming assignments in advance.3, 4 Without this protection, investigators and patients have been known to change who gets the next assignment, making the comparison groups less equivalent.5, 6 For example, suppose that an investigator creates an adequate allocation sequence using a random number table. However, the investigator then affixes the list of that sequence to a bulletin board, with no allocation concealment. Those responsible for admitting participants could ascertain the upcoming treatment allocations and then route participants with better prognoses to the experimental group and those with poorer prognoses to the control group, or vice versa. Bias would result. Inadequate allocation concealment also …
Synthesis of vinylindoles and vinylpyrroles by the Peterson olefination or by use of the Nysted reagent

Vinylindoles and vinylpyrroles were prepared from their corresponding aldehydes or ketones using the Peterson olefination, or by use of the Nysted reagent, a commercially available gem-dimetallic compound. The two methods provide efficient and convenient access to these useful heterocyclic 1,3-diene systems. J. Heterocyclic Chem., (2011).
A high-resolution interval timer and buffered storage system for neurophysiological experiments.

A high-resolution interval timer, designed as a computer peripheral for use in neurophysiological experiments, is described. With only minimal intervention by the controlling computer, this device detects, identifies and times the occurrence of discriminated neuronal discharges and changes in experimental status, and autonomously stores these encoded times in an on-board 4K×16 r.a.m. This device reduces the need for detailed software timing routines, while still permitting user selectible resolution (>1 to <100 μs/bit) and asynchronous access to the stored data by the controlling computer. The flexibility of this device and its ability to collect data autonomously make it extremely useful in a wide variety of sensory and behavioural neurophysiological experiments.
An effective lagrangian with broken scale and chiral symmetry applied to nuclear matter and finite nuclei

Abstract We study nuclear matter and finite nuclei in the mean field approximation with a chiral lagrangian which generalizes the linear σ model and also accounts for the QCD trace anomaly by means of terms which involve the σ and π fields as well as the glueball field φ. The scale invariant term which leads to an omega meson mass, after symmetry breaking, is strongly favored to be of the form ω μ ω μ φ 2 by the bulk properties of nuclei; they also rather strongly constrain the other parameters. A reasonable description of the closed shell nuclei oxygen, calcium and lead can be achieved and this can be improved by including a term( ω μm ω μm ) 2 in the lagrangian. This leads to a level of agreement with the data that is comparable to that of the nonlinear Walecka model.
Corrosion in the Oil and Gas Industry: An Increasing Challenge for Materials

Important reserves of oil and gas, which are left to be discovered and produced, are mainly concentrated in challenging locations and under severe conditions [i.e., high pressure (HP)/high temperature (HT)]. The HP/HT plus the presence of aggressive environments mean a highly demanding scenario for tubes used in producing oil and gas [oil country tubular goods (OCTG)]. Material property requirements include high mechanical properties at ambient and high temperatures (e.g., as high up to 200–250°C). Additionally, if H2S is present, resistance to sulfide stress cracking may be required, depending also on other environmental conditions. Even without H2S, contents of CO2, chlorides, and high temperatures and pressures can represent a risk of high corrosion rates. The improvement of some of the required properties of the materials (e.g., steels) can mean the impairment of other properties. Consequently, a careful balance is required and limits exist for the individual modification of the properties. The present article focuses on the two main environmental deterioration problems in the oil and gas business: (I) sulfide stress cracking and (II) CO2 corrosion. A description of the acting mechanisms and the effect of environmental and material factors are presented. Selection criteria and current material limitations are also discussed.
Discrete Morse theory and graph braid groups

If is any finite graph, then the unlabelled configuration space of n points on , denoted U C n , is the space of n-element subsets of . The braid group of on n strands is the fundamental group of U C n . We apply a discrete version of Morse theory to these U C n , for any n and any , and provide a clear description of the critical cells i n every case. As a result, we can calculate a presentation for the braid group of any tree, for any number of strands. We also give a simple proof of a theorem due to Ghrist: the space U C n strong deformation retracts onto a CW complex of dimension at most k, where k is the number of vertices in of degree at least 3 (and k is thus independent of n). AMS Classification 20F65, 20F36; 57M15, 57Q05, 55R80
Thermalization of field driven quantum systems

There is much interest in how quantum systems thermalize after a sudden change, because unitary evolution should preclude thermalization. The eigenstate thermalization hypothesis resolves this because all observables for quantum states in a small energy window have essentially the same value; it is violated for integrable systems due to the infinite number of conserved quantities. Here, we show that when a system is driven by a DC electric field there are five generic behaviors: (i) monotonic or (ii) oscillatory approach to an infinite-temperature steady state; (iii) monotonic or (iv) oscillatory approach to a nonthermal steady state; or (v) evolution to an oscillatory state. Examining the Hubbard model (which thermalizes under a quench) and the Falicov-Kimball model (which does not), we find both exhibit scenarios (i–iv), while only Hubbard shows scenario (v). This shows richer behavior than in interaction quenches and integrability in the absence of a field plays no role.
Stable Manifold Embeddings With Structured Random Matrices

The fields of compressed sensing (CS) and matrix completion have shown that high-dimensional signals with sparse or low-rank structure can be effectively projected into a low-dimensional space (for efficient acquisition or processing) when the projection operator achieves a stable embedding of the data by satisfying the Restricted Isometry Property (RIP). It has also been shown that such stable embeddings can be achieved for general Riemannian submanifolds when random orthoprojectors are used for dimensionality reduction. Due to computational costs and system constraints, the CS community has recently explored the RIP for structured random matrices (e.g., random convolutions, localized measurements, deterministic constructions). The main contribution of this paper is to show that any matrix satisfying the RIP (i.e., providing a stable embedding for sparse signals) can be used to construct a stable embedding for manifold-modeled signals by randomizing the column signs and paying reasonable additional factors in the number of measurements, thereby generalizing previous stable manifold embedding results beyond unstructured random matrices. We demonstrate this result with several new constructions for stable manifold embeddings using structured matrices. This result allows advances in efficient projection schemes for sparse signals to be immediately applied to manifold signal models.
Association between maternal urinary arsenic species and infant cord blood leptin levels in a New Hampshire Pregnancy Cohort.

Abstract Leptin is an important pleiotropic hormone involved in the regulation of nutrient intake and energy expenditure, and is known to influence body weight in infants and adults. High maternal levels of arsenic have been associated with reduced infant birth weight, but the mechanism of action is not yet understood. This study aimed to investigate the association between in utero arsenic exposure and infant cord blood leptin concentrations within 156 mother–infant pairs from the New Hampshire Birth Cohort Study (NHBCS) who were exposed to low to moderate levels of arsenic through well water and diet. In utero arsenic exposure was obtained from maternal second trimester urinary arsenic concentration, and plasma leptin levels were assessed through immunoassay. Results indicate that urinary arsenic species concentrations were predictive of infant cord blood leptin levels following adjustment for creatinine, infant birth weight for gestational age percentile, infant sex, maternal pregnancy-related weight gain, and maternal education level amongst 149 white mother–infant pairs in multivariate linear regression models. A doubling or 100% increase in total urinary arsenic concentration (iAs+MMA+DMA) was associated with a 10.3% (95% CI: 0.8–20.7%) increase in cord blood leptin levels. A 100% increase in either monomethylarsonic acid (MMA) or dimethylarsinic acid (DMA) was also associated with an 8.3% (95% CI: −1.0–18.6%) and 10.3% (95% CI: 1.2–20.2%) increase in cord blood leptin levels, respectively. The association between inorganic arsenic (iAs) and cord blood leptin was of similar magnitude and direction as other arsenic species (a 100% increase in iAs was associated with a 6.5% (95% CI: −3.4–17.5%) increase in cord blood leptin levels), albeit not significant. These results suggest in utero exposure to low levels of arsenic influences cord blood leptin concentration and presents a potential mechanism by which arsenic may impact early childhood growth.
Price formation in the OTC corporate bond markets: a field study of the inter-dealer market

Abstract Despite its importance the market-micro structure of the secondary market for corporate bonds remains something of a mystery. The major reason for this has been the OTC inter-dealer nature of this market. As far as we are aware this paper presents the first exploratory field study of the U.S. inter-dealer OTC corporate bond market. We construct a primary data-base from the trades of a major bond dealer and document the competitive structure of the market in terms of the number of active dealers and market trading mechanism. We find that the trading mechanism closely resembles a first-price sealed bid auction. We also examine the potential differences between segments of the market and develop a measure of competition based on the theory of auctions. Our measure indicates that competition is highest in US investment grade corporate bonds and lowest in junk bonds. We also examine the effect of the size of a trade on pricing and spreads.
Age Dating Ultraluminous Infrared Galaxies along the Merger Sequence

Imaging spectroscopy using the new Palomar Integral Field Spectrograph is presented for the Paα line in four ultraluminous infrared galaxies. The resulting integral field data cubes reveal line emission possessing a wide range of complex spatial morphologies, often quite different from the appearance of the continuum. The velocity fields are equally diverse in nature, often failing to resemble typical modes of galactic motion. We see a variety of interesting phenomena in the individual mergers including star formation rates of 2-5 M☉ yr-1 in young tidal tails; a postencounter disk that obeys the Tully-Fisher relation; a large-scale emission-line nebula possibly associated with a massive outflow; an apparently single merging system possessing two distinct kinematical axes belying the presence of a second galaxy, mostly obscured by its merging companion; and possible formation of tidal dwarf galaxies. In most cases, we are able to establish the geometry of the merger and thus estimate the time in the merger process at which we are viewing the system. The resulting range in estimated ages, some of which are very young encounters (~5 × 107 yr), is not predicted by merger models, which produce high rates of star formation either 1-2 × 108 yr after the first encounter or very late (~109 yr) in the merger process. Even in the very young mergers, despite a sample selection based on extended line emission, the ultraluminous activity appears to be centrally concentrated on the nucleus of one of the progenitor galaxies—namely, the galaxy with a prograde orbital geometry. The inferred extinction to these concentrations is high, usually at least 1 mag at the wavelength of Paα. The presence of a significant population of very young ultraluminous mergers, together with the majority of ultraluminous infrared galaxies existing in the final stages of merger activity, indicates that the ultraluminous galaxy phase is at least bimodal in time. An evolutionary scenario is proposed for ultraluminous infrared galaxies, wherein the far-infrared luminosity may undergo multiple ultraluminous bursts during the course of the encounter. A substantial fraction of the merger lifetime may be spent in a phase identified with the less powerful luminous infrared galaxy class.
Applying practice to theory

How can complexity theory and algorithms benefit from practical advances in computing? We give an overview of some prior work using practical computing to attack problems in computational complexity and algorithms, informally describe how linear program solvers may be used to help prove new lower bounds for satisfiability, and suggest a research program for developing new understanding in circuit complexity.
A Boltzmann machine for the organization of intelligent machines

A three-tier structure consisting of organization, coordination, and execution levels forms the architecture of an intelligent machine using the principle of increasing precision with decreasing intelligence from a hierarchically intelligent control. This system has been formulated as a probabilistic model, where uncertainty and imprecision can be expressed in terms of entropies. The optimal strategy for decision planning and task execution by the intelligent machine can be found by minimizing the total entropy in the system. The focus is on the design of the organization level of the intelligent machine as a Boltzmann machine, as described in current neural network literature. Since this level is responsible for planning the actions of the machine, the problem at this tier is formulated as the construction of the right sequence of tasks or events that minimizes the entropy for the desired action. The Boltzmann machine is reformulated to use entropy as the cost function to be minimized. Simulated annealing, expanding subinterval random search, and the genetic algorithm are presented as search techniques to efficiently find the desired action sequence. The genetic algorithm is modified to ensure convergence in probability to the minimum entropy of the system. Simulations of these algorithms are shown and performance is analyzed. >
Computational lattice-gas modeling of the electrosorption of small molecules and ions

Abstract We present two recent applications of lattice-gas modeling techniques to electrochemical adsorption on catalytically active metal substrates: urea on Pt(100) and (bi)sulfate on Rh(111). Both systems involve the specific adsorption of small molecules or ions on single-crystal electrodes, and they are characterized by a particularly good fit between the adsorbate geometry and the substrate structure. The close geometric fit facilitates the formation of ordered submonolayer adsorbate phases in a range of electrode potential positive of the range in which an adsorbed monolayer of hydrogen is stable. In both systems the ordered-phase region is separated from the adsorbed-hydrogen region by a phase transition, signalled in cyclic voltammograms by a sharp current peak. Based on data from in situ radiochemical surface concentration measurements, cyclic voltammetry, and scanning tunneling microscopy, and ex situ Auger electron spectroscopy and low-energy electron diffraction, we have developed specific lattice-gas models for the two systems. These models were studied by group-theoretical ground-state calculations and numerical Monte Carlo simulations, and effective lattice-gas interaction parameters were determined so as to provide agreement with the experimental results.
Transverse momentum analysis of collective motion in relativistic nuclear collisions

Abstract A novel transverse-momentum technique is used to analyse charged-particle exclusive data for collective motion in the Ar+KCl reaction at 1.8 GeV/nucleon. Previous analysis of this reaction, employing the standard sphericity tensor, revealed no significant effect. In the present analysis, collective effects are observed, and they are substantially stronger than in the Cugnon cascade model, but weaker than in the hydrodynamical model.
Radial Quantization in Rotating Space–Times

We examine the time discontinuity in rotating space–times for which the topology of time is S1. A kinematic restriction is enforced that requires the discontinuity to be an integral number of the periodicity of time. Quantized radii emerge for which the associated tangential velocities are less than the speed of light. Using the de Broglie relationship, we show that quantum theory may determine the periodicity of time. A rotating Kerr–Newman black hole and a rigidly rotating disk of dust are also considered; we find that the quantized radii do not lie in the regions that possess CTCs.
CONVERT: a high level translation definition language for data conversion

This paper describes in detail a translation definition language, CONVERT, for specifying the mapping of the instances of source items, which may be components of one or more files, into instances of target data, which may constitute multiple files.The language is designed for the class of users who are familiar with the logical aspects of their data, know what they want to be done, but do not want to be concerned with the details of how to accomplish it. It is high level and non-procedural according to current standards.The language provides very powerful and highly flexible restructuring capability. Although primarily designed for hierarchically structured data, it is applicable to other kinds of data structures as well. It is believed that the language can handle all common processes required in a data translation. Furthermore, the simple underlying concepts enable the users to visualize the translation processes, thus making data conversion a much simpler task. Examples to illustrate the languages' applications are included.
Pulmonary edema in severe preeclampsia-eclampsia: Analysis of thirty-seven consecutive cases

Abstract During approximately a 9-year period, 37 severe preeclamptic-eclamptic patients had pulmonary edema for an incidence of 2.9%. The incidence was significantly higher in older patients (p 530 1000 and neonatal morbidity was significant. Pulmonary edema is infrequent in severe preeclampsia-eclampsia without associated medical, surgical and obstetric complications. The occurrence of pulmonary edema in such patients is associated with high maternal and perinatal mortality and morbidity.
The Mars Water Cycle at Other Epochs: Recent History of the Polar Caps and Layered Terrain

A numerical model is presented of the integrated role of seasonal water cycle on the evolution of polar deposits on Mars over the last 10 million years. From the model, it is concluded that the only major difference between the polar caps which affects their long-term behavior is ultimately the difference in their elevations. Because of that difference, there is a preference for CO2 frost to stay longer on the northern polar cap. The average difference in sublimation at the caps results in a net south-to-north transport of water ice over long time scales. Superimposed on any long-term behavior is a transfer of water ice between the caps on the 10 exp 5 - 10 exp 6 yr time scales. The amount of water exchanged is small compared to the total ice content of the polar deposits.
Where CMOS is Going: Trendy Hype vs. Real Technology

Two important challenges facing Moore's Law and continued CMOS scaling are growing standby power dissipation and the increasing variability in device characteristics. Cooperative circuit/technology co-design and architectures developed in conjunction with new materials and device structures will provide a comprehensive solution to these challenges
Coordinating sensing and local navigation

Based on Navigation Templates (or NaTs), this work presents a new paradigm for local navigation which addresses the noisy and uncertain nature of sensor data. Rather than creating a new navigation plan each time the robot's perception of the world changes, the technique incorporates perceptual changes directly into the existing navigation plan. In this way, the robot's navigation plan is quickly and continuously modified, resulting in actions that remain coordinated with its changing perception of the world.
Spectroscopic Discovery of the Supernova 2003dh Associated with GRB 030329

We present early observations of the afterglow of GRB 030329 and the spectroscopic discovery of its associated supernova SN 2003dh. We obtained spectra of the afterglow of GRB 030329 each night from March 30.12 (0.6 days after the burst) to April 8.13 (UT) (9.6 days after the burst). The spectra cover a wavelength range of 350-850 nm. The early spectra consist of a power-law continuum (Fν ν-0.9) with narrow emission lines originating from H II regions in the host galaxy, indicating a low redshift of z = 0.1687. However, our spectra taken after 2003 April 5 show broad peaks in flux characteristic of a supernova. Correcting for the afterglow emission, we find that the spectrum of the supernova is remarkably similar to the Type Ic hypernova SN 1998bw. While the presence of supernovae has been inferred from the light curves and colors of gamma-ray burst afterglows in the past, this is the first direct, spectroscopic confirmation that a subset of classical gamma-ray bursts originate from supernovae.
Divisors of the Euler and Carmichael functions

Two of the most studied functions in the theory of numbers are Euler’s totient function φ(n) and Carmichael’s function λ(n), the first giving the order of the group (Z/nZ)∗ of reduced residues modulo n, and the latter giving the maximum order of any element of (Z/nZ)∗. The distribution of φ(n) and λ(n) has been investigated from a variety of perspectives. In particular, many interesting properties of these functions require knowledge of the distribution of prime factors of φ(n) and λ(n), e.g., [3], [5], [4], [6], [7], [12], [19]. The distribution of all of the divisors of φ(n) and λ(n) has thus far received little attention, perhaps due to the complicated way in which prime factors interact to form divisors. From results about the normal number of prime factors of φ(n) and λ(n) [5], one deduces immediately that τ(φ(n)) and τ(λ(n)) are each exp{ log 2 2 (log log n)} for almost all n. However, the determination of the average size of τ(φ(n)) and of τ(λ(n)) is more complex, and has been studied recently by Luca and Pomerance [13]. In this note we investigate problems about localization of divisors of φ(n) and λ(n). Our results have application to the structure of (Z/nZ)∗, since the set of divisors of λ(n) is precisely the set of orders of elements of (Z/nZ)∗. We say that a positive integer m is u-dense if whenever 1 ≤ y < m, there is a divisor of m in the interval (y, uy]. The distribution of u-dense numbers for general u has been investigated by Tenenbaum ([17], [18]) and Saias ([14], [15]). According to Theoreme 1 of [14], the number of u-dense integersm ≤ x is (x log u)/ log x, uniformly for 2 ≤ u ≤ x. In particular, the number of 2-dense integersm ≤ x is x/ log x, that is, the 2-dense integers are about as sparse as the primes. By contrast, we show that 2-dense values of φ(n) and λ(n) are very common.
Recent research related to the development of electrochromic windows

Abstract The results of recent research on each of the layers of a solid-state multilayer structure for electrochromic windows are reviewed. This includes a review of the requirements of the multilayer structure for building windows and especially the need to have an electrochemically balanched system. The results indicate that excess free electron scattering in polycrystalline WO 3 films (the electrochromatic layer) is not only the source of lower than desired reflectivity modulation, but it is also the major source of higher than desired absorptivity modulation. Research on LiAlF 4 indicates that it is a viable candidate for the ion conducting layer, being a good lithium ion conductor and a good electronic insulator. Finally, we have recently discovered that tin-doped and undoped In 2 O 3 films are mixed conductors, exhibiting lithium ion injection/extraction. This is significant since such films could possibly serve in the dual capacity of counterelectrode and transparent conductor, thereby reducing the complexity, the technical problems, and the cost of electrochromic window assemblies.
Synthesis and in vitro cancer cell growth inhibitory activity of monocyclic model compounds containing spongistatin triene side-chains

Two monosaccharides embodying triene side-chains of the spongistatins display significant in vitro activity against human cancer cell lines.
Dose-Response Effects of Zinc and Fluoride on Caries Lesion Remineralization

The present mechanistic in vitro study aimed to investigate dose-response effects of zinc and fluoride on caries lesion remineralization and subsequent protection from demineralization. Artificial caries lesions were created using a methylcellulose acid gel system. Lesions were remineralized for 2 weeks using citrate-containing artificial saliva which was supplemented with zinc (0–153 µmol/l) and fluoride (1.1 or 52.6 µmol/l) in a 7 × 2 factorial design. Lesions were also remineralized in the absence of zinc and citrate, but in the presence of fluoride. After remineralization, all lesions were demineralized for 1 day under identical conditions. Changes in mineral distribution characteristics of caries lesions after remineralization and secondary demineralization were studied using transverse microradiography. At 1.1 µmol/l fluoride, zinc exhibited detrimental effects on remineralization in a dose-response manner and mainly by preventing remineralization near the lesion surface. At 52.6 µmol/l fluoride, zinc retarded remineralization only at the highest concentration tested. Zinc enhanced overall remineralization at 3.8–15.3 µmol/l. At 76.5 and less so at 153 µmol/l, zinc showed extensive remineralization of deeper parts within the lesions at the expense of remineralization near the surface. Citrate did not interfere with remineralization at 1.1 µmol/l fluoride, but enhanced remineralization at 52.6 µmol/l fluoride. Lesions exhibiting preferential remineralization in deeper parts showed higher mineral loss after secondary demineralization, suggesting the formation of more soluble mineral phases during remineralization. In summary, zinc and fluoride showed synergistic effects in enhancing lesion remineralization, however only at elevated fluoride concentrations.
Gender differences in introductory university physics performance: The influence of high school physics preparation and affective factors

The attrition of females studying physics after high school is a growing concern to the science education community. Most undergraduate science programs require introductory physics coursework. Thus, success in introductory physics is usually necessary for students to progress to higher levels of science study. Success also influences attitudes; if females are well prepared, feel confident, and do well in introductory physics, they may be inclined to study physics further. This quantitative study using a hierarchical linear model focused on determining factors from high school physics preparation (content, pedagogy, and assessment) and the affective domain that predicted female and male performance in introductory university physics. The data analyzed came from 1973 introductory university physics surveys that included variables used as controls for student demographic and academic background characteristics. The results highlight high school physics and affective experiences that differentially predicted female and male performance. These experiences include learning requirements, long-written problems, cumulative tests/quizzes, father's encouragement, and family's belief that science leads to a better career. There were also factors that had a similar effect on female and male performance among which mathematics preparation was the overall strongest predictor of university physics performance. © 2007 Wiley Periodicals, Inc. Sci Ed91:847–876, 2007
Online learning in online auctions

We consider the problem of revenue maximization in online auctions, that is, auctions in which bids are received and dealt with one-by-one. In this paper, we demonstrate that results from online learning can be usefully applied in this context, and we derive a new auction for digital goods that achieves a constant competitive ratio with respect to the optimal (offline) fixed price revenue. This substantially improves upon the best previously known competitive ratio for this problem of O(exp(√log log h)). We also apply our techniques to the related problem of designing online posted price mechanisms, in which the seller declares a price for each of a series of buyers, and each buyer either accepts or rejects the good at that price. Despite the relative lack of information in this setting, we show that online learning techniques can be used to obtain results for online posted price mechanisms which are similar to those obtained for online auctions.
Extremal graphs without 4-cycles

We prove an upper bound for the number of edges a C"4-free graph on q^2+q vertices can contain for q even. This upper bound is achieved whenever there is an orthogonal polarity graph of a plane of even order q.
Relationship Between Stagnation Point Deflection and Forebody Vortex Asymmetry

The asymmetry in the vortex patterns in a cross-flow plane near the wing-body juncture is related to the stagnant point displacement. For the first time, the time scale of this response is captured. This is done by analyzing digitized video images of the stagnation point actuator (SPA) motion and the asymmetry in the vortex pattern and constructing a time series spanning several seconds. The resulting time series is sampled, transformed to the frequency domain, and analyzed by standard methods in digital signal processing to compute the autospectra, the cross spectrum, the coherence function, and the complex transfer function
Planar Collimated Illumination System Using Nano-Hybrid Low Index Materials

A nano hybrid organo silicate material system is successfully used to realize a planar area illumination system with a highly collimated light output.
Long-wavelength GaInNAs(Sb) lasers on GaAs

The boom in fiber-optic communications has caused a high demand for GaAs-based lasers in the 1.3-1.6-/spl mu/m range. This has led to the introduction of small amounts of nitrogen into InGaAs to reduce the bandgap sufficiently, resulting in a new material that is lattice matched to GaAs. More recently, the addition of Sb has allowed further reduction of the bandgap, leading to the first demonstration of 1.5-/spl mu/m GaAs-based lasers by the authors. Additional work has focused on the use of GaAs, GaNAs, and now GaNAsSb barriers as cladding for GaInNAsSb quantum wells. We present the results of photoluminescence, as well as in-plane lasers studies, made with these combinations of materials. With GaNAs or GaNAsSb barriers, the blue shift due to post-growth annealing is suppressed, and longer wavelength laser emission is achieved. Long wavelength luminescence out to 1.6 /spl mu/m from GaInNAsSb quantum wells, with GaNAsSb barriers, was observed. In-plane lasers from these samples yielded lasers operating out to 1.49 /spl mu/m, a minimum threshold current density of 500 A/cm/sup 2/ per quantum well, a maximum differential quantum efficiency of 75%, and pulsed power up to 350 mW at room temperature.
Hereditary systemic immunoglobulin light-chain amyloidosis

Several members of a family died from renal failure as a result of systemic amyloidosis. Extensive studies to detect previously documented gene mutations associated with amyloidosis failed to identify a causative factor. In search of the genetic basis for this syndrome, amyloid fibrils were isolated from renal tissue of a member of the kin who died while on renal dialysis. Amino acid sequencing of isolated amyloid protein identified sequences compatible with the constant region of the immunoglobulin κ light-chain. Isolation and characterization of κ light-chain protein from serum of an affected member of the kindred revealed mutation in the constant region of κ light-chain, with cysteine replacing serine at amino acid residue 131. This mutation (Ser131Cys) was confirmed by DNA analysis, which identified a single-base change of cytosine to guanine at the second position of codon 131 of the κ light-chain gene (TCT131TGT). DNA analysis of members of the extended family revealed transmission of the Ser131Cys mutation and association with systemic amyloidosis. This amyloid light-chain (AL) amyloidosis, which is a hereditary type of amyloidosis and not the result of a monoclonal plasma cell dyscrasia, may be misdiagnosed and lead to inappropriate chemotherapy.
Artificial Urinary Sphincter: Lessons Learned

Since its introduction in 1973 (American Medical Systems [AMS] model 721), the artificial urinary sphincter (AUS) has become a widely accepted therapy, particularly for male urinary incontinence. Over the years, improvements in product design, surgical techniques, and patient selection have led to increased reliability with durable success. The current American Medical Systems model 800 (AMS 800) AUS was introduced in 1983 and has a 20-year history of use. This device has become the gold-standard treatment for incontinence of many causes, including prostatectomy, radiation therapy, neuropathy, and as a part of reconstructive procedures. Outcomes with the device are excellent, and most patients are pleased with the results, an outcome that persists in the long term [1–3]. The authors review their experience with more than 600 AUS devices and discuss practical points concerning surgery and revisions. They describe their routine surgical approach as a means of reporting on technical lessons learned. Preoperative evaluation Evaluation of patients for treatment with an AUS starts with a comprehensive office visit, including taking a history and performing a physical examination, urinalysis, and urine culture. Each patient completes a 72-hour voiding diary and a 24-hour urinary pad weight test that is brought to the office visit. The pad-weight study is an invaluable objective measure of the magnitude of the incontinence. During the office visit, videourodynamics are performed. This step, along with the voiding diary and patient history, helps confirm the factors contributing to the incontinence and identifies factors that may mitigate against a good outcome. Some investigators have suggested that urodynamic study is superfluous to the selection of the patient for implantation, but the authors disagree. Cystoscopy is performed in all patients to evaluate the urethra for a healthy placement site and to exclude urethral strictures and anastomotic contracture.
Nurse-administered intravitreal injections: a systematic review

Dear Editor: The growing elderly population and prevalence of diabetes mellitus have increased the number of patients with exudative age-related macular degeneration (AMD) and diabetic macular edema (DME) [1–4]. This has created a need to explore more cost-effective methods of delivering anti-vascular endothelial growth factor (VEGF) therapy [5]. One approach is to use nurses instead of physicians to administer the intravitreal injections of anti-VEGF agents. We have systemically reviewed the literature on the safety and efficacy of this treatment model. We searched articles in PubMed, Medscape and Google Scholar for the terms “retina and nurses,” “nurse injection” and “demand for ophthalmologists” from 2006 to 2014. Our inclusion criterion was nurse administration of intravitreal injections. For each paper, we recorded the number of nurses administering the injections, the training received by nurses, the number of injections, and the length of the study. We determined safety through reported vision-threatening complications. We evaluated efficacy through reported measures of patient satisfaction and efficiency. Our search produced 20 publications; four met the inclusion criteria. All four studies described safety audits of nurseadministered intravitreal injections in the United Kingdom (UK); the studies’ salient features are outlined in Table 1. The previous experience and training of the nurse injectors and the number of initial injections they performed under direct supervision by an ophthalmologist varied in each study. In all studies, the ophthalmologists retained responsibility for diagnostic and therapeutic decisions. The study with the highest sample number (10,006 injections) over the longest duration (5.5 years) reported a 0.04 % rate of post-injection endophthalmitis [8]; the other studies reported no major adverse events. The three smaller studies [6, 7, 9] reported positive patient satisfaction surveys; the studies also reported improved clinic efficiency using measures such as increased mean number of injections over fewer injection clinic days, and improved patient access to injections with decreased wait time and increased access to retina specialists. The literature on nurse-administered intravitreal injections has several limitations. The small number of published studies and the localization of research to the UK restricted the generalizability of study findings. Additionally, the variability in nurse training and in measuring clinic efficiency precluded definitive conclusions regarding the most appropriate training for nurse injectors or the efficacy of nurse-versus-physician-administered injections. These limitations notwithstanding, the use of nurses to administer intravitreal injections merits further study, especially in healthcare settings outside the UK. Presentation This work was submitted for presentation at the Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting, 3–7 May 2015, in Denver, Colorado, USA. E. Li : P. B. Greenberg Division of Ophthalmology, The Warren Alpert Medical School of Brown University, Providence, RI, USA
Navier-Stokes Computations for a Spinning Projectile from Subsonic to Supersonic Speeds

A computational study has been undertaken to predict the static-aerodynamic, Magnus-moment, and roll-damping coefficients of a standard spinning projectile using a single, modern, unstructured Navier-Stokes flow solver. Numerical results without engraving and semi-empirical results have been obtained for a wide range of Mach numbers to include subsonic, transonic, and supersonic flight regimes. Effects of 0-, 2-, and 5-deg angles of attack have been investigated. Flowfield characteristics of each flight regime are briefly explored. A comparison of coefficients calculated from the computational fluid dynamics results are made to both experimental range data as well as semi-empirical aeroprediction code results with some success. Good predictive capabilities are found for the static aerodynamic coefficients throughout all of the flight regimes. Discrepancies arise between the computational results and the experimental results for the Magnus moment and roll-damping coefficients due in part to the lack of engraving on the computational model.
The toric Hilbert scheme of a rank two lattice is smooth and irreducible

The toric Hilbert scheme of a lattice L ⊆Zn is the multigraded Hilbert scheme parameterizing all homogeneous ideals I in S = k[x1,...,xn] such that the Hilbert function of the quotient S/I has value one for every g in the grading monoid G+ = Nn/ L. In this paper we show that if L is two-dimensional, then the toric Hilbert scheme of L is smooth and irreducible. This result is false for lattices of dimension three and higher as the toric Hilbert scheme of a rank three lattice can be reducible.
Displacement Interaction and Surface Curvature Effects on Hypersonic Boundary Layers

The title problem was studied employing implicit finite-difference methods to obtain numerical solutions to a composite set of boundary-layer equations valid to second order. Results are given for flow up a two-dimensional cubic compression ramp for free-stream Mach numbers of 6, 8, and 12.25 and for free-stream Re/inch equal to 85,800 and 25,800 at a wall-to-stagnation temperature ratio of 0.223. Comparisons with independent theories and experimental results are given. Nonsingular separation was produced at a free-stream Mach number of 12.25. For all cases considered, displacement and curvature effects canceled one another when a consistent treatment of inviscid and viscous curvature corrections was employed - the second-order theory virtually reproducing the first-order results.
Rationality in families of threefolds

We prove that in a family of projective threefolds defined over an algebraically closed field, the locus of rational fibers is a countable union of closed subsets of the locus of separably rationally connected fibers. When the ground field has characteristic zero, this implies that the locus of rational fibers in a smooth family of projective threefolds is the union of at most countably many closed subfamilies.
Learning, monetary policy rules, and macroeconomic stability

Abstract Several papers have documented a regime switch in US monetary policy from ‘passive’ and destabilizing in the pre-1979 period to ‘active’ and stabilizing afterwards. These studies typically work with DSGE models with rational expectations. This paper relaxes the assumption of rational expectations and allows for learning instead. Economic agents form expectations from simple models and update the parameters through constant-gain learning. In this setting, the paper aims to test whether monetary policy may have been a source of macroeconomic instability in the 1970s by inducing unstable learning dynamics. The model is estimated by Bayesian methods. The constant-gain coefficient is jointly estimated with the structural and policy parameters in the system. The results show that monetary policy was respecting the Taylor principle also in the pre-1979 period and, therefore, did not trigger macroeconomic instability.
Putting string / string duality to the test

After simultaneous compactification of spacetime and worldvolume on K3, the D = 10 heterotic fivebrane with gauge group SO(32) behaves like a D = 6 heterotic string with gauge group SO(28) × SU(2), but with Kac-Moody levels different from those of the fundamental string. Thus the string/ fivebrane duality conjecture in D = 10 gets replaced by a string/string duality conjecture in D = 6. Since D = 6 strings are better understood than D = 10 fivebranes, this provides a more reliable laboratory in which to test the conjecture. According to string/string duality, the Green-Schwarz factorization of the D = 6 spacetime anomaly polynomial I8 intoX4X44 means that just as X4 is the σ-model anomaly polynomial of the fundamental string worldsheet so X4 should be the corresponding polynomial of the dual string worldsheet. To test this idea we perform a classical dual string calculation of 94 and find agreement with the quantum fundamental string result. This also provides an a posteriori justification for assumptions made in a previous paper on string/fivebrane duality. Finally we speculate on the relevance of string/string duality to the vacuum degeneracy problem.
Chemistry, bonding and fracture of grain boundaries in Ni3Si

The chemistry and electronic structure at grain boundaries in B-free and B-doped Ni-23 at.% Si alloys were examined, with energy dispersive X-ray spectroscopy (EDX) providing information on the former and electron energy loss spectroscopy (EELS) on the latter. Ni-enrichment was seen at large angle boundaries, both in the absence and presence of B. EELS of the Ni L{sub 3} edge showed that the bonding at Ni-rich grain boundaries was similar in both undoped and doped alloys. Comparison of the Ni L{sub 3} edge recorded at the grain boundary and in the bulk suggests that reduced hybridization and weaker bonding occurs at Ni-rich grain boundaries in both doped and undoped alloys. These changes in bonding are interpreted in terms of changes in the cohesive energy of the boundaries. The relationship between the cohesive energy of grain boundaries and the fracture mode of Ni{sub 3}Si is discussed.
Preparation and reactions of tricarbonyl(3-trimethylstannylcycloheptadienyl)iron hexafluorophosphate and tricarbonyl(3-trimethylsilylcycloheptadienyl)iron hexafluorophosphate

The preparation of tricarbonyl(2-trimethylstannylcycloheptadiene)iron and tricarbonyl(2-trimethylsilylcycloheptadiene)iron is described. Hydride abstraction from these complexes, using triphenylmethyl hexafluorophosphate, leads to tricarbonyl(3-trimethyl-stannyl- and -silyl-cycloheptadienyl)iron complexes. Reaction of the trimethylstannyl-substituted dienyl complex with enolate nucleophiles gives the expected addition products, together with almost equal amounts of diene-Fe(CO)3 complexes resulting from a nucleophile addition/protiodestannylation reaction. The trimethylsilylcycloheptadienyl complex is better behaved, giving good yields of nucleophile addition products. Cyanide anion adds to this complex to give exclusively the C(1) addition product, in contrast to tricarbonylcycloheptadienyliron cation, which gives mixtures of C(1) and C(2) addition products. Treatment of tricarbonyl(5-methyl-3-trimethylsilylcyclohepta-1,3-diene)iron with triphenylmethyl hexafluorophosphate resulted in loss of a methyl group to give tricarbonyl(3-trimethylsilylcycloheptadienyl)iron hexafluorophosphate, a highly unusual reaction.