cssi/SciSciGPT-SciSciNet huggingface dataset:
End-to-end joint antenna selection strategy and distributed compress and forward strategy for relay channels

Multihop relay channels use multiple relay stages, each with multiple relay nodes, to facilitate communication between a source and destination. Previously, distributed space-time codes were proposed to maximize the achievable diversity-multiplexing tradeoff; however, they fail to achieve all the points of the optimal diversity-multiplexing tradeoff. In the presence of a low-rate feedback link from the destination to each relay stage and the source, this paper proposes an end-to-end antenna selection (EEAS) strategy as an alternative to distributed space-time codes. The EEAS strategy uses a subset of antennas of each relay stage for transmission of the source signal to the destination with amplifying and forwarding at each relay stage. The subsets are chosen such that they maximize the end-to-end mutual information at the destination. The EEAS strategy achieves the corner points of the optimal diversity-multiplexing tradeoff (corresponding to maximum diversity gain and maximum multiplexing gain) and achieves better diversity gain at intermediate values of multiplexing gain, versus the best-known distributed space-time coding strategies. A distributed compress and forward (CF) strategy is also proposed to achieve all points of the optimal diversity-multiplexing tradeoff for a two-hop relay channel with multiple relay nodes.
The physician–patient relationship: the impact of patient‐obtained medical information

We investigate the impact of patient-obtained medical information (POMI) on the physician–patient relationship when patients, as a group, are heterogeneously informed and a physician's interests do not coincide with those of her patients. Introducing additional well-informed patients to the population discontinuously affects the physician's strategy, having no effect unless a sufficient quantity is added. When few patients are well informed, increasing the precision of their information level has no effect on the physician's strategy. Alternately, when a sufficient number of well-informed patients exists, increasing the precision of their information allows all patients to free-ride by receiving more appropriate treatment recommendations. Counterintuitively, we also identify circumstances under which increasing the general level of information may potentially harm patients. Copyright © 2006 John Wiley & Sons, Ltd.
Random manifolds in non-linear resistor networks: applications to varistors and superconductors

We show that current localization in polycrystalline varistors occurs on paths which are usually in the universality class of the directed polymer in a random medium. We also show that, in ceramic superconductors, voltage localizes on a surface which maps to an Ising domain wall. The emergence of these manifolds is explained and their structure is illustrated using direct solution of non-linear resistor networks.
Trade credit, international trade costs and exports: cross-country firm-level evidence

This article finds that firms’ trade credit, the financing provided by upstream input suppliers along the supply chain, plays an important role in determining firms’ exportation. In a panel data set of manufacturing firms in 25 Eastern European and Central Asian countries between 2001 and 2007, we employ international trade cost shocks to identify the causal impacts of trade credit on firms’ exportation. We find that when trade costs decline, firms with less trade credit increase their exports disproportionately more because of the alleviation of their financing burdens. Results are robust after controlling for bank and other financing channels, country financial development, and the endogeneity of trade credit. Our findings contribute to the empirical identification of financial frictions on firms’ exports and to the role of trade credit on firms’ performance.
Determinants of the Hypergeometric Period Matrices of an Arrangement and its Dual

We fix three natural numbers k, n, N, such that n+k+1 = N, and introduce the notion of two dual arrangements of hyperplanes. One of the arrangements is an arrangement of N hyperplanes in a k-dimensional affine space, the other is an arrangement of N hyperplanes in an n-dimensional affine space. We assign weights α1, . . . , αN to the hyperplanes of the arrangements and for each of the arrangements consider the associated period matrices. The first is a matrix of k-dimensional hypergeometric integrals and the second is a matrix of n-dimensional hypergeometric integrals. The size of each matrix is equal to the number of bounded domains of the corresponding arrangement. We show that the dual arrangements have the same number of bounded domains and the product of the determinants of the period matrices is equal to an alternating product of certain values of Euler’s gamma function multiplied by a product of exponentials of the weights.
Kininase II (angiotensin converting enzyme) and endothelial cells in culture.

It is now well recognized that the lungs process the circulating vasoactive polypeptides, bradykinin and angiotensin I; the former being inactivated while the latter is activated (Ferreira & Vane, 1967; Ng & Vane, 1967; Ryan et al., 1968; 1970b, 1971, 1972). Previously (Ryan et al., 1968, 1969, 1970a & b, 1971; Smith & Ryan, 1972, 1973a), we have postulated that the enzymes responsible for the metabolism of these polypeptides are situated on or close to the luminal surface of the pulmonary endothelial cells. Over the past seven years much evidence from our laboratory (see references above) and those of others (Bakhle, 1968; Sander & Huggins, 1971; Lanzillo & Fanburg, 1974; Soffer et al., 1974) have supported this hypothesis. Recently (Dorer et al., 1972, 1974) have shown that the enzyme that activates angiotensin I (by conversion to angiotensin II) is also responsible in part for the inactivation of bradykinin. As described in the accompanying paper (Ryan, J.W., this volume), we have raised antibodies to this enzyme and are using the antibodies labelled for immunocytochemistry in efforts to provide a definitive test of our hypothesis. This report represents a fine focus on the localization of kininase II using a specific cell type in culture namely, pulmonary endothelial cells.
Intrinsic Volumes of the Brownian Motion Body

Motivated from Gaussian processes, we derive the intrinsic volumes of the infinite-dimensional Brownian motion body . The method is by discretization to a class of orthoschemes. Numerical support is offered for a conjecture of Sangwine-Yager, and another conjecture is offered on the rate of decay of intrinsic volume sequences.
Effect of Differential Rotation on the Maximum Mass of Neutron Stars: Realistic Nuclear Equations of State

The merger of binary neutron stars is likely to lead to differentially rotating remnants. In this paper, we survey several cold nuclear equations of state (EOSs) and numerically construct models of differentially rotating neutron stars in general relativity. For each EOS we tabulate maximum allowed masses as a function of the degree of differential rotation. We also determine effective polytropic indices and compare the maximum allowed masses with those for the corresponding polytropes. We consistently find larger mass increases for the polytropes, but even for the nuclear EOSs we typically find maximum masses 50% higher than the corresponding values for nonrotating (Tolman-Oppenheimer-Volkoff) stars. We evaluate our findings for the six observed binary neutron star (pulsar) systems, including the recently discovered binary pulsar J0737-3039. For each EOS we determine whether their merger could automatically lead to prompt collapse to a black hole, or whether the remnant can be supported against collapse by uniform rotation (possibly as a supramassive star) or differential rotation (possibly as a hypermassive star). For hypermassive stars, delayed collapse to a black hole is likely. For the most recent EOSs we survey the merger remnants can all be supported by rotation against prompt collapse, but their actual fate will depend on the nonequilibrium dynamics of the coalescence event. Gravitational wave observations of coalescing binary neutron stars may be able to distinguish these outcomes—no, delayed, or prompt collapse—and thereby constrain possible EOSs.
Time-dependent particle production and particle number in cosmological de Sitter space

In this paper, we consider the occupation number of induced quasi-particles which are produced during a time-dependent process using three different methods: Instantaneous diagonalization, the usual Bogolyubov transformation between two different vacua (more precisely the instantaneous vacuum and the so-called adiabatic vacuum), and the Unruh–DeWitt detector methods. Here we consider the Hamiltonian for a time-dependent Harmonic oscillator, where both the mass and frequency are taken to be time-dependent. From the Hamiltonian we derive the occupation number of the induced quasi-particles using the invariant operator method. In deriving the occupation number we also point out and make the connection between the Functional Schrodinger formalism, quantum kinetic equation, and Bogolyubov transformation between two different Fock space basis at equal times and explain the role in which the invariant operator method plays. As a concrete example, we consider particle production in the flat FRW chart of de Sitter...
A Life Study of AISI M-50 and Super Nitralloy Spur Gears With and Without Tip Relief

Tests were conducted at 350 K (170 deg F) with groups of 8.9 cm (3.5-in.)-pitch-diameter spur gear with and without tip relief made of consumable-electrode vacuum melted (CVM) Super Nitralloy (5Ni-2Al) and CVM AISI M-50 steel. The AISI M-50 gears without tip relief had lives approximately 50 percent longer than the Super Nitralloy gears without tip relief. However, the Super Nitralloy gears with tip relief had lives equal to the AISI M-50 gears without tip relief. The difference in lives were not statistically significant. All gears failed by classical pitting fatigue at the pitch circle. However, the AISI M-50 gears with tip relief failed by tooth fracture. AISI M-50 gear sets without tip relief having a spalled gear tooth which were deliberately overrun after spalling had occurred, failed by tooth fracture.
Decomposition of CO2 on (100) W

Abstract The binding states and condensation kinetics of CO 2 and its decomposition products CO and O 2 on (100) W are examined by flash desorption mass spectrometry. Carbon dioxide desorbs almost entirely as CO and oxygen at all coverages. At saturation there are three major states of CO. These correspond to the high temperature states of CO alone although all peaks are shifted and amounts are altered slightly. Carbon monoxide exhibits four major binding states. All of these obey first order desorption kinetics as expected except the most tightly bound state which obeys second order kinetics. Desorption from a bimolecular complex is postulated to explain these results. Initial sticking coefficients of CO 2 , CO, and O 2 at 300°K are 0.85, 0.49, and 1.0 respectively. Coverage dependences indicate precursor intermediates for the states occupied at low coverages. The initial sticking coefficient of CO 2 varies rather slowly with substrate temperature, falling to 0.3 at 1200°K.
Editing by example

An editing by example system is an automatic program synthesis facility embedded in a text editor that can be used to solve repetitive text editing problems. The user provides the editor with a few examples of a text transformation. The system analyzes the examples and generalizes them into a program that can perform the transformation to the rest of the user's text. This paper presents an overview of the design, analysis, and implementation of a practical editing by example system. It studies the problem of synthesizing a text processing program that generalizes the transformation implicitly described by a small number of input/output examples. A class of text processing programs called gap programs is defined and the problems associated with synthesizing them from examples are examined, leading to an efficient heuristic that provably synthesizes a gap program from examples of its input/output behavior. The editing by example system derived from this analysis has been embedded in a production text editor. By developing an editing by example system that solves a useful class of text processing problems, this work demonstrates that program synthesis is feasible in the domain of text editing.
An experimental economics approach toward quantifying online privacy choices

The importance of personal privacy to Internet users has been extensively researched using a variety of survey techniques. The limitations of survey research are well-known and exist in part because there are no positive or negative consequences to responses provided by survey participants. Such limitations are the motivation for this work. Experimental economics is widely accepted by economists and others as an investigative technique that can provide measures of economic choice-making that are substantially more accurate than those provided by surveys. This paper describes our efforts at applying the techniques of experimental economics to provide a foundation for (a) estimating the values that consumers place on privacy and various forms of security (encryption, HIPAA, etc.) and for (b) quantifying user responses to changes in the Internet environment. The contribution of this study is a better understanding of individual decision-making in the context of benefits and costs of making private information available to Internet sites. Preliminary results from a series of pilot studies are consistent with optimizing behaviors, indicating that continued application of experimental economics techniques in the quantification of Internet user actions in privacy/security space will be illuminating. Our results show that Internet users place great value on security measures, both regulatory and technical, that make identity theft much less likely. Our Web-based experiments indicate that privacy- and security- enhancing protections are likely to be subject to moral hazard responses, as participants in our online experiments became more aggressive in their Internet usage with greater protection in place.
The Effect of Patients' Noncompliance on Their Surgeons' Obligations

I recently had an instructive encounter with the word, ‘‘obligation.’’ Senior medical students had met, heard, and interacted with Paul Farmer, the Tanner Lecturer on human values. Dr. Farmer is an internationally respected physician who has dedicated his life and work to treatment of people in the developing world. More students than could be accommodated responded when invited to have lunch with Dr. Farmer. They eagerly queried him about opportunities to work with underserved populations. The next week in the Medical Ethics course, I asked all 104 students if they believed they had any obligation to serve the world’s poorest and most vulnerable populations. I was stunned when no one raised a hand. I acknowledged my surprise and asked them to share their reaction to the question. Many of them expressed interest, willingness, desire, and even a plan to do some medical service in the Third World. All of them, however, took issue with the concept of obligation. They were looking forward to their medical independence and freedom from the regimentation of medical school and the constraints of residency. Maybe it was the added awareness of their enormous loans, but ‘‘obligation’’ triggered strong negative reactions. They recognized that they were obliged to complete residencies to practice medicine, but they did not recognize a universal obligation to serve any particular patient or patient population. They resented the idea that others expected or asserted such a duty. These soon-to-be physicians were young and inexperienced. They had not yet sworn any oaths, received their licenses, or signed any contracts. Nevertheless, their reactions and comments made me realize that I may have made some assumptions about physicians’ obligations to patients that were not widely shared and perhaps not well supported. They reminded me that physicians value their freedom, autonomy, and authority, and do
Influence of Nozzle Geometry on the Noise of High-Speed Jets

The effectiveness of jet noise reduction by the use of different nozzle exit geometry is examined. Because there will be thrust loss associated with a nozzle of complex geometry, consideration is confined to practical configurations with reasonably small thrust loss. Only jets with a single stream are considered. The nozzle configurations examined are circular, elliptic, and rectangular. Plug nozzles as well as a suppressor nozzle are included. It is shown that the measured turbulent mixing noise of the jets from these nozzles consists of two independent components. The noise spectrum of each component is found to fit the shape of a seemingly universal similarity spectrum. It is also found that the maximum levels of the fitted noise power spectra of the jets are nearly the same. This finding suggests that nozzle geometry modification may not be an effective method for jet noise suppression.
Optical Spectroscopic Survey of High-latitude WISE-selected Sources

We report on the results of an optical spectroscopic survey at high Galactic latitude (|b| ≥ 30°) of a sample of WISE-selected targets, grouped by WISE W1 (λ_eff = 3.4 μm) flux, which we use to characterize the sources WISE detected. We observed 762 targets in 10 disjoint fields centered on ultraluminous infrared galaxy candidates using DEIMOS on Keck II. We find 0.30 ± 0.02 galaxies arcmin–2 with a median redshift of z = 0.33 ± 0.01 for the sample with W1 ≥ 120 μJy. The foreground stellar densities in our survey range from 0.23 ± 0.07 arcmin–2 to 1.1 ± 0.1 arcmin–2 for the same sample. We obtained spectra that produced science grade redshifts for ≥90% of our targets for sources with W1 flux ≥120 μJy that also had an i-band flux gsim 18 μJy. We used this for targeting very preliminary data reductions available to the team in 2010 August. Our results therefore present a conservative estimate of what is possible to achieve using WISE's Preliminary Data Release for the study of field galaxies.
Socially Optimal Charging Strategies for Electric Vehicles

Electric vehicles represent a promising technology for reducing emissions and dependence on fossil fuels, and have started entering different automotive markets. In order to bolster their adoption by consumers and hence enhance their penetration rate, a charging station infrastructure needs to be deployed. This paper studies decentralized policies that assign electric vehicles to a network of charging stations with the goal to achieve little to no queueing. This objective is especially important for electric vehicles, whose charging times are fairly long. The social optimality of the proposed policies is established when each station is equipped with multiple charging slots. Further, convergence issues of the algorithm that achieves the optimal policy are examined. The results provide insight into the optimal location deployment of the charging infrastructure.
Bonus Symmetry and the Operator Product Expansion of N=4 Super-Yang-Mills

Abstract The superconformal group of N = 4 super-Yang-Mills has two types of operator representations: short and long. We conjecture that operator product expansions for which at least two of the three operators are short exactly respect a bonus U (1) y R-symmetry, which acts as an automorphism of the superconformal group. This conjecture is for arbitrary gauge group G and gauge coupling g YM . A consequence is that n ⩽ 4-point functions involving only short operators exactly respect the U (1) Y symmetry, as has been previously conjectured based on AdS duality. This, in turn, would imply that all n ⩽ 3-point functions involving only short operators are not renormalized, as has also been previously conjectured and subjected to perturbative checks. It is argued that instantons are compatible with our conjecture. Some perturbative checks of the conjecture are presented and SL(2, Z ) modular transformation properties are discussed.
Production in Entrepreneurial Firms: The Effects of Financial Constraints on Labor and Capital

I model the contrasting capital-labor decisions of financially constrained and unconstrained firms. I show that financially restricted firms use relatively more labor than physical capital because informed employees provide more efficient financing than uninformed capital suppliers. I demonstrate that constrained firms cannot easily attract new employees to replace existing staff. Their greater employee retention aligns owner-worker incentives and encourages workers to make firm-specific investments. Constrained firms, however, gradually suffer from their inability to replace low-quality workers, such that their relative labor productivity decreases over time. Empirical tests utilizing instrumental variables confirm several implications of the theory.
Renormalizability Properties of Supergravity

The possible local counterterms in supergravity are investigated to all loop orders. Supersymmetry implies that (1) supergravity-matter coupling is one-loop nonrenormalizable, with a specific counterterm; (2) pure supergravity is renormalizable at both one and two loops; (3) it fails at three loops; (4) extended supergravity models may avoid the three-loop catastrophe, and have no dangerous local counterterms to any order. In that case, the nonleading divergences could be removed by field redefinitions, which would establish renormalizability for these systems.
Static solutions for brane models with a bulk scalar field

Abstract We present static solutions of the 5-dimensional Einstein equations in the brane-world scenario by using two different approaches for the stabilization of the extra dimension. Assuming a “phenomenological” stabilization mechanism, that creates a non-vanishing T 5 5 in the bulk, we construct a two-brane model, which allows both branes to have positive self-energies. We then consider a candidate theory for the dynamical stabilization, through the introduction of a massless scalar field in the bulk, which interacts with the branes. We find exact static solutions for the metric and scalar field in the bulk and demonstrate that the inter-brane distance is determined by the parameters of scalar field-brane interactions. However, these solutions are always accompanied by a correlation between the bulk cosmological constant, the brane self-energies and the interaction terms of the scalar field with the branes and thus cannot be considered as candidates for the phenomenologically viable stabilized geometry. We find that the aforementioned correlation cannot be avoided even in the case of a single-brane solution with positive self-energy where the fifth dimension ends on a singularity.
A non-additive decision-aid for venture capitalists' investment decisions

The current study uses theory from the resource-based view of strategy to hypothesize that VCs use non-additive decision policies when making their investment decision. A policy capturing experiment finds that VCs do indeed use non-additive decision policies. Specifically, we find that interactions between leadership experience and other internal resources, and between leadership experience and environmental munificence, affect venture capitalists' decision-making. Although venture capitalists always prefer greater general experience in leadership, they value it more highly in large markets, when there are many competitors, and when the competitors are relatively weak. Previous start-up experience of the venture's management team may substitute for leadership experience. Building on these results, we tested a main-effects-only decision-aid and a decision-aid that included interaction terms (non-additive) and found that both outperformed VCs' own decisions.
String-gauge dual description of deep inelastic scattering at small-x

The AdS/CFT correspondence in principle gives a new approach to deep inelastic scattering as formulated by Polchinski and Strassler. Subsequently Brower, Polchinski, Strassler and Tan (BPST) computed the strong coupling kernel for the vacuum (or Pomeron) contribution to total cross sections. By identifying deep inelastic scattering with virtual photon total cross section, this allows a self consistent description at small-x where the dominant contribution is the vacuum exchange process. Here we formulate this contribution and compare it with HERA small-x DIS scattering data. We find that the BPST kernel along with a very simple local approximation to the proton and current “wave functions” gives a remarkably good fit not only at large Q 2 dominated by conformal symmetry but also extends to small Q 2, supplemented by a hard-wall cut-off of the AdS in the IR. We suggest that this is a useful phenomenological parametrization with implications for other diffractive processes, such as double diffractive Higgs production.
Tight Hamilton cycles in random uniform hypergraphs

In this paper we show that 1=n is the asymptotic threshold for the existence of tight Hamilton cycles in random k-uniform hypergraphs, for all k � 3. We also determine thresholds for the existence of other types of Hamilton cycles.
An Anatomy of Trading Strategies

In this article we use a single unifying framework to analyze the sources of profits to a wide spectrum of returnbased trading strategies implemented in the literature. We show that less than 50% of the 120 strategies implemented in the article yield statistically significant profits and, unconditionally, momentum and contrarian strategies are equally likely to be successful. However, when we condition on the return horizon (short, medium, or long) of the strategy, or the time period during which it is implemented, two patterns emerge. A momentum strategy is usually profitable at the medium (3to 12-month) horizon, while a contrarian strategy nets statistically significant profits at long horizons, but only during the 19261947 subperiod. More importantly, our results show that the cross-sectional variation in the mean returns of individual securities included in these strategies plays an important role in their profitability. The cross-sectional variation can potentially account for the profitability of momentum strategies and it is also responsible for atten-
Observer-based control of systems with slope-restricted nonlinearities

An observer design is presented which makes use of bounds on the slope of system nonlinearities. Necessary and sufficient conditions are derived for the feasibility of the design. A class of state feedback control laws are characterized which, when implemented with the observer states, ensure global asymptotic stability. One such certainty-equivalence design is illustrated on an active magnetic bearing example.
Prevalence of dampness and mold in European housing stock

An assessment of the prevalence of dampness and mold in European housing stock was carried out. It is based on general indicators of dampness and mold in dwellings reported in the literature. The assessment relies on recent studies, taking into account regional and climatic differences, as well as differences in study design, methodology, and definitions. Data were available from 31 European countries. Weighted prevalence estimates are 12.1% for damp, 10.3% for mold, 10.0% for water damage, and 16.5% for a combination of any one or more indicators. Significant (up to 18%) differences were observed for dampness and mold prevalence estimates depending on survey factors, region, and climate. In conclusion, dampness and/or mold problems could be expected to occur in one of every six of the dwellings in Europe. Prevalence and occurrence of different types of problems may vary across geographical areas, which can be partly explained by differences in climate.
Surface analysis, ion implantation and tribological processes affecting steels

Abstract An analytical approach is presented for investigating surface processing treatments used to improve the friction and wear (i.e., tribological) behavior of engineering alloys, with specific examples cited for ion implantation of steels. Surface composition techniques such as scanning Auger microscopy, energy dispersive X-ray analysis and secondary ion mass spectroscopy and microscopies such as transmission electron microscopy (TEM), secondary electron microscopy and interferometry have eluciated the microstructure and chemistry of a variety of implant species (N, C, Ti and Ta) found to affect the tribological behavior of surfaces. Novel combinations of these techniques, along with metallography of ion-etched surfaces or TEM of ion-beam-etched foils, are shown to be useful methods for establishing microstructures of ion-implanted and worn surfaces. The tribological behavior of the thin implanted layer (∼ 200 nm) is examined by two devices: a stickslip machine and a polishing wear apparatus, the latter having wear rate versus depth resolution of 10 to 20 nm. Tribology studies of two implanted steels, 304 stainless steel and 52100 bearing steel, are presented, and analytical investigations which have led to models for their improved wear behavior are described. A process by which implanted metal ions can react with residual gases in the vacuum chamber to “carburize” steel and produce superior tribological surfaces is also discussed.
Gamma-ray emission from advection dominated accretion flows around black holes: Application to the galactic center

We calculate the flux and spectrum of γ-rays emitted by a two-temperature advection-dominated accretion flow (ADAF) around a black hole. The γ-rays are from the decay of neutral pions produced through proton-proton collisions. We discuss both thermal and power-law distributions of proton energies and show that the γ-ray spectra in the two cases are very different. We apply the calculations to the γ-ray source, 2EG J1746-2852, detected by EGRET from the direction of the Galactic center. We show that the flux and spectrum of this source are consistent with emission from an ADAF around the supermassive accreting black hole Sgr A* if the proton distribution is a power law. The model uses accretion parameters within the range made likely by other considerations. If this model is correct, it provides evidence for the presence of a two-temperature plasma in Sgr A* and predicts γ-ray fluxes from other accreting black holes that could be observed with more sensitive detectors.
On the accuracy of the pseudocompressibility method in solving the incompressible Navier-Stokes equations

The method of pseudocompressibility is being tested for its accuracy in solving the incompressible Navier-Stokes equations. An implicit, finite-difference computer code is used to solve the equations in a three-dimensional, curvilinear coordinate system. The code employs artificial compressibility for solving the pressure field, coupled with an implicit, approximate-factorization scheme. This coupling is known as the pseudocompressibility method. The pseudocompressibility method introduces pressure waves of finite speed into the fluid medium that would otherwise have an infinite sound speed. The waves die out as the solution converges, and the steady state solution approaches a divergence-free condition. However, these waves limit the time-accuracy of the computations. The effects of these waves are analyzed and criteria are set for choosing the pseudocompressibility parameters that govern the pressure wave speed. Test cases are presented that verify these criteria. The code is tested by computing laminar flow over a two-dimensional, backward-facing step and over a two-dimensional, impulsively started circular cylinder.
Emission Lines from Companion Galaxies of QSOs

Anticipating new spectroscopic studies of quasar companions, we calculate expected emission-line spectra for the companion galaxies. Under the assumption of isotropic photoionizing radiation, we predict equivalent widths for Hα, Hβ, [O III] λ5007, [O II] λ3727, [Ne III] λ3869, and Mg II λ2798 lines. We consider six quasars, two of which (PKS 2135-14 and PKS 2349-014) have very close companions with projected separation less than 4 h-1 kpc. For these companions the calculated emission lines should be easily observable, with Wλ 20 A for the [O III], [O II], and Hα lines. The presence of strong emission lines from the companions occupying only a tiny solid angle would suggest that (1) quasar radiation is isotropic; (2) companion galaxies have measurable amounts of gas, which can be assessed using the photoionization models; (3) host galaxies, if present, have been depleted of gas or do not interact with the companions.
Grain boundary studies of high-temperature superconducting materials using electron backscatter Kikuchi diffraction

Abstract Grain orientation and grain boundary misorientation distributions in high critical current density, high-temperature superconductors were determined using electron backscatter Kikuchi diffraction. It is found that depending on the type of superconductor and the processing method used to fabricate it, there exist different scales of biaxial texture from no biaxial texture, local biaxial texture, to complete biaxial texture. Experimentally obtained grain boundary misorientation distributions (GBMDs) were found to be skewed significantly to low angles in comparison to what is expected on the basis of macroscopic texture alone, suggesting that minimization of energy may be a driving force during the processing of high critical current density materials. In addition, a higher than expected fraction of coincident-site lattice boundaries is observed. Examination of maps of grain boundary misorientations in spatially correlated grains, i.e. the grain boundary mesotexture, suggests the presence of percolative paths of high critical current density. A combination of orientation measurements, theoretical modeling of GBMDs and modeling of percolative current flow through an assemblage of grain boundaries is performed to gain an insight into the important microstructural features dictating the transport properties of high-temperature superconductors. It is found that maximization of low energy, in particular, low-angle boundaries, is essential for higher critical currents. The combination of experimental and analytical techniques employed are applicable to other materials where physical properties are dominated by intergranular characteristics.
Synchronization of Swimming Microorganisms

Some microorganisms, such as spermatozoa, have been observed to synchronize their flagella when swimming in close proximity. Using a two-dimensional model we show that phase-locking can arise from hydrodynamic forces alone. In a Newtonian fluid, as a consequence of the kinematic reversibility of the field equations, there must exist front-back asymmetry in the geometry of their flagellar waveform. The time-evolution of the phase difference between co-swimming cells depends only on the nature of this geometrical asymmetry, and microorganisms can phase-lock into conformations which minimize or maximize energy dissipation. In a viscoelastic fluid the presence of polymeric stresses removes the geometrical asymmetry constraint, and therefore even symmetric swimmers synchronize. Such synchronization occurs on asymptotically faster time scales than in a Newtonian fluid, and the swimmers evolve into a stable in-phase conformation minimizing the energy dissipated in the surrounding fluid. Furthermore, we show that if we consider flexible sheets, with internal symmetric forcing instead of prescribed kinematics, they deform when interacting with each other through the fluid in such a way as to systematically break the overall waveform symmetry, thereby always evolving to an in-phase conformation where energy dissipation is minimized. These dynamics are shown to be mathematically equivalent to those obtained for prescribed waveforms in viscoelastic fluids, emphasizing the crucial role of flexibility in symmetry-breaking and synchronization - be it that of the fluid, or the swimmers themselves.
The design, synthesis and activity of non-ATP competitive inhibitors of pp60c-src tyrosine kinase. Part 2 : Hydroxyindole derivatives

A series of hydroxynaphthalene pp60(c-src) non-peptide inhibitors was designed, using the crystal structure of the insulin receptor tyrosine kinase as a qualitative model, to target the peptide substrate binding site. Representative inhibitors were shown to bind non-competitively with respect to ATP.
Scattering Study of Microstructurally Birefringent Glasses

Microstructurally birefringent, phase-separated borosilicate glasses were investigated by X-ray small-angle scattering and light scattering. X-ray small-angle scattering data confirmed the presence of ellipsoidal particles and the light-scattering data indicated the presence of anisotropic distribution of particles. These observations support the previous contention that the positive birefringence is due to the form birefringence and the negative birefringence is due to the anisotropic distribution of spherical particles.
On the Sample Complexity of Weak Learning

In this paper, we study the sample complexity of weak learning. That is, we ask how many data must be collected from an unknown distribution in order to extract a small but significant advantage in prediction. We show that it is important to distinguish between those learning algorithms that output deterministic hypotheses and those that output randomized hypotheses. We prove that in the weak learning model, any algorithm using deterministic hypotheses to weakly learn a class of Vapnik-Chervonenkis dimension d(n) requires ? (formula]) examples. In contrast, when randomized hypotheses are allowed, we show that ? (1) examples suffice in some cases. We then show that there exists an efficient algorithm using deterministic hypotheses that weakly learns against any distribution on a set of size d(n) with only O(d(n)2/3) examples. Thus for the class of symmetric Boolean functions over n variables, where the strong learning sample complexity is ? (n), the sample complexity for weak learning using deterministic hypotheses is ? (formula]) and O(n2/3), and the sample complexity for weak learning using randomized hypotheses is ? (1). Next we prove the existence of classes for which the distribution-free sample size required to obtain a slight advantage in prediction over random guessing is essentially equal to that required to obtain arbitrary accuracy. Finally, for a class of small circuits, namely all parity functions of subsets of n Boolean variables, we prove a weak learning sample complexity of ?(n). This bound holds even if the weak learning algorithm is allowed to replace random sampling with membership queries, and the target distribution is uniform on {0, 1}n.
Optimally Efficient Max-Log APP Demodulation in MIMO Systems

In this paper, we consider the design of multi-stream demodulators for multiple-input multiple-output (MIMO) systems. Our proposed MIMO demodulator is based on the stack tree-search strategy and provides soft-outputs in the form of exact max-log log-likelihood ratios (max-log LLRs). We prove that our proposed demodulator is optimally efficient in that it visits the least number of nodes among all optimal demodulators in a class of tree-search-based demodulators. We conduct a comprehensive complexity analysis of such optimally efficient demodulators. We also identify key parameters associated with our proposed demodulator that can be controlled to realize near max-log performance with substantially reduced complexity, as demonstrated via simulations.
Understanding the Errors of SHAPE-Directed RNA Structure Modeling

Single-nucleotide-resolution chemical mapping for structured RNA is being rapidly advanced by new chemistries, faster readouts, and coupling to computational algorithms. Recent tests have shown that selective 2'-hydroxyl acylation by primer extension (SHAPE) can give near-zero error rates (0−2%) in modeling the helices of RNA secondary structure. Here, we benchmark the method using six molecules for which crystallographic data are available: tRNA(phe) and 5S rRNA from Escherichia coli, the P4−P6 domain of the Tetrahymena group I ribozyme, and ligand-bound domains from riboswitches for adenine, cyclic di-GMP, and glycine. SHAPE-directed modeling of these highly structured RNAs gave an overall false negative rate (FNR) of 17% and a false discovery rate (FDR) of 21%, with at least one helix prediction error in five of the six cases. Extensive variations of data processing, normalization, and modeling parameters did not significantly mitigate modeling errors. Only one varation, filtering out data collected with deoxyinosine triphosphate during primer extension, gave a modest improvement (FNR = 12%, and FDR = 14%). The residual structure modeling errors are explained by the insufficient information content of these RNAs' SHAPE data, as evaluated by a nonparametric bootstrapping analysis. Beyond these benchmark cases, bootstrapping suggests a low level of confidence (<50%) in the majority of helices in a previously proposed SHAPE-directed model for the HIV-1 RNA genome. Thus, SHAPE-directed RNA modeling is not always unambiguous, and helix-by-helix confidence estimates, as described herein, may be critical for interpreting results from this powerful methodology.
Synthesis of the ABCD and ABCDE ring systems of azaspiracid-1.

The efficient syntheses of the ABCD ring system of the originally proposed structure of azaspiracid-1 and the ABCDE ring system of the revised structure of azaspiracid-1 containing the correct stereochemistry at C6, C10, C13, C14, C16, C17, C19, C21, C22, C24 and C25 have been achieved.
The clustering of risk behaviors among Caribbean youth.

Objective: To examine the relationships among risk behaviors for Caribbean youth; and to determine the correlations between initiation of sexual activity and other risk behaviors. Methods: The associations between cigarette smoking, alcohol and marijuana use, early initiation of sexual intercourse, involvement in violence and delinquency were examined using odds ratios on data from the Caribbean Youth Health Survey (n = 15,695). Survival analysis was then used to determine the association between initiation of sexual activity and the risk behaviors. Findings: There were statistically significant relationships between all pairs of risk behaviors for both male and female adolescents. Even though more males than females had engaged in each of the behaviors, the strengths of association were higher for females. From survival analysis, initiation of sexual activity was associated with gang involvement and weapon carrying among young adolescents and even more risk behaviors among the older adolescents. Conclusion: Health compromising behaviors cluster among Caribbean youth with associations being stronger for females. Initiating sexual activity was a predictor of other risk behaviors with the likelihood increasing among older adolescents and females.
Synthesis of novel tetrahydrobenzazepinones

Abstract The synthesis of novel tetrahydrobenzazepinones 1, 2, and 3 is described, as well as an improved synthesis of 4. The palladium catalyzed arylation approach to 1, 2, and 4 allows facile entry to benzazepinones lacking electron donating substituents on the benzo ring.
Of poems and patients.

Recently, my wife and I were out listening to a folk singer, and I realized how hard it is to listen to live music without leaning across a bar. It wasn't so long ago that 4 or 5 nights a week I po...
Orbital structure in oscillating galactic potentials

Subjecting a galactic potential to (possibly damped) nearly periodic, time-dependent variations can lead to large numbers of chaotic orbits experiencing systematic changes in energy, and the resulting chaotic phase mixing could play an important role in explaining such phenomena as violent relaxation. This paper focuses on the simplest case of spherically symmetric potentials subjected to strictly periodic driving with the aim of understanding precisely why orbits become chaotic and under what circumstances they will exhibit systematic changes in energy. Four unperturbed potentials V 0(r) were considered, each subjected to a time dependence of the form V(r, t) = V 0(r)(1 + m0 sin ωt). In each case, the orbits divide clearly into regular and chaotic, distinctions which appear absolute. In particular, transitions from regularity to chaos are seemingly impossible. Over finite time intervals, chaotic orbits subdivide into what can be termed ‘sticky’ chaotic orbits, which exhibit no large-scale secular changes in energy and remain trapped in the phase-space region where they started; and ‘wildly’ chaotic orbits, which do exhibit systematic drifts in energy as the orbits diffuse to different phase-space regions. This latter distinction is not absolute, transitions corresponding apparently to orbits penetrating a ‘leaky’ phase-space barrier. The three different orbit types can be identified simply in terms of the frequencies for which their Fourier spectra have the most power. An examination of the statistical properties of orbit ensembles as a function of driving frequency ω allows us to identify the specific resonances that determine orbital structure. Attention focuses also on how, for fixed amplitude m0, such quantities as the mean energy shift, the relative measure of chaotic orbits and the mean value of the largest Lyapunov exponent vary with driving frequency ω; and how, for fixed ω, the same quantities depend on m0.
Seigniorage, inflation, and reputation☆

Abstract This paper derives a reputational equilibrium for inflation in a model in which the sovereign obtains valuable seigniorage by issuing fiat money in exchange for real resources. With contemporaneous perception of actual sovereign behavior and immediate adjustment of real cash balances to new information, the Friedman elasticity solution for maximal seigniorage is a reputational equilibrium. More generally, the objective of maximal seigniorage produces an equilibrium inflation rate equal either to a generalization of the Friedman elasticity solution or to the rate at which the sovereign discounts future seigniorage adjusted for the growth rate, whichever is larger. The model formalizes the conjecture that inflation rates in excess of the Friedman solution are attributable to high discount rates for future seigniorage.
Scattering Pattern Analysis of Bacteria

There has been a strong need for a rapid automated technique to count bacteria in urine. This paper demonstrates that the optical scattering pattern analysis for a collection of heterogeneous particles in a tenuous solution can be effectively applied to species identification and concentration estimation for bacteria. The scattering patterns are measured with latex spheres and bacteria (Escherichia coli and Staphylococcus aureus). They agree well with theoretical calculations using the Mie theory and the Rayleigh-Debye approximation, taking into account size distribution and random orientation. The parameters such as average size, axial ratio, size variation and refractive index are estimated to give a good agreement between the theory and the measurement. The values of the parameters agree with those in the literature. The scattering pattern is found to be sensitive to the aggregation of scatterers. The parameters obtained from the scattering pattern analysis are used to improve the estimation of bacterial concentrations by turbidimetry. The estimated values agree within a factor of 10 with those obtained by conventional culturing technique.
Sculptured thin films: accomplishments and emerging uses

Abstract Sculptured thin films (STFs) are nano-engineered materials whose columnar morphology is tailored to elicit desired optical responses upon excitation. Two canonical forms of STFs have been identified. Linear constitutive relations for general STFs as unidirectionally nonhomogeneous (continuously or piecewise uniformly) and locally bianisotropic continuums are presented, along with a 4×4 matrix ordinary differential equation for wave propagation therein. A nominal model for the macroscopic properties of linear STFs is devised from nanoscopic considerations. The accomplished implementation of STFs as circular polarization filters and spectral hole filters is discussed, as also are emerging applications such as bioluminescence sensors and optical interconnects.