cssi/SciSciGPT-SciSciNet huggingface dataset:
Inapproximability of maximum weighted edge biclique and its applications

Given a bipartite graph G = (V1, V2, E) where edges take on both positive and negative weights from set S, the maximum weighted edge biclique problem, or S-MWEB for short, asks to find a bipartite subgraph whose sum of edge weights is maximized. This problem has various applications in bioinformatics, machine learning and databases and its (in)approximability remains open. In this paper, we show that for a wide range of choices of S, specifically when |min S/max S| ∈ Ω(ηδ-1/2) ∩ O(η1/2-δ) (where η = max{|V1|, |V2|}, and δ ∈ (0, 1/2), no polynomial time algorithm can approximate S-MWEB within a factor of nƐ for some Ɛ > 0 unless RP = NP. This hardness result gives justification of the heuristic approaches adopted for various applied problems in the aforementioned areas, and indicates that good approximation algorithms are unlikely to exist. Specifically, we give two applications by showing that: 1) finding statistically significant biclusters in the SAMBA model, proposed in [18] for the analysis of microarray data, is nƐ-inapproximable; and 2) no polynomial time algorithm exists for the Minimum Description Length with Holes problem [4] unless RP = NP.
The Effects of Merit-Based Financial Aid on Drinking in College

We study the effect of state-level merit aid programs (such as Georgia's HOPE scholarship) on alcohol consumption among college students. Such programs have the potential to affect drinking through a combination of channels--such as raising students' disposable income and increasing the incentive to maintain a high GPA--that could theoretically raise or lower alcohol use. We find that the presence of a merit-aid program in one's state generally leads to an overall increase in (heavy) drinking. This effect is concentrated among men, students with lower parental education, older students, and students with high college GPA's. Our findings are robust to several alternative empirical specifications including event-study analyses by year of program adoption. Furthermore, no difference in high-school drinking is observed for students attending college in states with merit-aid programs.
New examples (and counterexamples) of complete finite-rank differential varieties

ABSTRACTDifferential algebraic geometry seeks to extend the results of its algebraic counterpart to objects defined by differential equations. Many notions, such as that of a projective algebraic variety, have close differential analogues but their behavior can vary in interesting ways. Workers in both differential algebra and model theory have investigated the property of completeness of differential varieties. After reviewing their results, we extend that work by proving several versions of a “differential valuative criterion" and using them to give new examples of complete differential varieties. We conclude by analyzing the first examples of incomplete, finite-rank projective differential varieties, demonstrating a clear difference from projective algebraic varieties.
Understanding Nonprofit Financial Health: Exploring the Effects of Organizational and Environmental Variables

Using Internal Revenue Service Form 990 information for all filing 501(c)(3) organizations from 1998 to 2003, this article explores the organizational and environmental factors that affect nonprofi...
Hypergraph limits: A regularity approach

A sequence of k-uniform hypergraphs H1,H2,' is convergent if the sequence of homomorphism densities tF,H1,tF,H2,' converges for every k-uniform hypergraph F. For graphs, Lovasz and Szegedy showed that every convergent sequence has a limit in the form of a symmetric measurable function W:[0,1]2i¾?[0,1]. For hypergraphs, analogous limits W:[0,1]2k-2i¾?[0,1] were constructed by Elek and Szegedy using ultraproducts. These limits had also been studied earlier by Hoover, Aldous, and Kallenberg in the setting of exchangeable random arrays. In this paper, we give a new proof and construction of hypergraph limits. Our approach is inspired by the original approach of Lovasz and Szegedy, with the key ingredient being a weak Frieze-Kannan type regularity lemma. © 2014 Wiley Periodicals, Inc. Random Struct. Alg., 47, 205-226, 2015
Improved dynamic schedules for belief propagation

Belief propagation and its variants are popular methods for approximate inference, but their running time and even their convergence depend greatly on the schedule used to send the messages. Recently, dynamic update schedules have been shown to converge much faster on hard networks than static schedules, namely the residual BP schedule of Elidan et al. [2006]. But that RBP algorithm wastes message updates: many messages are computed solely to determine their priority, and are never actually performed. In this paper, we show that estimating the residual, rather than calculating it directly, leads to significant decreases in the number of messages required for convergence, and in the total running time. The residual is estimated using an upper bound based on recent work on message errors in BP. On both synthetic and real-world networks, this dramatically decreases the running time of BP, in some cases by a factor of five, without affecting the quality of the solution.
Chapter 2 – Epidemiology

Publisher Summary This chapter provides an overview of the epidemiology of asthma and chronic obstructive pulmonary disease (COPD). Epidemiology studies have used questionnaires to assess for the presence of disease, but are limited by recall and misclassification bias. Incidence rates for asthma and COPD vary depending on the age of the population under consideration. For example, asthma is commonly diagnosed in early childhood and COPD is commonly diagnosed after age 60. Although data indicates that asthma incidence has been increasing, minimal information has been available for trends in COPD incidence. Ninety percent of all childhood asthma is diagnosed before the age of 6 years. Since there is a crude inverse relationship between respiratory symptoms and level of lung function, it is not surprising that as lung function increases in childhood respiratory symptoms decrease and often disappear. Both asthma and COPD are defined as syndromes, and the definitions are loose; thus it is not surprising that there is substantial overlap between the conditions at any given age. Indeed, there are no substantive data to suggest that individuals cannot have both reversible and fixed airflow obstruction, and hence asthma and COPD at the same time. Increased health service utilization has occurred for asthma and COPD during the last two decades. Overall, hospital admissions and discharges have increased for both diseases.
The impacts of metering and climate conditions on residential electricity demand : the case of Albania

Albania is among the most vulnerable countries to external energy shocks and climatic conditions, because of its high dependency on hydropower for electricity. Given highly volatile international energy prices and expected global warming, it is becoming increasingly important to manage the demand for electricity. However, the country has long been faced with a significant problem of electricity metering. About one-third of total energy is lost for technical and nontechnical reasons. This paper estimates the residential demand function by applying a two-stage system equation method for an endogenous censored variable, because the lack of metering makes the electricity consumption partially observable for the econometrician. It is found that metering is important to curb non-essential electricity use by households. The electricity demand could also be reduced by raising the first block rate and lowering the second block rate and the threshold between the two blocks. In addition, weather conditions and home appliance ownership would affect the demand for electricity. But the latter looks more influential than the former.
Fast moment-based estimation for hierarchical models

Summary Hierarchical models allow for heterogeneous behaviours in a population while simultaneously borrowing estimation strength across all subpopulations. Unfortunately, existing likelihood-based methods for fitting hierarchical models have high computational demands, and these demands have limited their adoption in large-scale prediction and inference problems. The paper proposes a moment-based procedure for estimating the parameters of a hierarchical model which has its roots in a method originally introduced by Cochran in 1937. The method trades statistical efficiency for computational efficiency. It gives consistent parameter estimates, competitive prediction error performance and substantial computational improvements. When applied to a large-scale recommender system application and compared with a standard maximum likelihood procedure, the method delivers competitive prediction performance while reducing the sequential computation time from hours to minutes.
Model criticism of Bayesian networks with latent variables

The application of Bayesian networks (BNs) to cognitive assessment and intelligent tutoring systems poses new challenges for model construction. When cognitive task analyses suggest constructing a BN with several latent variables, empirical model criticism of the latent structure becomes both critical and complex. This paper introduces a methodology for criticizing models both globally (a BN in its entirety) and locally (observable nodes), and explores its value in identifying several kinds of misfit: node errors, edge errors, state errors, and prior probability errors in the latent structure. The results suggest the indices have potential for detecting model misfit and assisting in locating problematic components of the model.
Interactive Discretionary Disclosures

We consider two managers’ sequential disclosure strategies. We show how the lead disclosing firm’s manager chooses his strategy anticipating the subsequent disclosure choice by a second firm’s manager. Prior studies of a single firm offer little insight into how sequential disclosure strategies interact. We show how strategies of both the leader and the follower depend on their signals’ correlation. For imperfectly and positively correlated signals, the follower benefits from the leader’s disclosures and free-rides by disclosing less frequently. With imperfectly and negatively correlated signals, the follower discloses more frequently to overcome investors’ rational revisions of beliefs based on the leader’s disclosures. Our results change if the correlation is perfect. With perfect positive correlation, the leader has an advantage as he can free-ride on the subsequent disclosures by the other manager. With perfect negative correlation, no disclosure arises only for intermediate values of each signal.Our findings provide insights into existing empirical work and directions for future empirical work on voluntary disclosure, including potentially testable empirical hypotheses that may be used to assess the validity of our model. More specifically, our findings explain how correlation, sequence, disclosing decision and non-disclosure can affect empirical results.
Online Product Rating Manipulation and Market Performance

Manipulating online ratings of a product, in terms of both volume and value, can substantially influence its market performance, but the profits of a particular strategy can vary across products and might not be maximized by the highest rating values.
Tunneling in theories with many fields

The possibility of a landscape of metastable vacua raises the question of what fraction of vacua are truly long lived. Naively any would-be vacuum state has many nearby decay paths, and all possible decays must be suppressed. An interesting model of this phenomena consists of N scalars with a random potential of fourth order. Here we show that the scaling of the typical minimal bounce action with N is readily understood, and differs from statements in the literature. We discuss the extension to more realistic landscape models.
A2MnU3O11 (A = K, Rb) and Li3.2Mn1.8U6O22: Three New Alkali-Metal Manganese Uranium(VI) Oxides Related to Natrotantite.

Single crystals of three new alkali-metal manganese uranium oxides, K2MnU3O11, Rb2MnU3O11, and Li3.2Mn1.8U6O22, have been grown from molten chloride fluxes and structurally characterized by single-crystal X-ray diffraction. The first two compounds crystallize in the trigonal space group, R3c, in the three-dimensional (3D), natrotantite structure composed of α-U3O8-topological layers connected via MnO6 octahedra. The Li-containing compound crystallizes in the monoclinic space group, Cc, with a related 3D structure, composed of β-U3O8-topological sheets connected via irregular MnO7 polyhedra. All three compounds exhibit typical uranyl, UO22+, coordination environments consisting of either UO7 pentagonal bipyramids or UO6 flattened octahedra. The lattice parameters of the new oxides are K2MnU3O11, a = 6.8280(2) A, c = 36.8354(17) A; Rb2MnU3O11, a = 6.8407(2) A, c = 37.5520(17) A; and Li3.2Mn1.8U6O22, a = 11.8958(8) A, b = 10.9639(7) A, c = 13.3269(8) A, and β = 91.442(4)°. The magnetic susceptibilities of t...
Liquidity as Social Expertise

This paper proposes a theory of liquidity dynamics. Illiquidity results from asymmetric information. Observing the historical track record teaches agents how to interpret public information and helps overcome information asymmetry. There can be an illiquidity trap: too much asymmetric information leads to the breakdown of trade, which interrupts learning and perpetuates illiquidity. Liquidity falls in response to unexpected events that lead agents to question their valuation models, especially in newer markets, may be slow to recover after a crisis and is higher in periods of stability.
Measurements of higher-order mode damping in the PEP-II low-power test cavity

The paper describes the results of measurements of the higher-order mode (HOM) spectrum of the low-power test model of the PEP-II RF cavity and the reduction in the Q's of the modes achieved by the addition of dedicated damping waveguides. All the longitudinal (monopole) and deflecting (dipole) modes below the beam pipe cut-off are identified by comparing their measured frequencies and field distributions with calculations using the URMEL code. Field configurations were determined using a perturbation method with an automated bead positioning system. The loaded Q's agree well with the calculated values reported previously, and the strongest HOMs are damped by more than three orders of magnitude. This is sufficient to reduce the coupled-bunch growth rates to within the capability of a reasonable feedback system. A high-power test cavity will now be built to validate the thermal design at the 150 kW nominal operating level, as described elsewhere at this conference. >
Software support for virtual memory-mapped communication

Virtual memory-mapped communication (VMMC) is a communication model providing direct data transfer between the sender's and receiver's virtual address spaces. This model eliminates operating system involvement in communication, provides full protection, supports user-level buffer management and zero-copy protocols, and minimizes software communication overhead. This paper describes system software support for the model including its API, operating system support, and software architecture, for two network interfaces designed in the SHRIMP project. Our implementations and experiments show that the VMMC model can indeed expose the available hardware performance to user programs. On two Pentium PCs with our prototype network interface hardware over a network, we have achieved user-to-user latency of 4.8 /spl mu/sec and sustained bandwidth of 23 MB/s, which is close to the peak hardware bandwidth. Software communication overhead is only a few user-level instructions.
Takeover laws and financial development

The issue of 'an appropriate' legal framework, especially in the case of the takeover market, has been poorly studied in the case of emerging markets, yet it is of immediate relevance and practical policymaker interest. The study makes a first attempt to analyze takeover regulations in a comparative context across 50 countries. It proposes a methodology to create a detailed index on the most salient features of capital market laws, and illustrates the approach on the case of takeover legislation. The methodology allows better understanding of the impact of laws on markets and development, allows a detailed quantification of a given regulation, in this case takeover market rules, and helps determine relevant policy implications. Specifically, the framework permits the exploration of the effects of individual regulations, their substitutability and interplay, as well as the overall extent of friendliness of the laws to investors, or particular groups thereof (such as minority shareholders), and the links of specialized regulation with the overall legal system. Finally, the study explores the effect of the investor-friendliness of takeover laws on stock market development.
From guesstimates to GPStimates : land area measurement and implications for agricultural analysis

Land area measurement is a fundamental component of agricultural statistics and analysis. Yet, commonly employed self-reported land area measures used in most analysis are not only potentially measured with error, but these errors may be correlated with agricultural outcomes. Measures employing Global Positioning Systems, on the other hand, while not perfect especially on smaller plots, are likely to provide more precise measures and errors less correlated with agricultural outcomes. This paper uses data from four African countries to compare the use of self-reported and Global Positioning Systems land measures to (1) examine the differences between the measures, (2) identify the sources of the differences, and (3) assess the implications of the different measures on agricultural analysis focusing on the inverse productivity relationship. The results indicate that self-reported land areas systematically differ from Global Positioning Systems land measures and that this difference leads to potentially biased estimates of the relationship between land and productivity.
The macro financing of natural hazards in developing countries

Mahul and Gurenko propose a financial model to address the design of efficient risk financing strategies against natural disasters at the country level. This risk financing problem is decomposed into two steps. First, the resource gap, defined as the difference between potential losses and available ex post resources (self-retention and international ex post disaster funds), is identified. It determines the losses to be financed by ex ante financial instruments (e.g., reserves, insurance and contingent debt). Second, the cost minimizing financial arrangements are examined within the resource gap, based on the comparison of the marginal costs of the financial instruments. It is solved through a series of graphical analyses that make this complex financial problem easier to apprehend. This model captures and explains the main impacts of financial parameters (e.g., insurance premium, cost of capital) on efficient risk financing structures.
A Simple Proof for the Number of Tilings of Quartered Aztec Diamonds

We get four quartered Aztec diamonds by dividing an Aztec diamond region by two zigzag cuts passing its center. W. Jockusch and J. Propp (in an unpublished work) found that the number of tilings of quartered Aztec diamonds is given by simple product formulas. In this paper we present a simple proof for this result.
Two-wave mixing with an applied field and a moving grating

The theory for two-wave mixing in a photorefractive material with an external electric field and a moving grating is developed. Large gain enhancements are predicted for grating periods of 10–100 μm and compared with recent observations in Bi12SiO20. Predictions are made for enhancements in GaAs, which has recently been found to be photorefractive in the near infrared.
Performance advantage of complex LMS for controlling narrow-band adaptive arrays

In narrow-band adaptive-array applications, the mean-square convergence of the discrete-time real least mean-square (LMS) algorithm is slowed by image-frequency noises generated in the LMS loops. The complex LMS algorithm proposed by Widrow et aL is shown to eliminate these noises, yielding convergence of the mean-squared error (MSE) at slightly over twice the rate. This paper includes a comprehensive analysis of the MSE of adaptation for LMS. The analysis is based upon the method developed in the 1968 dissertation by K. D. Senne, and it represents the most complete treatment of the subject published to date.
Atomic calculation for the atmospheres of strongly-magnetized neutron stars

Complete modeling of radiative transfer in neutron star atmospheres is in progress, taking into account the anisotropy induced by magnetic fields, nonideal effects, and general relativity. As part of our modeling, we present a novel atomic calculation method producing an extensive atomic data set including energy values and oscillator strengths in the so-called Landau regime (B > 4.7 × 109Z2 G). Conventional atmosphere models for B = 0 are not applicable to typical field strengths of cooling neutron stars (B ~ 1012-1013 G), since an atom no longer keeps its spherical shape. The elemental composition and the configuration of the magnetic field in the atmosphere are presently unknown, so that atomic data must be produced for ground and excited states of several ions as a function of magnetic field. To accomplish this efficiently, we minimized the iterations in the Hartree equation and treated exchange terms and higher Landau states by perturbation methods. This method has the effect of reducing the computation time significantly. Inclusion of higher Landau states gives us much more accurate data for inner orbitals unlike other methods based on the adiabatic approximation. While existing atomic data in the Landau regime are available only for low-Z atoms, our method can be used in elements up to Fe with sufficient accuracy to be of use for spectroscopic missions such as Chandra, XMM-Newton, and next-generation X-ray telescopes.
Computational Prediction of Roll Damping for the F/A -18E at Transonic Speeds

Computational fluid dynamics was used to predict the roll -damping characteristics for the F/A -18E Super Hornet at transonic sp eeds . The calcu lations were made for Mach 0.8 at both wind tunnel and flight conditions . Three different wing configurations were analyzed during this study. For the first two configurations, the F/A -18E Super Hornet was modeled with the pre -production wing. The first of these configurations had flap settings of 6° leading -edge flaps, 8° trailing -edge flaps and 4° aileron , while the second configuration had flap settings of 10° leading -edge flaps, 10° trailing -edge flaps and 5° aileron. The third confi guration analyzed was that of the F/A -18E with the wing developed from the Transonic Flying Qualities Improvement Program . This wing includes a sawtooth leading edge and a chordwise fence on the wing box. The sawtooth geometry eliminated the snag that exi sted on the leading edge of the pre -production wing. The flow solver used during this project was USM3D , which was developed at NASA Langley Research Center. In preparation for this study, USM3D was modified to simulate a constant -rate rolling moti on of the grid so that the roll -damping characteristics of the aircraft could be determined. With this modification to USM3D, the roll -damping characteristics at each condition could be determined at the expense of a steady -state CFD calculation . This approach to determining roll damping is much simpler and faster than the traditional approach, which required a time -accurate calculation on a moving grid. The results of this study indicate that computational fluid dynamics can be a useful analysis tool for scre ening a configuration for potential loss of roll damping and the associated deterioration of lateral handling qualities .
The politics and epidemiology of transition: PEPFAR and AIDS in South Africa.

As South Africa (SA) and the US craft a new political relationship on AIDS, the stakes of success have never been higher. SA remains the country with the largest HIV epidemic in the world; yet, new science shows that an aggressive response could enable an epidemiologic transition, cutting HIV incidence and substantially improving overall population mortality. One of the most effective foreign aid efforts in history, the US President’s Emergency Plan for AIDS Relief (PEPFAR) SA, now is managing the largest “transition” of a global health program — withdrawing direct staff and funding for the treatment of hundreds of thousands of HIV-positive patients as the SA public sector takes over. Recent commentary has painted an optimistic picture of the transition and “country ownership” in SA. In important ways, however, the politics are outpacing effective health policy and the accelerated process is undermining the prospects for “getting to zero.” Thousands of patients and the health system have experienced significant disruption. PEPFAR should take urgent steps to ensure that the transition does not undermine hard-fought gains in SA. More broadly, the SA experience has important lessons for the future of aid to fight global HIV.
On the classification of gradient Ricci solitons

We show that the only shrinking gradient solitons with vanishing Weyl tensor and Ricci tensor satisfying a weak integral condition are quotients of the standard ones S n , S n 1 R and R n . This gives a new proof of the Hamilton‐Ivey‐Perelman classification of 3‐dimensional shrinking gradient solitons. We also show that gradient solitons with constant scalar curvature and suitably decaying Weyl tensor when noncompact are quotients of H n , H n 1 R, R n , S n 1 R or S n . 53C25
Enantioselective α-Arylation of Aldehydes via the Productive Merger of Iodonium Salts and Organocatalysis

The enantioselective α-arylation of aldehydes has been accomplished using diaryliodonium salts and a combination of copper and organic catalysts. These mild catalytic conditions provide a new strategy for the enantioselective construction and retention of enolizable α-formyl benzylic stereocenters, a valuable synthon for the production of medicinal agents. As one example, this new asymmetric protocol has been applied to the rapid synthesis of (S)-ketoprofen, a commercially successful oral and topical analgesic.
A Little Flexibility Is All You Need: On the Asymptotic Value of Flexible Capacity in Parallel Queuing Systems

We analytically study optimal capacity and flexible technology selection in parallel queuing systems. We consider N stochastic arrival streams that may wait in N queues before being processed by one of many resources technologies that differ in their flexibility. A resource's ability to process k different arrival types or classes is referred to as level-k flexibility. We determine the capacity portfolio consisting of all resources at all levels of flexibility that minimizes linear capacity and linear holding costs in high-volume systems where the arrival rate λ → ∞. We prove that “a little flexibility is all you need”: the optimal portfolio invests Oλ in specialized resources and only O√λ in flexible resources and these optimal capacity choices bring the system into heavy traffic. Further, considering symmetric systems with type-independent parameters, a novel “folding” methodology allows the specification of the asymptotic queue count process for any capacity portfolio under longest-queue scheduling in closed form that is amenable to optimization. This allows us to sharpen “a little flexibility is all you need”: the asymptotically optimal flexibility configuration for symmetric systems with mild economies of scope invests a lot in specialized resources but only a little in flexible resources and only in level-2 flexibility, but effectively nothing o√λ in level-k > 2 flexibility. We characterize “tailored pairing” as the theoretical benchmark configuration that maximizes the value of flexibility when demand and service uncertainty are the main concerns.
International food stamps

Abstract The author suggests a new direction for farm and food aid policy — an international food stamp programme that will increase prices received by farmers in both developed and developing countries, thereby stimulating food production, and also provide food efficiently for the poor people who need it. The proposed programme will cost no more than is currently spent on farm income support and food aid programmes and could eventually replace those programmes.
Macromolecular Engineering by Atom Transfer Radical Polymerization

This Perspective presents recent advances in macromolecular engineering enabled by ATRP. They include the fundamental mechanistic and synthetic features of ATRP with emphasis on various catalytic/initiation systems that use parts-per-million concentrations of Cu catalysts and can be run in environmentally friendly media, e.g., water. The roles of the major components of ATRP—monomers, initiators, catalysts, and various additives—are explained, and their reactivity and structure are correlated. The effects of media and external stimuli on polymerization rates and control are presented. Some examples of precisely controlled elements of macromolecular architecture, such as chain uniformity, composition, topology, and functionality, are discussed. Syntheses of polymers with complex architecture, various hybrids, and bioconjugates are illustrated. Examples of current and forthcoming applications of ATRP are covered. Future challenges and perspectives for macromolecular engineering by ATRP are discussed.
Metastable carbon in two chondritic porous interplanetary dust particles

An understanding of carbonaceous matter in primitive extraterrestrial materials is an essential component of studies on dust evolution in the interstellar medium and the early history of the Solar System. Analytical Electron Microscopy (AEM) on carbonaceous material in two Chondritic Porous (CP) aggregrates is presented. The study suggests that a record of hydrocarbon carbonization may also be preserved in these materials.
Engineering quantum states, nonlinear measurements and anomalous diffusion by imaging

We show that well-separated quantum superposition states, measurements of strongly nonlinear observables and quantum dynamics driven by anomalous diffusion can all be achieved for single atoms or molecules by imaging spontaneous photons that they emit via resonance florescence. To generate anomalous diffusion we introduce continuous measurements driven by Levy processes and prove a number of results regarding their properties. In particular, we present strong evidence that the only stable Levy density that can realize a strictly continuous measurement is the Gaussian.
Aminomethylations via Cross-Coupling of Potassium Organotrifluoroborates with Aryl Bromides

[reaction: see text] The Suzuki-Miyaura cross-coupling reaction of N,N-dialkylaminomethyltrifluoroborates with aryl halides allows the construction of an aminomethyl aryl linkage through a disconnection based on dissonant reactivity patterns. A variety of these aminomethyltrifluoroborate substrates were prepared in good to excellent yields and then shown to cross-couple with equal facility to both electron-rich and electron-poor aryl halides as well as to a variety of heteroaromatic bromides.
Does osteoarthritis of the lumbar spine cause chronic low back pain

The lumbar spine is a common location for osteoarthritis. The axial skeleton demonstrates the same classic alterations of cartilage loss, joint instability, and osteophytosis characteristic of symptomatic disease in the appendages. Despite these similarities, questions remain regarding the lumbar spine facet joints as a source of chronic back pain. The facet joints undergo a progression of degeneration that may result in pain. The facet joints have sensory input from two spinal levels that makes localization of pain difficult. Radiographic studies describe intervertebral disc abnormalities in asymptomatic individuals that are associated with, but not synonymous for, osteoarthritis. Patients who do not have osteoarthritis of the facet joints on magnetic resonance scan do not have back pain. Single photon emission computed tomography scans of the axial skeleton are able to identify painful facet joints with increased activity that may be helped by local anesthetic injections. Low back pain is responsive to therapies that are effective for osteoarthritis in other locations. Osteoarthritis of the lumbar spine does cause low back pain.
An Analysis of Financial Analysts' Optimism in Long-term Growth Forecasts

A large body of literature has rejected rational expectations in relation to analyst forecasts. In this paper we start with a boundedly rational premise that analysts and managers adopt are influenced by the availability heuristic (Tversky and Kahneman [1973]). In the presence of business cycles, a rational growth forecast presupposes precise knowledge of the factors that cause a business cycle. In contrast, under the availability heuristic the current state is overweighted in the growth forecast and so whatever part of the business cycle the economy is currently in will be preserved by the investment decision. As a result, under the hypothesis of the availability heuristic we will observe ex-post, a systematic association between the drivers of this behavior (e.g., current state of the economy, industry, current performance) and subsequent forecast errors and (realized) growth when related to specific properties of the business cycle. We test for this condition and find evidence in support of it. The bou...
Solid Hydrogen Experiments for Atomic Propellants: Particle Formation Energy and Imaging Analyses

This paper presents particle formation energy balances and detailed analyses of the images from experiments that were conducted on the formation of solid hydrogen particles in liquid helium during the Phase II testing in 2001. Solid particles of hydrogen were frozen in liquid helium and observed with a video camera. The solid hydrogen particle sizes and the total mass of hydrogen particles were estimated. The particle formation efficiency is also estimated. Particle sizes from the Phase I testing in 1999 and the Phase II testing in 2001 were similar. Though the 2001 testing created similar particles sizes, many new particle formation phenomena were observed. These experiment image analyses are one of the first steps toward visually characterizing these particles and it allows designers to understand what issues must be addressed in atomic propellant feed system designs for future aerospace vehicles.
Fixed-rate encoding of nonstationary information sources

An expression is obtained for the optimum distortion theoretically attainable when an information source with finite alphabet is encoded at a fixed rate with respect to a single-letter fidelity criterion. The expression is demonstrated by means of an appropriate coding theorem and converse; This new result generalizes the coding theorem of Shannon for stationary ergodic sources, the coding theorem of Gray-Davisson for stationary nonergodic sources, that of Gray-Saadat for asymptotically mean stationary sources, and that of Ziv for an individual sequence.
A simple analysis for bend-stretch forming of aluminum extrusions

Bend-stretch forming is a cold-forming operation used to bend initially straight aluminum extrusions. The process consists of bending the parts over a curved die in the presence of axial tension. Higher tensions reduce the springback of the part but can induce relatively large, permanent cross-sectional distortions. This work presents an efficient formulation to predict the cross-sectional distortion of extrusions with relatively arbitrary, thin-walled cross-section. The results show good agreement with calculations for simple tubular sections and experimental results in the literature. The numerical implementation has short computer run times and should be useful in the design of extrusion cross-sections and in the optimization of the process variables.
CONFIRMATION OF A FARADAY ROTATION MEASURE ANOMALY IN CYGNUS

We confirm the reality of a reversal of the sign of the Faraday rotation measure in the Galactic plane in Cygnus (Lazio et al. 1990), possibly associated with the Cygnus OB1 association. The rotation measure changes by several hundred rad m–2 over an angular scale of 2°-5°. We show that a simple model of an expanding plasma shell with an enhanced density and magnetic field can account for the magnitude and angular scale of this feature. This model is consistent with observations of Hα emission as well as other observations in this part of sky. We suggest that this structure is physically associated with a superbubble produced by the Cygnus OB1 association.
Enantiomerically pure bicyclo[3.3.1]nona-2,6-diene as the sole source of enantioselectivity in BIPHEP-Rh asymmetric hydrogenation

In situ resolution of the rapidly racemising diphosphine BIPHEP and its relatives with the cationic Rh complex of (S,S)-bicyclonona-2,6-diene permits the asymmetric hydrogenation of dehydroamino esters.
Smoke-free ordinances increase restaurant profit and value.

This study estimates the economic value added to a restaurant by a smoke-free policy using regression analysis of the purchase price of restaurants, as a function of the presence of a smoke-free law and other control variables. There was a median increase of 16% (interquartile range 11% to 25%) in the sale price of a restaurant in a jurisdiction with a smoke-free law compared to a comparable restaurant in a community without such a law. This result indicates that, contrary to claims made by the tobacco industry and other opponents of smoke-free laws, these laws are associated with an increase in restaurant profitability.
An improved algorithm for approximate string matching

Given a text string, a pattern string, and an integer k, a new algorithm for finding all occurrences of the pattern string in the text string with at most k differences is presented. Both its theoretical and practical variants improve upon the known algorithms.
The quark-gluon plasma at RHIC☆

Abstract I present a theory-guided review of RHIC data, arguing that they provide strong evidence for formation of a thermalized quark-gluon plasma at RHIC. Strong radial flow reflects high thermal pressure in the reaction zone. Large elliptic flow proves that the pressure builds up quickly and the system thermalizes on a very short time scale of c . The observed hadron yields are consistent with statistical hadron formation from a quark-gluon plasma, followed by immediate chemical decoupling due to strong radial expansion. The observed suppression of jets appears to confirm the predicted large energy loss suffered by hard partons moving through a quark-gluon plasma; more work is required to quantitatively understand this effect. Source size measurements using two-particle correlations do not seem to fit into this picture; the origin of this discrepancy (“HBT puzzle”) is presently not understood.
Progesterone and subsequent polar metabolites are essential for completion of the first meiotic division in amphibian oocytes

We find that completion of the first meiotic division in Rana pipiens oocytes requires the sequential action of at least two steroids: progesterone and one or more subsequent polar metabolites of progesterone. Progesterone binding in vitro to oocyte surface receptors increases during the first 4-5h of exposure, followed by internalization of plasma membrane together with membrane-bound progesterone over the next hour. The internalized progesterone is metabolized to highly polar polyhydroxylated steroid(s) prior to nuclear membrane disappearance at 8-9h. Polar steroids alone cannot induce meiosis, but do so in oocytes pretreated with progesterone for 1h. Similarly, the non-metabolizable progestin R5020 cannot induce meiosis but does if oocytes are subsequently exposed to polar steroids. An inhibitor of steroid alpha-reductase (4-MA) prevents both progesterone metabolism and progesterone-induced meiosis. However, meiosis does occur if 4-MA is followed by a polar steroid. Thus, progesterone binding at the oocyte surface initiates a process which requires polar progesterone metabolites for completion of the first meiotic division.
Determination of the Pd-Gd exchange constant by neutron diffuse scattering and the Pd polarization in PdGd alloys☆

Abstract The field and temperature dependence of the Gd moment in Pd 0.98 Fe 0.01 Gd 0.01 was determined by neutron scattering methods. The observed behavior is consistent with a B 7 2 ( x ) dependence with a Pd-Gd exchange constant of -0.018 eV. This exchange constant in a simple molecular field model accounts for the existing magnetization data for paramagnetic Pd Gd alloys and suggest a negative spontaneous Pd polarization for the ferromagnetic alloys that can be reversed in high magnetic fields.
The Preparation of Cyclobutadienyliron Tricarbonyl Complexes Using Disodium Tetracarbonylferrate (-2)

Abstract An improved preparation for cyclobutadienyliron tricarbonyl complexes from 3,4-carbonyldioxycyclobutenes has been developed. The development of the procedure revealed a number of the details of the reaction and the importance of the method used to prepare tetracarbonylferrate (-2) on subsequent reactions.
Master Transcription Factors and Mediator Establish Super-Enhancers at Key Cell Identity Genes

Master transcription factors Oct4, Sox2, and Nanog bind enhancer elements and recruit Mediator to activate much of the gene expression program of pluripotent embryonic stem cells (ESCs). We report here that the ESC master transcription factors form unusual enhancer domains at most genes that control the pluripotent state. These domains, which we call super-enhancers, consist of clusters of enhancers that are densely occupied by the master regulators and Mediator. Super-enhancers differ from typical enhancers in size, transcription factor density and content, ability to activate transcription, and sensitivity to perturbation. Reduced levels of Oct4 or Mediator cause preferential loss of expression of super-enhancer-associated genes relative to other genes, suggesting how changes in gene expression programs might be accomplished during development. In other more differentiated cells, super-enhancers containing cell-type-specific master transcription factors are also found at genes that define cell identity. Super-enhancers thus play key roles in the control of mammalian cell identity.
THE REVERSAL OF THE HYDROGEN SERIES IN THE EXTREME ULTRA-VIOLET

IN the course of the presentation of a paper on the spectrum of neon at the spring meeting of the American Physical Society a year ago, I mentioned that I had been able to obtain the first three members of the hydrogen series in the extreme ultra-violet reversed. Recently I have repeated the experiment with the purpose of improving the technique and confirming the results.
Synthesis of Well-Defined Diphenylvinyl(cyclopropyl)phosphine-Palladium Complexes for the Suzuki–Miyaura Reaction and Buchwald–Hartwig Amination

The successful synthesis of novel and well-defined Pd-complexes (PBR and PBD) is developed.
Global Random Optimization by Simultaneous Perturbation Stochastic Approximation

We examine the theoretical and numerical global convergence properties of a certain ldquogradient freerdquo stochastic approximation algorithm called the ldquosimultaneous perturbation stochastic approximation (SPSA)rdquo that has performed well in complex optimization problems. We establish two theorems on the global convergence of SPSA, the first involving the well-known method of injected noise. The second theorem establishes conditions under which ldquobasicrdquo SPSA without injected noise can achieve convergence in probability to a global optimum, a result with important practical benefits.
An arithmetic formula for certain coefficients of the Euler product of Hecke polynomials

Abstract In 1997 the author found a criterion for the Riemann hypothesis for the Riemann zeta function, involving the nonnegativity of certain coefficients associated with the Riemann zeta function. In 1999 Bombieri and Lagarias obtained an arithmetic formula for these coefficients using the “explicit formula” of prime number theory. In this paper, the author obtains an arithmetic formula for corresponding coefficients associated with the Euler product of Hecke polynomials, which is essentially a product of L -functions attached to weight 2 cusp forms (both newforms and oldforms) over Hecke congruence subgroups Γ 0 ( N ) . The nonnegativity of these coefficients gives a criterion for the Riemann hypothesis for all these L -functions at once.
Can lessons from public health disease surveillance be applied to environmental public health tracking

Disease surveillance has a century-long tradition in public health, and environmental data have been collected at a national level by the U.S. Environmental Protection Agency for several decades. Recently, the CDC announced an initiative to develop a environmental public health tracking (EPHT) network with "linkage" of existing environmental and chronic disease data. On the basis of experience with established disease surveillance systems, we suggest how a system capable of linking routinely collected disease and exposure data should be developed. The primary operational goal of EPHT has to be the "treatment" of the environment to prevent and/or reduce exposures and minimize population risk for developing chronic diseases. Thus, EPHT should be synonymous with a dynamic process requiring regular system updates to a) incorporate new technologies to improve population-level exposure and disease assessment, b) allow public dissemination of new data that become available, c) allow the policy community to address new and emerging exposures and disease "threads," and d) evaluate the effectiveness of EPHT over some time interval. It will be necessary to weigh the benefits of surveillance against its costs, but the major challenge will be to maintain support for this important new system.
Metabolic syndrome impairs notch signaling and promotes apoptosis in chronically ischemic myocardium

Objective Impaired angiogenesis is a known consequence of metabolic syndrome (MetS); however, the mechanism is not fully understood. Recent studies have shown that the notch signaling pathway is an integral component of cardiac angiogenesis. We tested, in a clinically relevant swine model, the effects of MetS on notch and apoptosis signaling in chronically ischemic myocardium. Methods Ossabaw swine were fed either a regular diet (control [CTL], n = 8) or a high-cholesterol diet (MetS, n = 8) to induce MetS. An ameroid constrictor was placed to induce chronic myocardial ischemia. Eleven weeks later, the wine underwent cardiac harvest of the ischemic myocardium. Results Downregulation of pro-angiogenesis proteins notch2, notch4, jagged2, angiopoietin 1, and endothelial nitric oxide synthase were found in the MetS group compared with the CTL group. Also, upregulation of pro-apoptosis protein caspase 8 and downregulation of anti-angiogenesis protein phosphorylated forkhead box transcription factor 03 and pro-survival proteins phosphorylated P38 and heat shock protein 90 were present in the MetS group. Cell death was increased in the MetS group compared with the CTL group. Both CTL and MetS groups had a similar arteriolar count and capillary density, and notch3 and jagged1 were both similarly concentrated in the smooth muscle wall. Conclusions MetS in chronic myocardial ischemia significantly impairs notch signaling by downregulating notch receptors, ligands, and pro-angiogenesis proteins. MetS also increases apoptosis signaling, decreases survival signaling, and increases cell death in chronically ischemic myocardium. Although short-term angiogenesis appears unaffected in this model of early MetS, the molecular signals for angiogenesis are impaired, suggesting that inhibition of notch signaling might underlie the decreased angiogenesis in later stages of MetS.