cssi/SciSciGPT-SciSciNet huggingface dataset:
Expectation of quadratic forms in normal and nonnormal variables with applications

We derive some new results on the expectation of quadratic forms in normal and nonnormal variables. Using a nonstochastic operator, we show that the expectation of the product of an arbitrary number of quadratic forms in noncentral normal variables follows a recurrence formula. This formula includes the existing result for central normal variables as a special case. For nonnormal variables, while the existing results are available only for quadratic forms of limited order (up to 3), we derive analytical results to a higher order 4. We use the nonnormal results to study the effects of nonnormality on the finite sample mean squared error of the OLS estimator in an AR(1) model and the QMLE in an MA(1) model.
DELIGNE PAIRINGS AND THE KNUDSEN-MUMFORD EXPANSION

Let X → B be a proper flat morphism between smooth quasiprojective varieties of relative dimension n, and L → X a line bundle which is ample on the fibers. We establish formulas for the first two terms in the Knudsen-Mumford expansion for det(π�L k ) in terms of Deligne pairings of L and the relative canonical bundle K. This generalizes the theorem of Deligne [1], which holds for families of relative dimension one. As a corollary, we show that when X is smooth, the line bundle η associated to X → B, which was introduced in Phong-Sturm [12], coincides with the CM bundle defined by Paul-Tian [10, 11]. In a second and third corollaries, we establish asymptotics for the K-energy along Bergman rays generalizing the formulas obtained in [11].
Synthesis of uniform GaN quantum dot arrays via electron nanolithography of D2GaN3

We demonstrate the deposition of periodic arrays of uniformly sized GaN quantum dots onto a SiOx substrate. The dots are deposited using a nanolithography technique based on a combination of electron-beam-induced chemical vapor deposition and single-source molecular hydride chemistries. Under appropriate deposition conditions, we can deposit uniform dots of height 5 nm and full widths at half-maxima of 4 nm. The dot size is controlled by the spatial distribution of secondary electrons leaving the substrate surface. The smallest, most uniform void-free dots are created via nanolithography of molecules adsorbed on the substrate surface.
DARK ENERGY TASK FORCE: FINDINGS AND RECOMMENDATIONS

NASA, NSF, and the Department of Energy established the Dark Energy Task Force to examine the opportunities for exploration of dark energy and to report on the various techniques that might be employed to further our understanding of this remarkable phenomenon. The Task Force examined dozens of white papers outlining the plans of teams to measure dark energy's properties. I present here the findings and recommendations of the Task Force. Our methodology is explained in another talk at this conference.
Determination of tire-wheel interface loads for aircraft wheels

A numerical tool is developed for determining the pressure distribution at the tire-wheel interface of an aircraft wheel from experimentally obtained strains. The methodology employs an axisymmetric finite element model which is subjected to asymmetric loading. The loading is represented as a double Fourier series, and the components are determined by a least squares fit using the experimentally determined strains. A finite element code was developed to perform this analysis. Sample experiments are presented to illustrate the validity and the robustness of the algorithm. Finally, the limitations of this type of analysis are discussed and future directions are indicated.
Multi-User Diversity vs. Accurate Channel Feedback for MIMO Broadcast Channels

A multiple transmit antenna, single receive antenna (per receiver) downlink channel with limited channel feedback is considered. Given a constraint on the total system-wide channel feedback, the following question is considered: is it preferable to get low-rate feedback from a large number of receivers or to receive high-rate/high-quality feedback from a smaller number of (randomly selected) receivers? Acquiring feedback from many users allows multi-user diversity to be exploited, while high- rate feedback allows for very precise selection of beamforming directions. It is shown that systems in which a limited number of users feedback high-rate channel information significantly outperform low-rate/many user systems. While capacity increases only double logarithmically with the number of users, the marginal benefit of channel feedback is very significant up to the point where the CSI is essentially perfect.
Price-Quality Tradeoffs in the Selection of Fresh Fruit: A Look at Apples

This study used supermarket scanner data to analyze purchase behavior for higher- and lower-income shoppers in six stores in Columbus, Ohio. Three higher- and three lower-income stores are selected and consumer purchases are observed for 17 varieties of apples. The results show that lower-income shoppers pay lower per unit prices for most varieties of apples. More importantly, these purchases are made without sacrificing quality for a lower price.
Modeling and Integrating Background Knowledge in Data Anonymization

Recent work has shown the importance of considering the adversary's background knowledge when reasoning about privacy in data publishing. However, it is very difficult for the data publisher to know exactly the adversary's background knowledge. Existing work cannot satisfactorily model background knowledge and reason about privacy in the presence of such knowledge.This paper presents a general framework for modeling the adversary's background knowledge using kernel estimation methods. This framework subsumes different types of knowledge (e.g., negative association rules) that can be mined from the data. Under this framework, we reason about privacy using Bayesian inference techniques and propose the skyline (B, t)-privacy model, which allows the data publisher to enforce privacy requirements to protect the data against adversaries with different levels of background knowledge. Through an extensive set of experiments, we show the effects of probabilistic background knowledge in data anonymization and the effectiveness of our approach in both privacy protection and utility preservation.
Intermolecular reactions of electron-rich heterocycles with copper and rhodium carbenoids

This tutorial review describes the reactions of the electron-rich heterocycles pyrrole, furan, indole and benzofuran with copper and rhodium carbenoids. Two main reaction pathways are possible, involving either a concerted non-synchronous cyclopropanation or zwitterionic intermediates. A diverse range of products are possible and the outcome is very dependent on the structure of the heterocycle and the carbenoid. To emphasize this point the carbenoids are considered in terms of three classes: acceptor, acceptor–acceptor and donor–acceptor carbenoids. Unusual catalytic asymmetric transformations can be achieved with this chemistry while the asymmetric induction is strongly influenced by how the carbenoid can approach the heterocycles. This tutorial review gives an overview of the general features that govern the chemistry of metal carbenoids with heterocycles and presents a mechanistic rationale for the range of products that can be formed.
Gamma Ray Bursts and their links with Supernovae and Cosmology

Gamma-ray bursts are the most luminous explosions in the Universe, whose origin and mechanism are the focus of intense interest. They appear connected to supernova remnants from massive stars or the merger of their remnants, and their brightness makes them temporarily detectable out to the largest distances yet explored in the universe. After pioneering breakthroughs from space and ground experiments, their study is entering a new phase with observations from the recently launched Fermi satellite, as well as the prospect of detections or limits from large neutrino and gravitational wave detectors. The interplay between such observations and theoretical models of gamma-ray bursts is reviewed, as well as their connections to supernovae and cosmology.
Synthesis of a 2,9-dioxabicyclo[3.3.1]nonane via double intramolecular hetero-Michael addition: entry to the F-G ring system of the azaspiracids.

An effective approach to form a 1,3-disubstituted 2,9-dioxabicyclo[3.3.1]nonane system representing the core of the F and G rings (C28−C34) of the azaspiracid natural products has been developed. The double intramolecular hetero-Michael addition (DIHMA) of a diol upon an ynone generated the bicyclic ketal in a highly diastereoselective fashion.
On the verification of sequential equivalence

The state-explosion problem limits formal verification on large sequential circuits partly because the sizes of binary decision diagrams (BDDs) sizes heavily depend on the number of variables dealt with. In the worst case, a BDD size grows exponentially with the number of variables. Thus, reducing this number can possibly increase the verification capacity. In particular, this paper shows how sequential equivalence checking can be done in the sum state space. Given two finite state machines M/sub 1/ and M/sub 2/ with numbers of state variables m/sub 1/ and m/sub 2/, respectively, conventional formal methods verify equivalence by traversing the state space of the product machine with m/sub 1/+m/sub 2/ registers. In contrast, this paper introduces a different possibility, based on partitioning the state space defined by a multiplexed machine, which can have merely max{m/sub 1/,m/sub 2/}+1 registers. This substantial reduction in state variables potentially enables the verification of larger instances. Experimental results show the approach can verify benchmarks with up to 312 registers, including all of the control outputs of microprocessor 8085.
Regime-switching in exchange rate policy and balance sheet effects

It is well accepted that exchange rate policy in many emerging markets has been characterized by shifts between a stronger and weaker commitment to peg. This raises the following questions, which we address in our paper: Does intervention policy exhibit clearly defined and periodic shifts? What drives this policy variability? We identify clearly defined switches between high and low intervention in all the countries in our sample. We also find strong evidence that balance sheet effects, proxied by the stock ratio of external liabilities to assets, and economic performance, as measured by GDP and stock market indices, determine the likelihood of the regime shift. Specifically, an increase in reserve currency debt raises potential capital losses from devaluation and reduces the probability of switching to a low intervention regime. We use a panel of quarterly data starting 1985 through 2004 for a sample of 15 countries, mostly from East Asia and Latin America. We adopt a novel two-step empirical strategy in this paper. First, we measure the policy response of the central bank in two ways, both derived from the monetarist model: a standard exchange market pressure index and a model-based volatility ratio that is endogenized relative to Japan, our “benchmark” floater. We apply regime-switching methods to these “policy response indices.” This generates a time-series of unconditional probabilities of switching between high and low intervention. In the second step, we establish a set of variables that explains changes in these probabilities.
Panel Data Techniques and the Elasticity of Taxable Income

This paper examines the elasticity of taxable income with special focus on income controls designed to control for divergence in the income distribution and mean reversion. Additional emphasis is placed on the difference between short-run and longer-run responses to tax rate changes. Several panel techniques are applied to tax return data for years 1991 to 1997, followed by a cross-section analysis covering the same period. For each panel regression, an innovative inverted panel regression framework is employed to test the efficacy of the controls for mean reversion apart from controls for divergence in the income distribution. Finally, cross-section (and repeated cross-section) regressions are estimated for comparison. A major finding from comparing estimates from the standard and inverted panels is that even some of the more sophisticated techniques likely fail to adequately control for mean reversion at the top of the income distribution. Furthermore, the residual impact from mean reversion may still exert an enormous influence on elasticity estimates, which could help explain the lack of robustness reported in a number of papers in this literature. Analysis of cross-section data circumvents the problem of mean reversion and results in estimates that are robust with respect to sample income cutoffs. However when vast differences likely exist between those experiencing a specific change in tax rates and other filers, estimates relying on either panel or cross-section data are likely to be poorly identified.
WHO PARTICIPATES IN EQIP

Abstract The Environmental Quality Incentive Program is designed to improve environmental stewardship of crop and livestock production. Funds requested through the program greatly exceed the supply. Recent changes make the program more attractive for larger farmers. A survey of farmers in Missouri and Iowa found that larger farmers (in terms of farm sales) and those without a personal concern for water quality in their county are significantly more likely to be aware of EQIP. Those who plan to expand in the next five years, and those who use and trust public information sources, are more likely to be aware of the program and also to participate in EQIP. Age and education variables were not significant. Key Words EQIP, adoption, farm size. Introduction The Environmental Quality Incentive Program (EQIP) was initiated in the 1996 Farm Act to promote improved environmental stewardship on lands in agricultural production. This is in contrast to the Conservation Reserve Program that retired land in order to promote environmental objectives. Demand for participation in EQIP exceeds the funds available even though the 2002 Farm Act significantly increased funding for the program from $200 million per year up to 1.3 billion in 2007. About $1 is available for every $10 that are requested (Carpenter). In the amended program, livestock practices are to receive 60% of the available funding, compared to 50% under the 1996 Farm Act. The maximum payment was raised to $450,000 over the life of the farm bill, which may make the program relatively more attractive for larger farmers. Also, under the 2002 Farm Act, CAFOs are able to apply for EQIP funding. Livestock farms, whether they are CAFOs or not, are required to have Comprehensive Nutrient Management Plans (CNMPs) in order to participate in EQIP which can be a barrier to
Forming a Moon with an Earth-Like Composition via a Giant Impact

In the giant impact theory, the Moon formed from debris ejected into an Earth-orbiting disk by the collision of a large planet with the early Earth. Prior impact simulations predict that much of the disk material originates from the colliding planet. However, Earth and the Moon have essentially identical oxygen isotope compositions. This has been a challenge for the impact theory, because the impactor’s composition would have likely differed from that of Earth. We simulated impacts involving larger impactors than previously considered. We show that these can produce a disk with the same composition as the planet’s mantle, consistent with Earth-Moon compositional similarities. Such impacts require subsequent removal of angular momentum from the Earth-Moon system through a resonance with the Sun as recently proposed.
Heteroskedasticity-Robust Standard Errors for Fixed Effects Panel Data Regression

The conventional heteroskedasticity-robust (HR) variance matrix estimator for cross-sectional regression (with or without a degrees-of-freedom adjustment), applied to the fixed-effects estimator for panel data with serially uncorrelated errors, is inconsistent if the number of time periods T is fixed (and greater than 2) as the number of entities n increases. We provide a bias-adjusted HR estimator that is -consistent under any sequences (n, T) in which n and/or T increase to ∞. This estimator can be extended to handle serial correlation of fixed order.
A SYSTEM FOR THE SIMULATION AND EVALUATION OF SATELLITE COMMUNICATION NETWORKS

With the emergence of a new era in satellite communications, brought about by NASA's thrust into the Ka band with multibeam and onboard processing technologies, new and innovative techniques for evaluating these concepts and systems are required. To this end, NASA, in conjunction with its extensive program for advanced communications technology development, has undertaken to develop a concept for the simulation and evaluation of a complete communications network. Incorporated in this network will be proof-of-concept models of the latest technologies proposed for future satellite communications systems. These include low noise receivers, matrix switches, baseband processors, and solid state and tube type high power amplifiers. To accomplish this, numerous supporting technologies must be added to those aforementioned proof-of-concept models. These include controllers for synchronization, order wire, resource allocation, gain compensation, signal leveling, power augmentation, and rain fade and range delay simulation. Taken together, these will be assembled to comprise a system capable of addressing numerous design and performance questions. The simulation and evaluation system, as planned, will be modular in design and implementation, capable of modification and updating to track and evaluate a continuum of emerging concepts and technologies. Previously announced in STAR as N84-13400
Irredundant families of subcubes

AbstractWe consider the problem of ﬁnding the maximum possible size of afamily of k-dimensional subcubes of the n-cube {0,1} n , none of whichis contained in the union of the others. (We call such a family ‘irre-dundant’). Aharoni and Holzman [1] conjectured that for k > n/2,the answer is nk (which is attained by the family of all k-subcubescontaining a ﬁxed point). We give a new proof of a general upperbound of Meshulam [6], and we prove that for k≥ n/2, any irredun-dant family in which all the subcubes go through either (0,0,...,0) or(1,1,...,1) has size at most nk . We then give a general lower bound,showing that Meshulam’s upper bound is always tight up to a factorof at most e. 1 Introduction Let {0,1} n denote the n-dimensional discrete cube, the set of all 0-1 vectorsof length n. A k-dimensional subcube (or k-subcube) of {0,1} n is a subset of{0,1} n of the form{x ∈ {0,1} n : x i = a i ∀i ∈ T}where T is a set of n−k coordinates, called the ﬁxed coordinates, and the a i ’sare ﬁxed elements of {0,1}. The other coordinates S = [n]\T are called themoving coordinates. We will represent a subcube by an n-tuple of 0’s, 1’s and∗’s, where the ∗’s denote moving coordinates and the 0’s and 1’s denote ﬁxedcoordinates. For example, (∗,∗,∗,0,1) denotes a 3-dimensional subcube of{0,1}
Ways of regulating one's drinking: a factor analysis of a Finnish general population sample.

Introduction and Aims. This article studies the various ways of regulating drinking used by Finns and how these vary between men and women, and in different groups of age, educational attainment and alcohol consumption. Design and Methods. The data consist of a cross-section of survey data collected in Finland in 2005. The response rate was 53%. The analysis was restricted to respondents who had used alcohol in the last 12 months and were between 15 and 71 years of age (n = 1013). A factor analysis was performed to discover underlying dimensions in the ways of regulation. In order to study the relationship between the ways of regulation and drinking habits, correlations and regression analyses were used. Results. The ways of regulating one’s drinking extracted to three factors which were named self-control, social control and external control. Self-control was the most common way of regulation. Stronger reliance on external control of drinking increased the probability of heavy alcohol use. Discussion and conclusions. These survey results indicate that external control of drinking, for example the restriction of availability of alcohol, could have a greater impact on heavy drinking than on moderate drinking. [Huhtanen P, Raitasalo K. Ways of regulating one’s drinking: A factor analysis of a Finnish general population sample. Drug Alcohol Rev 2012;31:847–853]
Participation and Duration of Environmental Agreements

We analyze participation in international environmental agreements in a dynamic game in which countries pollute and invest in green technologies. If complete contracts are feasible, participants eliminate the holdup problem associated with their investments; however, most countries prefer to free ride rather than participate. If investments are noncontractible, countries face a holdup problem every time they negotiate; but the free-rider problem can be mitigated and significant participation is feasible. Participation becomes attractive because only large coalitions commit to long-term agreements that circumvent the holdup problem. Under well-specified conditions even the first-best outcome is possible when the contract is incomplete.
Pressure distribution on a surface with large normal injection.

The changes in forces acting on a body moving at high speed because of large normal injection are investigated. The injection velocity is assumed to be much smaller than the velocity of the body but much larger than the value allowed for the boundary-layer theory. Based on these two conditions, the flowfield is governed by the inviscid equations with a discontinuity in velocity along the streamline that separates the inner region of the injected fluid from the outer region of freestream, and the flowfield in the inner region is assumed to be incompressible. Using linearized supersonic theory for the outer region, analytic solutions for injection with constant stagnation pressure (pSj) along the surface of a wedge are obtained. The dividing streamline is inclined to the wedge surface at a small angle 0o continuing nearly straight over the portion of the wedge with injection, and thereafter turning parallel to the wedge surface. The deflection of the outer flow by the angle 00 raises the pressure from the downstream value pm to psj. The additional force and moment caused by injection are obtained with the leading term equivalent to the rise of pressure from pm to pSj over the portion of the surface with injection, and the correction term is of the order 0o.
Trimethyl lock: a trigger for molecular release in chemistry, biology, and pharmacology

The trimethyl lock is an o-hydroxydihydrocinnamic acid derivative in which unfavorable steric interactions between three pendant methyl groups encourage lactonization to form a hydrocoumarin. This reaction is extremely rapid, even when the electrophile is an amide and the leaving group is an amino group of a small-molecule drug, fluorophore, peptide, or nucleic acid. O-Acylation of the phenolic hydroxyl group prevents reaction, providing a trigger for the reaction. Thus, the release of an amino group from an amide can be coupled to the hydrolysis of a designated ester (or to another chemical reaction that regenerates the hydroxyl group). Trimethyl lock conjugates are easy to synthesize, making the trimethyl lock a highly versatile module for chemical biology and related fields.
Combustion of Boron-Titanium Nanocomposite Powders in Different Environments

Combustion of nanocomposite powders with the bulk composition 2B+Ti was compared with combustion of blended boron and titanium powders with the same bulk composition and with combustion of aluminum in wet and dry gas environments. Nanocomposite powders were prepared by Arrested Reactive Milling. The gas environments were N2/O 2/CH 4 mixtures with oxygen concentration fixed at 22.5 % and methane concentration varied from 0 to 12 %. The experiments were conducted in a constant volume explosion vessel. The mass loads of metallic fuel were determined from thermodynamic calculations to ensure the maximum flame temperature for each metal fuel – gas mixture combination. The calculations showed that despite the higher adiabatic flame temperatures for Al than for 2B+Ti, a greater energy per unit mass of metal fuel was released to produce heated gaseous combustion products in combustion of 2B+Ti as compared to Al. Experiments with Al powders showed that the flame temperature did not change noticeably as a function of gas composition and remained close to 2560 K. The combustion temperature for the nanocomposite 2B+Ti increased from about 2180 to 2370 K as the methane concentration increased from 0 to 12 %. The bulk burn rates inferred from the rates of pressure rise were consistently higher for the nanocomposite 2B+Ti powder, followed by Al and then by the blended 2B+Ti powder. The efficiency of combustion for all the fuels was assessed by comparing the predicted and experimental portions of the combustion energy used to produce the heated gaseous products. Based on this assessment, nanocomposite boron-based fuels outperformed Al for all environments, with the difference increasing at the increased methane concentrations. Nearly complete combustion was observed for both 2B+Ti fuels (nanocomposite and blended powders) at high methane concentration, when the highest rates of combustion were also observed. Thus, the effect of kinetic trap associated with formation of HOBO could not be detected. It was concluded that nanocomposite 2B+Ti powders enable one to achieve rapid and highly efficient combustion in both dry and wet gaseous environments.
The Road Not Taken: Dred Scott, Judicial Authority, and Political Questions

The Supreme Court's decision in Dred Scott v. Sandford is widely regarded as among the worst decisions it has ever made. In addition to embracing reviled substantive values, the decision deeply wounded the Court's status and authority. By embracing a theory of judicial supremacy that held that the Court alone could resolve all important constitutional disputes, however, the Court had been gradually moving toward such a debacle. An important Jeffersonian tradition criticized the Court for encouraging political actors to forego their own constitutional responsibilities. The dissenting opinion of Justice Benjamin Curtis suggested a more appropriate course for the Court, one that carved out a clear place for the exercise of judicial review but that recognized an important sphere of constitutional politics outside the judiciary.
Application of Expurgated PPM to Indoor Visible Light Communications—Part I: Single-User Systems

Visible light communications (VLC) in indoor environments suffer from the limited bandwidth of LEDs as well as from the inter-symbol interference (ISI) imposed by multipath. In this work, transmission schemes to improve the performance of indoor optical wireless communication (OWC) systems are introduced. Expurgated pulse-position modulation (EPPM) is proposed for this application since it can provide a wide range of peak to average power ratios (PAPR) needed for dimming of the indoor illumination. A correlation decoder used at the receiver is shown to be optimal for indoor VLC systems, which are shot noise and background-light limited. Interleaving applied on EPPM in order to decrease the ISI effect in dispersive VLC channels can significantly decrease the error probability. The proposed interleaving technique makes EPPM a better modulation option compared to PPM for VLC systems or any other dispersive OWC system. An overlapped EPPM pulse technique is proposed to increase the transmission rate when bandwidth-limited white LEDs are used as sources.
Seshadri constants at very general points

We study the local positivity of an ample line bundle at a very general point of a smooth projective variety. We obtain a slight improvement of the result of Ein, Kuchle, and Lazarsfeld.
Rhapsody. I. Structural Properties and Formation History from a Statistical Sample of Re-simulated Cluster-size Halos

We present the rst results from the Rhapsody cluster re-simulation project: a sample of 96 \zoom-in" simulations of dark matter halos of 10 14:8 0:05 h 1 M , selected from a 1 h 3 Gpc 3 volume. This simulation suite is the rst to resolve this many halos with 5 10 6 particles per halo in the cluster mass regime, allowing us to statistically characterize the distribution of and correlation between halo properties at xed mass. We focus on the properties of the main halos and how they are aected by formation history, which we track back to z = 12, over ve decades in mass. We give particular attention to the impact of the formation history on the density proles of the halos. We nd that the deviations from the Navarro{Frenk{White (NFW) model and the Einasto model depend on formation time. Late-forming halos tend to have considerable deviations from both models, partly due to the presence of massive subhalos, while early-forming halos deviate less but still signicantly from the NFW model and are better described by the Einasto model. We nd that the halo shapes depend only moderately on formation time. Departure from spherical symmetry impacts the density proles through the anisotropic distribution of massive subhalos. Further evidence of the impact of subhalos is provided by analyzing the phase-space structure. A detailed analysis of the properties of the subhalo population in Rhapsody is presented in a companion paper.
The Effective Static Stability Experienced by Eddies in a Moist Atmosphere

Water vapor directly affects the dynamics of atmospheric eddy circulations through the release of latent heat. But it is difficult to include latent heat release in dynamical theories because of the associated nonlinearity (precipitation generally occurs where there is upward motion). A new effective static stability is derived that fundamentally captures the effect of latent heat release on moist eddy circulations. It differs from the usual dry static stability by an additive term that depends on temperature and a parameter measuring the up–down asymmetry of vertical velocity statistics. Latent heat release reduces the effective static stability experienced by eddies but cannot reduce it to zero so long as there are nonprecipitating regions of the eddies. Evaluation based on reanalysis data indicates that the effective static stability in the lower troposphere ranges from ;80% of the dry static stability at high latitudes to ;25% in the tropics. The effective static stability provides a solution to the longstanding problem of how to adapt dry dynamical theories to the moist circulations in the atmosphere. Its utility for climate change problems is illustrated based on simulations with an idealized general circulation model. It is shown to help account for changes in the thermal stratification of the extratropical troposphere, the extent of the Hadley cells, the intensity of extratropical transient eddies, and the extratropical eddy length.
Convergence in the age of mass migration

Between 1870 and 1913 economic convergence among present OECD members (or an even wider sample of countries) was dramatic, about as dramatic as it has been over the past century and a half. What were the sources of the convergence? One prime candidate is mass migration. This paper offers some estimates which suggest that migration could account for very large shares of the convergence in labour productivity and real wages, though a much smaller share in GDP per capita. One might conclude, therefore, that virtual cessation of convergence in the interwar period could be partially explained by the imposition of quotas and other barriers to migration.The exportation of labourers and capital from old to new countries, from a place where their productive power is less to a place where it is greater, increases by so much the aggregate produce of wealth of the old and the new country.… Colonization, in the present state of the world, is the best affair of business, in which the capital of an old and wealthy country can engage.–John Stuart MillMill (1929 [1848])It must be emphasized that without the change in the proportions of the factors of production that occurs as a result of migration or population growth, differences in factor prices in various countries will persist, and the factors of production of the world as a whole will not be used to their best advantage.–Eli F. HeckscherFlam and Flanders (1991, 59). Heckscher understood that with impediments to trade or with specialization outside cones of diversification (a failure of ‘harmonic equilibrium’, in his words), factor price convergence would be incomplete and factor migration necessary to obtain factor price equalization.
Ring formation from an oscillating black hole

Massive black hole (BH) mergers can result in the merger remnant receiving a “kick,” of order 200 km s 1 or more, which will cause the remnant to oscillate about the galaxy centre. Here we analyze the case where the BH oscillates through the galaxy centre perpendicular or parallel to the plane of the galaxy for a model galaxy consisting of an exponential disk, a Plummer model bulge, and an isothermal dark matter halo. For the perpendicular motion we find that there is a strong resonant forcing of the disk radial motion near but somewhat less than the “resonant radii” rR where the BH oscillation frequency is equal one-half, one-fourth, (1=6, etc.) of the radial epicyclic frequency in the plane of the disk. Near the resonant radii there can be a strong enhancement of the radial flow and disk density which can lead to shock formation. In turn the shock may trigger the formation of a ring of stars near rR. As an example, for a BH mass of 10 8 M and a kick velocity of 150 km s 1 , we find that the resonant radii lie between 0:2 and 1 kpc. For BH motion parallel to the plane of the galaxy we find that the BH leaves behind it a supersonic wake where star formation may be triggered. The shape of the wake is calculated as well as the slow-down time of the BH. The differential rotation of the disk stretches the wake into ring-like segments.
Decisions of the Appellate Body of the World Trade Organization

WTO Appellate Body Report: Guatemala–Anti-Dumping Investigation Regarding Portland Cement from Mexico, AB-1998–6, WT/DS60/AB/R (98–4190), adopted by Dispute Settlement Body, 25 November 1998. Guatemala, Appellant; Mexico, Appellee; United States, Third Participant. Division: Lacarte-Muro, Beeby and El-Naggar. Major topics addressed by Appellate Body: relationship of DSU to Anti-Dumping Agreement; requirements for commencement of panel proceedings.
Elephantid Genomes Reveal the Molecular Bases of Woolly Mammoth Adaptations to the Arctic

Summary Woolly mammoths and living elephants are characterized by major phenotypic differences that have allowed them to live in very different environments. To identify the genetic changes that underlie the suite of woolly mammoth adaptations to extreme cold, we sequenced the nuclear genome from three Asian elephants and two woolly mammoths, and we identified and functionally annotated genetic changes unique to woolly mammoths. We found that genes with mammoth-specific amino acid changes are enriched in functions related to circadian biology, skin and hair development and physiology, lipid metabolism, adipose development and physiology, and temperature sensation. Finally, we resurrected and functionally tested the mammoth and ancestral elephant TRPV3 gene, which encodes a temperature-sensitive transient receptor potential (thermoTRP) channel involved in thermal sensation and hair growth, and we show that a single mammoth-specific amino acid substitution in an otherwise highly conserved region of the TRPV3 channel strongly affects its temperature sensitivity.
An Electrical Surge Arrestor (ESA) Model for Electromagnetic Pulse Analysis

Electrical Surge Arrestors (ESA's) have been used extensively for lightning and EMP protection. These components are characterized by (a) presenting an open circuit (high impedance) below the gap breakdown potential, (b) becoming a virtual short-circuit above the gap breakdown and (c) displaying a significantly higher level of apparent gap breakdown for very fast input voltage rise-times (dv/dt). This paper describes a mathematical model for a spark gap surge arrestor which has been used successfully to characterize ESA response to the following stimulus: 1. Below DC Gap Breakdown 2. At or above Gap Breakdown 3. At high apparent Gap Breakdown voltage as a function of increased rise-time 4. Damped Sinewave Input (below and at Gap Breakdown) 5. Exposed to prompt gamma radiation using a Flash X-Ray source and an electrical input
Reconstructing Ancestral Haplotypes with a Dictionary Model

We propose a dictionary model for haplotypes. According to the model, a haplotype is constructed by randomly concatenating haplotype segments from a given dictionary of segments. A haplotype block is defined as a set of haplotype segments that begin and end with the same pair of markers. In this framework, haplotype blocks can overlap, and the model provides a setting for testing the accuracy of simpler models invoking only nonoverlapping blocks. Each haplotype segment in a dictionary has an assigned probability and alternate spellings that account for genotyping errors and mutation. The model also allows for missing data, unphased genotypes, and prior distribution of parameters. Likelihood evaluations rely on forward and backward recurrences similar to the ones encountered in hidden Markov models. Parameter estimation is carried out with an EM algorithm. The search for the optimal dictionary is particularly difficult because of the variable dimension of the model space. We define a minimum description le...
Building the bridge between design and manufacturing

The efforts made by IBM to accommodate the design-to-manufacturing transfer process are presented, and the groundwork that has been laid to accelerate key leverage areas as they become viable is described. Highlights are presented of the changes that have been made-and are continuing to be made-in the design process. This study addresses the design process in product laboratories that enable system engineers to design packaged electronic products specifically to meet their requirements. The technology development process that has become an integral part of the design and release transfer is examined. The complexities of a multilaboratory environment and the impact that it has on the reduction of the total product development cycle time are reviewed. A discussion on managing this entire process, the need to strictly adhere to standards, and the synchronization of engineering changes with system and software enhancements is provided. >
Backward stealing and forward manipulation in the WTO

Abstract Motivated by the structure of WTO negotiations, we analyze a bargaining environment in which negotiations proceed bilaterally and sequentially under the most-favored-nation (MFN) principle. We identify backward-stealing and forward-manipulation problems that arise when governments bargain under the MFN principle in a sequential fashion. We show that these problems impede governments from achieving the multilateral efficiency frontier unless further rules of negotiation are imposed. We identify the WTO nullification-or-impairment and renegotiation provisions and its reciprocity norm as rules that are capable of providing solutions to these problems. In this way, we suggest that WTO rules can facilitate the negotiation of efficient multilateral trade agreements in a world in which the addition of new and economically significant countries to the world trading system is an ongoing process.
Some personal observations on the debate on the link between financial reporting quality and the cost of equity capital

Within the last decade there has been much written about the possible link between the quality of a firm’s external financial reporting and its cost of equity capital. In this paper I provide my personal observations about the literature. I make the following points. First, I find the Francis, Lafond, Olsson and Schipper (2005) paper interesting and innovative. This paper documents a positive association between portfolio returns formed on the basis of accrual quality and firms’ realized returns after controlling for the Fama-French three factors. Francis et al. conclude that accrual quality is a priced risk factor. Second, while this conclusion might be too strong based on their results, I think the Core, Guay and Verdi (2008) critique of the Francis et al. claim is also too strong and does not lead me to reject accrual quality as a priced risk factor. Third, the evidence between financial reporting quality and implied cost of capital estimates is robust. However several papers question the construct validity of these measures which are based on analyst earnings forecasts. I discuss these papers and conclude that the implied cost of capital does have empirical validity. Finally, various papers model the relation between financial reporting quality and cost of capital and, while interesting, mostly restrict themselves to a single factor asset pricing model. However, restricting the model to a single factor model by assumption rules out the possibility of information quality being a separately priced risk factor and further restricts the role information quality to informing about a firm’s covariances (or estimation error in the CAPM beta) because it is assumed that information quality is diversifiable. I think whether something is diversifiable is an empirical question that cannot be resolved by assumption within a theoretical model.
Precision Timing of Two Anomalous X-Ray Pulsars.

We report on long-term X-ray timing of two anomalous X-ray pulsars, 1RXS J170849.0-400910 and 1E 2259+586, using the Rossi X-Ray Timing Explorer. In monthly observations made over 1.4 and 2.6 yr for the two pulsars, respectively, we have obtained phase-coherent timing solutions which imply that these objects have been rotating with great stability throughout the course of our observations. For 1RXS J170849.0-400910, we find a rotation frequency of 0.0909169331(5) Hz and frequency derivative -15.687(4) × 10-14 Hz s-1 for epoch MJD 51215.931. For 1E 2259+586, we find a rotation frequency of 0.1432880613(2) Hz and frequency derivative -1.0026(7) × 10-14 Hz s-1 for epoch MJD 51195.583. The rms phase residuals from these simple models are only ~0.01 cycles for both sources. We show that the frequency derivative for 1E 2259+586 is inconsistent with that inferred from incoherent frequency observations made over the last 20 yr. Our observations are consistent with the magnetar hypothesis and make binary accretion scenarios appear unlikely.
Induction of Word and Phrase Alignments for Automatic Document Summarization

Current research in automatic single-document summarization is dominated by two effective, yet naive approaches: summarization by sentence extraction and headline generation via bag-of-words models. While successful in some tasks, neither of these models is able to adequately capture the large set of linguistic devices utilized by humans when they produce summaries. One possible explanation for the widespread use of these models is that good techniques have been developed to extract appropriate training data for them from existing document/abstract and document/headline corpora. We believe that future progress in automatic summarization will be driven both by the development of more sophisticated, linguistically informed models, as well as a more effective leveraging of document/abstract corpora. In order to open the doors to simultaneously achieving both of these goals, we have developed techniques for automatically producing word-to-word and phrase-to-phrase alignments between documents and their human-written abstracts. These alignments make explicit the correspondences that exist in such document/abstract pairs and create a potentially rich data source from which complex summarization algorithms may learn. This paper describes experiments we have carried out to analyze the ability of humans to perform such alignments, and based on these analyses, we describe experiments for creating them automatically. Our model for the alignment task is based on an extension of the standard hidden Markov model and learns to create alignments in a completely unsupervised fashion. We describe our model in detail and present experimental results that show that our model is able to learn to reliably identify word- and phrase-level alignments in a corpus of document, abstract pairs.
How will computing change education

This article discusses nine aspects of education which will be increasingly affected by integrating computing into educational activities to any significant degree. They involve the learner and instructor, the materials and content, the processes followed, and the overall societal perception of education.
Improved Approximation of Linear Threshold Functions

We prove two main results on how arbitrary linear threshold functions $${f(x) = {\rm sign}(w \cdot x - \theta)}$$ over the n-dimensional Boolean hypercube can be approximated by simple threshold functions. Our first result shows that every n-variable threshold function f is $${\epsilon}$$ -close to a threshold function depending only on $${{\rm Inf}(f)^2 \cdot {\rm poly}(1/\epsilon)}$$ many variables, where $${{\rm Inf}(f)}$$ denotes the total influence or average sensitivity of f. This is an exponential sharpening of Friedgut's well-known theorem (Friedgut in Combinatorica 18(1):474---483, 1998), which states that every Boolean function f is $${\epsilon}$$ -close to a function depending only on $${2^{O({\rm Inf}(f)/\epsilon)}}$$ many variables, for the case of threshold functions. We complement this upper bound by showing that $${\Omega({\rm Inf}(f)^2 + 1/\epsilon^2)}$$ many variables are required for $${\epsilon}$$ -approximating threshold functions. Our second result is a proof that every n-variable threshold function is $${\epsilon}$$ -close to a threshold function with integer weights at most $${{\rm poly}(n) \cdot 2^{\tilde{O}(1/\epsilon^{2/3})}.}$$ This is an improvement, in the dependence on the error parameter $${\epsilon}$$ , on an earlier result of Servedio (Comput Complex 16(2):180---209, 2007) which gave a $${{\rm poly}(n) \cdot 2^{\tilde{O}(1/\epsilon^{2})}}$$ bound. Our improvement is obtained via a new proof technique that uses strong anti-concentration bounds from probability theory. The new technique also gives a simple and modular proof of the original result of Servedio (Comput Complex 16(2):180---209, 2007) and extends to give low-weight approximators for threshold functions under a range of probability distributions other than the uniform distribution.
1,3-Dipolar Cycloaddition Chemistry for the Preparation of Novel Indolizinone-Based Compounds

Starting from methyl 5-oxo-6-trifluoromethanesulfonyloxy-1,2,3,5-tetrahydroindolizine-8-carboxylate, obtained by a Rh(II)-catalyzed 1,3-dipolar cycloaddition reaction of 1-(2-benzenesulfonyl-2-diazoacetyl)pyrrolidin-2-one and methyl acrylate, several indolo- and furano-fused indolizinones were efficiently prepared. In the first case, a palladium-mediated C−N coupling of the triflate with a variety of substituted anilines provided the desired methyl 5-oxo-6-(arylamino)-1,2,3,5-tetrahydroindolizine-8-carboxylates in high yield. Methyl 6-(2-bromophenylamino)-5-oxo-1,2,3,5-tetrahydroindolizine-8-carboxylate as well as its decarboxylated analogue, 6-(2-bromophenylamino)-2,3-dihydro-1H-indolizin-5-one, were synthesized in excellent yield and were found to undergo an intramolecular Heck cyclization to give 1,2,3,6-tetrahydroindolizino[6,7-b]indol-5-ones. To prepare furano-fused indolizinones, methyl 6-hydroxy-5-oxo-1,2,3,5-tetrahydroindolizine-8-carboxylate was etherified with different allyl halides, and the re...