cssi/SciSciGPT-SciSciNet huggingface dataset:
EOS Terra Validation Program

The EOS Terra mission will be launched in July 1999. This mission has great relevance to the atmospheric radiation community and global change issues. Terra instruments include Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Clouds and Earth's Radiant Energy System (CERES), Multi-Angle Imaging Spectroradiometer (MISR), Moderate Resolution Imaging Spectroradiometer (MODIS) and Measurements of Pollution in the Troposphere (MOPITT). In addition to the fundamental radiance data sets, numerous global science data products will be generated, including various Earth radiation budget, cloud and aerosol parameters, as well as land surface, terrestrial ecology, ocean color, and atmospheric chemistry parameters. Significant investments have been made in on-board calibration to ensure the quality of the radiance observations. A key component of the Terra mission is the validation of the science data products. This is essential for a mission focused on global change issues and the underlying processes. The Terra algorithms have been subject to extensive pre-launch testing with field data whenever possible. Intensive efforts will be made to validate the Terra data products after launch. These include validation of instrument calibration (vicarious calibration) experiments, instrument and cross-platform comparisons, routine collection of high quality correlative data from ground-based networks, such as AERONET, and intensive sites, such as the SGP ARM site, as well as a variety field experiments, cruises, etc. Airborne simulator instruments have been developed for the field experiment and underflight activities including the MODIS Airborne Simulator (MAS) AirMISR, MASTER (MODIS-ASTER), and MOPITT-A. All are integrated on the NASA ER-2 though low altitude platforms are more typically used for MASTER. MATR is an additional sensor used for MOPITT algorithm development and validation. The intensive validation activities planned for the first year of the Terra mission will be described with emphasis on derived geophysical parameters of most relevance to the atmospheric radiation community.
Everything you ever wanted to know about DTDs, but were afraid to ask

For the last two years, XML has become an increasingly popular data-format unanimously accepted by a lot of different communities. In this paper, we present some preliminary results that explore how XML DTDs are actually being used. By studying some publicly available DTDs, we look at how people are actually (mis)using DTDs, show some shortcomings, list some requirements and discuss possible replacements.
Finding a feasible flow in a strongly connected network

We give a linear-time algorithm to find a feasible flow in a strongly connected network with fixed supplies and demands, each summing to a common value that is at most the minimum arc capacity. This algorithm speeds up the Goldberg-Rao maximum flow method by a constant factor.
Optimal Economic Landscapes with Habitat Fragmentation Effects

Habitat fragmentation is widely considered a primary threat to biodiversity. This paper develops a theoretical model of land use to analyze the optimal conservation of landscapes when land quality is spatially heterogeneous and wildlife habitat is fragmented and socially valuable. When agriculture is the primary cause of fragmentation, we show that reforestation efforts should be targeted to the most fragmented landscapes with an aggregate share of forest equal to a threshold, defined by the ratio of the opportunity cost of conversion to the social value of core forest. When urban development is the primary cause of fragmentation, we show how spatial heterogeneity in amenities and household neighbor preferences affect the optimal landscape and the design of land-use policies.
Incentive audits : a new approach to financial regulation

A large body of evidence points to misaligned incentives as having a key role in the run-up to the global financial crisis. These include bank managers' incentives to boost short-term profits and create banks that are "too big to fail," regulators' incentives to forebear and withhold information from other regulators in stressful times, and credit rating agencies' incentives to keep issuing high ratings for subprime assets. As part of the response to the crisis, policymakers and regulators also attempted to address some incentive issues, but various outside observers have criticized the response for being insufficient. This paper proposes a pragmatic approach to re-orienting financial regulation to have at its core the objective of addressing incentives on an ongoing basis. Specifically, the paper proposes "incentive audits" as a tool that could help in identifying incentive misalignments in the financial sector. The paper illustrates how such audits could be implemented in practice, and what the implications would be for the design of policies and frameworks to mitigate systemic risks.
Regular and chaotic dynamics of a piecewise smooth bouncer.

The dynamical properties of a particle in a gravitational field colliding with a rigid wall moving with piecewise constant velocity are studied. The linear nature of the wall's motion permits further analytical investigation than is possible for the system's sinusoidal counterpart. We consider three distinct approaches to modeling collisions: (i) elastic, (ii) inelastic with constant restitution coefficient, and (iii) inelastic with a velocity-dependent restitution function. We confirm the existence of distinct unbounded orbits (Fermi acceleration) in the elastic model, and investigate regular and chaotic behavior in the inelastic cases. We also examine in the constant restitution model trajectories wherein the particle experiences an infinite number of collisions in a finite time, i.e., the phenomenon of inelastic collapse. We address these so-called “sticking solutions” and their relation to both the overall dynamics and the phenomenon of self-reanimating chaos. Additionally, we investigate the long-term behavior of the system as a function of both initial conditions and parameter values. We find the non-smooth nature of the system produces novel bifurcation phenomena not seen in the sinusoidal model, including border-collision bifurcations. The analytical and numerical investigations reveal that although our piecewise linear bouncer is a simplified version of the sinusoidal model, the former not only captures essential features of the latter but also exhibits behavior unique to the discontinuous dynamics.
Information Heterogeneity in the Macroeconomy

This paper considers the role that information heterogeneity can play in generating wealth inequality. We solve a model where households face both aggregate and idiosyncratic shocks to returns and wages under two assumptions about information – fully-informed (FI) economies have agents who observe all states while partially-informed (PI) economies have agents that must rely on the Kalman filter to extract estimates of the states based on observed prices. We find that the PI economy has higher aggregate activity (output, consumption, investment) and larger fluctuations in output and investment. Quantitatively, we find that the most important factor is the gap between the PI agents’ beliefs about the state of the world and the true state; the other two factors at play, the heterogeneity of forecasts tomorrow and the higher risk faced by PI agents, generate only small changes in behavior.
Cosmology with the Very Large Telescope Interferometer: Using a Space Based Astrometric Reference Frame

Cosmology with large interferometric telescopes is a rich and largely unexplored subject, involving three types of measurement: astrometric measurement of absolute distances and proper motions, dispersions of relative proper motions, and images. The ground based interferometers can have huge apertures, which are necessary for faint cosmological targets. But, alone, they are limited to astrometry within the iso-planatic patch, and hence to relative positions, which are of little use for parallaxes and proper motions because reference stars have unknown parallaxes and huge (500 μarcsec) unknown motions. We propose that space missions should measure global astrometric parallaxes and proper motions for (V> 16) reference stars within the isoplanatic patches of important cosmological and Galactic targets. Ground based interferometers can then measure absolute distances (parallaxes) and proper motions to 10 μarcsec, tied to these reference stars. In combination, space and ground based interferometers can make a wide variety of measurements, some of which were believed to be restricted to space missions, and others where not considered possible because space missions lack light gathering power: absolute distances accurate to <10% for most globular clusters and about ten near by galaxies; proper motions of stars in near by dwarf galaxies and stars near to giant black holes; the masses and distances to individual MACHOS which cause microlensing events in the halo and bulge of our galaxy; proper motions of 1000 galaxies out to Virgo; and images of giant black holes, AGN and distant galaxies.
Designing Economic Mechanisms

1. Mechanisms and mechanism design 1.1. Introduction to mechanisms and mechanism design 1.2. Environments and goal functions 1.3. Mechanisms: message exchange processes and game forms 1.4. Initial dispersion of information and privacy preservation 1.5. Mechanism design 1.6. Mechanism design Illustrated in a Walrasian example 1.7. The rectangles method applied to the Walrasian goal function-informal 1.8. Introductory discussion of informational efficiency concepts 1.9. Regulation of logging in a national forest - an example of mechanism design 2. From goals to means: constructing mechanisms 2.1. Mechanism construction: phase one 2.2. Phase two: constructing decentralized 2.3.1. Flagpoles-principles 2.4.1. Phase two: via condensation: principles 2.5. Overlaps 2.6.1 Main results 3. Designing informationally efficient mechanisms using the language of aets 3.1. Introduction 3.2. Mechanism design 3.3. Mechanisms and coverings 3.4. A systematic process (an algorithm) for constructing and rRM covering 3.5 Transversals 3.6. Coverings and partitions 3.7. Informational efficiency 3.8. Example 1.9 revisited - a graphical presentation 3.9. Informationally efficient mechanisms with strategic behavior 4. Revelation mechanisms (co-authored with Kenneth R. Mount) 4.1. Introduction 4.2. Initial set theoretic constructions 4.3. The topological case 4.4. Proofs and examples.
Quantifying the Sources of Firm Heterogeneity

We develop and structurally estimate a model of heterogeneous multiproduct firms that can be used to decompose the firm-size distribution into the contributions of costs, "appeal" (quality or taste), markups, and product scope. Using Nielsen barcode data on prices and sales, we find that variation in firm appeal and product scope explains at least four fifths of the variation in firm sales. We show that the imperfect substitutability of products within firms, and the fact that larger firms supply more products than smaller firms, implies that standard productivity measures are highly dependent on implicit demand system assumptions and probably dramatically understate the relative productivity of the largest firms. Although most firms are well approximated by the monopolistic competition benchmark of constant markups, we find that the largest firms that account for most of aggregate sales depart substantially from this benchmark, and exhibit both variable markups and substantial cannibalization effects. JEL Codes: L11, L21, L25, L60.
A Case Study in E-Journal Developments: The Scandinavian Position

A short overview of the current situation in Scandinavia is given with regard to peer-reviewed scientific and scholarly electronic journals. The emphasis is on a publisher's point of view, trying to take into account the needs of the market, and the challenges and dilemmas facing publishers when electronic publishing is part of their strategy and publishing programme.
Genus 3 hyperelliptic curves with (2, 4, 4)-split Jacobians

We study degree 2 and 4 elliptic subcovers of hyperelliptic curves of genus 3 defined over the complex field. The family of genus 3 hyperelliptic curves which have a degree 2 cover to an elliptic curve E and degree 4 covers to elliptic curves E1 and E2 is a 2-dimensional subvariety of the hyperelliptic moduli H3. We determine this subvariety explicitly. For any given moduli point p in H3 we determine explicitly if the corresponding genus 3 curve X belong or not to such family. When it does, we can determine elliptic subcovers E, E1, and E2 in terms of the absolute invariants t1 ... t6. This variety provides a new family of hyperelliptic curves of genus 3 for which the Jacobians completely split.
Multiple Endpoints, P Level Procedures†

In clinical trials, multiple endpoints are often used to investigate a treatment effect. There has been substantial debate in determining the appropriate approach to analyze these multiple endpoints. Global procedures provide a single statistic and are used to compare treatments in an overall sense but do not look at how the treatments affect each endpoint individually. Endpoint-specific procedures are intended to be used to identify the significance of the individual endpoints. These procedures are also called P level procedures because they usually involve making statistical decisions on the basis of the P level, resulting from examining the endpoints separately. P level procedures can be used in the primary analyses or as a second-step analyses in conjunction with multivariate global tests. There are three categories of endpoint specific methods, Bonferroni-type tests, normal-based tests and resampling procedures. Keywords: multiple groups comparisons; multiplicity; global procedures; omnibus tests; familywise error rate; Bonferroni-type tests; normal-based tests; resampling procedures; single-step; step-down; step-up; Bonferroni inequality; Bonferroni adjustment; Holm; Hochberg; Hommel; Simes; bootstrap; permutational resampling
Regular components of moduli spaces of stable maps

We construct regular components of the moduli space of stable maps from curves of genus g to a product of two projective spaces. These components are generically smooth and have the expected dimension predicted by deformation theory. This result can be seen as a general position theorem for loci in M g consisting of curves carrying exceptional linear series.
International Law Firms in China: Market Access and Ethical Risks

Unlike their Chinese counterparts seeking to expand overseas, international law firms in China face enormous difficulties establishing and expanding their presence in the Chinese legal market. In the United States, Japan, and the European Union, Chinese law firms are generally able to establish offices, hire local lawyers, and engage in comprehensive corporate law and litigation services. Their ability to engage in these services is consistent with global trends to provide comprehensive legal services to clients who desire legal advice for their key global markets. Similar opportunities are denied or restricted from foreign law firms within China. The situation of foreign law firms, ten years after World Trade Organization (WTO) accession, has very much become one where the “cobbler’s son wears no shoes.” Market access liberalization offered to foreign law firms at WTO accession was comparatively small, and was largely limited to permitting foreign law firms to open up more than one representative office. However, such offices continued to be restricted in the type of services they could provide.1 By contrast, accounting, bookkeeping, and taxation services were considerably more liberalized, including permitting the licensing of foreign accountants by Chinese authorities.2 As a result, many WTO members continue to encourage China to liberalize its legal services market, although little progress has been made since the implementation of China’s accession commitments.3
Evaluation of shape-based normalization in the corpus callosum for white matter connectivity analysis

Recently, concerns have been raised that the correspondences computed by volumetric registration within homogeneous structures are primarily driven by regularization priors that differ among algorithms. This paper explores the correspondence based on geometric models for one of those structures, mid-sagittal section of the corpus callosum (MSCC), and compared the result with registration paradigms. We use geometric model called continuous medial representation (cm-rep) to normalize anatomical structures on the basis of medial geometry, and use features derived from diffusion tensor tractography for validation. We show that shape-based normalization aligns subregions of the MSCC, defined by connectivity, more accurately than normalization based on volumetric registration. Furthermore, shape-based normalization helps increase the statistical power of group analysis in an experiment where features derived from diffusion tensor tractography are compared between two cohorts. These results suggest that cm-rep is an appropriate tool for normalizing the MSCC in white matter studies.
Do Wealth Fluctuations Generate Time-Varying Risk Aversion? Micro-Evidence on Individuals' Asset Allocation

We use data from the Panel Study of Income Dynamics to investigate how households' portfolio allocations change in response to wealth fluctuations. Persistent habits, consumption commitments, and subsistence levels can generate time-varying risk aversion with the consequence that when the level of liquid wealth changes, the proportion a household invests in risky assets should also change in the same direction. In contrast, our analysis shows that the share of liquid assets that households invest in risky assets is not affected by wealth changes. Instead, one of the major drivers of household portfolio allocation seems to be inertia: households rebalance only very slowly following inflows and outflows or capital gains and losses.
Life-style and travel demand

(Added to the original text) A fundamental solution to the issue of congestion cannot be reached without addressing the question of life-style. This paper reviews the definitions of life-style found in the literature, and identifies variables that have been commonly associated with life-style. Using US consumer expenditure data, life-styles are analyzed longitudinally (examining trends during the 1953–1983 time frame) and cross-sectionally (comparing segments of the population stratified by income, life-cycle stage, and age), and likely relationships to travel behavior are noted. The usefulness of existing empirical findings to long-range forecasting is explored by speculating on shifts of behavioral units across life-style segments, and on shifts in the behavioral patterns within each life-style segment.
Discrete extension operators for mixed finite element spaces on locally refined meshes

The existence of uniformly bounded discrete extension operators is established for conforming Raviart-Thomas and N\'ed\'elec discretisations of $H(div)$ and $H(curl)$ on locally refined partitions of a polyhedral domain into tetrahedra.
Sieving for Pseudosquares and Pseudocubes in Parallel Using Doubly-Focused Enumeration and Wheel Datastructures

We extend the known tables of pseudosquares and pseudocubes, discuss the implications of these new data on the conjectured distribution of pseudosquares and pseudocubes, and present the details of the algorithm used to do this work. Our algorithm is based on the space-saving wheel data structure combined with doubly-focused enumeration, run in parallel on a cluster supercomputer.
Well Isn't That Spatial?! Handbook of Regional and Urban Economics: A View From Economic Theory

Review of the 'Handbook of Regional and Urban Economics: Volume 4: Cities and Geography' edited by J.V. Henderson and J.-F. Thisse
Recent advances in gaseous dielectrics

Recent developments in gaseous dielectrics are discussed with emphasis on dielectric gas mixtures containing SF 6 . Recent findings on the isotopic, pressure, and nonuniform field dependence of the dielectric strength of gases are also presented, and ways to enhance the corona-stabilization characteristics of gas mixtures by appropriate additives (e.g., to SF 6 ) are outlined. In addition, results are presented on the spark decomposition products of SF6 and the alleviation of the harmful effects of conducting particles by particle coating in situ. Finally, electron attachment, electrode drift velocity, and breakdown properties of gas mixtures (e.g., C 2 F 6 or C 3 F 8 in Ar or CH 4 )—comprised of electron attaching and electron conductivity enhancing components—which have promise for use in pulsed power technologies are reported.
Fringe Formation in Dual-Hologram Interferometry

Reference-fringe formation in nondiffuse dual-hologram interferometry is described by combining a first-order geometrical hologram treatment with interference fringes generated by two point sources. The first-order imaging relationships can be used to describe reference-fringe patterns for the geometry of the dual-hologram interferometry. The process can be completed without adjusting the two holograms when the reconstructing wavelength is less than the exposing wavelength, and the process is found to facilitate basic intereferometer adjustments.
Bounds for graph regularity and removal lemmas

We show, for any positive integer k, that there exists a graph in which any equitable partition of its vertices into k parts has at least ck 2/log* k pairs of parts which are not $${\epsilon}$$ -regular, where $${c,\epsilon >0 }$$ are absolute constants. This bound is tight up to the constant c and addresses a question of Gowers on the number of irregular pairs in Szemeredi’s regularity lemma. In order to gain some control over irregular pairs, another regularity lemma, known as the strong regularity lemma, was developed by Alon, Fischer, Krivelevich, and Szegedy. For this lemma, we prove a lower bound of wowzer-type, which is one level higher in the Ackermann hierarchy than the tower function, on the number of parts in the strong regularity lemma, essentially matching the upper bound. On the other hand, for the induced graph removal lemma, the standard application of the strong regularity lemma, we find a different proof which yields a tower-type bound. We also discuss bounds on several related regularity lemmas, including the weak regularity lemma of Frieze and Kannan and the recently established regular approximation theorem. In particular, we show that a weak partition with approximation parameter $${\epsilon}$$ may require as many as $${2^{\Omega}(\epsilon^{-2})}$$ parts. This is tight up to the implied constant and solves a problem studied by Lovasz and Szegedy.
Learning Bayesian networks with local structure

In this paper we examine a novel addition to the known methods for learning Bayesian networks from data that improves the quality of the learned networks. Our approach explicitly represents and learns the local structure in the conditional probability tables (CPTs), that quantify these networks. This increases the space of possible models, enabling the representation of CPTs with a variable number of parameters that depends on the learned local structures. The resulting learning procedure is capable of inducing models that better emulate the real complexity of the interactions present in the data. We describe the theoretical foundations and practical aspects of learning local structures, as well as an empirical evaluation of the proposed method. This evaluation indicates that learning curves characterizing the procedure that exploits the local structure converge faster than these of the standard procedure. Our results also show that networks learned with local structure tend to be more complex (in terms of arcs), yet require less parameters.
Origins of the 1/4 keV soft X-ray background

Snowden and coworkers have presented a model for the keV soft X-ray diffuse background in which the observed flux is dominated by a ~106 K thermal plasma located in a 100-300 pc diameter bubble surrounding the Sun but has significant contributions from a very patchy Galactic halo. Halo emission provides about 11% of the total observed flux and is responsible for half of the H I anticorrelation. The remainder of the anticorrelation is presumably produced by displacement of disk H I by the varying extent of the Local Hot Bubble (LHB). The ROSAT R1 and R2 bands used for this work had the unique spatial resolution and statistical precision required for separating the halo and local components but provide little spectral information. Some consistency checks had been made with older observations at lower X-ray energies, but we have made a careful investigation of the extent to which the model is supported by existing sounding rocket data in the Be (73-111 eV) and B (115-188 eV) bands, where the sensitivities to the model are qualitatively different from the ROSAT bands. We conclude that the two-component model is well supported by the low-energy data. We find that these combined observations of the local component may be consistent with single-temperature thermal emission models in collisional ionization equilibrium if depleted abundances are assumed. However, different model implementations give significantly different results, offering little support for the conclusion that the astrophysical situation is so simple.
Generation and Regioselective Trapping of a 3,4-Piperidyne for the Synthesis of Functionalized Heterocycles

We report the generation of the first 3,4-piperidyne and its use as a building block for the synthesis of annulated piperidines. Experimental and computational studies of this intermediate are disclosed, along with comparisons to the well-known 3,4-pyridyne. The distortion/interaction model is used to explain the observed regioselectivities.
Experimental realization of a quantum algorithm

Quantum computers1,2,3,4,5 can in principle exploit quantum-mechanical effects to perform computations (such as factoring large numbers or searching an unsorted database) more rapidly than classical computers1,2,6,7,8. But noise, loss of coherence, and manufacturing problems make constructing large-scale quantum computers difficult9,10,11,12,13. Although ion traps and optical cavities offer promising experimental approaches14,15, no quantum algorithm has yet been implemented with these systems. Here we report the experimental realization of a quantum algorithm using a bulk nuclear magnetic resonance technique16,17,18, in which the nuclear spins act as ‘quantum bits’19. The nuclear spins are particularly suited to this role because of their natural isolation from the environment. Our simple quantum computer solves a purely mathematical problem in fewer steps than is possible classically, requiring fewer ‘function calls’ than a classical computer to determine the global properties of an unknown function.
High-throughput mutate-map-rescue evaluates SHAPE-directed RNA structure and uncovers excited states

The three-dimensional conformations of noncoding RNAs underpin their biochemical functions but have largely eluded experimental characterization. Here, we report that integrating a classic mutation/rescue strategy with high-throughput chemical mapping enables rapid RNA structure inference with unusually strong validation. We revisit a 16S rRNA domain for which SHAPE (selective 2'-hydroxyl acylation with primer extension) and limited mutational analysis suggested a conformational change between apo- and holo-ribosome conformations. Computational support estimates, data from alternative chemical probes, and mutate-and-map (M(2)) experiments highlight issues of prior methodology and instead give a near-crystallographic secondary structure. Systematic interrogation of single base pairs via a high-throughput mutation/rescue approach then permits incisive validation and refinement of the M(2)-based secondary structure. The data further uncover the functional conformation as an excited state (20 ± 10% population) accessible via a single-nucleotide register shift. These results correct an erroneous SHAPE inference of a ribosomal conformational change, expose critical limitations of conventional structure mapping methods, and illustrate practical steps for more incisively dissecting RNA dynamic structure landscapes.
Design pattern-based extension of class hierarchies to support runtime invariant checks

We present a technique for automatically weaving structural invariant checks into an existing collection of classes. Using variations on existing design patterns, we use a concise specification to generate from this collection a new set of classes that implement the interfaces of the originals, but with the addition of user-specified class invariant checks. Our work is notable in the scarcity of assumptions made. Unlike previous design pattern approaches to this problem, our technique requires no modification of the original source code, relies only on single inheritance, and does not require that the attributes used in the checks be publicly visible. We are able to instrument a wide variety of class hierarchies, including those with pure interfaces, abstract classes and classes with type parameters. We have implemented the construction as an Eclipse plug-in for Java development.
Convergent and correct message passing schemes for optimization problems over graphical models

The max-product algorithm, which attempts to compute the most probable assignment (MAP) of a given probability distribution, has recently found applications in quadratic minimization and combinatorial optimization. Unfortunately, the max-product algorithm is not guaranteed to converge and, even if it does, is not guaranteed to produce the MAP assignment. In this work, we provide a simple derivation of a new family of message passing algorithms by "splitting" the factors of our graphical model. We prove that, for any objective function that attains its maximum value over its domain, this new family of message passing algorithms always contains a message passing scheme that guarantees correctness upon convergence to a unique estimate. Finally, we adopt an asynchronous message passing schedule and prove that, under mild assumptions, such a schedule guarantees the convergence of our algorithm.
Deriving forecast probability distributions of harvest-time corn futures prices

Preharvest corn price forecasts are typically presented as price ranges or point estimates, while the probabilities associated with alternative grain price forecast scenarios are usually not identified. For example, United States Department of Agriculture (USDA) preharvest price forecasts are typically given as price ranges, while preharvest forecasts from university extension and other private sources are often given as point estimates. When alternative market scenario probabilities are provided, they are often based on rudimentary statistical analysis of historic weather conditions and/or the analyst's intuition rather than on accepted econometric methods. Preharvest grain price probability information would be useful to farmers, grain buyers, and processors in making price risk management decisions. Farmers implicitly make probability judgements regarding the likelihood of alternative supply, demand, and price scenarios as they carry out preharvest grain marketing strategies. All grain buyers and sellers could benefit by knowing the probability of financially-adverse price outcomes. With accurate price forecast probability information, probability-based price risk management strategies could be developed to limit the risk of financial loss to the farmer or the firm. A number of structural models of grain market supply and demand have been developed for forecasting and policy analysis purposes. Examples are found in Houck, Ryan, and Subotnik; Chen; Arzac and Wilkinson; and Westhoff et al. Reduced form equations from these multiple equation systems guide the
The Seiberg-Witten map for noncommutative gauge theories

The Seiberg-Witten map for noncommutative Yang-Mills theories is studied and methods for its explicit construction are discussed which are valid for any gauge group. In particular the use of the evolution equation is described in some detail and its relation to the cohomological approach is elucidated. Cohomological methods which are applicable to gauge theories requiring the Batalin-Vilkoviskii antifield formalism are briefly mentioned. Also, the analogy of the Weyl-Moyal star product with the star product of opestring field theory and possible ramifications of this analogy are briefly mentioned.
Modeling Intratumor Gene Copy Number Heterogeneity Using Fluorescence in Situ Hybridization Data

Tumorigenesis is an evolutionary process which involves a significant number of genomic rearrangements typically coupled with changes in the gene copy number profiles of numerous cells. Fluorescence in situ hybridization (FISH) is a cytogenetic technique which allows counting copy numbers of genes in single cells. The study of cancer progression using FISH data has received considerably less attention compared to other types of cancer datasets.
Nonparametric independence testing for small sample sizes

This paper deals with the problem of nonparametric independence testing, a fundamental decision-theoretic problem that asks if two arbitrary (possibly multivariate) random variables X; Y are independent or not, a question that comes up in many fields like causality and neuroscience. While quantities like correlation of X; Y only test for (univariate) linear independence, natural alternatives like mutual information of X; Y are hard to estimate due to a serious curse of dimensionality. A recent approach, avoiding both issues, estimates norms of an operator in Reproducing Kernel Hilbert Spaces (RKHSs). Our main contribution is strong empirical evidence that by employing shrunk operators when the sample size is small, one can attain an improvement in power at low false positive rates. We analyze the effects of Stein shrinkage on a popular test statistic called HSIC (Hilbert-Schmidt Independence Criterion). Our observations provide insights into two recently proposed shrinkage estimators, SCOSE and FCOSE - we prove that SCOSE is (essentially) the optimal linear shrinkage method for estimating the true operator; however, the nonlinearly shrunk FCOSE usually achieves greater improvements in test power. This work is important for more powerful nonparametric detection of subtle nonlinear dependencies for small samples.
Automated abstraction methodology for genetic regulatory networks

In order to efficiently analyze the complicated regulatory systems often encountered in biological settings, abstraction is essential. This paper presents an automated abstraction methodology that systematically reduces the small-scale complexity found in genetic regulatory network models, while broadly preserving the large-scale system behavior. Our method first reduces the number of reactions by using rapid equilibrium and quasi-steady-state approximations as well as a number of other stoichiometry-simplifying techniques, which together result in substantially shortened simulation time. To further reduce analysis time, our method can represent the molecular state of the system by a set of scaled Boolean (or n-ary) discrete levels. This results in a chemical master equation that is approximated by a Markov chain with a much smaller state space providing significant analysis time acceleration and computability gains. The genetic regulatory network for the phage λ lysis/lysogeny decision switch is used as an example throughout the paper to help illustrate the practical applications of our methodology.
The benefits of growth for Indonesian Workers

Indonesia's adopted development model has proved to be the most successful in alleviating poverty and benefiting workers in developing countries. The government's development efforts focused on agriculture, education, and transport infrastructure. It emphasized providing productive employment opportunities and gradually improving the labor quality through education and training. The wage, employment, and income growth rates were left to market forces. Although the rapid growth of labor-intensive manufacturing has led to more jobs and higher wages benefiting workers, workers employed in these industries have expressed growing dissatisfaction. They complain about problems of child labor, the denial of centrally mandated wages and benefits to workers, poor working conditions, and the abuse of young female workers. The government has tried to improve worker's wages and working conditions by centrally mandating higher labor standards, relying principally on minimum wages. Enforcement has improved and, despite low compliance, minimum wages are beginning to bite. Indonesians are debating whether they need labor intensive industries and whether it is a mistake to base Indonesia's growth on cheap labor. They argue that if labor is more expensive, manufacturers must substitute some capital for labor. However, if labor-intensive industries are rejected, the capacity of the economy to absorb plentiful workers will be reduced. The main alternatives are to push up wages now, or to let wages be determined by market forces and strengthen institutions that could improve working conditions, such as labor unions. The author recommends maintaining flexible labor markets and allowing market forces to set the pace of change, while strengthening labor unions.
Pseudorandom generators without the XOR lemma

Summary form only given. R. Impagliazzo and A. Wigderson (1997) have recently shown that if there exists a decision problem solvable in time 2/sup O(n)/ and having circuit complexity 2/sup /spl Omega/(n)/ (for all but finitely many n) then P=BPP. This result is a culmination of a series of works showing connections between the existence of hard predicates and the existence of good pseudorandom generators. The construction of Impagliazzo and Wigderson goes through three phases of "hardness amplification" (a multivariate polynomial encoding, a first derandomized XOR Lemma, and a second derandomized XOR Lemma) that are composed with the Nisan-Wigderson (1994) generator. In this paper we present two different approaches to proving the main result of Impagliazzo and Wigderson. In developing each approach, we introduce new techniques and prove new results that could be useful in future improvements and/or applications of hardness-randomness trade-offs.
Joint group and topic discovery from relations and text

We present a probabilistic generative model of entity relationships and textual attributes; the model simultaneously discovers groups among the entities and topics among the corresponding text. Block models of relationship data have been studied in social network analysis for some time, however here we cluster in multiple modalities at once. Significantly, joint inference allows the discovery of groups to be guided by the emerging topics, and vice-versa. We present experimental results on two large data sets: sixteen years of bills put before the U.S. Senate, comprising their corresponding text and voting records, and 43 years of similar data from the United Nations. We show that in comparison with traditional, separate latent-variable models for words or block structures for votes, our Group-Topic model's joint inference improves both the groups and topics discovered. Additionally, we present a non-Markov continouous-time group model to capture shifting group structure over time.
Three-dimensional N = 2 gauge theories and degenerations of Calabi-Yau four-folds

Three-dimensional N = 2 gauge theories with arbitrary gauge group and fundamental flavors are engineered from degenerations of Calabi-Yau four-folds. We show how Coulomb and Higgs branches emerge in the geometric picture. The analysis of instanton generated superpotentials unravels interesting aspects of the five-brane effective action in M-theory.
Photoluminescence and cathodoluminescence of GaN doped with Pr

We report on our observation of visible photoluminescence and cathodoluminescence of Pr-implanted GaN. The implanted samples were subjected to isochronal thermal annealing treatments at a temperature of 1100 °C in N 2 at atmospheric pressure to recover from implantation damage and activate the rare earth ions. The sharp characteristic emission lines corresponding to Pr 3+ intra- 4f n -shell transitions are resolved in the spectral range from 400 to 1000 nm and observed over the temperature range from 12 to 335 K. We have developed an energy level diagram for Pr 3+ ions in GaN using recorded spectra. The photoluminescence decay kinetics measurements of 3 P 1 , 3 P 0 , and 1 D 2 levels and quenching mechanism analysis allow us to conclude that the dominant de-excitation process is of electric dipole–electric quadrupole type. We found also that the 1 D 2 level separated from the upper 3 P 0 level by 3755 cm−1 energy gap can be populated in several ways, by direct energy transfer processes, cross relaxation | 3 P 0 , 3 H 4 〉→| 1 D 2 , 3 H 6 〉 and cascade processes from the 3 P 0 or higher levels. The full width at half maximum of the strongest photoluminescence line at 653 nm, the 3 P 0 level, is 2.9 meV at 13 K, with a 1.86 meV blue peak shift in going from 13 to 330 K temperature, while the line at 670 nm, 3 P 1 level, has a full width at half maximum of 4 meV at 13 K and a 1.6 meV red peak shift. The thermal stability of GaN:Pr 3+ epilayers indicates the suitability of this material for visible optoelectronic devices.
PKP travel times at near antipodal distances: implications for inner core anisotropy and lowermost mantle structure

Abstract Previous studies from PKP(AB–DF) differential travel times at large distances suggest that the central part of the inner core is very anisotropic. These differential times, however, can be affected greatly by strong heterogeneity in the lowermost mantle. Here we examine a unique data set of PKP travel times from global digital and analog stations at near antipodal distances, where the effects of both inner core anisotropy and mantle heterogeneity are the greatest. Our results show that the AB–DF residuals for the polar paths are consistently larger than those of the equatorial paths by over 3–4 standard deviations. We also measured DF and AB absolute times, and found that the DF residuals are negatively correlated with the AB–DF residuals while the AB residuals have a much weaker correlation with the AB–DF residuals. We compare several mantle models with the data. Our results suggest that the mantle structure can explain part of the residuals of the equatorials paths, but cannot explain the polar path anomalies. These results strongly suggest that most of the AB–DF anomalies for the polar paths are likely from the inner core anisotropy and not from mantle heterogeneity. Assuming a uniform cylindrical anisotropy model, the average inner core anisotropy amplitude is about 2.5%. On the other hand, equatorial paths from events in the west Pacific and recorded at South America show a steep azimuthal change in AB–DF times (about 4 s over a 60° azimuthal range). The sharp change is well predicted by existing P and S tomographic models: the azimuthal change occurs as the AB paths sweep across the great slow anomaly in the central Pacific. The high correlation between the P and S velocities suggests that the central Pacific slow anomaly may be of thermal origin.
Regioselective Fluorination of Substituted Guanines with Dilute F2: A Facile Entry to 8-Fluoroguanine Derivatives

The authors wish to report the first direct fluorination of guanine derivatives with dilute F{sub 2} for the synthesis of 8-fluoroguanines. When 9-substituted guanines (1 and 2) were reacted with elemental fluorine (1% in helium) a clean reaction took place and the 8-fluoro-9-substituted guanines 4 and 3, respectively, were isolated (Scheme 1).
Bounded homotopy theory and the K-theory of weighted complexes

Given a bounding class B, we construct a bounded refinement BK(−) of Quillen’s K-theory functor from rings to spaces. As defined, BK(−) is a functor from weighted rings to spaces, and is equipped with a comparison map BK → K induced by “forgetting control.” In contrast to the situation with B-bounded cohomology, there is a functorial splitting BK(−) ≅ K(−)×BK rel(−) where BK rel(−) is the homotopy fiber of the comparison map.
What Drives Star Formation

Understanding star formation is one of the outstanding challenges of modern astrophysics. However, in spite of significant progress in recent years, there remain unanswered fundamental questions about the basic physics of star formation. In particular, what drives the star formation process? The prevailing view has been that self-gravitating clouds are supported against collapse by magnetic fields, with ambipolar diffusion reducing support in cores and hence driving star formation, e.g., [8]. The other extreme is that molecular clouds are intermittent phenomena in an interstellar medium dominated by turbulence, and the problem of cloud support for long time periods is irrelevant, e.g., [7]. Clouds form and disperse by the operation of compressible turbulence, with clumps sometimes becoming gravitationally bound. Turbulence then dissipates rapidly, and the cores collapse to form stars. Hence, there are two competing models for driving the star formation process. The issue of what drives star formation is far from settled, on either observational or theoretical grounds. In this contribution we discuss how observations of magnetic fields in molecular clouds can distinguish between and test these models.
Total synthesis of epothilones B and D.

A highly convergent total synthesis of the natural products epothilone B and D is described. The route is highlighted by efficient generation of a C12−C13 trisubstituted olefin which exploits a sequential Nozaki−Hiyama−Kishi coupling and a stereoselective thionyl chloride rearrangement.
Assessment of Surface-Heating Problems in Laser-Fusion Reactors

The surface-heating problems associated with the pulsed photon and ion irradiations of the first walls and liners of inertially-confined fusion reactor cavities are investigated. Analytical models for predicting the thermal response of these surfaces as a function of the different design and operational parameters of the system and the nature of the incident irradiations are developed. The effectiveness of residual gas as a means for protecting the wall from the ions and soft X-rays is assessed.
Nonlinear income effects in random utility models: revisiting the accuracy of the representative consumer approximation

This article investigates the implications of nonlinear income effects in Random Utility Models (RUM) for measuring general equilibrium welfare impacts. A popular approach in applied welfare analysis is to approximate the expected compensating variation (cv) for an amenity change as the cv of a representative consumer whose indirect utility is given by the expected maximum utility. However, this approach can be misleading in the case of nonmarginal changes as it implies that changes in income do not affect the consumer's choice. In this case the true expected cv can be obtained via simulation. Empirical applications to recreational demand find that the bias from the representative approach is small. This article re-evaluates the accuracy of the representative consumer approximation in the context of measuring the general equilibrium welfare impacts of large environmental changes. Our findings suggest that, though the representative consumer approximation could lead to biased point estimates of the expecte...