cssi/SciSciGPT-SciSciNet huggingface dataset:
Lattices that admit logarithmic worst-case to average-case connection factors

We exhibit an average-case problem that is as hard as finding γ(n)-approximate shortest nonzero vectors in certain n-dimensional lattices in the worst case, for γ(n) = O(√log n). The previously best known factor for any non-trivial class of lattices was γ(n) = O(n).Our results apply to families of lattices having special algebraic structure. Specifically, we consider lattices that correspond to ideals in the ring of integers of an algebraic number field. The worst-case problem we rely on is to find approximate shortest vectors in these lattices, under an appropriate form of preprocessing of the number field.For the connection factors γ(n) we achieve, the corresponding decision problems on ideal lattices are not known to be NP-hard; in fact, they are in P. However, the search approximation problems still appear to be very hard. Indeed, ideal lattices are well-studied objects in computational number theory, and the best known algorithms for them seem to perform no better than the best known algorithms for general lattices.To obtain the best possible connection factor, we instantiate our constructions with infinite families of number fields having constant root discriminant. Such families are known to exist and are computable, though no efficient construction is yet known. Our work motivates the search for such constructions. Even constructions of number fields having root discriminant up to O(n2/3-e) would yield connection factors better than O(n).As an additional contribution, we give reductions between various worst-case problems on ideal lattices, showing for example that the shortest vector problem is no harder than the closest vector problem. These results are analogous to previously-known reductions for general lattices.
The Close Relationships of Lesbians and Gay Men

This article reviews empirical studies of same-sex couples in the United States, highlighting consistent findings, drawing comparisons to heterosexual couples, and noting gaps in available research. U.S. Census data indicate that there were more than 600,000 samesex couples living together in 2000. Research about relationship formation, the division of household labor, power, satisfaction, sexuality, conflict, commitment, and relationship stability is presented. Next, we highlight three recent research topics: the legalization of samesex relationships through civil unions and same-sex marriage, the experiences of same-sex couples raising children, and the impact of societal prejudice and discrimination on same-sex partners. We conclude with comments about the contributions of empirical research to debunking negative stereotypes of same-sex couples, testing the generalizability of theories about close relationships, informing our understanding of gender and close relationships, and providing a scientific basis for public policy.
Single Integration Optimization of Linear Time-Varying Switched Systems

This technical note considers the switching time optimization of time-varying linear switched systems subject to quadratic cost-also potentially time-varying. The problem is formulated so that only a single set of differential equations need to be solved prior to optimization. Once these differential equations have been solved, the cost may be minimized over an arbitrary number of modes and mode sequences without requiring additional simulation. The differential equations that need to be simulated are as smooth as the system's vector fields, despite the fact that the optimization itself is nonsmooth. The technique is illustrated in examples from the literature.
Planning graph heuristics for belief space search

Some recent works in conditional planning have proposed reachability heuristics to improve planner scalability, but many lack a formal description of the properties of their distance estimates. To place previous work in context and extend work on heuristics for conditional planning, we provide a formal basis for distance estimates between belief states. We give a definition for the distance between belief states that relies on aggregating underlying state distance measures. We give several techniques to aggregate state distances and their associated properties. Many existing heuristics exhibit a subset of the properties, but in order to provide a standardized comparison we present several generalizations of planning graph heuristics that are used in a single planner. We compliment our belief state distance estimate framework by also investigating efficient planning graph data structures that incorporate BDDs to compute the most effective heuristics. We developed two planners to serve as test-beds for our investigation. The first, CAltAlt, is a conformant regression planner that uses A* search. The second, POND, is a conditional progression planner that uses AO* search. We show the relative effectiveness of our heuristic techniques within these planners. We also compare the performance of these planners with several state of the art approaches in conditional planning.
TRANSIENT RELATIVISTICALLY SHIFTED LINES AS A PROBE OF BLACK HOLE SYSTEMS

X-ray spectra of Seyfert-type Active Galaxies have revealed a new type of X-ray spectral feature, one which appears to offer important new insight into the black hole system. XMM revealed several narrow emission lines redward of Fe Kalpha in NGC 3516. Since that discovery in NGC 3516, the phenomenon has been observed in other Seyfert galaxies, e.g. NGC 7314 and ESO 198-G24. We present new evidence for a redshifted Fe line in XMM spectra of Mrk 766. These data reveal the first evidence for a significant shift in the energy of a redshift Fe line, the shift occurs over just a few tens of kiloseconds. This shift may be interpreted as deceleration of ejected gas, the velocity of the material lies just above the escape velocity at the implied radial location of the emitter.
The Discrete Character of High-Lethality Youth Violence

The purpose of this paper is to derive lessons about high-lethality adolescent violence from study of the extraordinary increase, and then decrease, in youth homicide arrests over the period 1985-2001 in the United States. This effort continues a long tradition of exploring the possible causes of shifts in homicide rates by examining patterns of violence to see whether there are important changes in types of violence. The first section of the paper discusses two dimensions of criminal youth violence over the whole range of reported offenses. The second section shows that one subset of attacks-firearms cases-accounts for the major changes in youth homicide when it increased from 1985-1993 and during the years of decrease, 1994-2001. A third section explores the linkage between rates of adolescent homicide in various cultures and the relative rate of homicide among all ages. My central conclusion is that high-lethality violence among youth is not representative of the fighting and group assaults that are relatively frequent among adolescents. Instead, the attacks that often lead to death differ with respect to the use of weapons and, to some extent, geography. But there is usually a strong relationship between homicide rates for all ages and youth homicide rates in a particular location.
The Effects of Rotation on the Evolution of Rising Omega Loops in a Stratified Model Convection Zone

We present three-dimensional MHD simulations of buoyant magnetic flux tubes that rise through a stratified model convection zone in the presence of solar rotation. The equations of MHD are solved in the anelastic approximation, and the results are used to determine the effects of solar rotation on the dynamic evolution of an Ω-loop. We find that the Coriolis force significantly suppresses the degree of fragmentation at the apex of the loop during its ascent toward the photosphere. If the initial axial field strength of the tube is reduced, then, in the absence of forces due to convective motions, the degree of apex fragmentation is also reduced. Our simulations confirm the results of thin flux-tube calculations that show the leading polarity of an emerging active region positioned closer to the equator than the trailing polarity and the trailing leg of the loop oriented more vertically than the leading leg. We show that the Coriolis force slows the rise of the tube and induces a retrograde flow in both the magnetized and unmagnetized plasma of an emerging active region. Observationally, we predict that this flow will appear to originate at the leading polarity and will terminate at the trailing polarity.
Finite Type and the Effective Nullstellensatz

Improved local and global versions of the effective Nullstellensatz for ideal sheaves on nonsingular complex varieties are obtained, based on a new invariant motivated by the notion of finite type from the theory of several complex variables. Two closely related curve selection theorems for curves with maximal adjusted tangency orders to a given ideal sheaf are established along the way, using normalized blow-ups and integral closures.
Poverty, inequality, and social disparities during China's economic reform

China has been the most rapidly growing economy in the world over the past 25 years. This growth has fueled a remarkable increase in per capita income and a decline in the poverty rate from 64 percent at the beginning of reform to 10 percent in 2004. At the same time, however, different kinds of disparities have increased. Income inequality has risen, propelled by the rural-urban income gap and by the growing disparity between highly educated urban professionals and the urban working class. There have also been increases in inequality of health and education outcomes. Some rise in inequality was inevitable as China introduced a market system, but inequality may have been exacerbated rather than mitigated by a number of policy features. Restrictions on rural-urban migration have limited opportunities for the relatively poor rural population. The inability to sell or mortgage rural land has further reduced opportunities. China has a uniquely decentralized fiscal system that has relied on local government to fund basic health and education. The result has been that poor villages could not afford to provide good services, and poor households could not afford the high private costs of basic public services. Ironically, the large trade surplus that China has built up in recent years is a further problem, in that it stimulates an urban industrial sector that no longer creates many jobs while restricting the government's ability to increase spending to improve services and address disparities. The government's recent policy shift to encourage migration, fund education and health for poor areas and poor households, and rebalance the economy away from investment and exports toward domestic consumption and public services should help reduce social disparities.
Duality Theory for Variable Costs in Joint Production

Duality methods for incomplete systems of consumer demand equations are adapted to the dual structure of variable cost functions in joint production. This allows identification of necessary and sufficient restrictions on technology and cost so that con- ditional factor demands can be written as functions of input prices, fixed inputs, and cost. These are observable when variable inputs are chosen and committed to production, hence the identified restrictions allow ex ante conditional demands to be studied using observable data. This class of production technologies is consistent with all von Neu- mann-Morgenstern utility functions when ex post production and/or output prices are un- certain.
On Matrix Rigidity and Locally Self-Correctable Codes

e describe a new approach for the problem of finding {\rm rigid} matrices, as posed by Valiant \cite{Val77}, by connecting it to the, seemingly unrelated, problem of proving lower bounds for linear locally self-correctable codes. This approach, if successful, could lead to a non-natural property (in the sense of Razborov and Rudich \cite{RR97}) implying super-linear lower bounds for linear functions in the model of logarithmic-depth arithmetic circuits. Our results are based on a lemma saying that, if the generating matrix of a locally decodable code is {\bf not} rigid, then it defines a locally self-correctable code with rate close to one. Thus, showing that such codes cannot exist will prove that the generating matrix of {\em any} locally decodable code (and in particular Reed Muller codes) is rigid.
Signal Coordination and Arterial Capacity in Oversaturated Conditions

Models for estimation of the capacities of oversaturated arterials were developed. The input variables in these models are capacities of individual intersections, offsets, and vehicle queue lengths. Models for quantification of capacity loss due to blockage caused by downstream queues are also presented. The proposed models show that when arterial capacity is determined in oversaturated conditions, it is not sufficient to consider only the capacities of critical intersections; instead, the capacities of critical subsystems must be considered. A critical subsystem is any two intersections plus the link that joins them where traffic processing capability is the lowest. This traffic processing capability, or critical subsystem capacity, determines the arterial capacity. It is a function of the capacities of the respective intersections, the offset between them, and the queue length on the link joining them. It is shown that a critical subsystem is not unique in that it may change location over the course of ...
Segue 1: An Unevolved Fossil Galaxy from the Early Universe

We present Magellan/MIKE and Keck/HIRES high-resolution spectra of six red giant stars in the dwarf galaxy Segue?1. Including one additional Segue?1 star observed by Norris et?al., high-resolution spectra have now been obtained for every red giant in Segue?1. Remarkably, three of these seven stars have metallicities below [Fe/H] = ?3.5, suggesting that Segue?1 is the least chemically evolved galaxy known. We confirm previous medium-resolution analyses demonstrating that Segue?1 stars span a metallicity range of more than 2?dex, from [Fe/H] = ?1.4 to [Fe/H] = ?3.8. All of the Segue?1 stars are ?-enhanced, with [?/Fe] ~ 0.5. High ?-element abundances are typical for metal-poor stars, but in every previously studied galaxy [?/Fe] declines for more metal-rich stars, which is typically interpreted as iron enrichment from supernova Ia. The absence of this signature in Segue?1 indicates that it was enriched exclusively by massive stars. Other light element abundance ratios in Segue?1, including carbon enhancement in the three most metal-poor stars, closely resemble those of metal-poor halo stars. Finally, we classify the most metal-rich star as a CH star given its large overabundances of carbon and s-process elements. The other six stars show remarkably low neutron-capture element abundances of [Sr/H] < ?4.9 and [Ba/H] < ?4.2, which are comparable to the lowest levels ever detected in halo stars. This suggests minimal neutron-capture enrichment, perhaps limited to a single r-process or weak s-process synthesizing event. Altogether, the chemical abundances of Segue?1 indicate no substantial chemical evolution, supporting the idea that it may be a surviving first galaxy that experienced only one burst of star formation.
Prediction of Compressor Stage Performance From Choke Through Stall

The results of an investigation in which the predicted aerodynamic performance of the NASA Stage35 singlestage compressor is compared with the measured experimental data over the entire design speedline from choke through stall are presented. Particular attention has been given to the geometric model and boundary conditions in the numerical study to enable the aerodynamic performance to be predicted through stall. The total pressure ratios of both the rotor and stator as well as circumferential profiles of the total pressure and total temperature up- and downstream of the rotor are compared with experimental data. A time-accurate approach for predicting stall inception caused by both long- and short-wave length phenomena is introduced. The results from a series of Stage35 unsteady-flow simulations near stall with this approach are presented to demonstrate the flow physics responsible for stall inception.
Emerging economies and the emergence of south-south protectionism

Do exports resume when import-restricting temporary trade barriers such as antidumping are finally removed? To establish the importance of this question for emerging economies, this paper uses newly available data from the World Bank's Temporary Trade Barriers Database to update a number of inter-temporal indicators of import protection along three dimensions: additional time coverage through 2011, additional policy-imposing country coverage, and a more comprehensive depiction of impacted trading partner coverage. It then turns to the emerging economy exporters affected by temporary trade barriers and highlights the economic significance of frequently bilateral import restrictions imposed by other emerging economies, i.e., South-South protectionism. Finally, it then investigates empirically whether country-level exports resume when the previously imposed -- but temporary -- import protection is finally removed. China's exporters respond quickly and aggressively to the market access opening embodied in the removal of such import restrictions. This differs markedly from the slow and tepid export response of other emerging economies, especially when the import protection had been imposed by another emerging economy trading partner. This evidence suggests a previously unidentified long-run cost associated with such South-South protectionism that merits further research and inquiry.
Theory of the Transmission of Infection in the Spread of Epidemics: Interacting Random Walkers with and Without Confinement

A theory of the spread of epidemics is formulated on the basis of pairwise interactions in a dilute system of random walkers (infected and susceptible animals) moving in $$n$$ dimensions. The motion of an animal pair is taken to obey a Smoluchowski equation in $$2n$$ -dimensional space that combines diffusion with confinement of each animal to its particular home range. An additional (reaction) term that comes into play when the animals are in close proximity describes the process of infection. Analytic solutions are obtained, confirmed by numerical procedures, and shown to predict a surprising effect of confinement. The effect is that infection spread has a non-monotonic dependence on the diffusion constant and/or the extent of the attachment of the animals to the home ranges. Optimum values of these parameters exist for any given distance between the attractive centers. Any change from those values, involving faster/slower diffusion or shallower/steeper confinement, hinders the transmission of infection. A physical explanation is provided by the theory. Reduction to the simpler case of no home ranges is demonstrated. Effective infection rates are calculated, and it is shown how to use them in complex systems consisting of dense populations.
Synthesis of (+)-biotin derivatives as HIV-1 protease inhibitors

Abstract Several bis- N -alkylated (+)-biotin derivatives were synthesized and evaluated for activities against HIV-1 protease. The most potent inhibitor, 2D , synthesized in two steps from (+)-biotin, has K i of 0.50 μM and antiviral IC 90 of 7 μM. The (+)-biotin analogs in general have good translations from enzymatic K i to antiviral cell assay IC 90 .
Evaluating Dialogue Schemata with the Wizard of Oz Computer-Assisted Algebra Tutor

The Wooz tutor of the North Carolina A&T algebra tutorial dialogue project is a computer program that mediates keyboard-to-keyboard tutoring of algebra problems, with the feature that it can suggest to the tutor canned structures of tutoring goals and canned sentences to insert into the tutoring dialogue. It is designed to facilitate and record a style of tutoring where the tutor and student collaboratively construct an answer in the form of an equation, a style often attested in natural tutoring of algebra. The algebra tutoring dialogue project collects and analyzes these dialogues with the aim of describing tutoring strategies and language with enough rigor that they may be evaluated and incorporated in machine tutoring. By plugging our analyzed dialogues into the computer-suggested tutoring component of the Wooz tutor we can evaluate the fitness of our dialogue analysis.
Recent experiments with the free-electron laser at Los Alamos

Improvements in the operational characteristics of the Los Alamos National Laboratory free-electron laser have produced experimental results in reasonable agreement with theory and simulation. The results of experiments on a uniform wiggler and on several tapered wigglers are presented. Lasing with uniform wigglers is considered with emphasis on sideband suppression and harmonic lasing. Electron trapping, efficiency, and detuning are considered for tapered wigglers. >
Vibrational Modes and Instabilities of a Dust-Particle Pair in a Complex Plasma

Vibrational modes and instabilities of a dust-particle pair in a terrestrial laboratory complex plasma are investigated by employing an analytical method whereby the plasma wakefield induced by an external electric field is modeled using an image-charge method. It is found that for both horizontally and vertically aligned dust-particle pairs in equilibrium, four normal modes exist. Variations of the confinement parameters cause a single type of instability in the horizontal pair and two types of instabilities in the vertical pair.
Demographic variation in housing cost adjustments with US family migration

This paper examines the demographic variation in housing cost adjustment associated with family migration in the United States. The American population continues to migrate away from very large metropolitan areas down the urban hierarchy to smaller metropolitan and micropolitan areas, according to studies based on the 2000 Census and beyond. The exodus from the largest metropolitan areas is frequently attributed to the push effects of diseconomies and congestion, increasing presence of foreign population, and housing affordability problems particularly in the large gateway cities. Yet, there is no empirical study of the housing cost adjustments associated with migration. This study aims to redress this gap by empirically addressing three questions. First, is migration associated with housing affordability adjustments? Second, when families migrate do they increase or decrease their housing costs and what are the demographic variations in these housing cost adjustments? Lastly, are there significant differences in the geographies of housing cost adjustments among migrant families? The first of these questions is addressed using the Census 2000 county-to-county migration flows merged with Census 2000 measures for median housing value and median income. The remaining questions are examined using the 2000 Public Use Micro Sample 5% National file. The results indicate evidence of significant changes in housing costs associated with migration in general, and interstate migration in particular. On average the direction of migration is to more affordable places. Families migrating from the traditional gateway cities with relatively high percentage of foreign born populations are the most likely to make enormous shifts in affordability. However, these moves do not translate neatly into the regional white flight theory. In particular, Hispanics are far more likely to decrease housing costs with migration, as are non US citizens and naturalized citizens. While primarily empirical, this research makes an important contribution to debates within the family migration literature, including conjectures of regional white flight and gendered theories of migration. Family migration towards greater housing affordability is strategic and embedded in larger issues of family work-life balance.
Applications of tert -butanesulfinamide in the asymmetric synthesis of amines

tert-Butanesulfinamide is prepared using catalytic enantioselective methods in two steps from the extremely inexpensive oil waste by-product, tert-butyl disulfide. Direct con- densation of tert-butanesulfinamide with aldehydes and ketones provides tert-butanesulfinyl imines in uniformly high yields. The tert-butanesulfinyl group activates the imines for the addition of many different classes of nucleophiles, serves as a powerful chiral directing group, and after nucleophilic addition is readily cleaved by treatment with acid. A wide range of highly enantioenriched amines, including α-branched and α,α-dibranched amines, α- and β-amino acids, 1,2- and 1,3-amino alcohols and α-trifluoromethyl amines are efficiently syn- thesized using this methodology.
Sleep in Chronic Obstructive Pulmonary Disease

COPD is the fourth leading cause of death in the US, affecting 14 millions adults. Symptoms related to sleep disturbances are common in individuals with moderate to severe COPD, particularly in elderly patients. One cause of morbidity in this population is abnormalities in gas exchange and resultant hypoxemia, which can lead to elevated pulmonary pressures, dyspnea, and right ventricular overload and failure. Sleep has profound adverse effects on respiration and gas exchange in patients with COPD. Smoking cessation, bronchodilation, inhaled steroids in those with a reversible component, and pulmonary rehabilitation are cornerstones of treatment. Improvement in lung mechanics and gas exchange should lead to better sleep quality and health status.
Catalytic conjugate addition of allyl groups to styryl-activated enones

Conjugate addition of pinacolato(allyl)boron to benzylidenealkylidene ketones is remarkably facile when catalyzed by Ni(0) and Pd(0) complexes. Simple enones are inert to the reaction conditions, suggesting a significant activating effect by the auxiliary benzylidene unit. A comparison of different catalysts and substrates is provided, as is a mechanistic rationale, and an example of asymmetric catalysis.
Mining Generalized Graph Patterns Based on User Examples

There has been a lot of recent interest in mining patterns from graphs. Often, the exact structure of the patterns of interest is not known. This happens, for example, when molecular structures are mined to discover fragments useful as features in chemical compound classification task, or when web sites are mined to discover sets of web pages representing logical documents. Such patterns are often generated from a few small subgraphs (cores), according to certain generalization rules (GRs). We call such patterns "generalized patterns "(GPs). While being structurally different, GPs often perform the same function in the network. Previously proposed approaches to mining GPs either assumed that the cores and the GRs are given, or that all interesting GPs are frequent. These are strong assumptions, which often do not hold in practical applications. In this paper, we propose an approach to mining GPs that is free from the above assumptions. Given a small number of GPs selected by the user, our algorithm discovers all GPs similar to the user examples. First, a machine learning-style approach is used to find the cores. Second, generalizations of the cores in the graph are computed to identify GPs. Evaluation on synthetic data, generated using real cores and GRs from biological and web domains, demonstrates effectiveness of our approach.
A Desulfonylative Approach in Oxidative Gold Catalysis: Regiospecific Access to Donor‐Substituted Acyl Gold Carbenes

Donor-substituted acyl gold carbenes are challenging to access selectively by gold-promoted intermolecular oxidation of internal alkynes as the opposite regioisomers frequently predominate. By using alkynyl sulfones or sulfonates as substrates, the oxidative gold catalysis in the presence of substituted pyridine N-oxides offers regiospecific access to acyl/aryl, acyl/alkenyl, and acyl/alkoxy gold carbenes by in situ expulsion of sulfur dioxide. The intermediacies of these reactive species are established by their reactivities, including undergoing further oxidation by the same oxidant, cyclopropanation of styrenes, engaging in a [3+2] cycloaddition with α-methylstyrene, and conversion into dienones.
Coexisting spinel and silicates in alpine peridotites of the granulite facies

Abstract The Irvine-Jackson model has been used to evaluate the compositional relationships between spinel and silicates in two occurrences of hornblende-bearing alpine peridotites of the granulite facies, the Seiad ultramafic complex of northern California and the Finero ultramafic mass of northern Italy. Despite differences in origin, the two ultramafic bodies exhibit systematic partitioning of Mg and Fe 2+ between spinel and silicates, characteristic of recrystallization under granulite facies conditions.
Studying composite demand using scanner data: the case of ground beef in the US

This article reports tests of aggregation over elementary ground beef products and estimates composite demand elasticities. Results suggest that we obtain reliable information on consumers’ actual ground beef purchases by grouping data according to either lean percentage or brand type. The results also suggest that we obtain reliable information by using the data to form a single ground beef composite. By testing for valid aggregates and providing estimates of composite demand elasticities the analysis provides economists and policymakers with information regarding the effects of food and agricultural policies on consumers and producers that buy and produce ground beef.
Value of time: Speeding behavior and gasoline prices

Abstract ‘Value of Time’ (VOT) is a key parameter in economics and policy. This paper presents an alternative method to estimate VOT by analyzing an hourly dataset on drivers speeding behavior as a function of the gasoline price. Our identification strategy is novel as it is based on the intensive margin. In comparison, previous studies reveal VOT on the extensive margin, but choice alternatives have multiple attributes thereby potentially confounding estimates. Consistent with the range of the prior literature, we find a VOT of about 50% of the wage rate and analyze sources of bias from accidents and traffic tickets. These bias functions suggest that previous stated preference VOT estimates are likely downward whereas previous revealed preference estimates are likely upward biased.
Effects of Wake Passing on Stagnation Region Heat Transfer

In the present experimental study, an annular-flow wind tunnel fitted with a spoked-wheel wake generator was used to ascertain both time-averaged and time-resolved effects of wake passing in a cylinder stagnation region; the cylindrical spokes generated wakes simulating those of a turbine inlet guide vanes. The time-averaged heat transfer results obtained indicate an asymmetric heat-transfer coefficient distribution about the stagnation line, with higher heat-transfer coefficients on the side corresponding to the suction side of the turbine blade. Spectra of the hot-film records indicate that vortex-shedding is a major contributor to the unsteady buffeting of the test-cylinder boundary layer at circumferential stations located at both + and -60 deg from the stagnation line, despite making only a minor contribution to the stagnation line itself.
Experiments in cross-language morphological annotation transfer

Annotated corpora are valuable resources for NLP which are often costly to create. We introduce a method for transferring annotation from a morphologically annotated corpus of a source language to a target language. Our approach assumes only that an unannotated text corpus exists for the target language and a simple textbook which describes the basic morphological properties of that language is available. Our paper describes experiments with Polish, Czech, and Russian. However, the method is not tied in any way to these languages. In all the experiments we use the TnT tagger ([3]), a second-order Markov model. Our approach assumes that the information acquired about one language can be used for processing a related language. We have found out that even breathtakingly naive things (such as approximating the Russian transitions by Czech and/or Polish and approximating the Russian emissions by (manually/automatically derived) Czech cognates) can lead to a significant improvement of the tagger’s performance.
Collusion-secure fingerprinting for digital data

This paper discusses methods for assigning code-words for the purpose of fingerprinting digital data, e.g., software, documents, music, and video. Fingerprinting consists of uniquely marking and registering each copy of the data. This marking allows a distributor to detect any unauthorized copy and trace it back to the user. This threat of detection will deter users from releasing unauthorized copies. A problem arises when users collude: for digital data, two different fingerprinted objects can be compared and the differences between them detected. Hence, a set of users can collude to detect the location of the fingerprint. They can then alter the fingerprint to mask their identities. We present a general fingerprinting solution which is secure in the context of collusion. In addition, we discuss methods for distributing fingerprinted data.
Field tests of electroseismic hydrocarbon detection

Geophysicists, looking for new exploration tools, have studied the coupling between seismic and electromagnetic waves in the near-surface since the 1930s. Our research explores the possibility that electromagnetic-to-seismic (ES) conversion is useful at greater depths. Field tests of ES conversion over gas sands and carbonate oil reservoirs succeeded in delineating known hydrocarbon accumulations from depths up to 1500 m . This is the first observation of electromagnetic-to-seismic coupling from surface electrodes and geophones. Electrodes at the earth’s surface generate electric fields at the target and digital accelerometers detect the returning seismic wave. Conversion at depth is confirmed with hydrophones placed in wells. The gas sands yielded a linear ES response, as expected for electrokinetic energy conversion, and in qualitative agreement with numerical simulations. The carbonate oil reservoirs generate nonlinear conversions; a qualitatively new observation and a new probe of rock properties. The...
Couette flow of two fluids between concentric cylinders

We consider the flow of two immiscible fluids lying between concentric cylinders when the outer cylinder is fixed and the inner one rotates. The interface is assumed to be concentric with the cylinders, and gravitational effects are neglected. We present a numerical study of the effect of different viscosities, different densities and surface tension on the linear stability of the Couette flow. Our results indicate that, with surface tension, a thin layer of the less-viscous fluid next to either cylinder is linearly stable and that it is possible to have stability with the less dense fluid lying outside. The stable configuration with the less-viscous fluid next to the inner cylinder is more stable than the one with the less-viscous fluid next to the outer cylinder. The onset of Taylor instability for one-fluid flow may be delayed by the addition of a thin layer of less-viscous fluid on the inner wall and promoted by a thin layer of more-viscous fluid on the inner wall.
Complementary measures of the mass density and cosmological constant

The distance-redshift relation depends on the amount of matter of each type in the universe. Measurements at different redshifts constrain differing combinations of these matter densities and thus may be used in combination to constrain each separately. The combination of Ω0 and ΩΛ measured in supernovae at z 1 is almost orthogonal to the combination probed by the location of features in the cosmic microwave background (CMB) anisotropy spectrum. We analyze the current combined data set in this framework, which shows that the regions preferred by the supernova and CMB measurements are compatible. We then quantify the favored region and also discuss models in which the matter density in the universe is augmented by a smooth component to give critical density. These models, by construction and in contrast, are not strongly constrained by the combination of the data sets.
Divergent Pathways in the Biosynthesis of Bisindole Natural Products

Two molecules of the amino acid L-tryptophan are the biosynthetic precursors to a class of natural products named the "bisindoles." Hundreds of these bisindole molecules have been isolated from natural sources, and many of these molecules have potent medicinal properties. Recent studies have clarified the biosynthetic construction of six bisindole molecules, revealing novel enzymatic mechanisms and leading to combinatorial synthesis of new bisindole compounds. Collectively, these results provide a vantage point for understanding how much of the diversity of the bisindole class is generated from a small number of diverging pathways from L-tryptophan, as well as enabling identification of bisindoles that are likely derived via completely distinct biosynthetic pathways.
Cobalt catalyzed sp3 C–H amination utilizing aryl azides

A dinuclear Co(II) complex supported by a modular, tunable redox-active ligand system is capable of selective C–H amination to form indolines from aryl azides in good yields at low (1 mol%) catalyst loading. The reaction is tolerant of medicinally relevant heterocycles, such as pyridine and indole, and can be used to form 5-, 6-, and 7-membered rings. The synthetic versatility obtained using low loadings of an earth abundant transition metal complex represents a significant advance in catalytic C–H amination technology.
Generalized Entropy Power Inequalities and Monotonicity Properties of Information

New families of Fisher information and entropy power inequalities for sums of independent random variables are presented. These inequalities relate the information in the sum of n independent random variables to the information contained in sums over subsets of the random variables, for an arbitrary collection of subsets. As a consequence, a simple proof of the monotonicity of information in central limit theorems is obtained, both in the setting of independent and identically distributed (i.i.d.) summands as well as in the more general setting of independent summands with variance-standardized sums.
Tight Bounds on the Complexity of Parallel Sorting

In this paper, we prove tight upper and lower bounds on the number of processors, information transfer, wire area, and time needed to sort N numbers in a bounded-degree fixed-connection network. Our most important new results are: 1) the construction of an N-node degree-3 network capable of sorting N numbers in O(log N) word steps; 2) a proof that any network capable of sorting N (7 log N)-bit numbers in T bit steps requires area A where AT2 = ?(N2 log2 N); and 3) the construction of a ``small-constant-factor'' bounded-degree network that sorts N ?(log N)-bit numbers in T = ?(log N) bit steps with A = ?(N2) area.
Short-term culture of peritoneum explants confirms attachment of endometrium to intact peritoneal mesothelium

Abstract Objective: To evaluate the initial adhesion of endometrium to the peritoneum. Design: Descriptive study using light and confocal laser-scanning microscopy, immunohistochemistry, and transmission electron microscopy. Setting: University-based laboratory. Patient(s): Women without endometriosis undergoing surgery for benign conditions. Intervention(s): None. Main Outcome Measure(s): Explants of peritoneum ( n = 20), prepared from four patients, were cultured for 1 hour with mechanically dispersed proliferative or secretory endometrium. Peritoneum was cultured with endometrium from the same patient. Specimens were fixed and serially sectioned for hematoxylin and eosin stain, immunohistochemistry using an anti-cytokeratin monoclonal antibody, and transmission electron microscopy. Result(s): In 17 of 20 explants, endometrium was adherent to intact mesothelium. There was no evidence of transmesothelial invasion at any sites of attachment. Although in most cases endometrium was adherent to mesothelium via endometrial stroma, there were many sites of endometrial epithelium–mesothelium attachment. Confocal laser scanning microscopy demonstrated an intact monolayer of cytokeratin-positive cells below the sites of endometrial implantation. Transmission electron microscopy demonstrated intact, viable, mesothelial cells below sites of attachment. Conclusion(s): This study demonstrates that endometrium rapidly adheres to intact peritoneal mesothelium. In addition, this study demonstrates that endometrial epithelial cells, as well as stroma, can attach to mesothelium. Further studies are needed that characterize the mechanism of endometrial–mesothelial cell adhesion.
The Evolving Role of Chemical Synthesis in Antibacterial Drug Discovery

The discovery and implementation of antibiotics in the early twentieth century transformed human health and wellbeing. Chemical synthesis enabled the development of the first antibacterial substances, organoarsenicals and sulfa drugs, but these were soon outshone by a host of more powerful and vastly more complex antibiotics from nature: penicillin, streptomycin, tetracycline, and erythromycin, among others. These primary defences are now significantly less effective as an unavoidable consequence of rapid evolution of resistance within pathogenic bacteria, made worse by widespread misuse of antibiotics. For decades medicinal chemists replenished the arsenal of antibiotics by semisynthetic and to a lesser degree fully synthetic routes, but economic factors have led to a subsidence of this effort, which places society on the precipice of a disaster. We believe that the strategic application of modern chemical synthesis to antibacterial drug discovery must play a critical role if a crisis of global proportions is to be averted.
Directional variations in thermal emission from geologic surfaces

We investigated the directional emission properties of geologic surfaces using a ground-based, hand-held infrared radiometer and thermistor probe. Field sites involved surfaces ranging from smooth playa and sand surfaces to a very rough aa lava flow in the Lunar Crater Volcanic Field, NV, as part of the Geological Remote Sensing Field Experiment. Large directional variations in thermal emission were found; they result from the presence of surface roughness–at large scales producing spatial variations in kinetic temperature and at small scales producing emissivity variations. These variations are important in remotely determining surface structure and understanding surface energy balance and emission spectra.
Still dead after all these years: interpreting the failure of general equilibrium theory

More than 25 years after the discovery that the equilibrium point of a general equilibrium model is not necessarily either unique or stable, there is still a need for an intuitively comprehensible explanation of the reasons for this discovery. Recent accounts identify two causes of the finding of instability: the inherent difficulties of aggregation, and the individualistic model of consumer behaviour. The mathematical dead end reached by general equilibrium analysis is not due to obscure or esoteric aspects of the model, but rather arises from intentional design features, present in neoclassical theory since its beginnings. Modification of economic theory to overcome these underlying problems will require a new model of consumer choice, nonlinear analyses of social interactions, and recognition of the central role of institutional and social constraints.
Latent Growth Modeling for Information Systems: Theoretical Extensions and Practical Applications

This paper presents and extends Latent Growth Modeling LGM as a complementary method for analyzing longitudinal data, modeling the process of change over time, testing time-centric hypotheses, and building longitudinal theories. We first describe the basic tenets of LGM and offer guidelines for applying LGM to Information Systems IS research, specifically how to pose research questions that focus on change over time and how to implement LGM models to test time-centric hypotheses. Second and more important, we theoretically extend LGM by proposing a model validation criterion, namely "d-separation," to evaluate why and when LGM works and test its fundamental properties and assumptions. Our d-separation criterion does not rely on any distributional assumptions of the data; it is grounded in the fundamental assumption of the theory of conditional independence. Third, we conduct extensive simulations to examine a multitude of factors that affect LGM performance. Finally, as a practical application, we apply LGM to model the relationship between word-of-mouth communication online product reviews and book sales over time with longitudinal 26-week data from Amazon. The paper concludes by discussing the implications of LGM for helping IS researchers develop and test longitudinal theories.
A Large-Area Search for Low-Mass Objects in Upper Scorpius. II. Age and Mass Distributions

We present continued results from a wide-field, � 150 deg 2 , optical photometric and spectroscopic survey of the northern part of the � 5 Myr old Upper Scorpius OB association. Photometry and spectral types were used to derive effective temperatures and luminosities and place newly identified association members onto a theoretical Hertzsprung-Russell diagram. From our survey, we have discovered 145 new low-mass members of the association and determined � 10% of these objects to be actively accreting material from a surrounding circumstellar disk. Based on comparison of the spatial distributions of low- and high-mass association members, we find no evidence for spatial segregation by mass within the northern portion of the association. Measured data are combined with pre-mainsequence evolutionary models to derive a mass and age for each star. Using Monte Carlo simulations, we show that, taking into account known observational uncertainties, the observed age dispersion for the low-mass population in USco is consistent with all stars forming in a single burst � 5 Myr ago, and we place an upper limit of � 3 Myr on the age spread if the star formation rate has been constant in time. We derive the first spectroscopic mass function for USco that extends into the substellar regime and compare these results to those for three other young clusters and associations.
Fabrication issues for free-space optics at the board packaging level

The successful application of optical interconnects to electronic processing systems requires careful consideration of the: electronic system in which it will be used; optical system and electro-optical device performance; electrical-electro optic interface characteristics; packaging of micro optic components and electro-optic devices with electronic substrates; and the reliability of optical interconnects. In addition, the optical system must be performance and cost competitive with advanced electrical connection methods. We consider several of the above issues at the board packaging level, and the design of relevant optical components for these systems. >
Alternating, pattern-avoiding permutations

We study the problem of counting alternating permutations avoiding collections of permutation patterns including 132. We construct a bijection between the set Sn(132) of 132-avoiding permutations and the set A2n+1(132) of alternating, 132avoiding permutations. For every set p1; : : : ; pk of patterns and certain related patterns q1; : : : ; qk, our bijection restricts to a bijection between Sn(132; p1; : : : ; pk), the set of permutations avoiding 132 and the pi, and A2n+1(132; q1; : : : ; qk), the set of alternating permutations avoiding 132 and the qi. This reduces the enumeration of the latter set to that of the former.