cssi/SciSciGPT-SciSciNet huggingface dataset:
Quantized control via locational optimization

This paper studies state quantization schemes for feedback stabilization of control systems with limited information. The focus is on designing the least destabilizing quantizer subject to a given information constraint. We explore several ways of measuring the destabilizing effect of a quantizer on the closed-loop system, including (but not limited to) the worst-case quantization error. In each case, we show how quantizer design can be naturally reduced to a version of the so-called multicenter problem from locational optimization. Algorithms for obtaining solutions to such problems, all in terms of suitable Voronoi quantizers, are discussed. In particular, an iterative solver is developed for a novel weighted multicenter problem which most accurately represents the least destabilizing quantizer design. A simulation study is also presented.
Gluonic excitations' millennial finale

We provide an overview of theoretical developments on hybrid mesons and glueballs in the last year at this turn of the millenium conference. Cracks in potential models of conventional mesons are developing. Hybrid meson adiabatic surfaces have been calculated and interpreted, experimental J^PC exotics have hybrid meson, four-quark state or non-resonant interpretations, and the strong decay mechanism of hybrids has been studied. All theoretical progress on hybrid mesons in the last year is mentioned. Overall features of glueballs are visited: decays and the successes of the large N_c limit. Two promising experimental areas are mentioned: charmonium hybrids at B-factories and s sbar hybrids at Jefferson Lab.
Analyzing Moment-to-Moment Data Using a Bayesian Functional Linear Model: Application to TV Show Pilot Testing

Researchers often collect continuous consumer feedback moment-to-moment, or MTM, data to understand how consumers respond to a variety of experiences e.g., viewing a TV show, undergoing a colonoscopy. Analyzing how MTM judgments are integrated into overall evaluations allows researchers to determine how the structure of an experience influences consumers' post-experience satisfaction. However, this analysis is challenging because of the functional nature of MTM data. As such, previous research has typically been limited to identifying the influence of heuristics, such as relying on the average intensity, peak, and ending. We develop a Bayesian functional linear model to study how the different “moments” in the MTM data contribute to the overall judgment. Our approach incorporates a temporally weighted average of MTM data as well as specific “patterns” such as peak and trough, thus nesting previous approaches such as the “peak-end” rule as special cases. We apply our methodology to analyze data on TV show pilots collected by CBS. Our results reveal several interesting empirical findings. First, the last quintile of a TV show is weighted about four times as much as each of the first four quintiles. Second, patterns such as peak and trough do not play substantial roles in driving overall evaluations for TV shows. Finally, the last quintile is more important for procedural dramas than for serial dramas. We discuss the managerial implications of our results and other potential applications of our general methodology.
Maternal Employment, Migration, and Child Development.

We analyze the roles of and interrelationships among school inputs and parental inputs in affecting child development through the specification and estimation of a behavioral model of household migration and maternal employment decisions. We integrate information on these decisions with observations on child outcomes over a 13-year period from the National Longitudinal Study of Youth (NLSY). We find that the impact of our school quality measures diminishes by factors of 2 to 4 after accounting for the fact that families may choose where to live in part based on school characteristics and labor market opportunities. The positive statistical relationship between child outcomes and maternal employment reverses sign and remains statistically significant after controlling for its possible endogeneity. Our estimates imply that when parental responses are taken into account, policy changes in school quality end up having only minor impacts on child test scores.
DUSTY DEBRIS AROUND SOLAR-TYPE STARS: TEMPORAL DISK EVOLUTION

Using ISO-ISOPHOT, we carried out a survey of almost 150 stars to search for evidence of emission from dust orbiting young main-sequence stars, both in clusters and isolated systems. Over half of the detections are new examples of dusty stellar systems and demonstrate that such dust can be detected around numerous stars older than a few times 106 yr. Fluxes at 60 and either 90 or 100 μm for the new excess sources together with improved fluxes for a number of IRAS-identified sources are presented. Analysis of the excess luminosity relative to the stellar photosphere shows a systematic decline of this excess with stellar age consistent with a power-law index of -2.
Dimension and torsion theories for a class of Baer *-rings

Abstract Many known results on finite von Neumann algebras are generalized, by purely algebraic proofs, to a certain class C of finite Baer *-rings. The results in this paper can also be viewed as a study of the properties of Baer *-rings in the class C . First, we show that a finitely generated module over a ring from the class C splits as a direct sum of a finitely generated projective module and a certain torsion module. Then, we define the dimension of any module over a ring from C and prove that this dimension has all the nice properties of the dimension studied in [W. Luck, J. Reine Angew. Math. 495 (1998) 135–162] for finite von Neumann algebras. This dimension defines a torsion theory that we prove to be equal to the Goldie and Lambek torsion theories. Moreover, every finitely generated module splits in this torsion theory. If R is a ring in C , we can embed it in a canonical way into a regular ring Q also in C . We show that K 0 ( R ) is isomorphic to K 0 ( Q ) by producing an explicit isomorphism and its inverse of monoids Proj ( P ) → Proj ( Q ) that extends to the isomorphism of K 0 ( R ) and K 0 ( Q ) .
Effects of collective potentials on pion spectra in relativistic heavy-ion collisions

The effect of collective potentials on pion spectra in ultrarelativistic heavy-ion collisions is investigated. We find the effect of these potential to be very small, too small to explain the observed enhancement at low transverse momenta.
Taxation, Wage Bargaining, and Unemployment

Introduction: does the welfare state hurt unemployment 1. The economic and political consequences of welfare state maturation 2. A quantitative analysis 3. Sweden 4. Germany 5. Britain Conclusion: new social pacts in contemporary Europe.
Total Synthesis of Secobatzelline B

Abstract A concise and efficient total synthesis of Secobatzelline B is reported. The synthesis involves eight steps starting from known 4,6,7‐trimethoxyindole. Synthetic tactics involve a one‐step reduction of an indole‐3‐glyoxalic ester using LiAlH4, resulting in complete reduction of the ester group and a partial reduction of the vinylogous amide carbonyl group. Synthesis also involves the use of a mixture of NaCl and oxone as a new reagent for regioselective chlorination of an indoloquinone derivative.
A New Limit on the Antiproton Lifetime

Measurements of the cosmic-ray /p ratio are compared with predictions from an inhomogeneous disk-diffusion model of production and propagation within the Galaxy, combined with a calculation of the modulation of the interstellar cosmic-ray spectra as the particles propagate through the heliosphere to the Earth. The predictions agree with the observed /p spectrum. Adding a finite lifetime to the model, we obtain the limit τ > 0.8 Myr (90% CL).
Taking Stock Seriously: Equity-Market Performance, Government Policy, and Financial Globalization

Are equity markets just another facet of global finance, or are they unique in their responses to—and influences on—government policies and institutions? Recent work has explored the impact of political factors on bond market behavior and foreign direct investment, but little attention has been paid to stock markets. On the basis of the particular concerns of equity investors, we hypothesize a positive association between stock-market valuations and levels of democracy, shareholder rights, legal traditions, and capital-account liberalization, a negative association with real interest rates, and no association with fiscal deficits or surpluses. We assess our expectations by analyzing the political and institutional determinants of aggregate price-to-earnings ratios for a sample of up to 37 countries from 1985 to 2004, using both cross-sectional and time-series cross-sectional analyses. We find support for most, but not all, of our hypotheses. Our findings suggest that we must disaggregate the effects of different asset markets to understand the impact of economic globalization on government policies.
Kaons in dense matter, kaon production in heavy-ion collisions, and kaon condensation in neutron stars

Abstract The recent past witnesses the growing interdependence between the physics of hadrons, the physics of relativistic heavy-ion collisions, and the physics of compact objects in astrophysics. A notable example is the kaon which plays special roles in all the three fields. In this paper, we first review the various theoretical investigations of kaon properties in nuclear medium, focusing on possible uncertainties in each model. We then present a detailed transport model study of kaon production in heavy-ion collisions at SIS energies. We shall discuss especially the elementary kaon and antikaon production cross sections in hadron-hadron interactions, that represent one of the most serious uncertainties in the transport model study of particle production in heavy-ion collisions. The main purpose of such a study is to constrain kaon in-medium properties from the heavy-ion data. This can provide useful guidances for the development of theoretical models of the kaon in medium. In the last part of the paper, we apply the kaon in-medium properties extracted from heavy-ion data to the study of neutron star properties. Based on a conventional equation of state of nuclear matter that can be considered as one of the best constrained by available experimental data on finite nuclei, we find that the maximum mass of neutron stars is about 2 M ⊙ , which is reduced to about 1.5 M ⊙ once kaon condensation as constrained by heavy-ion data is introduced.
Mild Little Ice Age and unprecedented recent warmth in an 1800 year lake sediment record from Svalbard

The Arctic region is subject to a great amplitude of climate variability and is currently undergoing large-scale changes due in part to anthropogenic global warming. Accurate projections of future change depend on anticipating the response of the Arctic climate system to forcing, and understanding how the response to human forcing will interact with natural climate variations. The Svalbard Archipelago occupies an important location for studying patterns and causes of Arctic climate variability; however, available paleoclimate records from Svalbard are of restricted use due to limitations of existing climate proxies. Here we present a sub-decadal- to multidecadal-scale record of summer temperature for the past 1800 yr from lake sediments of Kongressvatnet on West Spitsbergen, Svalbard, based on the first instrumental calibration of the alkenone paleothermometer. The age model for the High Arctic lake sediments is based on 210 Pb, plutonium activity, and the first application of tephrochronology to lake sediments in this region. We find that the summer warmth of the past 50 yr recorded in both the instrumental and alkenone records was unmatched in West Spitsbergen in the course of the past 1800 yr, including during the Medieval Climate Anomaly, and that summers during the Little Ice Age (LIA) of the 18 th and 19 th centuries on Svalbard were not particularly cold, even though glaciers occupied their maximum Holocene extent. Our results suggest that increased wintertime precipitation, rather than cold temperatures, was responsible for LIA glaciations on Svalbard and that increased heat transport into the Arctic via the West Spitsbergen Current began ca. A.D. 1600.
To elect or to appoint? Bias, information, and responsiveness of bureaucrats and politicians

In this paper, we address empirically the trade-offs involved in choosing between bureaucrats and politicians. In order to do this, we map institutions of selection and retention of public officials to the type of public officials they induce. We do this by specifying a collective decision-making model, and exploiting its equilibrium information to obtain estimates of the unobservable types. We focus on criminal decisions across US states' Supreme Courts. We find that justices that are shielded from voters' influence (“bureaucrats”) on average (i) have better information, (ii) are more likely to change their preconceived opinions about a case, and (iii) are more effective (make less mistakes) than their elected counterparts (“politicians”). We evaluate how performance would change if the courts replaced majority rule with unanimity rule.
Attitudes Toward Managing Hazardous Waste: What Should Be Cleaned Up and Who Should Pay for It?

Hazardous waste policy in the United States uses a liability-based approach, including strict, retroactive, and joint and several liability. To assess attitudes toward these basic principles of liability, and toward priorities for clean-up of wastes, a questionnaire was mailed to legislators, judges, executives of oil and chemical companies, environmentalists, and economists. The questionnaire consisted of abstract, simplified cases, which contrasted basic principles rather than dealing with real-world scenarios. Subjects were asked how they would allocate clean-up costs between companies and government as a function of such factors as adherence to standards, adoption of best available technology (BAT), and influence of penalties on future behavior. Most subjects felt that, if the company followed government standards or used the best available technology (BAT), it should pay for only a portion of the clean-up cost, with the government paying the rest. In general, responses did not support the principles underlying current law - strict, retroactive, and joint-and-several liability. Most subjects were more interested in polluters paying for damages than in deterrence or future benefit - even to the extent that they would have harmless' waste sites cleaned up. A bias was found toward complete clean-up of some sites, or zero risk.' Different groupsmore » of subjects gave similar answers, although more committed environmentalists were more willing to make companies pay and to clean up waste regardless of the cost. 21 refs., 3 tabs.« less
Vortex tubes in turbulent flows: identification, representation, reconstruction

A new algorithm for identifying vortices in complex flows is presented. The scheme uses both the vorticity and pressure fields. A skeleton line along the center of a vortex is produced by a two-step predictor-corrector scheme. The technique uses the vector field to move in the direction of the skeleton line and the scalar field to correct the location in the plane perpendicular to the skeleton line. With an economical description of the vortex tube's cross-section, the skeleton compresses the representation of the flow by a factor of 4000 or more. We show how the reconstructed geometry of vortex tubes can be enhanced to help visualize helical motion. >
Si implant-assisted Ohmic contacts to GaN

Abstract The contact resistance, ρ C , was measured for the traditional Ti/Al/Ni/Au Ohmic contact for samples implanted with Si to >10 20 cm −3 and annealed at 1100, 1150, 1200, or 1250 °C for 2, 5 or 10 min using an AlN annealing cap. These results are compared with those for samples annealed in the same way, but were not implanted. The as-grown samples were doped to 3.56 × 10 17 or 6.67 × 10 16 cm −3 or were unintentionally (UI) doped. In almost all cases, ρ C for the implanted sample was lower, and a record low ρ C = 2.66 × 10 −8 Ω cm 2 was achieved for the more heavily doped implanted sample annealed at 1200 °C for 10 min. ρ C decreased with the doping concentration, and for the UI samples, Ohmic contacts could be made only if the samples were implanted. The surface roughness was also measured, and it was found for an as-grown with an RMS roughness of 0.303 nm, the roughness increased from 0.623 after an 1100 °C anneal to 3.197 nm after a 1250 °C anneal for the implanted samples annealed for 10 min, and it increased from 1.280 nm to 5.357 nm under the same conditions for the samples that were not implanted.
Counterexamples to the 0-1 Conjecture

For permutations x and w, let mu(x,w) be the coefficient of highest possible degree in the Kazhdan-Lusztig polynomial P_{x,w}. It is well-known that the coefficients mu(x,w) arise as the edge labels of certain graphs encoding the representations of S_n. The 0-1 Conjecture states that the mu(x,w) are either 0 or 1. We present two counterexamples to this conjecture, the first in S_16, for which x and w are in the same left cell, and the second in S_10. The proof of the counterexample in S_16 relies on computer calculations.
Background X-ray Radiation Fields Produced by Young Embedded Star Clusters

ABSTRACT.Most star formation in our galaxy occurs within embedded clusters, and these background environments can affect the star and planet formation processes occurring within them. In turn, young stellar members can shape the background environment and thereby provide a feedback mechanism. This work explores one aspect of stellar feedback by quantifying the background X-ray radiation fields produced by young stellar objects. Specifically, the distributions of X-ray luminosities and X-ray fluxes produced by cluster environments are constructed as a function of cluster membership size NN. Composite flux distributions, for given distributions of cluster sizes NN, are also constructed. The resulting distributions are wide and the X-ray radiation fields are moderately intense, with the expected flux levels exceeding the cosmic and galactic X-ray backgrounds by factors of ∼10–1000∼10–1000 (for energies 0.2–15 keV). For circumstellar disks that are geometrically thin and optically thick, the X-ray flux from t...
CONCORDANCE OF BOUNDARY LINKS

We show that the twisted signature invariants of boundary link concordance derived from unitary representations of the free group are actually invariants of ordinary link concordance. We also show how the discontinuity locus of this signature function is determined by Seifert matrices of the link.
Redox Processes and Water Quality of Selected Principal Aquifer Systems

Reduction/oxidation (redox) conditions in 15 principal aquifer (PA) systems of the United States, and their impact on several water quality issues, were assessed from a large data base collected by the National Water-Quality Assessment Program of the USGS. The logic of these assessments was based on the observed ecological succession of electron acceptors such as dissolved oxygen, nitrate, and sulfate and threshold concentrations of these substrates needed to support active microbial metabolism. Similarly, the utilization of solid-phase electron acceptors such as Mn(IV) and Fe(III) is indicated by the production of dissolved manganese and iron. An internally consistent set of threshold concentration criteria was developed and applied to a large data set of 1692 water samples from the PAs to assess ambient redox conditions. The indicated redox conditions then were related to the occurrence of selected natural (arsenic) and anthropogenic (nitrate and volatile organic compounds) contaminants in ground water. For the natural and anthropogenic contaminants assessed in this study, considering redox conditions as defined by this framework of redox indicator species and threshold concentrations explained many water quality trends observed at a regional scale. An important finding of this study was that samples indicating mixed redox processes provide information on redox heterogeneity that is useful for assessing common water quality issues. Given the interpretive power of the redox framework and given that it is relatively inexpensive and easy to measure the chemical parameters included in the framework, those parameters should be included in routine water quality monitoring programs whenever possible.
Behavioral Intervention to Reduce Child Distress During Self-Injection

We investigated the effects of a cognitive-behavioral treatment package on reduction of anticipatory fear of pain during self-administered insulin injections. Two patients diagnosed with insulin-dependent diabetes mellitus participated. An ABAB design was employed; the intervention conditions consisted of cue-controlled breathing, filmed modeling, pacing, and reinforcement. A substantial reduction in the mean time for injection and a reduction in behaviors indicative of anticipatory distress were achieved under intervention conditions. The clinical importance of the study is discussed and areas for future research are identified.
Influence of Conformational Asymmetry on the Phase Behavior of Ternary Homopolymer/Block Copolymer Blends around the Bicontinuous Microemulsion Channel

We have developed a new ternary polymeric system, poly(ethylene-alt-propylene) (PEP)/poly(butylene oxide) (PBO)/PEP−PBO, to study the complex phase behavior near the bicontinuous microemulsion phas...
Multi-user Cognitive Interference Channels: A Survey and New Capacity Results

This paper provides a survey of the state-of-the-art information theoretic analysis for overlay multi-user (more than two pairs) cognitive networks and reports new capacity results. In an overlay scenario, cognitive/secondary users share the same frequency band with licensed/primary users to efficiently exploit the spectrum. They do so without degrading the performance of the incumbent users, and may possibly even aid in transmitting their messages as cognitive users are assumed to possess the message(s) of primary user(s) and possibly other cognitive user(s). The survey begins with a short overview of the two-user overlay cognitive interference channel. The evolution from two-user to three-user overlay cognitive interference channels is described next, followed by generalizations to multi-user (arbitrary number of users) cognitive networks. The rest of the paper considers $K$ -user cognitive interference channels with different message knowledge structures at the transmitters. Novel capacity inner and outer bounds are proposed. Channel conditions under which the bounds meet, thus, characterizing the information theoretic capacity of the channel, for both linear deterministic and Gaussian channel models, are derived. The results show that for certain channel conditions distributed cognition, or having a cumulative message knowledge structure at the nodes, may not be worth the overhead as (approximately) the same capacity can be achieved by having only one global cognitive user whose role is to manage all the interference in the network. This paper concludes with future research directions.
On the Inverse Cascade of Magnetic Helicity

We study the inverse cascade of magnetic helicity in conducting fluids, as pertinent to the generation and dynamics of magnetic fields as observed, e.g., in the solar corona, by investigating the detailed transfer of helicity between different spherical shells in Fourier space in direct numerical simulations of three-dimensional magnetohydrodynamics (MHD). Two different numerical simulations are used, one in which the system is forced with an electromotive force in the induction equation and one in which the system is forced mechanically with an ABC flow and the magnetic field is solely sustained by a dynamo action. The magnetic helicity cascade at the initial stages of both simulations is observed to be inverse and local (in scale space) at large scales and direct and local at small scales. When saturation is approached, most of the helicity is concentrated at large scales and the cascade is nonlocal. Helicity is transferred directly from the forced scales to the largest scales. At the same time, a smaller in amplitude direct cascade is observed from the largest scale to small scales.
Counting Independent Sets of a Fixed Size in Graphs with a Given Minimum Degree

Galvin showed that for all fixed δ and sufficiently large n, the n-vertex graph with minimum degree δ that admits the most independent sets is the complete bipartite graph . He conjectured that except perhaps for some small values of t, the same graph yields the maximum count of independent sets of size t for each possible t. Evidence for this conjecture was recently provided by Alexander, Cutler, and Mink, who showed that for all triples with , no n-vertex bipartite graph with minimum degree δ admits more independent sets of size t than . Here, we make further progress. We show that for all triples with and , no n-vertex graph with minimum degree δ admits more independent sets of size t than , and we obtain the same conclusion for and . Our proofs lead us naturally to the study of an interesting family of critical graphs, namely those of minimum degree δ whose minimum degree drops on deletion of an edge or a vertex.
Numerical Simulation of Natural Convection in Solar Cavity Receivers

Cavity receivers used in solar power towers and dish concentrators may lose considerable energy by natural convection, which reduces the overall system efficiency. A validated numerical receiver model is desired to better understand convection processes and aid in heat loss minimization efforts. The purpose of this investigation was to evaluate heat loss predictions using the commercial computational fluid dynamics software packages FLUENT 13.0 and SolidWorks Flow Simulation 2011 against experimentally measured heat losses for a heated cubical cavity model [1] and a cylindrical dish receiver model [2]. Agreement within 10% was found between software packages across most simulations. However, simulated convective heat loss was under predicted by 45% for the cubical cavity when experimental wall temperatures were implemented on cavity walls, and 32% when implementing the experimental heat flux from the cavity walls. Convective heat loss from the cylindrical dish receiver model was accurately predicted within experimental uncertainties by both simulation codes using both isothermal and constant heat flux wall boundary conditions except at inclination angles below 15° and above 75°, where losses were under- and over-predicted by FLUENT and SolidWorks, respectively. Comparison with empirical correlations for convective heat loss from heated cavities showed that correlations by Siebers and Kraabel [1] and for an assembly of heated flat plates oriented to the cavity geometry [3] predicted heat losses from the cubical cavity within experimental uncertainties, while correlations by Clausing [4] and Paitoonsurikarn et al. [8] were able to do the same for the cylindrical dish receiver. No single correlation was valid for both receiver models. Different turbulence and air-property models within FLUENT were also investigated and compared in this study.Copyright © 2012 by ASME
A Primer of Swarm Equilibria

We study equilibrium configurations of swarming biological organisms subject to exogenous and pairwise endogenous forces. Beginning with a discrete dynamical model, we derive a variational description of the corresponding continuum population density. Equilibrium solutions are extrema of an energy functional and satisfy a Fredholm integral equation. We find conditions for the extrema to be local minimizers, global minimizers, and minimizers with respect to infinitesimal Lagrangian displacements of mass. In one spatial dimension, for a variety of exogenous forces, endogenous forces, and domain configurations, we find exact analytical expressions for the equilibria. These agree closely with numerical simulations of the underlying discrete model. The exact solutions provide a sampling of the wide variety of equilibrium configurations possible within our general swarm modeling framework. The equilibria typically are compactly supported and may contain δ-concentrations or jump discontinuities at the edge of the support. We apply our methods to a model of locust swarms, which in nature are observed to consist of a concentrated population on the ground separated from an airborne group. Our model can reproduce this configuration; quasi-two-dimensionality of the model plays a critical role.
Allene Synthesis from 2-Alkyn-1-Ols

Abstract Activation of 2-alkyn-1-ols as their methanesulfonate esters and displacement with hydrazine furnishes the corresponding alkynyl hydrazine derivatives which undergo smooth oxidative rearrangement with diethyl azodicarboxylate (DEAD) or 4-methyl-1,2,4-triazoline-3,5-dione (MTAD) to form allenes.
Carbaporphyrins, porphyrin isomers and the legacy of Emanuel Vogel

Vogel discovered a large number of bridged annulene structures, including constitutional porphyrin isomers, heteroporphyrinoid species such as the tetraoxaporphyrin dication, corrole isomers and novel expanded porphyrinoid systems. In this review, the impact of Vogel's work on the author's research program is discussed. Carbaporphyrinoid systems with one or two carbocyclic rings replacing the usual pyrrole subunits have been synthesized and their diatropic characteristics can be related to the presence of 18π electron delocalization pathways within these macrocycles. The preparation of a dideazaporphyrin also provides strong support for the concept, espoused by Vogel, that porphyrins are examples of bridged annulenes. Ring contractions of azuliporphyrins to benzocarbaporphyrins with tert-butyl hydroperoxide in the presence of base have been proposed to involve a Cope rearrangement where a cycloheptatriene unit rearranges to give a norcaradiene-fused carbaporphyrinoid, followed elimination of tert-butyl alcohol, and Vogel's investigations into these types of valence tautomerization processes provides insights into these unusual transformations. In addition, a new class of porphyrin isomers has been synthesized and these porphyrin analogs extend the observations previously made for N-confused porphyrins and Vogel's constitutional isomers.
Historical Property Rights, Sociality, and the Emergence of Impersonal Exchange in Long-Distance Trade

This laboratory experiment explores the extent to which impersonal exchange emerges from personal exchange with opportunities for long-distance trade. We design a three-commodity production and exchange economy in which agents in three geographically separated villages must develop multilateral exchange networks to import a good only available abroad. For treatments, we induce two distinct institutional histories to investigate how past experience with prop- erty rights affects the evolution of specialization and exchange. We find that a history of unenforced property rights hinders our subjects' ability to develop the requisite personal social arrangements to support specialization and effec- tively exploit impersonal long-distance trade. (JEL C90, D23, D5�, P�4)
A convenient approach to cyclic enol phosphates via ring-closing metathesis

A strategy employing the second generation Grubbs catalyst in order to facilitate the generation of a variety of cyclic enol phosphates, including 2H-chromen-4-yl, 1,2-dihydroquinolin-4-yl, 2H-thiochromen-4-yl, 2H-thiochromen-4-yl 1,1-dioxide, and benzofuran-2-yl enol phosphate scaffolds is described. This work represents the first case of an olefin metathesis reaction in which one of the groups participating in the metathesis event is an enol phosphate moiety.
Robust stability of systems with integral control

A number of necessary and sufficient conditions are derived, which must be satisfied by the plant d.c. gain matrix of a linear time invariant system in order for an integral controller to exist for which the closed loop system is stable. Based on these results, the robustness of integral control systems is analyzed, i.e., the family of plants is defined which are stable when controlled with the same integral controller. Conditions for actuator/sensor failure tolerance of systems with integral control are also given. Finally, parallels are drawn between the results of this paper and the bifurcation theory of nonlinear systems.
Stability of Silicon Carbonitride Phases

Important hard phases are included in the quaternary compositional system Si-N-C-B. This paper reviews ternary amorphous and crystalline phases in the system Si-N-C and deliberates on the issue of stability of the binary C 3 N 4 , a hypothetical phase harder than diamond, and instability of nitrides in general. There is a tendency for nitrogen atoms to agglomerate and be released as nitrogen molecules. Stabilization of CN radicals can be achieved through ternary phases: carbonitrides metal-C-N. Ternary Si-N-C phases have been synthesized by pyrolysis of polyorganosilazanes, physical vapor deposition, and chemical vapor deposition. The crystalline α-Si 3 N 4 :C phase can incorporate about 6 at.% C and yields enhancement of hardness and wear resistance. Other crystalline phases contain more carbon, for example, Si 2 CN 4 .
Cyclin D1 and p16 expression in recurrent nasopharyngeal carcinoma

Cyclin D1 and p16 are involved in the regulation of G1 checkpoint and may play an important role in the tumorigenesis of nasopharyngeal carcinoma (NPC). Previous studies have examined the level of expression of cyclin D1 and p16 in primary untreated NPC but no such information is available for recurrent NPC. We set out in this study to examine the expression level of cyclin D1 and p16 in recurrent NPC that have failed previous treatment with radiation +/- chemotherapy. A total of 42 patients underwent salvage nasopharyngectomy from 1984 to 2001 for recurrent NPC after treatment failure with radiation +/- chemotherapy. Twenty-seven pathologic specimens were available for immunohistochemical study using antibodies against cyclin D1 and p16. Positive expression of cyclin D1 was observed in 7 of 27 recurrent NPC specimens (26%) while positive p16 expression was seen in only 1 of 27 recurrent NPC (4%). While the level of expression of cyclin D1 in recurrent NPC was similar to that of previously untreated head and neck cancer, the level of p16 expression in recurrent NPC samples was much lower than that reported for previously untreated cancer. The finding that almost all (96%) of the recurrent NPC lack expression of p16 suggested that loss of p16 may confer a survival advantage by making cancer cells more resistant to conventional treatment with radiation +/- chemotherapy. Further research is warranted to investigate the clinical use of p16 both as a prognostic marker and as a potential therapeutic target.
Wind tunnel noise reduction at Mach 5 with a rod-wall sound shield

A method of shielding a wind-tunnel model from noise radiated by the tunnel-wall boundary layer has been developed and tested at the Langley Research Center. The shield consists of a rectangular array of longitudinal rods with boundary-layer suction through gaps between the rods. Tests were conducted at Mach 5 over a unit Reynolds number range of 1.0-3.5 x 10 to the 7th/m. Hot-wire measurements indicated the freestream noise, expressed in terms of the rms pressure fluctuations normalized by the mean pressure, was reduced from about 1.4 percent just upstream of the shielded region of a minimum level of about 0.4 percent in the forward portion of the shielded flow.
Inhibition of the Metabolism of Streptococci and Salmonella by Specific Antisera

Streptococcal and salmonella antisera inhibited carbohydrate metabolism for groups A, B, C, and D streptococci and group E salmonella, as measured by the formation of [(14)C]dioxide from [(14)C]glucose metabolism. For salmonella, the inhibition was type specific since group E salmonella were inhibited only by salmonella E antisera and not by anti-salmonella A or C(1). For streptococci, quantitative differences were demonstrated, but major cross-reactivity was observed. At high concentrations, the antisera were bactericidal; at more dilute concentrations, for both salmonella and streptococci, carbohydrate metabolism was suppressed, but subculture on chocolate agar showed abundant growth. Cross-reacting antibodies could be absorbed by incubation with either antigen, e.g., streptococcal antisera versus heat-killed salmonella. The results suggest that the radiometric technique can be more sensitive than either capillary flocculation or visual detection of bacterial growth for detecting the inhibition of streptococci and salmonella by specific antibodies. The use of specific antisera may prove useful for bacterial species identification in an automated system for detection of bacterial growth.
Commensurations of the Johnson kernel

Let K be the subgroup of the extended mapping class group, Mod(S), generated by Dehn twists about separating curves. Assuming that S is a closed, orientable surface of genus at least 4, we confirm a conjecture of Farb that Comm(K) � Aut(K) � Mod(S). More generally, we show that any injection of a finite index subgroup of K into the Torelli group I of S is induced by a homeomorphism. In particular, this proves that K is co-Hopfian and is characteristic in I. Further, we recover the result of Farb and Ivanov that any injection of a finite index subgroup of I into I is induced by a homeomorphism. Our method is to reformulate these group theoretic statements in terms of maps of curve complexes.
Power and Area Minimization for Multidimensional Signal Processing

Sensitivity-based methodology is applied to optimization of performance, power and area across several levels of design abstraction for a complex wireless baseband signal processing algorithm. The design framework is based on a unified, block-based graphical description of the algorithm to avoid design re-entry in various phases of chip development. The use of architectural techniques for minimization of power and area for complex signal processing algorithms is demonstrated using this framework. As a proof of concept, an ASIC realization of the MIMO baseband signal processing for a multi-antenna WLAN is described. The chip implements a 4times4 adaptive singular value decomposition (SVD) algorithm with combined power and area minimization achieving a power efficiency of 2.1 GOPS/mW (12-bit add equivalent) in just 3.5 mm 2 in a standard 90 nm CMOS process. The computational throughput of 70 GOPS is implemented with 0.5 M cells at a 100 MHz clock and 385 mV supply, dissipating 34 mW of power. With optimal channel conditions the algorithm implemented can deliver up to 250 Mb/s over 16 sub-carriers
Improving precision of type analysis using non-discriminative union

This paper presents a new type analysis for logic programs. The analysis is performed with a priori type definitions; and type expressions are formed from a fixed alphabet of type constructors. Non-discriminative union is used to join type information from different sources without loss of precision. An operation that is performed repeatedly during an analysis is to detect if a fixpoint has been reached. This is reduced to checking the emptiness of types. Due to the use of non-discriminative union, the fundamental problem of checking the emptiness of types is more complex in the proposed type analysis than in other type analyses with a priori type definitions. The experimental results, however, show that use of tabling reduces the effect to a small fraction of analysis time on a set of benchmarks.
Transcriptional profiling of native inner medullary collecting duct cells from rat kidney

Vasopressin acts on the inner medullary collecting duct (IMCD) in the kidney to regulate water and urea transport. To obtain a “parts list” of gene products expressed in the IMCD, we carried out mR...
On semi-global stabilization of minimum phase nonlinear systems without vector relative degrees

Recently, we developed a structural decomposition for multiple input multiple output nonlinear systems that are affine in control but otherwise general. This structural decomposition simplifies the conventional backstepping design and allows a new backstepping design procedure that is able to stabilize some systems on which the conventional backstepping is not applicable. In this paper we further exploit the properties of such a decomposition for the purpose of solving the semi-global stabilization problem for minimum phase nonlinear systems without vector relative degrees. By taking advantage of special structure of the decomposed system, we first apply the low gain design to the part of system that possesses a linear dynamics. The low gain design results in an augmented zero dynamics that is locally stable at the origin with a domain of attraction that can be made arbitrarily large by lowering the gain. With this augmented zero dynamics, backstepping design is then apply to achieve semi-global stabilization of the overall system.
Optimal Hankel-norm model reductions: Multivariable systems

This paper represents a first attempt to derive a closed-form (Hankel-norm) optimal solution for multivariable system reduction problems. The basic idea is to extend the scalar ease approach in [5] to deal with the multivariable systems. The major contribution lies in the development of a minimal degree approximation (MDA) theorem and a computation algorithm. The main theorem describes a closed-form formulation for the optimal approximants, with the optimality verified by a complete error analysis. In deriving the main theorem, some useful singular value/vector properties associated with block-Hankel matrices are explored and a key extension theorem is also developed. Imbedded in the polynomial-theoretic derivation of the extension theorem is an efficient approximation algorithm. This algorithm consists of three steps: i) compute the minimal basis solution of a polynomial matrix equation; ii) solve an algebraic Riccati equation; and iii) find the partial fraction expansion of a rational matrix.
Universally measurable subgroups of countable index

It is proved that any countable index, universally measurable subgroup of a Polish group is open. By consequence, any universally measurable homomorphism from a Polish group into the infinite symmetric group S1 is continuous. It is also shown that a universally measure homomorphism from a Polish group into a second countable, locally compact group is necessarily continuous. The present work is motivated by an old problem of J.P.R. Christensen, which asks whether any universally measurable homomorphism between Polish groups is continuous. To fix the terminology, let us recall that a Polish space is a separable topological space whose topology can be induced by a complete metric. Also, a topological group is Polish in case its topology is Polish. A subset A of a Polish space X is said to be Borel if it belongs to the �-algebra generated by the open sets and A is universally measurable if it is measurable with respect to any Borel probability (or eq uivalently, �-finite) measure on X, i.e., if for any Borel probability measure µ on X, A differs from a Borel set by a set of µ-measure 0. The class of universally measurable sets clearly forms a �-algebra, but contrary to the class of Borel sets, there is no "algebrai c" procedure for generating the universally measurable sets from the open sets. Thus, the extent of this class is somewhat elusive and largely depends on additional set theoretical a xioms. A function f : X → Y between Polish spaces X and Y is said to be Borel measurable, resp. universally measurable, if f −1 (U) is Borel, resp. universally measurable, in X for all open U ⊆ Y. A classical result due to H. Steinhaus and A. Weil states that if G is a second countable, locally compact group (and hence Polish) and H is a Polish group, then any universally measurable homomorphism �: G → H is continuous. Actually, for this it suffices thatis measurable with respect to left or right Haar measure on G. However, this result relies heavily on the translation inva riance of Haar measure, and, as any Polish group with a non-zero, quasi-invariant, �-finite Borel measure is necessarily locally compact, the proof gives no indication whether the result should hold for general Polish G. Nevertheless, in the late 1960's, J.P.R. Christensen (1) ( see also (2)) introduced a notion of Haar null sets in more general Polish groups and was able to use this to prove an analogue of the Steinhaus-Weil result for Abelian Polish groupsG. In fact, a consequence of Christensen's proof is that any universally measurable h omomorphism from a Polish groupG into a Polish groupH, whereH admits a compatible two-sided invariant metric, is continuous. In particular, this applies to the case when H is Abelian, compact or countable discrete. It immediately follows from this that if G is Polish and N 6 G is a countable index, universally measurable, normal subgroup, then N is open in G. To see this, one just considers the quotient mapping �: G → G/N , where G/N is taken discrete. Recently,
Organizational Life and Political Incorporation of Two Asian Immigrant Groups: A Case Study.

Civil society is the foundation of a healthy democracy but its immigrant element has received little attention. This paper is a case study of immigrant organizations of highly skilled Asian Indians and Chinese immigrants in a suburban town of Edison, New Jersey. I find that civic participation of Asian Indian immigrants spills over into political incorporation while Chinese immigrant organizations remain marginalized. I argue that local processes of racialization are central in explaining differences in political incorporation of immigrants. In the local context, the Chinese are seen as successful but conformist model minorities and Asian Indians as invaders and troublemakers. The racialization of Asian Indians has resulted in more political activity and higher levels of political visibility of their organizations. The results highlight shortcomings of current assimilation theories, which give little space to civic and political incorporation and view human capital in an unqualifiedly positive light.
Selective oxidation of zirconocyclopentenes via organoboranes.

A new, convenient, one-pot protocol is described for oxidation of zirconocyclopent-2-enes selectively at the sp3 carbon by efficient transfer to electrophilic (cHex)2BCl followed by oxidation with H2O2/NaOH to afford 1-alkylidene-2-hydroxymethylcyclopentanes. Results with several substrates show that overall reaction efficiencies for the zirconocene-mediated enyne cyclization, boron transmetalation, and oxidation sequence are generally comparable to yields obtained from protonation of intermediate zirconocycles. The formation of E/Z olefin isomers from the cyclization-oxidation sequence and an acid-catalyzed pinacol-type rearrangement of a vinylsilane are described.
On the inverse fractal problem for two–dimensional attractors

We give a theoretical, geometric solution of the inverse fractal problem for a large class of two-dimensional attractors which we call polyhulled disjoint (PHD) attractors. These are attractors of iterated function systems (IFS) with affine maps and range over a wide spectrum of shapes, both abstract and natural. Encoding the objects of a two-dimensional image in terms of their IFS results in enormous data compression. Given a PHD attractor we present an algorithm to find its IFS code by performing a geometric analysis based on the extreme points theorem. We introduce an edge detection device, the springbar function, to extract the affine orbits entangled inside the attractor and then use the elementary properties of these orbits to determine the mappings which generated them. Our solution is amenable to numerical implementation.