cssi/SciSciGPT-SciSciNet huggingface dataset:
Aminophylline in undifferentiated out-of-hospital asystolic cardiac arrest.

Abstract Primary objective: To determine if the introduction of intravenous aminophylline, a nonspecific adenosine receptor antagonist, into the resuscitation algorithm of asystole will increase return of spontaneous circulation when used in undifferentiated prehospital cardiac arrest. Methods: An urban, prehospital, prospective, randomized, double-blind, placebo-controlled trial of nonpregnant normothermic adults suffering nontraumatic out-of-hospital asystolic cardiac arrest. Subjects were treated in accordance with published advanced cardiac life support guidelines and standard pharmacotherapy. They were randomly assigned to receive either placebo or aminophylline along with the initial boluses of atropine and epinephrine. Cardiac rhythms and carotid pulses were monitored throughout the resuscitation. Results: Eighty-two patients were entered into the trial. Forty-five patients were assigned to the placebo group and 37 received aminophylline. Nine of 45 controls (20%; 95% CI 10–35%) achieved return of spontaneous circulation compared to ten of 37 (27%; 95% CI 14–44%) in the aminophylline group. Conclusions: We were not able to show a statistically significant improvement in return of spontaneous circulation when aminophylline was given during the early resuscitation phase of undifferentiated asystolic cardiac arrest in the prehospital setting with this sample size.
Flavor changing neutral currents in a realistic composite technicolor model

Abstract We consider the phenomenology of a composite technicolor model proposed recently by Georgi. Composite technicolor interactions produce four-quark operators in the low energy theory that contribute to flavor changing neutral current processes. While we expect operators of this type to be induced at the compositeness scale by the flavor-symmetry breaking effects of the preon mass matrices, the Georgi model also includes operators from higher scales that are not GIM-suppressed. Since these operators are potentially large, we study their impact on flavor changing neutral currents and CP violation in the neutral K, B, and D meson systems. Notably, we find that this model gives rise to a typical value for ϵ′ ϵ that is much smaller than most standard model estimates.
Magnetic Properties of Epitaxial Metallic Superlattices

Superlattices (SL's) and films of rare-earth elements have been grown by means of molecular-beam epitaxy with both the c-axis and b-axis as the growth direction. Long range order spanning many bilayers is observed for both Er-Y and Dy-Y SL's grown along the c-axis, but not for Dy-Y SL's with b-axis growth. This is explained in terms of the anisotropy of the effective exchange interaction. Suppression of the low-temperature ferromagnetic transition is found in all SL's and in Er films grown on Y. This is analyzed in terms of the changes in magnetoelastic energy imposed by epitaxy. Preliminary results on Er films grown on Lu support this picture. The suppression of ferromagnetism permits the study of modulated phases to lower temperatures and higher magnetic fields, with new intermediate phases appearing that are stabilized by the magnetic field.
Thin Position for Tangles

If a tangle, $K\subset {\mathbb B}^3$ , has no planar, meridional, essential surfaces in its exterior then thin position for K has no thin levels.
Scaling of perceptual errors can predict the shape of neural tuning curves.

Weber’s law, first characterized in the 19th century, states that errors estimating the magnitude of perceptual stimuli scale linearly with stimulus intensity. This linear relationship is found in most sensory modalities, generalizes to temporal interval estimation, and even applies to some abstract variables. Despite its generality and long experimental history, the neural basis of Weber’s law remains unknown. This work presents a simple theory explaining the conditions under which Weber’s law can result from neural variability and predicts that the tuning curves of neural populations which adhere to Weber’s law will have a log-power form with parameters that depend on spike-count statistics. The prevalence of Weber’s law suggests that it might be optimal in some sense. We examine this possibility, using variational calculus, and show that Weber’s law is optimal only when observed real-world variables exhibit power-law statistics with a specific exponent. Our theory explains how physiology gives rise to the behaviorally characterized Weber’s law and may represent a general governing principle relating perception to neural activity.
Common volatility across Latin American foreign exchange markets

This article uses high-frequency exchange rate data for a group of 13 Latin American countries in order to analyse volatility co-movements. Particular interest is posed on understanding the existence of a common volatility process during the 1995–2008 period. The analysis relies on bivariate common factor models. We test for second-order common features using the common autoregressive conditional heteroskedasticity-feature methodology developed by Engle and Kozicki (1993). Overall, the results of this article indicate that while most currencies display evidence of time-varying variance, the volatility movements in the Latin American foreign exchange markets seems to be mainly country specific. Common volatility processes seem to be present only for a few South American markets.
p-Version axisymmetric shell element for geometrically nonlinear analysis

Abstract This paper presents a p-version geometrically nonlinear (GNL) formulation based on total Lagrangian approach for a three-node axisymmetric curved shell element. The approximation functions and the nodal variables for the element are derived directly from the Lagrange family of interpolation functions of order pξ and pη. This is accomplished by first establishing one-dimensional hierarchical approximation functions and the corresponding nodal variable operators in the ξ and η directions for the three- and one-node equivalent configurations that correspond to pξ + 1 and pη+ 1 equally spaced nodes in the ξ and η directions and then taking their products. The resulting element approximation functions and the nodal variables are hierarchical and the element approximation ensures C0 continuity. The element geometry is described by the coordinates of the nodes located on the middle surface of the element and the nodal vectors describing top and bottom surfaces of the element. The element properties are established using the principle of virtual work and the hierarchical element approximation. In formulating the properties of the element complete axisymmetric state of stresses and strains are considered, hence the element is equally effective for very thin as well as extremely thick shells. The formulation presented here removes virtually all of the drawbacks present in the existing GNL axisymmetric shell finite element formulations and has many additional benefits. First, the currently available GNL axisymmetric shell finite element formulations are based on fixed interpolation order and thus are not hierarchical and have no mechanism for p-level change. Secondly, the element displacement approximations in the existing formulations are either based on linearized (with respect to nodal rotation) displacement fields in which case a true Lagrangian formulation is not possible and the load step size is severely limited or are based on nonlinear nodal rotation functions approach in which case though the kinematics of deformation is exact but additional complications arise due to the noncummutative nature of nonlinear nodal rotation functions. Such limitations and difficulties do not exist in the present formulation. The hierarchical displacement approximation used here does not involve traditional nodal rotations that have been used in the existing shell element formulations, thus the difficulties associated with their use are not present in this formulation. Incremental equations of equilibrium are derived and solved using the standard Newton method. The total load is divided into increments, and for each increment of load, equilibrium iterations are performed until each component of the residuals is within a preset tolerance. Numerical examples are presented to show the accuracy, efficiency and advantages of the preset formulation. The results obtained from the present formulation are compared with those available in the literature.
Compact broadband polarizer based on shallowly-etched silicon-on-insulator ridge optical waveguides

A novel type of optical polarizer based on silicon-on-insulator shallowly-etched ridge waveguide is designed, fabricated and characterized. The present polarizer is compact, broad-band, and easy-fabricated.
Thieno[3,4-b]pyrazines and their applications to low band gap organic materials

The application of fused-ring thieno[3,4-b]pyrazines in conjugated organic polymers has been found to be a powerful approach to the production of low band gap materials. While thieno[3,4-b]pyrazine-based materials date back to the early 1990s, significant advances in the preparation and scope of thieno[3,4-b]pyrazine-based materials have been reported in recent years, primarily in response to the increasing demand for reduced band gap materials in photovoltaic devices. In this review, we provide an overview of thieno[3,4-b]pyrazines and their application to conjugated materials, highlighting in particular the recent advances in the breadth of thieno[3,4-b]pyrazine building blocks and the promise of tuning materials to achieve optimal properties for specific applications.
Quantifying self-organization in cyclic cellular automata

Cyclic cellular automata (CCA) are models of excitable media. Started from random initial conditions, they produce several different kinds of spatial structure, depending on their control parameters. We introduce new tools from information theory that let us calculate the dynamical information content of spatial random processes. This complexity measure allows us to quantitatively determine the rate of self-organization of these cellular automata, and establish the relationship between parameter values and self-organization in CCA. The method is very general and can easily be applied to other cellular automata or even digitized experimental data.
Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence

We present a series of models for the plasma properties along open magnetic flux tubes rooted in solar coronal holes, streamers, and active regions. These models represent the first self-consistent solutions that combine (1) chromospheric heating driven by an empirically guided acoustic wave spectrum; (2) coronal heating from Alfven waves that have been partially reflected, then damped by anisotropic turbulent cascade; and (3) solar wind acceleration from gradients of gas pressure, acoustic wave pressure, and Alfven wave pressure. The only input parameters are the photospheric lower boundary conditions for the waves and the radial dependence of the background magnetic field along the flux tube. We have not included multifluid or collisionless effects (e.g., preferential ion heating), which are not yet fully understood. For a single choice for the photospheric wave properties, our models produce a realistic range of slow and fast solar wind conditions by varying only the coronal magnetic field. Specifically, a two-dimensional model of coronal holes and streamers at solar minimum reproduces the latitudinal bifurcation of slow and fast streams seen by Ulysses. The radial gradient of the Alfven speed affects where the waves are reflected and damped, and thus whether energy is deposited below or above the Parker critical point. As predicted by earlier studies, a larger coronal "expansion factor" gives rise to a slower and denser wind, higher temperature at the coronal base, less intense Alfven waves at 1 AU, and correlative trends for commonly measured ratios of ion charge states and FIP-sensitive abundances that are in general agreement with observations. These models offer supporting evidence for the idea that coronal heating and solar wind acceleration (in open magnetic flux tubes) can occur as a result of wave dissipation and turbulent cascade.
The Iowa connection

Abstract A summary of the Fluorinated Ylide Chemistry, Organometallic Chemistry, Phosphonate Chemistry, Single-Electron-Transfer Chemistry and Metal Hydride Chemistry carried out at the University of Iowa is described.
Cofiniteness and associated primes of local cohomology modules

Abstract Let R be a d -dimensional regular local ring, I an ideal of R , and M a finitely generated R -module of dimension n . We prove that the set of associated primes of Ext R i (R/I,H I j (M)) is finite for all i and j in the following cases: (a) dim M⩽3 ; (b) dim R⩽4 ; (c) dim M/IM⩽2 and M satisfies Serre's condition S n−3 ; (d) dim M/IM⩽3 , ann R M=0 , R is unramified, and M satisfies S n−3 . In these cases we also prove that H I i (M) p is I p -cofinite for all but finitely many primes p of R . Additionally, we show that if dim R/I⩾2 and Spec R/I−{m/I} is disconnected then H I d−1 (R) is not I -cofinite, generalizing a result due to Huneke and Koh.
The chemistry of multiply deuterated molecules in protoplanetary disks : I. the outer disk

We present new models of the deuterium chemistry in protoplanetary disks, including, for the first time, multiply deuterated species. We use these models to explore whether observations in combination with models can give us clues as to which desorption processes occur in disks.We find, in common with other authors, that photodesorption can allow strongly bound molecules such as HDO to exist in the gas phase in a layer above the midplane. Models including this process give the best agreement with the observations. In the midplane, cosmic-ray heating can desorb weakly bound molecules such as CO and N2. We find the observations suggest that N2 is gaseous in this region, but that CO must be retained on the grains to account for the observed DCO+/HCO+. This could be achieved by CO having a higher binding energy than N2 (as may be the case when these molecules are accreted onto water ice) or by a smaller cosmic-ray desorption rate for CO than assumed here, as suggested by recent theoretical work. For gaseous molecules the calculated deuteration can be greatly changed by chemical processing in the disk from the input molecular cloud values. On the grains singly deuterated species tend to retain the D/H ratio set in the molecular cloud, whereas multiply deuterated species are more affected by the disk chemistry. Consequently, the D/H ratios observed in comets may be partly set in the parent cloud and partly in the disk, depending on the molecule.
Asymmetric Synthesis of Bryostatin 2.

The potent bryostatin antitumor agents are currently in phase II clinical trials for the treatment of a variety of forms of cancer. Aldol reactions and directed reductions are among the essential steps for the formation of fragments A-C in the total synthesis of the title compound. Coupling of these fragments by sulfone-based olefination and alkylation reactions was followed by macrocyclization and introduction of the enoate moieties on rings B and C.
Kinetics of carbon dioxide sorption on potassium-doped lithium zirconate

Potassium-doped lithium zirconate (Li2ZrO3) sorbents with similar crystallite but different aggregate sizes were prepared by a solid-state reaction method from mixtures of Li2CO3, K2CO3, and ZrO2 of different particle sizes. Carbon dioxide sorption rate on the prepared Li2ZrO3 sorbents increases with decreasing sorbent aggregate size. It is the size of the aggregate, not the crystallite, of Li2ZrO3 that controls the sorption rate. Temperature effect on CO2 sorption is complex, depending on both kinetic and thermodynamic factors. A mathematical model based on the double-shell sorption mechanism was established for CO2 sorption kinetics and it can fit experimental data quite well. Above 500°C, the rate-limiting step of CO2 sorption is the diffusion of oxygen ions through the ZrO2 shell formed during the carbonation reaction. Oxygen ion conductivities in the ZrO2 shell were obtained by regression of the experimental CO2 uptake curves with the model and are consistent with the literature data.
Post-Polymerization Crosslinked Polyurethane Shape-Memory Polymers

Novel urethane shape-memory polymers (SMPs) of significant industrial relevance have been synthesized and characterized. Chemically crosslinked SMPs have traditionally been made in a one-step polymerization of monomers and crosslinking agents. However, these new post-polymerization crosslinked SMPs can be processed into complex shapes by thermoplastic manufacturing methods and later crosslinked by heat exposure or by electron beam irradiation. Several series of linear, olefinic urethane polymers were made from 2-butene-1,4-diol, other saturated diols, and various aliphatic diisocyanates. These thermoplastics were melt-processed into desired geometries and thermally crosslinked at 200°C or radiation crosslinked at 50 kGy. The SMPs were characterized by solvent swelling and extraction, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing, and qualitative shape-recovery analysis. Swelling and DMA results provided concrete evidence of chemical crosslinking, and further characterization revealed that the urethanes had outstanding mechanical properties. Key properties include tailorable transitions between 25 and 80°C, tailorable rubbery moduli between 0.2 and 4.2 MPa, recoverable strains approaching 100%, failure strains of over 500% at T(g), and qualitative shape-recovery times of less than 12 seconds at body temperature (37°C). Because of its outstanding thermo-mechanical properties, one polyurethane was selected for implementation in the design of a complex medical device. These post-polymerization crosslinked urethane SMPs are an industrially relevant class of highly processable shape-memory materials.
Cognitive Mapping, Travel Behavior, and Access to Opportunity

Past theoretical and empirical research on cognitive mapping is combined with the authors' initial research to suggest how cognitive mapping might be employed to understand and predict travel behavior better, with an emphasis on how spatial cognition shapes access to opportunity. It is argued that the path-based cumulative process of spatial learning—during which the cognitive map develops through wayfinding and travel experience—affects accessibility by determining whether and how destinations are encoded into a person's cognitive map. Variations in cognitive mapping, spatial knowledge, and resultant travel behavior can occur between individuals or among groups in systematic ways. Some of these differences are related to previous travel experience, including experience with travel modes. Such variations in spatial knowledge can result in different levels of functional accessibility despite similar locations, demographics, and other factors thought to influence travel behavior. The initial survey in three...
Applications of ortho-Quinone Methide Intermediates in Catalysis and Asymmetric Synthesis

Ortho-quinone methides are important synthetic intermediates and widely implicated in biological processes. In this Synopsis, recent advances concerning the synthesis and utility of these intermediates are discussed with a particular emphasis on metal-catalyzed formation of quinone methide intermediates. Additionally, applications of these intermediates as partners in asymmetric synthesis will be discussed including methods we have developed that involve the enantioselective Pd-catalyzed formation of ortho-quinone methides and the trapping of aforementioned intermediates with diverse nucleophiles.
Use of the Kalman filter for inference in state-space models with unknown noise distributions

The Kalman filter is frequently used for state estimation in state-space models when the standard Gaussian noise assumption does not apply. A problem arises, however, in that inference based on the incorrect Gaussian assumption can lead to misleading or erroneous conclusions about the relationship of the Kalman filter estimate to the true (unknown) state. This note shows how inequalities from probability theory associated with the probabilities of convex sets have potential for characterizing the estimation error of a Kalman filter in such a non-Gaussian (distribution-free) setting.
Steady state populations of Apollo-Amor objects

Abstract The steady-state distribution of orbits of Apollo-Amor objects is calculated for a variety of possible sources. These include asteroids near the inner edge of the belt, cometary orbits similar to Encke, and hypothetical extinct cometary orbits with perihelia larger than that of Encke. In all but one case, the steady-state distributions are similar for all these sources, and predict Amor/Apollo ratios of 1.5 to 3. These ratios are lower than those predicted by work in which the effects of the ν 6 secular resonance were not considered. These results are in general agreement with observation, although the higher (∼3) Amor/Apollo ratios found for many of the sources may turn out to be unacceptably high. The absolute number of Apollo-Amors observed is found to require an injection rate of ∼15 objects/(10 6 years). This rate is easily achieved if the present existence of Encke is assumed to be a reasonably probable event, and if Encke becomes a ∼1-km-diameter Apollo object following exhaustion of its volatile material; best estimates of the injection rate from the asteroid belt [∼1.5/(10 6 years)] are too low. Hence a dominant cometary component is suggested. The predicted number of Apollo objects in small ( q a
Hydrogeology and geochemistry of near-shore submarine groundwater discharge at Flamengo Bay, Ubatuba, Brazil

Abstract Near-shore discharge of fresh groundwater from the fractured granitic rock at Flamengo Bay, Ubatuba, Brazil, is strongly controlled by the local geology. Freshwater flows primarily through a zone of weathered granite to a distance of 24 m offshore. In the nearshore environment this weathered granite is covered by about 0.5 m of well-sorted, coarse sands containing pore water with sea water salinity, with an abrupt transition to much lower salinity once the weathered granite is penetrated. Further offshore, low-permeability marine sediments contain saline porewater, marking the limit of offshore migration of freshwater. Freshwater flux rates based on tidal signal and hydraulic gradient analysis indicate a fresh submarine groundwater discharge of 0.17–1.6 m 3 /day per m of shoreline. Dissolved inorganic nitrogen and silicate are elevated in the porewater relative to seawater, and appeared to be a net source of nutrients to the overlying water column. The major ion concentrations suggest that the freshwater within the aquifer has a short residence time. Major element concentrations do not reflect in situ alteration of the granitic rocks, possibly because the alteration occurred prior to development of the current discharge zones, or because of large volumes of water discharge in this high rainfall region.
A Note on the Benefits of Homeownership

Abstract This brief note adds to recent work that attempts to identify externalities associated with homeownership. The results suggest that some of the homeownership effect found by Green and White is driven by family characteristics associated with homeownership, especially residential stability. However, as much as homeownership increases residential stability, it appears to be correlated with higher school attainment. Attempts to control for endogeneity cannot eliminate this finding.
Digitization and Distribution of the Large Photographic Surveys

All-sky photographic surveys made with the large Schmidt telescopes have long been a major resource for research support; within a few years the second generation surveys now in progress with teh UK and the Oschin (Palomar) Schmidts will generalize this coverage to at least two epochs and two passbands. The quantitative use of these plate collections depends on their digitization. For the five modern high-speed systems currently devoted to this work (APM, Cambridge; SuperCosmos, ROE; GAMMA, ST ScI; APS, Minnesota; and PPM, Flagstaff), the machine properties, together with the associated accomplishments and plans are summarized. Additional discussion topics include the complementary role of object lists (i.e., catalogs) and pixel data (rasters), naming conventions, the need for an adequate level of independent checking, together with the construction of a master object list, and the future of measuring photographic plates.
Synthesis of the melanoma-associated ganglioside 9-O-acetyl GD3 through regioselective enzymatic acetylation of GD3 using subtilisin

Abstract The melanoma-associated disialoganglioside 9- O -acetyl GD3 has been synthesized for the first time through regioselective enzymatic acetylation of GD3 using subtilisin as the biocatalyst and vinyl acetate as the acetyl donor.
Genetically designed Peptide-based molecular materials.

With recent developments of nanoscale engineering in the physical and chemical sciences and advances in molecular biology, molecular biomimetics is combining genetic tools and evolutionary approaches with synthetic nanoscale constructs to create a new hybrid methodology: genetically designed peptide-based molecular materials. Following the fundamental principles of genome-based design, molecular recognition, and self-assembly in nature, we can now use recombinant DNA technologies to design single or multifunctional peptides and peptide-based molecular constructs that can interact with solids and synthetic systems. These solid-binding peptides have made significant impact as inorganic synthesizers, nanoparticle linkers, and molecular assemblers, or simply as molecular building blocks, in a wide range of fields from chemistry to materials science to medicine. As part of the programmatic theme, “Nanoscience: Challenges for the Future”, the current developments, challenges, and future prospects of the field w...
Rapid microscale synthesis: Solution phase parallel synthesis of a library of piperazines and piperidines using a water soluble base

A library of 1086 piperazines and 835 piperidines was prepared via Rapid Microscale Synthesis (RMS) using the water soluble base 1,1,3,3-tetramethylguanidine to catalyze the reactions and to simplify purification.
Grazing and Chaos in a Periodically Forced, Piecewise Linear System

The criteria for the grazing bifurcation of a periodically forced, piecewise linear system are developed and the initial grazing manifolds are obtained. The initial grazing manifold is invariant. The grazing flows are illustrated to verify the analytic prediction of grazing. The mechanism of the strange attractors fragmentation caused by the grazing is discussed, and an illustration of the fragmentized strange attractor is given through the Poincare mapping. This fragmentation phenomenon exists extensively in nonsmooth dynamical systems. The mathematical structure of the fragmentized strange attractors should be further developed.
Multifrequency Observations of Giant Radio Pulses from the Millisecond Pulsar B1937+21

Giant pulses are short, intense outbursts of radio emission with a power-law intensity distribution that have been observed from the Crab pulsar and PSR B1937+21. We have undertaken a systematic study of giant pulses from PSR B1937+21 using the Arecibo telescope at 430, 1420, and 2380 MHz. At 430 MHz, interstellar scattering broadens giant pulses to durations of ~50 μs, but at higher frequencies the pulses are very short, typically lasting only ~1-2 μs. At each frequency, giant pulses are emitted only in narrow (10 μs) windows of pulse phase located ~55-70 μs after the main and interpulse peaks. Although some pulse-to-pulse jitter in arrival times is observed, the mean arrival phase appears stable; a timing analysis of the giant pulses yields precision competitive with the best average profile timing studies. We have measured the intensity distribution of the giant pulses, confirming a roughly power-law distribution with approximate index of -1.8, contributing 0.1% to the total flux at each frequency. We also find that the intensity of giant pulses falls off with a slightly steeper power of frequency than the ordinary radio emission.
Fundamental symmetries and theory

Abstract Nuclei are powerful laboratories for studying fundamental symmetries because they filter and enhance specific interactions. I discuss four examples — hadronic parity violation, atomic electric dipole moments, precision β decay tests, and nuclear tests of neutrino masses — to illustrate some of the progress that has been made in the past few years.
Exercise electrocardiography as an estimation of cardiac function.

SUMMARY More than two score years of experience with the standardized two-step test have confirmed it to be a safe, simple and reliable procedure for aiding in the discovery and evaluation of coronary heart disease and for the evaluation of the adequacy of the coronary circulation on exercise in those with other forms of heart disease. "Ischemic" depression of the RS-T segment is the chief finding of a "positive" response, but "junctional" type depressions may also occur in patients who have compromised coronary artery circulation. A positive test suggests myocardial ischemia, and carries with it increased risk of cardiac morbidity or death, even in asymptomatic persons. A negative response has statistically proven favorable prognosis. The test may be performed in the presence of an abnormal control ECG, provided it is stable and does not represent "impending" myocardial infarction. Monitoring the ECG during exercise is also feasible, but does not appear to increase the overall diagnostic yield. It is worthwhile, however, in the detection of arrhythmias which may appear only in the exercise period. Monitoring techniques, both electronic and "hard-wire," depend on careful and secure application of electrodes, the most convenient of which are commercially available band-aid types. Various "bipolar" leads or conventional unipolar leads V 4 , V 5 , or V 6 can now also be recorded.
High resolution angle-resolved photoemission study of high temperature superconductors: charge-ordering, bilayer splitting and electron–phonon coupling

Abstract The latest development of angle-resolved photoemission spectroscopy (ARPES) technique has seen extremely high energy resolution and momentum resolution, as well as multiple angle detection. These advancements have led to new findings through efficient Fermi surface mapping, fine electronic structure resolving, and direct determination of electron self-energy. In this paper, we will highlight some recent high resolution ARPES work on high temperature superconductors. These include: (1) charge-ordering and evolution of electronic structure with doping; (2) bilayer splitting and Fermi surface topology of Bi2212; and (3) strong electron–phonon coupling and electron–electron interaction in high temperature superconductors.
Does Peer Ability Affect Student Achievement

Empirical analysis of peer effects on student achievement has been open to question because of the difficulties of separating peer effects from other confounding influences. While most econometric attention has been directed at issues of simultaneous determination of peer interactions, we argue that issues of omitted and mismeasured variables are likely to be more important. We control for the most important determinants of achievement that will confound peer estimates by removing student and school-by-grade fixed effects in addition to observable family and school characteristics. The analysis also addresses the reciprocal nature of peer interactions and the interpretation of estimates based upon models using past achievement as the measure of peer group quality. The results indicate that peer achievement has a positive effect on achievement growth. Moreover, students throughout the school test score distribution appear to benefit from higher achieving schoolmates. On the other hand, the variance in achievement appears to have no systematic effect. Copyright © 2003 John Wiley & Sons, Ltd.
Significance of Many-Body Contributions to Casimir Energies

Irreducible many-body contributions to Green's functions and Casimir energies are defined. We show that the irreducible three-body contribution to Casimir energies are significant and can be more than twenty percent of the total interaction energy. Irreducible three-body contribution for three parallel semitransparent plates in the limit when two plates overlap is obtained in terms of irreducible two-body contributions and shown to be finite and well defined in this limit.
POLARIZATION OF ABSORPTION LINES AS A DIAGNOSTICS OF CIRCUMSTELLAR, INTERSTELLAR AND INTERGALACTIC MAGNETIC FIELDS: FINE STRUCTURE ATOMS

The relative population of the fine-structure sublevels of an atom's ground state is affected by radiative transitions induced by an anisotropic radiation flux. This causes the alignment of atomic angular momentum. In terms of observational consequences for the interstellar and intergalactic medium, this results in the polarization of the absorption lines. In the paper we consider the conditions necessary for this effect and provide calculations of polarization from a few astrophysically important atoms and ions with multiple upper and lower levels for an arbitrary orientation of magnetic fields to the (1) source of optical pumping, (2) direction of observation, and (3) absorbed source. We also consider an astrophysically important degenerate case, in which the source of optical pumping coincides with the source of the absorbed radiation. We present analytical expressions that relate the degree of linear polarization and the intensity of absorption to the three-dimensional orientation of the magnetic field with respect to the pumping source, the source of the absorbed radiation, and the direction of observations. We discuss how all these parameters can be determined via simultaneous observations of several absorption lines and suggest graphical means that are helpful in practical data interpretation. We prove that studies of absorption line polarization provide a unique tool to study three-dimensional magnetic field topology in various astrophysical conditions.
Subducted slabs and the geoid: Constraints on mantle rheology and flow

The total geoid anomaly which is the result of a given density contrast in a convecting viscous earth is affected by the mass anomalies associated with the flow induced deformation of the upper surface and internal compositional boundaries, as well as by the density contrast itself is discussed. If the internal density contrasts can be estimated, the depth and variation of viscosity with depth of the convecting system can be constrained. The observed long wavelength geoid is highly correlated with that predicted by a density model for seismically active subducted slabs. The amplitude of the correlation is explained if the density contrasts associated with subduction extend into the lower mantle or if subducted slabs exceeding 350 km in thickness are piled up over horizontal distances of thousands of km at the base of the upper mantle. Mantle wide convection in a mantle that has a viscosity increasing with depth provides the explanation of the long-wavelength geoid anomalies over subduction zones.
IRIS : Our prototype rule generation system

Our goal is to design a knowledge discovery tool that has the ability to accurately generate rules, using concepts and structured data values, extracted from semi-structured documents. To date, two of our major contributions have been the design of a system architecture that facilitates the discovery of rules from HTML documents, and the development of an efficient association rule algorithm that generates rule sets, based on user specified constraints. This paper discusses each of these contributions within the framework of our prototype system IRIS. IRIS allows users to specify a set of constraints associated with a particular domain and then generates association rules based on these constraints. One of the unique features of IRIS, is that it generates rules using the more structured component of the HTML documents, as well as the conceptual knowledge extracted from the unstructured blocks of text.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Synthesis of Harmonic Motion Generating Linkages—Part II: Path and Motion Generation

Synthese d'un mecanisme generant un mouvement harmonique. Generation d'une trajectoire et d'un mouvement
Total synthesis, stereochemical reassignment, and absolute configuration of chlorofusin

Chlorofusin is a recently isolated, naturally occurring inhibitor of p53−MDM2 complex formation whose structure is composed of a densely functionalized azaphilone-derived chromophore linked through the terminal amine of ornithine to a nine-residue cyclic peptide. Herein we report full details of the total synthesis of chlorofusin, resulting in the assignment of the absolute stereochemistry and reassignment of the relative stereochemistry of the complex chromophore. Condensation of each enantiomer of an azaphilone chromophore precursor with the Nδ-amine of a protected ornithine-threonine dipeptide, followed by a one-step oxidative spirocyclization of the most reactive olefin provided all eight diastereomers of the fully elaborated chromophore-dipeptide conjugate. Comparison of the spectroscopic properties for these eight compounds with simpler models and with that reported for the natural product allowed the full assignment of the (4R,8S,9R)-stereochemistry of the chlorofusin chromophore. The desired, but ...
The New Institutionalism Contradictory Notions of Change

It is suggested that the new institutionalism contains ambiguous and contradictory notions of change. By setting up a model that explains institutional constraints on decision makers, the new institutionalism correctly points out the limits of a rational choice framework of economic decision making. However, by failing to explain the sources and avenues of modifications of those constraints, the new institutionalism is unable to provide a satisfactory explanation of change. Instead, a patchwork of exogenous factors is found, such as technology, culture, and ideology, which feed into institutional change in unclear ways. Those factors for change should be examined directly, rather than through the proxy of institutions.
Pressure Die Casting: A Model of Vacuum Pumping

Multifunctional characteristics of die casting parts are significantly compromised by the presence of voids, which can result in a substantial decrease in the elastic moduli and thermal conductivity. Gas/air porosity constitutes a large part of the total porosity. To reduce the porosity due to the gas/air entrainment, a vacuum can be applied to remove the residual air in the die. In some cases vacuum castings have low porosity, while in other cases the results are not satisfactory. These differing results can be explained in some instances by an analysis of the vent area. A simple model is proposed based on conservation laws which describes the relationship between vent area and pressure variation in the die. The analysis of vacuum venting indicates that there is a critical/optimum vent area below which the ventilation is poor and above which the resistance to the air flow is minimal. The model yields a simple equation to select the optimum area which is a function of the duct resistance, the evacuated volume, and the filling time. This result should be useful to the design engineer. The result also provides a tool to “measure” the vent size for numerical simulations of the cavity filling, taking into account the compressibility of the gas.
Bound states can stabilize electroweak strings

Abstract We show that the stability of the electroweak Z -string is greatly improved by the presence of bound states of a complex scalar field. This stabilization mechanism could work for other embedded defects and also for unstable solutions such as the sphaleron.
Fatigue Cracking in Fiber-Reinforced Metal Matrix Composites Under Mechanical and Thermal Loads

This article reviews micromechanical models developedforfatigue cracking in fiber-reinforced metal matrix composites under mechanical and thermal loads. Emphasis is placed on the formulae and design charts that can quantify the fatigue crack growth and fiber fracture. The composite is taken to be linear elastic, with unidirectional aligned fibers. Interfacial debonding is assumed to occur readily, allowing fibers to slide relative to the matrix resisted by a uniform shear stress. The fibers therefore bridge any matrix crack that develops. The crack bridging traction law includes the effect of thermal expansion mismatch between the fiber and the matrix and a temperature dependence of the frictional shear stress. Predictions are made of the crack tip stress intensities, matrix fatigue crack growth, and maximum fiber stresses under mechanical or thermomechanical loads. For composites under thermomechanical load, both in-phase and out-of-phase fatigue are modeled. The implications for life prediction for fiber-reinforced metal matrix composites are discussed.
Click Chemistry-Based Functionalization on Non-Oxidized Silicon Substrates

Copper-catalyzed azide–alkyne cycloaddition (CuAAC), combined with the chemical stability of the SiC-bound organic layer, serves as an efficient tool for the modification of silicon substrates, particularly for the immobilization of complex biomolecules. This review covers recent advances in the preparation of alkynyl- or azido-terminated “clickable” platforms on non-oxidized silicon and their further derivatization by means of the CuAAC reaction. The exploitation of these “click”-functionalized organic thin films as model surfaces to study many biological events was also addressed, as they are directly relevant to the on-going effort of creating silicon-based molecular electronics and chemical/biomolecular sensors.
Cost and technical change: Effects from bank deregulation

Banks were substantially deregulated during the 1980s. This altered the cost-minimising mix between deposit interest payments and operating expenses (capital and labor for branch convenience and “free” deposit services). Measured bank output was relatively unaffected by these changes. The proportion of deposits receiving higher interest rates increased more rapidly than factor quantities were reduced, so unit deposit costs rose. Consumers benefited, but the measured net effects for banks were negative, averaging —0.8% to —1.4% a year in net technical change from 1977 to 1988. These influences were measured three different ways and for both equilibrium and disequilibrium factor input specifications. All three approaches—a standard time trend, a time-specific index, and shifts in cross-sectional cost functions—gave consistent results. The results were robust whether measured at the banking firm or branch office level or on the cost frontier.
Predicted electronic and thermodynamic properties of a newly discovered Zn8Sb7 phase.

A new binary compound, Zn_8Sb_7, has recently been prepared in nanoparticulate form via solution synthesis. No such phase is known in the bulk phase diagram; instead, one would expect phase separation to the good thermoelectric semiconductors ZnSb and Zn_4Sb_3. Here, density functional calculations are employed to determine the free energies of formation, including effects from vibrations and configurational disorder, of the relevant phases, yielding insight into the phase stability of Zn_8Sb_7. Band structure calculations predict Zn_8Sb_7, much like ZnSb and Zn_4Sb_3, to be an intermetallic semiconductor with similar thermoelectric properties. If sufficient entropy or surface energy exists to stabilize the bulk material, it would be stable in a limited temperature window at high temperature.
Performance study of a soft X-ray harmonic generation FEL seeded with an EUV laser pulse

The performance of a free electron laser (FEL) using a low-power extreme ultraviolet (EUV) pulse as an input seed is investigated. The parameters are appropriate for 30 nm seeds produced from high-power Ti:Sapphire pulses using high harmonic generation schemes. It is found that, for reasonable beam parameters, robust FEL performance can be obtained. Both time-independent and time-dependent simulations are performed for varying system parameters using the GENESIS simulation code. A comparison is made with a two-stage harmonic FEL that is seeded by a high-power Ti:Sapphire pulse.
Recent water release in the Tharsis Region of Mars

The anastomosing form and associated streamlined islands of the numerous channels identified in the northwestern Tharsis region of Mars indicate that they were probably formed by flowing water. An account is given of a channel-formation model for Tharsis which invokes the (most probable) action of the tectonic release of water from a deep groundwater system, or (less probably) the intrusive heating of deep-seated ice lenses. It is speculated, in view of the channels' occurrence in some of the youngest lava flows on Mars, that either water or ice may have existed in the equatorial latitudes of Mars until as recently as 1 billion years ago.
A Probabilistic Approach to the Evaluation of the PTS Issue

Reexamen du programme et des regles de prevision de la rupture par choc thermique des cuves de reacteur a eau pressurisee.
A Personal Journey Through Hadronic Exotica

The search for exotic hadrons has been forever fascinating and challenging. A review of many such searches, successful and unsuccessful, in which the author has been involved, is presented.
OPTIMIZATION OF COUPLED SYSTEMS: A CRITICAL OVERVIEW OF APPROACHES

A unified overview is given of problem formulation approaches for the optimization of multidisciplinary coupled systems. The overview includes six fundamental approaches upon which a large number of variations may be made. Consistent approach names and a compact approach notation are given. The approaches are formulated to apply to general nonhierarchic systems. The approaches are compared both from a computational viewpoint and a managerial viewpoint. Opportunities for parallelism of both computation and manpower resources are discussed. Recommendations regarding the need for future research are advanced.
FAST STAR, SLOW STAR; OLD STAR, YOUNG STAR: SUBGIANT ROTATION AS A POPULATION AND STELLAR PHYSICS DIAGNOSTIC

Stellar rotation is a strong function of both mass and evolutionary state. Missions such as Kepler and CoRoT provide tens of thousands of rotation periods, drawn from stellar populations that contain objects at a range of masses, ages, and evolutionary states. Given a set of reasonable starting conditions and a prescription for angular momentum loss, we address the expected range of rotation periods for cool field stellar populations (∼0.4-2.0 M{sub ☉}). We find that cool stars fall into three distinct regimes in rotation. Rapid rotators with surface periods less than 10 days are either young low-mass main sequence (MS) stars, or higher mass subgiants which leave the MS with high rotation rates. Intermediate rotators (10-40 days) can be either cool MS dwarfs, suitable for gyrochronology, or crossing subgiants at a range of masses. Gyrochronology relations must therefore be applied cautiously, since there is an abundant population of subgiant contaminants. The slowest rotators, at periods greater than 40 days, are lower mass subgiants undergoing envelope expansion. We identify additional diagnostic uses of rotation periods. There exists a period-age relation for subgiants distinct from the MS period-age relations. There is also a period-radius relation that can be used as a constraint onmore » the stellar radius, particularly in the interesting case of planet host stars. The high-mass/low-mass break in the rotation distribution on the MS persists onto the subgiant branch, and has potential as a diagnostic of stellar mass. Finally, this set of theoretical predictions can be compared to extensive datasets to motivate improved modeling.« less