cssi/SciSciGPT-SciSciNet huggingface dataset:
Physical Aspects of Deposition From Coal-Water Fuels Under Gas Turbine Conditions

Deposition, erosion, and corrosion (DEC) experiments were conducted using three coal-water fuels (CWF) in a staged subscale turbine combustor operated at conditions of a recuperated turbine. This rich-quench-lean (RQL) combustor appears promising for reducing NO{sub x} levels to acceptable levels for future turbines operating with CWF. Specimens were exposed in two test sections to the combustion products from the RQL combustor. The gas and most surface temperatures in the first and second test sections represented temperatures in the first stators and rotors, respectively, of a recuperated turbine. The test results indicate deposition is affected substantially by gas temperature, surface temperature, and unburned carbon due to incomplete combustion. The high rates of deposition observed at first stator conditions showed the need for additional tests to identify CWF coals with lower deposition tendencies and to explore deposition control measures such as hot gas cleanup.
ω-Pentafluoro-λ6-sulfanyl(SF5)-n-perfluoroalkyl benzene derivatives

Abstract The reaction of pentafluoro-λ 6 -sulfanyl(SF 5 )-perfluoroalkyl iodides with benzene is a convenient route for preparing SF 5 -perfluoroalkyl benzene derivatives, SF 5 (CF 2 ) n C 6 H 5 ( n =2, 4, 6, 8), a new class of perfluoroalkylaromatic compounds. The preparation and characterization of these new materials are described.
A fast method for estimating discrete field values in early engineering design

Much of the analysis done in engineering design involves the solution of partial differential equations (PDEs) that are subject to initial-value or boundary-value conditions; generically, these are called "field problems". Finite-element and finite-difference methods (FEM, FDM) are the predominant solution techniques, but these are often too expensive or too tedious to use in the early phases of design. What's needed is a fast method to compute estimates of field values at a few critical points that uses simple and robust geometric tools. This paper describes such a method. It is based on an old technique-integrating PDEs through stochastic (Monte Carlo) sampling-that is accelerated through the use of ray representations (ray-reps). In the first (pre-processing) stage, the domain (generally a mechanical part) is coherently sampled to produce a ray-rep. The second stage involves the usual stochastic sampling of the field, which is now enhanced by exploiting the semi-discrete character of ray-reps. The method is relatively insensitive to the complexity of the shape being analyzed, and it has adjustable precision. Its mechanics and advantages are illustrated by using Laplace's equation as an example.
Relative Perturbation Theory: II. Eigenspace and Singular Subspace Variations

The classical perturbation theory for Hermitian matrix eigenvalue and singular value problems provides bounds on invariant subspace variations that are proportional to the reciprocals of absolute gaps between subsets of spectra or subsets of singular values. These bounds may be bad news for invariant subspaces corresponding to clustered eigenvalues or clustered singular values of much smaller magnitudes than the norms of matrices under considerations. In this paper, we consider how eigenspaces of a Hermitian matrix A change when it is perturbed to $\widetilde A=D^*AD$ and how singular spaces of a (nonsquare) matrix B change when it is perturbed to $\widetilde B=D_1^*BD_2$, where D, D1, and D2 are nonsingular. It is proved that under these kinds of perturbations, the changes of invariant subspaces are proportional to the reciprocals of relative gaps between subsets of spectra or subsets of singular values. The classical Davis--Kahan $\sin\theta$ theorems and Wedin $\sin\theta$ theorems are extended.
An Empirical Examination of Ownership Structure in Family and Professionally Managed Firms

The literature applying agency theory to management has focused on the performance advantages to be gained when ownership and control of the firm are aligned. This article investigates that premise by comparing family-owned and -managed and professionally managed firms. The article presents the results of a field survey that examined the extent to which family-owned and -managed firms differ across structural, process, and performance dimensions from their professionally managed counterparts. Significant differences exist between these two groups on both structural and process dimensions, and there is evidence that family-owned and -managed firms exhibit performance advantages as a result of the unification of ownership and control.
Machine Teaching for Bayesian Learners in the Exponential Family

What if there is a teacher who knows the learning goal and wants to design good training data for a machine learner? We propose an optimal teaching framework aimed at learners who employ Bayesian models. Our framework is expressed as an optimization problem over teaching examples that balance the future loss of the learner and the effort of the teacher. This optimization problem is in general hard. In the case where the learner employs conjugate exponential family models, we present an approximate algorithm for finding the optimal teaching set. Our algorithm optimizes the aggregate sufficient statistics, then unpacks them into actual teaching examples. We give several examples to illustrate our framework.
Parallel and distributed model checking in Eddy

Model checking of safety properties can be scaled up by pooling the CPU and memory resources of multiple computers. As compute clusters containing 100s of nodes, with each node realized using multi-core (e.g., 2) CPUs will be widespread, a model checker based on the parallel (shared memory) and distributed (message passing) paradigms will more efficiently use the hardware resources. Such a model checker can be designed by having each node employ two shared memory threads that run on the (typically) two CPUs of a node, with one thread responsible for state generation, and the other for efficient communication, including (1) performing overlapped asynchronous message passing, and (2) aggregating the states to be sent into larger chunks in order to improve communication network utilization. We present the design details of such a novel model checking architecture called Eddy. We describe the design rationale, details of how the threads interact and yield control, exchange messages, as well as detect termination. We have realized an instance of this architecture for the Murphi modeling language. Called Eddy_Murphi, we report its performance over the number of nodes as well as communication parameters such as those controlling state aggregation. Nearly linear reduction of compute time with increasing number of nodes is observed. Our thread task partition is done in such a way that it is modular, easy to port across different modeling languages, and easy to tune across a variety of platforms.
Antiremodeling Agents Influence Osteoblast Activity Differently in Modeling and Remodeling Sites of Canine Rib

Antiremodeling agents reduce bone loss in part through direct actions on osteoclasts. Their effects on osteoblasts and bone formation activity are less clear and may differ at sites undergoing modeling vs. remodeling. Skeletally mature intact beagles, 1-2 years old at the start of the study, were treated daily with clinically relevant doses of alendronate (0.10 or 0.20 mg/kg), risedronate (0.05 or 0.10 mg/kg), raloxifene (0.50 mg/kg), or vehicle (1 mL/kg). Dynamic bone formation parameters were histologically assessed on periosteal, endocortical/trabecular, and intracortical bone envelopes of the rib. Raloxifene significantly increased periosteal surface mineral apposition rate (MAR), a measure of osteoblast activity, compared to all other treatments (+108 to +175%, P < 0.02), while having no significant effect on MAR at either the endocortical/trabecular or intracortical envelope. Alendronate (both 0.10 and 0.20 doses) and risedronate (only the 0.10 dose) significantly (P < or = 0.05) suppressed MAR on the endocortical/trabecular envelope, while none of the bisphosphonate doses significantly altered MAR at either the periosteal or intracortical envelopes compared to vehicle. Based on these results, we conclude that (1) at clinically relevant doses the two classes of antiremodeling agents, bisphosphonates and selective estrogen receptor modulators, exert differential effects on osteoblast activity in the canine rib and (2) this effect depends on whether modeling or remodeling is the predominant mechanism of bone formation.
Ill-Posed Inverse Problems in Economics

A parameter of an econometric model is identified if there is a one-to-one or many-to-one mapping from the population distribution of the available data to the parameter. Often, this mapping is obtained by inverting a mapping from the parameter to the population distribution. If the inverse mapping is discontinuous, then estimation of the parameter usually presents an ill-posed inverse problem. Such problems arise in many settings in economics and other fields in which the parameter of interest is a function. This article explains how ill-posedness arises and why it causes problems for estimation. The need to modify or regularize the identifying mapping is explained, and methods for regularization and estimation are discussed. Methods for forming confidence intervals and testing hypotheses are summarized. It is shown that a hypothesis test can be more precise in a certain sense than an estimator. An empirical example illustrates estimation in an ill-posed setting in economics.
SYNTHESIS OF DIASTEREOMERICALLY ENRICHED CYCLIC HOMOALLYLIC ALCOHOLS USING MOLYBDENUM π-ALLYL COMPLEXES

Condensation of CpMo(NO)(π-allyl)I complexes bearing a tethered aldehyde gave cyclic homoallylic alcohols with a varying degree of diastereoselectivity. Cyclohexyl and tetrahydronaphthyl derivatives were prepared in moderate to good yields. The diastereoselectivity is highly dependent on the substituents on the ring.
Superconducting RF cavity R&D for a separated kaon beam at Fermilab

Fermilab is considering the implementation of a high flux pure kaon beam in order to study rare K/sup /spl plusmn// decays and to produce K/sub 0/ beams for K/sub L/-K/sub S/ interference experiments. The 22-25 GeV/c kaon beam is produced using an RF cavity beam separator scheme which rejects most of the more numerous pions and protons emitted from the production target. With a beam spill time of 1 sec out of 3 sec, superconducting cavities are preferred for providing the required transverse deflection. Although the separator scheme is not a new idea, the technology involved with this program will push the envelope of RF superconductivity technology. Cavities operating at 3.9 GHz in the TM 110 /spl pi/ mode are under evaluation. An R&D program to construct and test these cavities has been initiated. A goal of 5 MV/m deflection has been chosen. Description of the superconducting RF R&D program and status is given.
An Economic Analysis of “Acting White”

This paper formalizes a widely discussed peer eect entitled 'acting white'. 'Acting White'is modeled as a two audience signaling quandary: signals that induce high wages can be signals that induce peer group rejection. Without peer eects, equilibria involve all ability types choosing dierent levels of education. 'Acting White'alters the equilibrium dramatically: the (possibly empty) set of lowest ability individuals and the set of highest ability individuals continue to reveal their type through investments in education; ability types in the middle interval pool on a common education level. Only those in the lower intervals are accepted by the group. The model's predictions …t many stylized facts in the anthropology and sociology literatures regarding social interactions among minority group members.
Interference focusing for mitigating cross-phase modulation in a simplified optical fiber model

A memoryless interference network model is introduced that is based on non-linear phenomena observed when transmitting information over optical fiber using wavelength-division multiplexing. The main characteristic of the model is that amplitude variations on one carrier wave are converted to phase variations on another carrier wave, i.e., the carriers interfere with each other through amplitude-to-phase conversion. For the case of two carriers, a new technique called interference focusing is proposed where each carrier achieves the capacity pre-log 1, thereby doubling the pre-log of 1/2 achieved by using conventional methods. The technique requires neither channel time variations nor global channel state information. Generalizations to more than two carriers are outlined.
The optimal projection equations for fixed-order, sampled-data dynamic compensation with computation delay

For an LQG-type sampled-data regulator problem which accounts for computational delay and utilizes an averaging A/D device, the equivalent discrete-time problem is shown to be of increased order due to the inclusion of delayed measurement states. The optimal projection equations for reduced-order, discrete-time compensation are applied to the augmented problem to characterize low-order controllers. The design results are illustrated on a tenth-order flexible beam example.
Observation of intra-molecular vibrational dynamics using high-harmonic generation as a probe

As one of the first observations of intra-molecular dynamics using high-order harmonic generation, we impulsively excite vibrations in SF 6 and observe oscillations in the intensity of high-order harmonic emission from these molecules.
DOUBLE BETA DECAY

Double beta (ββ) decay is a rare transition between two nuclei with the same mass number that changes the nuclear charge number by two units. It has been long recognized as a powerful tool for the study of lepton conservation in general and of neutrino properties in particular. Because the lifetimes of ββ decay are so long, the experimental study of ββ decay is particularly challenging and has spawned a whole field of experiments requiring very low background.
Nonmetrizable ANR's admitting a group structure are manifolds

It is shown that a nonmetrizable ANR-space of weight ?, admitting a group structure, is (topologically) an R -manifold
A DETAILED FAR-ULTRAVIOLET SPECTRAL ATLAS OF O-TYPE STARS

In this paper we present a spectral atlas covering the wavelength interval 930–1188 u for O2–O9.5 stars using Far Ultraviolet Spectroscopic Explorer archival data. The stars selected for the atlas were drawn from three populations: Galactic main sequence (class III-V) stars, supergiants, and main sequence stars in the Magellanic Clouds, which have low metallicities. For each of these stars we have prepared FITS files comprised of pairs of merged spectra for user access via the Multi-Mission Archives at Space Telescope. We chose spectra from the first population with spectral types O4, O5, O6, O7, O8, and O9.5 and used them to compile tables and figures with identifications of all possible atmospheric and ISM lines in the region 949-1188 u Our identified line totals for these six representative spectra are 821 (500), 992 (663), 1077 (749), 1178 (847), 1359 (1001), and 1798 (1392) lines, respectively, where the numbers in parentheses are the totals of lines formed in the atmospheres, according to spectral synthesis models. The total number of unique atmospheric identifications for the six main sequence O star template spectra is 1792, whereas the number of atmospheric lines in common to these spectra is 300. The number of identified lines decreases toward earlier types (increasing effective temperature), while the percentages of “missed” features (lines not predicted from our spectral syntheses) drops from a high of 8% at type B0.2, from our recently published B star far-UV atlas, to 1–3% for type O spectra. The percentages of overpredicted lines are similar, despite their being much higher for B star spectra. We discuss the statistics of line populations among the various elemental ionization states. Also, as an aid to users we list those isolated lines that can be used to determine stellar temperatures and the presence of possible chemical anomalies. Finally, we have prepared FITS files giving pairs of merged spectra for stars in our population sequences for access via the Multi-Mission Archives at Space Telescope. Subject headings: atlases – stars: early-type – ultraviolet: stars –line: identification – atlases
Modal dispersion effects on coherent signal processing parameters

Acoustic signals propagated in deep ocean ducts are geometrically (or modally) dispersed. The effects of the dispersion on coherent signal processing is examined in this paper. Using a model, which for long range-deep ocean propagation has been shown to adequately predict dispersion measures, it is determined that the effects of dispersion on the bandwidth of the signal are small. However, in coherently correlating spectrally separated but related signals, the effect on the allowable integration time is significant. Curves relating the allowable integration time as functions of frequency and range rate between the source and receiver are presented.
Reply to the Comments on “Curvature capillary migration of microspheres” by P. Galatola and A. Würger

We have studied microparticle migration on curved fluid interfaces in experiment and derived an expression for the associated capillary energy E for two cases, i.e., pinned contact lines and equilibrium contact lines, which differ from expressions derived by others in the literature. In this article, a particle of radius a makes a disturbance in a large domain characterized by principal radii of curvature R1 and R2. Since a is smaller than all associated geometric and physico-chemical length scales, analysis calls for a singular perturbation approach. We recapitulate these concepts, identify conceptual errors in the Comments about our work, and provide evidence from experiments and simulations that support our view.
Consequences of Cisplatin Binding on Nucleosome Structure and Dynamics

The effects of cisplatin binding to DNA were explored at the nucleosome level to incorporate key features of the eukaryotic nuclear environment. An X-ray crystal structure of a site-specifically platinated nucleosome carrying a 1,3-cis-{Pt(NH₃)₂}²+-d(GpTpG) intrastrand cross-link reveals the details of how this adduct dictates the rotational positioning of DNA in the nucleosome. Results from in vitro nucleosome mobility assays indicate that a single platinum adduct interferes with ATP-independent sliding of DNA around the octamer core. Data from in vitro transcription experiments suggest that RNA polymerases can successfully navigate along cisplatin-damaged DNA templates that contain nucleosomes, but stall when the transcription elongation complex physically contacts a platinum cross-link located on the template strand. These results provide information about the effects of cisplatin binding to nuclear DNA and enhance our understanding of the mechanism of transcription inhibition by platinum anticancer compounds.
“Arctic Tides” by Rollin A. Harris (1911) Revisited

Rollin A. Harris used a few scattered tide observations on the periphery of the Arctic Ocean to contradict Nansen's statement that the Arctic Sea was an open basin of deep water occupying all, or nearly all, of the large unexplored area (in 1911) of the Arctic. Harris concluded that there was either a land mass or some shallow water near the north pole. Fjeldstad disagreed with Harris in 1923, and in 1927, Sverdrup supported Fjeldstad, using additional tide and current observations to reach this conclusion. Later, about 1950, Soviet scientists discovered the Lomonosov and Mendeleyev ridges, and shortly thereafter, U.S. scientists found the Alpha Ridge, all three ridges lying at least partially in what was in 1911 unexplored territory. It appears that Harris' hypothesis was at least partially accurate.
Field-Induced Rheology in Uniaxial and Biaxial Fields

Steady and oscillatory shear 3-D simulations of electro- and magnetorheology in uniaxial and biaxial fields are presented, and compared to the predictions of the chain model. These large scale simulations are three dimensional, and include the effect of Brownian motion. In the absence of thermal fluctuations, the expected shear thinning viscosity is observed in steady shear, and a striped phase is seen to rapidly form in a uniaxial field, with a shear slip zone in each sheet. However, as the influence of Brownian motion increases, the fluid stress decreases, especially at lower Mason numbers, and the striped phase eventually disappears, even when the fluid stress is still high. In a biaxial field, an opposite trend is seen, where Brownian motion decreases the stress most significantly at higher Mason numbers. To account for the uniaxial steady shear data we propose a microscopic chain model of the role played by thermal fluctuations on the rheology of ER and MR fluids that delineates the regimes where an applied field can impact the fluid viscosity, and gives an analytical prediction for the thermal effect. In oscillatory shear, a striped phase again appears in a uniaxial field, at strain amplitudes greater than ~0.15, and the presence of a shear slip zone creates strong stress nonlinearities at low strain amplitudes. In a biaxial field, a shear slip zone is not created, and so the stress nonlinearities develop only at expected strain amplitudes. The nonlinear dynamics of these systems is shown to be in good agreeement with the Kinetic Chain Model.
Limited verification of identities to induce false-name-proofness

In open, anonymous environments such as the Internet, mechanism design is complicated by the fact that a single agent can participate in the mechanism under multiple identifiers. One way to address this is to design false-name-proof mechanisms, which choose the outcome in such a way that agents have no incentive to use more than one identifier. Unfortunately, there are inherent limitations on what can be achieved with false-name-proof mechanisms, and at least in some cases, these limitations are crippling. An alternative approach is to verify the identities of all agents. This imposes significant overhead and removes any benefits from anonymity.In this paper, we propose a middle ground. Based on the reported preferences, we check, for various subsets of the reports, whether the reports in the subset were all submitted by different agents. If they were not, then we discard some of them. We characterize when such a limited verification protocol induces false-name-proofness for a mechanism, that is, when the combination of the mechanism and the verification protocol gives the agents no incentive to use multiple identifiers. This characterization leads to various optimization problems for minimizing verification effort. We study how to solve these problems. Throughout, we use combinatorial auctions (using the Clarke mechanism) and majority voting as examples.
Non-linear modeling and performance of oscillators using thin-film bulk-acoustic wave devices

Thin-film bulk-acoustic-wave resonators (TFR) and TFR-based filters have been used in single-line-spectra UHF and L-band oscillators in both hybrid and monolithic integrated versions. Two methods are proposed for modeling the behavior of the amplifier in a SPICE simulation. The first uses a nonlinear controlled generator derived from measured gain compression data. The second involves a circuit model of the amplifier used in a closed-loop simulation. The method of deriving the amplifier models is presented along with experimental results for the actual oscillator circuits. The oscillators, using commercial hybrid Darlington amplifiers as the gain element, are evaluated with fundamental mode frequencies in the area of 1 GHz. >
On the motion of oblique bevel geared robot wrists

It is shown that the principle of superposition can be used to analyze the spatial motion of a bevel-geared three-roll wrist with nonzero oblique angle. The total motion of the wrist is decomposed into three independent component motions, which are easier to analyze. A superposition tabulation is then constructed to derive the relations among the three wrist-joint variables and three coaxial actuation variables. The approach is straightforward and can be adapted for analyzing the motion of other geared wrists that are variations of the wrist considered. >
Gold(I)-catalyzed intramolecular enantioselective hydroarylation of allenes with indoles.

Treatment of 2-allenyl indole 4 with a catalytic 1:2 mixture of [(S)-2]Au2Cl2 [(S)-2 = (S)-3,5-tBu-4-MeO-MeOBIPHEP] and AgBF4 in toluene at −10 °C for 17 h led to isolation of tetrahydrocarbazole 5 in 88% yield with 92% ee. The protocol was effective for the cyclization of terminally disubstituted allenes and for the formation of seven-membered rings.
Multiple Reinjections and Crystal-mush Compaction in the Beacon Sill, McMurdo Dry Valleys, Antarctica

The Beacon Sill, a member of the Jurassic Ferrar group of the Transantarctic Mountains, South Victoria Land, is a 150 m thick tholeiitic diabase intrusion. Uniform on a field and macroscopic scale, it displays chemical and textural variability indicative of a sustained and complex history of emplacement and differentiation. Emplacement of the sill consisted of at least two, and probably four, discrete massive injections of magma, each averaging � 35 m thick, over a time span of � 100 years. The final injection event is marked by a 30 m thick interval of significantly finer-grained rock at the sill center.These fine-grained textures can be successfully reproduced by combining the results of thermal and crystal growth models, but only if the sill was a multiple intrusion. With the exception of a minor reinjection event captured in the chilled margin of the sill, earlier reinjection events are not evident texturally, most probably because of textural overprinting during prolonged cooling after initial crystallization. The dominant process involved in the postemplacement differentiation of the Beacon Sill was compactiondriven redistribution of interstitial liquid. Transfer of residual liquid from the compacting lower solidification front to the dilating upper solidification front resulted in characteristic chemical and mineralogical effects, such as the depletion of the lower half of the sill and the enrichment of the upper half of the sill in incompatible elements (e.g. TiO2, Zr) and modal granophyre. Based on thermodynamic models, most of the compaction occurred at a crystallinity of roughly 33%. Geochemical profiles are distinctly segmented, suggesting that the sill was repeatedly split and reinjected with fresh magma near the center after compaction had redistributed the interstitial liquid within the partially solidified magma. The recognition of evidence for reinjection and compaction in a macroscopically uniform, relatively quickly cooled sill suggests that these processes may be common in the construction of sills and other mesoscale igneous intrusions in general.
Stress Evolution in Composite Silicon Electrodes during Lithiation/Delithiation

We report real-time average stress measurements on composite silicon electrodes made with two different binders – viz. Carboxymethyl cellulose (CMC) and Polyvinylidene fluoride (PVDF) – during electrochemical lithiation and delithiation. During galvanostatic lithiation at very slow rates, the stress in a CMC-based electrode becomes compressive and increases to 70 MPa, where it reaches a plateau and increases slowly thereafter with capacity. The PVDF-based electrode exhibits similar behavior, although with lower peak compressive stress of about 12 MPa. These initial experiments indicate that the stress evolution in a Si composite electrode depends strongly on the mechanical properties of the binder. Stress data obtained from a series of lithiation/delithiation cycles suggests plasticity induced irreversible shape changes in contacting Si particles, and as a result, the stress response of the system during any given lithiation/delithiation cycle depends on the cycling history of the electrode. While these results constitute the first in situ stress measurements on composite Si electrodes during electrochemical cycling, the diagnostic technique described herein can be used to assess the mechanical response of a composite electrode made with other active material/binder combinations.
Customizable coherent servo demodulation for disk drives

This paper describes a servo demodulator which provides greatly improved performance over the currently used servo demodulation methods for disk drives. The demodulation algorithm proposed here makes better use of knowledge about the readback signal coming from the disk to provide better noise immunity and more immunity to other nonidealities in the magnetic head response. The net result is a demodulated position error signal which has a much cleaner response.
A highly efficient and enantioselective access to tetrahydroisoquinoline alkaloids: asymmetric hydrogenation with an iridium catalyst.

The iridium hydrido complex in combination with elemental iodine allows the preparation of tetrahydro derivatives with high levels of enantioselectivity.
Simulating the effects of soil organic nitrogen and grazing on arctic tundra vegetation dynamics on the Yamal Peninsula, Russia

Sustainability of tundra vegetation under changing climate on the Yamal Peninsula, northwestern Siberia, home to the world’s largest area of reindeer husbandry, is of crucial importance to the local native community. An integrated investigation is needed for better understanding of the effects of soils, climate change and grazing on tundra vegetation in the Yamal region. In this study we applied a nutrient-based plant community model—ArcVeg—to evaluate how two factors (soil organic nitrogen (SON) levels and grazing) interact to affect tundra responses to climate warming across a latitudinal climatic gradient on the Yamal Peninsula. Model simulations were driven by field-collected soil data and expected grazing patterns along the Yamal Arctic Transect (YAT), within bioclimate subzones C (high arctic), D (northern low arctic) and E (southern low arctic). Plant biomass and NPP (net primary productivity) were significantly increased with warmer bioclimate subzones, greater soil nutrient levels and temporal climate warming, while they declined with higher grazing frequency. Temporal climate warming of 2 ◦ C caused an increase of 665 g m −2 in total biomass at the high SON site in subzone E, but only 298 g m −2 at the low SON site. When grazing frequency was also increased, total biomass increased by only 369 g m −2 at the high SON site in contrast to 184 g m −2 at the low SON site in subzone E. Our results suggest that high SON can support greater plant biomass and plant responses to climate warming, while low SON and grazing may limit plant response to climate change. In addition to the first order factors (SON, bioclimate subzones, grazing and temporal climate warming), interactions among these significantly affect plant biomass and productivity in the arctic tundra and should not be ignored in regional scale studies.
Recent Progress in Reducing the Uncertainty in and Improving Pyranometer Calibrations

The Measurements and Instrumentation Team within the Distributed Energy Resources Center at the National Renewable Energy Laboratory, NREL, calibrates pyranometers for outdoor testing solar energy conversion systems. The team also supports climate change research programs. These activities led NREL to improve pyranometer calibrations. Low thermal-offset radiometers measuring the sky diffuse component of the reference solar irradiance removes bias errors on the order of 20 Watts per square meter (W/m 2 ) in the calibration reference irradiance. Zenith angle dependent corrections to responsivities of pyranometers removes 15 to 30 W/m 2 bias errors from field measurements. Detailed uncertainty analysis of our outdoor calibration process shows a 20% reduction in the uncertainty in the responsivity of pyranometers. These improvements affect photovoltaic module and array performance characterization, assessment of solar resources for design, sizing, and deployment of solar renewable energy systems, and ground-based validation of satellite-derived solar radiation fluxes.
Linkage maps in pea.

We have analyzed segregation patterns of markers among the late generation progeny of several crosses of pea. From the patterns of association of these markers we have deduced linkage orders. Salient features of these linkages are discussed, as is the relationship between the data presented here and previously published genetic and cytogenetic data.
Illustrating Adverse Selection in Health Insurance Markets with a Classroom Game

This paper describes a classroom game that illustrates the effects of asymmetric information and adverse selection in health insurance markets. The first part of this game simulates a market in which buyers can purchase insurance from sellers; in some periods, government regulation prevents sellers from using information about buyer type to determine premiums. The results demonstrate the classic prediction that asymmetric information will result in adverse selection. Here, low-risk buyers will forego the purchase of insurance at a measurable loss of potential earnings. In the second part of the game, sellers and buyers can trade two different types of health insurance policies, one moderate and another generous. Under government-mandated community rating and limits on premium increases, no buyers will purchase the generous plan. Questions are provided to stimulate discussion of the causes and consequences of adverse selection for consumers and insurers and possible solutions for employer- and government-sponsored programs.
Mapping Parallel FFT Algorithm onto SmartCell Coarse-Grained Reconfigurable Architecture

Fast Fourier Transform (FFT) is an important algorithm in many digital signal processing applications, and it often requires parallel implementation for high throughput. In this paper, we first present the SmartCell coarse-grained reconfigurable architecture targeted for stream processing. A SmartCell prototype integrates 64 processing elements, configurable interconnections, and dedicated instruction and data memories into a single chip, which is able to provide high performance parallel processing while maintaining post-fabrication flexibility. Subsequently, we present a parallel FFT architecture targeted for multi-core platforms computing systems. This algorithm provides an optimized data flow pattern that reduces both communication and configuration overheads. The proposed parallel FFT algorithm is then mapped onto the SmartCell prototype device. Results show that the parallel FFT implementation on SmartCell is about 14.9 and 2.7 times faster than network-on-chip (NoC) and MorphoSys implementations, respectively. SmartCell also achieves the energy efficiency gains of 2.1 and 28.9 when compared with FPGA and DSP implementations.
Authigenic Carbonate and the History of the Global Carbon Cycle

We present a framework for interpreting the carbon isotopic composition of sedimentary rocks, which in turn requires a fundamental reinterpretation of the carbon cycle and redox budgets over Earth's history. We propose that authigenic carbonate, produced in sediment pore fluids during early diagenesis, has played a major role in the carbon cycle in the past. This sink constitutes a minor component of the carbon isotope mass balance under the modern, high levels of atmospheric oxygen but was much larger in times of low atmospheric O(2) or widespread marine anoxia. Waxing and waning of a global authigenic carbonate sink helps to explain extreme carbon isotope variations in the Proterozoic, Paleozoic, and Triassic.
Three-Dimensional Inviscid Computation of an Impeller Flow

The flow in a centrifugal impeller is analyzed by a quasi-three-dimensional streamline curvature method, by a three-dimensional Euler code, and by a three-dimensional finite element potential flow method. Comparison with Eckardt’s published data for a backswept impeller shows that full three-dimensional methods better predict the loading at the hub and shroud.Copyright © 1983 by ASME
Teaching skills for accessing and interpreting information from systematic reviews/meta-analyses, practice guidelines, and the Internet.

Skills and practice related to accessing and interpreting clinical information from systematic reviews/meta-analyses, practice guidelines, and the Internet have been integrated into a new senior year elective designed to teach medical students how to critically appraise information from a variety of sources and evaluate its applicability to patient care. Small groups of senior medical students under the direction of a multidisciplinary team (behavioral scientist, information specialist, physician) facilitate discussions of clinical articles using checklists designed to evaluate their quality. The central feature of the course is a demonstration of the Cochrane Database of Systematic Reviews (CDSR), an electronic journal distributed by BMJ Publishing, and the requirement that students conduct a literature review on a topic of their choice and present an oral and written summary in the form of a “draft” meta-analysis. Students are provided with strategies to “surf” the Internet/WWW for information, e.g., practice guidelines/treatment protocols, descriptions of ongoing clinical trials. A total of 33 students have participated to date. Students have selected project topics across a wide range of medical disciplines, including internal medicine, family practice, OB/GYN, pediatrics, surgery, neurology, emergency medicine, and psychiatry. The course is one of the most favourably evaluated of all senior electives, rated more favourably than the overall mean ratings for all electives on 8 of 9 scales, including “Quality of course overall” (4.36 vs. 3.79 on 5-point scale).
Spanning the Institutional Abyss: The Intergovernmental Network and the Governance of Foreign Direct Investment

Global economic transactions such as foreign direct investment (FDI) must extend over an institutional abyss between the jurisdiction, and therefore protection, of the states involved. Intergovernmental organizations (IGOs) represent an important attempt to span this abyss. The authors use a network approach to demonstrate that the connections between two countries, through joint membership in the same IGOs, are associated with a large positive influence on the FDI that flows between them. Moreover, they show that this effect occurs not only in the case of connections through economic IGOs but also through those with social and cultural mandates. This demonstrates that relational governance is important and feasible in the global context, even for the most risky transactions. The authors also examine the interdependence between the IGO network and the domestic institutions of states. Social and cultural IGO connections do more and economic IGO connections less to increase FDI when the target country is mo...
Prior-knowledge and opportunity identification

An entrepreneur’s prior knowledge and experience play a critical role in his ability to identify and exploit entrepreneurial opportunities. Although entrepreneurship research has acknowledged the role that prior information and prior knowledge play in opportunity recognition, few studies have explored their role in entrepreneurial discovery. We test the role of a particular prior knowledge in entrepreneurial discovery within a laboratory setting. Participants were randomly assigned to one of two treatment groups. Those in the propitious treatment were given prior knowledge that oriented them toward the arbitrage opportunity within the experiment, and those in the unpropitious treatment were given prior knowledge that oriented them away. As hypothesized, those in the propitious treatment were significantly more likely to discover the arbitrage opportunity.
Self-Protection and Averting Behavior, Values of Statistical Lives, and Benefit Cost Analysis of Environmental Policy

Situations in which risk is at least partly a matter of choice provide opportunities to analyze behavior and estimate the willingness to pay for small changes in mortality risks. Individuals engage in household production of health and safety as long as the value of the gain in risk reduction is worth the money, time, and any disutility necessary to produce the reduction in risk. This paper reviews values of statistical life inferred from choices about highway speeds, traveler use of protective equipment, crash- worthiness of motor vehicles, and housing location near Superfund sites. The best estimates, close to $4 million in year 2000 dollars, are valuable complements to estimates from labor and constructed markets. Interestingly some evidence suggests that values for children and seniors are not less than middle-aged adults. Issues of risk perception and other challenges related to estimation are discussed.
Wing-alone aerodynamic characteristics at high angles of attack

An experimental investigation has been conducted to determine wing-alone supersonic aerodynamic characteristics at high angles of attack. The family of wings tested had aspect ratios of 0.5-4.0 and taper ratios of 0.0-1.0. The wings were tested at angles of attack ranging from -5 to +60 deg and Mach numbers of 1.6-4.6. The aerodynamic characteristics were obtained by integrating local pressures measured over the wing surface. Presented and discussed are results showing the effects of model geometry, Mach number, and angle of attack on aerodynamic characteristics consisting of normal force, pitching moment, bending moment, longitudinal center-of-pressure locations, and lateral center-of-pressure locations.
Simple performance model for ring and line cusp ion thrusters

A model is developed for high magnetic field strength cusped thrusters, which results in a single algebraic equation describing the thruster performance. Such a simple result is made possible by formulating the model in terms of the average energy expended in producing ions in the discharge plasma and the fraction of these ions extracted into the beam. A key feature of the model is that it allows one to calculate the average plasma ion energy cost as a function of the propellant utilization, knowing only thruster geometric design parameters and the propellant gas. The model can be used to calculate the effects on performance resulting from changes in the extracted-ion fraction, the quality of the containment of primary electrons, the propellant mass flow rate, the propellant gas, and the transparency of the accelerator system to neutral atoms.
Skellam Shrinkage: Wavelet-Based Intensity Estimation for Inhomogeneous Poisson Data

The ubiquity of integrating detectors in imaging and other applications implies that a variety of real-world data are well modeled as Poisson random variables whose means are in turn proportional to an underlying vector-valued signal of interest. In this article, we first show how the so-called Skellam distribution arises from the fact that Haar wavelet and filterbank transform coefficients corresponding to measurements of this type are distributed as sums and differences of Poisson counts. We then provide two main theorems on Skellam shrinkage, one showing the near-optimality of shrinkage in the Bayesian setting and the other providing for unbiased risk estimation in a frequentist context. These results serve to yield new estimators in the Haar transform domain, including an unbiased risk estimate for shrinkage of Haar-Fisz variance-stabilized data, along with accompanying low-complexity algorithms for inference. We conclude with a simulation study demonstrating the efficacy of our Skellam shrinkage estimators both for the standard univariate wavelet test functions as well as a variety of test images taken from the image processing literature, confirming that they offer some performance improvements over existing alternatives.
Representing first-order causal theories by logic programs

Nonmonotonic causal logic, introduced by McCain and Turner (McCain, N. and Turner, H. 1997. Causal theories of action and change. In Proceedings of National Conference on Artificial Intelligence (AAAI), Stanford, CA, 460-465) became the basis for the semantics of several expressive action languages. McCain's embedding of definite propositional causal theories into logic programming paved the way to the use of answer set solvers for answering queries about actions described in such languages. In this paper we extend this embedding to nondefinite theories and to the first-order causal logic.
Fluorous synthesis of hydantoins and thiohydantoins.

A fluorous synthesis of hydantoins is introduced. The reaction of perfluoroalkyl (Rfh)-tagged amino esters with an isocyanate is followed by the cyclization of ureas and simultaneous cleavage of the fluorous tag to afford hydantoins. The product purification is performed by solid-phase extraction over FluoroFlash cartridges, no fluorous solvent is involved in either the reaction or the separation processes. The same method applies to synthesis of thiohydantoins.
Atrial Fibrillation: A Historical Perspective

Atrial fibrillation (AF) has undoubtedly become one of the most well-studied arrhythmias today in terms of pathophysiology and diagnostic and therapeutic (interventional) electrophysiology. Although it lends itself to an apparently easy diagnosis on the surface electrocardiography, myriad electromechanical mechanisms underlie its origin. We have now reached an era of technology that makes AF not only "treatable" but potentially "curable." This article aims at walking through the historical "corridors" and "mazes" that led to the present day understanding of this common yet complex arrhythmia.
Relativity Parameters Determined from Lunar Laser Ranging

Analysis of 24 years of lunar laser ranging data is used to test the principle of equivalence, geodetic precession, the PPN parameters beta and gamma, and G/G. Recent data can be fitted with a rms scatter of 3 cm. (a) Using the Nordtvedt effect to test the principle of equivalence, it is found that the Moon and Earth accelerate alike in the Sun's field. The relative accelerations match to within 5 x 10(exp -13) . This limit, combined with an independent determination of y from planetary time delay, gives beta. Including the uncertainty due to compositional differences, the parameter beta differs from unity by no more than 0.0014; and, if the weak equivalence principle is satisfied, the difference is no more than 0.0006. (b) Geodetic precession matches its expected 19.2 marc sec/yr rate within 0.7%. This corresponds to a 1% test of gamma. (c) Apart from the Nordtvedt effect, beta and gamma can be tested from their influence on the lunar orbit. It is argued theoretically that the linear combination 0.8(beta) + 1.4(gamma) can be tested at the 1% level of accuracy. For solutions using numerically derived partial derivatives, higher sensitivity is found. Both 6 and y match the values of general relativity to within 0.005, and the linear combination beta+ gamma matches to within 0,003, but caution is advised due to the lack of theoretical understanding of these sensitivities. (d) No evidence for a changing gravitational constant is found, with absolute value of G/G less than or equal to 8 x lO(exp -12)/yr. There is significant sensitivity to G/G through solar perturbations on the lunar orbit.
Append-only signatures

We present a new primitive – Append-only Signatures (AOS) – with the property that any party given an AOS signature Sig[M1] on message M1 can compute Sig[M1 || M2] for any message M2, where M1 || M2 is the concatenation of M1 and M2. We define the security of AOS, present concrete AOS schemes, and prove their security under standard assumptions. In addition, we find that despite its simple definition, AOS is equivalent to Hierarchical Identity-based Signatures (HIBS) through efficient and security-preserving reductions. Finally, we show direct applications of AOS to problems in network security. Our investigations indicate that AOS is both useful in practical applications and worthy of further study as a cryptographic primitive.
Synthesis and X-ray structure of a three dimensional calixphyrin

The synthesis of an unprecedented pyrrole-containing, cryptand-like system with sp2 hybridized apical bridging carbon atoms is reported.