cssi/SciSciGPT-SciSciNet huggingface dataset:
Initiation of subduction by small-scale convection

[1] The possibility of initiation of subduction by sublithospheric small-scale convection is investigated with the help of Fowler's theory, numerical constraints on the lithospheric stresses generated by convection, and direct numerical simulations of subduction. The derived scaling laws show that the critical yield stress for initiation of subduction by small-scale convection is of the order of 30 MPa. This value is comparable with the critical yield stress required for initiation of subduction by plate forces and with the estimates of stresses in the subduction zone. This implies that small-scale convection can play an important role in the initiation of subduction on the present-day Earth. This also implies that small-scale convection can initiate subduction in the absence of already occurring plate tectonics and thus can be a trigger mechanism for plate tectonics on the early Earth and other terrestrial planets. The critical yield stress for initiation of subduction by either mechanism is at least one order of magnitude smaller than the estimates of the lithospheric strength suggested by laboratory experiments on rock deformation. Such a low lithospheric strength is most likely caused by a relatively high abundance of water in the interior of the Earth. Since the critical yield stress depends only weakly on planetary parameters, water seems to be the key condition required for plate tectonics to occur on a terrestrial planet.
Audience Measurement and Media Fragmentation: Revisiting the Monopoly Question

Many studies have examined contests between audience measurement systems in media markets. These suggest that the audience measurement industry is a natural monopoly. This study revisits the question with a novel approach by investigating a market at a time when two measurement services provided data. Executives were interviewed in the Indian television market on how they used information available from two competing ratings services. Although market participants recognized only one system (TAM, which provided weekly ratings) as the currency for trading advertising time, many used the second system (aMAP, an overnight ratings service) selectively for improving network performance. Therefore, fragmented markets can support multiple systems if they serve distinct institutional interests.
Variable, optically thick, hot plasma observed in interacting binaries

We report recent International Ultraviolet Explorer (IUE) observations of two interacting binaries, R Arae and HD 207739. The ultraviolet spectra indicate the presence of optically-thick, variable hot plasma in those binary systems. These two binaries may belong to a class of binaries that are currently undergoing a rarely observed and probably short-lived phase in their evolution. Their properties are compared with those of two other interacting binaries, U Cephei and β Lyrae.
Structural phase transition in CeCu6

The structure of CeCu/sub 6/ has been studied at eight temperatures from 10K to 295K by time-of-flight neutron powder diffraction. The high temperature orthorhombic cell transforms to a monoclinic cell at 230K. Rietveld structural refinements at each temperature give details of the structural distortion associated with the transition. The space groups and the temperature dependence of the monoclinic strain are consistent with a second order transition driven by a soft acoustic phonon mode. However, small atom displacements perpendicular to the shear direction suggest that an optic mode may also be involved in the transition.
Interactions of disparate scales in drift-wave turbulence

Renormalized statistical theory is used to calculate the interactions between short scales (wave vector k) and long scales (wave vector q<<k) in the Hasegawa-Mima model of drift-wave turbulence (generalized to include proper nonadiabatic response for k{sub {parallel}}=0 fluctuations). The calculations include the zonal-flow growth rate as a special case, but also describe long-wavelength fluctuations with q oriented at an arbitrary angle to the background gradient. The results are fully renormalized. They are subtly different from those of previous authors, in both mathematical form and physical interpretation. A term arising in previous treatments that is related to the propagation of short-scale wave packets is shown to be a higher-order effect that must consistently be neglected to lowest order in a systematic expansion in q/k. Rigorous functional methods are used to show that the long-wavelength growth rate {gamma}{sub q} is related to second-order functional variations of the short-wavelength energy and to derive a heuristic algorithm. The principal results are recovered from simple estimates involving the first-order wave-number distension rate {tilde {gamma}}{sub k}{sup (1)}{dot e}q{dot k}{del}{tilde {Omega}}{sub k}/k{sup 2}, where {tilde {Omega}}{sub k} is a nonlinear random advection frequency. Fokker-Planck analysis involving {tilde {gamma}}{sub k}{sup (1)} is used to heuristically recover the evolutionmore » equation for the small scales, and a random-walk flux argument that relates {tilde {gamma}}{sub k}{sup (1)} to an effective autocorrelation time is used to give an independent calculation of {gamma}{sub q}. Both the rigorous and heuristic derivations demonstrate that the results do not depend on, and cannot be derived from, properties of linear normal modes; they are intrinsically nonlinear. The importance of random-Galilean-invariant renormalization is stressed.« less
Widder’s Representation Theorem for Symmetric Local Dirichlet Spaces

In classical PDE theory, Widder’s theorem gives a representation for non-negative solutions of the heat equation on $$\mathbb{R }^n$$ . We show that an analogous theorem holds for local weak solutions of the canonical “heat equation” on a symmetric local Dirichlet space satisfying a local parabolic Harnack inequality.
Direct measurement of the spatial modes of a laser pulse: theory

We make an electric-field measuring apparatus by using optical processing, tapered optical fibers, and a pair of detectors at the end of each optical fiber. Using an appropriate computer-generated hologram (CGH), we show it is possible to discriminate among a set of orthonormal modes used to represent the spatial features of the electric field with a SNR of at least 100 to 1. The tapered fiber is a mode filter that is used in the transform plane of the CGH. This fiber allows precise determination of the strength of each of the orthonormal modes being used as the spatial basis of the electric field before the optical processing.
Factors affecting the demand for softwood lumber in the United States

Abstract This study sets out to examine whether the demand for softwood lumber in the United States is responsive to various market factors including the price of softwood lumber, the price of other building materials, and the level of economic activity (e.g., housing starts). Concern in the analysis is focused on overcoming some of the methodological shortcomings found in previous studies of this issue. The results are conclusive. The quantity of softwood lumber demanded does respond to the various economic factors considered. Moreover, when the structural stability of the estimated relationships is investigated, the results suggest that the demand for softwood lumber regionally in the United States has remained unaltered over the sample period (1950–1985).
Behavioral Housing Search Choice Set Formation: A Hazard-Based Screening Model of Property Value and Work Distance

Residential location search has been an interesting topic to both practitioners and researchers. The housing search process starts with an alternative formation and screening practice. At this level households evaluate all potential alternatives based on their lifestyle, preferences, and utilities to form a manageable choice set with limited number of plausible alternatives. This paper attempts to study this screening and filtering practice in more details and to develop a modeling framework that can replicate this process. The average desired property value and work distance are considered as two potential attributes, among others, which are examined by the household to evaluate feasible housing alternatives. It is postulated that alternatives will be included in the choice set only if the average property value meets the household budget and the work distance satisfies the household distance threshold. The search process will then continue until the choice set is complete. A hazard-based model is formulated that can model the desired property value and average work distance together. Several household socio-demographic attributes from eight waves of the Puget Sound Transportation Panel (PSTP) were utilized for model estimation along with built environment variables, characteristics of the supply side of the market, and several other economic indicators. The approach presented in the paper provides a remedy for the large choice set problem typically faced in discrete choice modeling.”
Femtosecond laser hyperdoping and micro/nanotexturing of silicon for photovoltaics

We have developed a technique, optical hyperdoping, for doping semiconductors to unusually high levels and endowing them with remarkable optoelectronic properties. By irradiating silicon (Si) with a train of femtosecond laser pulses in the presence of heavy chalcogen (sulfur, selenium, and tellurium) compounds, a 100-300 nm thin layer of Si is doped to nonequilibrium levels (~1 at. %). Hyperdoped silicon exhibits near-unity photon absorptance from the ultraviolet (λ < 0.25 μm) to the mid-infrared (λ > 2.5 μm), even though crystalline silicon is normally transparent to wavelengths λ > 1.1 μm due to its band gap at 1.1 eV. Concurrent to doping, we are also able to use fs-laser irradiation to create light-trapping surface textures on the micro- and nanometer scales. Together, optical hyperdoping and surface texturing represent a route towards high-performance thin film photovoltaic devices.
Inhibition of DPP4/CD26 and dmPGE2 treatment enhances engraftment of mouse bone marrow hematopoietic stem cells

Enhancing the engraftment of hematopoietic stem cells (HSC) is especially important when times to engraftment are prolonged due either to limiting numbers of HSC in the donor graft or to intrinsic slower engrafting time of the tissue sources of HSC. Both inhibition of dipeptidylpeptidase (DPP) 4/CD26 and treatment of cells with 16,16 dimethyl prostaglandin E2 (dmPGE2) have been shown to enhance hematopoietic stem cell engraftment in murine transplantation models and have been evaluated in clinical settings for their influence on engraftment of cord blood cells, a tissue source of HSC known to manifest an extended time to engraftment of donor cells compared to that of bone marrow (BM) and mobilized peripheral blood for hematopoietic cell transplantation (HCT). Herein, we present new experimental data, using a CD45(+) head-to-head congenic model of donor mouse BM cells for engraftment of lethally irradiated mice, demonstrating that similar levels of enhanced engraftment are detected by pulsing donor BM cells with diprotin A, a DPP4 inhibitor, or with dmPGE2 prior to infusion, or by pretreating recipient mice with sitagliptin, also a DPP4 inhibitor, by oral gavage. Moreover, the combined effects of pretreating the donor BM cells with dmPGE2 in context of pretreating the recipient mice with sitagliptin after the administration of a lethal dose of radiation resulted in significantly enhanced competitively repopulating HCT compared to either treatment alone. This information is highly relevant to the goal of enhancing engraftment in human clinical HCT.
The impact of negative selection on thymocyte migration in the medulla

Developing thymocytes are screened for self-reactivity before they exit the thymus, but how thymocytes scan the medulla for self antigens is unclear. Using two-photon microscopy, we observed that medullary thymocytes migrated rapidly and made frequent, transient contacts with dendritic cells. In the presence of a negative selecting ligand, thymocytes slowed, became confined to areas of approximately 30 microm in diameter and had increased contact with dendritic cells surrounding confinement zones. One third of polyclonal medullary thymocytes also showed confined, slower migration and may correspond to autoreactive thymocytes. Our data suggest that many autoreactive thymocytes do not undergo immediate arrest and death after encountering a negative selecting ligand but instead adopt an altered migration program while remaining in the medullary microenvironment.
Energy functionals and canonical Kahler metrics

Yau [Y2] has conjectured that a Fano manifold admits a Kahler-Einstein metric if and only if it is stable in the sense of geometric invariant theory. There has been much progress on this conjecture by Tian [T1], [T2], Donaldson [Do1], [Do2], and others. The Mabuchi energy functional plays a central role in these ideas. We study the Ek functionals introduced by X. X. Chen and G. Tian [CT1] which generalize the Mabuchi energy. We show that if a Fano manifold admits a Kahler-Einstein metric, then the functional E1 is bounded from below and, modulo holomorphic vector fields, is proper. This answers affirmatively a question raised by Chen [C2]. In fact, we show that E1 is proper if and only if there exists a Kahler-Einstein metric, giving a new analytic criterion for the existence of this canonical metric, with possible implications for the study of stability. We also show that on a Fano Kahler-Einstein manifold, all of the functionals Ek are bounded below on the space of metrics with nonnegative Ricci curvature
Experimental investigations on wear resistance characteristics of alternative die materials for stamping of advanced high-strength steels (AHSS)

Newer sheet alloys (such as Al, Mg, and advanced high-strength steels) are considered for automotive body panels and structural parts to achieve lightweight construction. However, in addition to issues with their limited formability and high springback, tribological conditions due to increased surface hardness and work hardening necessitate the use of alternative microstructurally improved die materials, coatings, and lubricants to minimize the wear-related die-life issues in stamping of advanced high-strength steel grades. This study aims to investigate and compare the wear performances of seven different, uncoated die materials (AISI D2, Vanadis 4, Vancron 40, K340 ISODUR, Caldie, Carmo, 0050A) using a newly developed wear testing device. DP600 AHSS (advanced high-strength steel) sheets were used in these tests. It was concluded that the tested die materials demonstrated higher wear resistance performance when compared to the conventional tool steel AISI D2 die material.
Comparison of radiogenic helium and lead in zircon

Abstract A direct comparison of helium and radiogenic lead in nonmetamict zircon crystals has indicated a 25 per cent discrepancy between these radiogenic constituents. It appears that the amount of helium is only three-quarters of the amount that should be present according to the content of radiogenic lead. Approximately the same proportion was found in zircon having a wide range in age, activity, and total alpha irradiation, and in large pegmatite zircon crystals, as well as in microscopic crystals from igneous rocks.
Surface Effects on Deposits From Jet Fuels

Flow experiments in a single-pass heat exchanger using JP-8 and certain additives were initiated under controlled conditions to explore the effects of a metal surface on deposition. The experimental apparatus permitted a unique viewing of the time evolution of deposits at different axial locations under conditions of limited oxygen availability somewhat similar to those in jet aircraft. Scanning electron microscopy was used to examine deposit microstructure. In addition, x-ray photoelectron spectroscopy and Auger electron spectroscopy determined the chemical composition of the deposits. Oxygen concentration measurements in the bulk flow were also performed, and the observed transient oxidation behavior was related to measured time-dependent changes in the deposit. Increasing dissolved oxygen levels and large changes in deposition were characteristic of the induction time. Mechanisms offouling in the heated and cooled sections were different. Spectroscopic analysis indicated that deposits formed in the heated section had chemical compositions different from those formed in the cooled section. Scanning electron microscopy revealed differences in microstructure between the heated and cooled sections: More uniform deposits formed in the cooled section as a result of once-soluble species becoming insoluble at low temperatures. In addition, the JP-8 additives significantly reduced fouling in the heated section, but their effectiveness in the cooled section, especially after long periods, was unclear.
Predictors of Red Cell Folate Level in Women Attempting Pregnancy

Objective. —To identify predictors of red cell folate level in women attempting to become pregnant. Design. —Cohort study. Setting. —A health maintenance organization serving the Minneapolis-St Paul, Minn, area. Participants. —A total of 189 healthy, primarily white women aged 22 to 35 years enrolled in the Diana Project, a population-based prospective study of preconceptional and prenatal risks to reproductive outcomes. The sample represents 189 of 219 enrolled women who were sequentially selected from the total Diana Project sample to receive additional laboratory analyses. Main Outcome Measure. —Red cell folate level. Results. —Folic acid supplements, folic acid intake from fortified cereals, vitamin C supplements, and serum zinc level (inverse) were found to predict red cell folate levels. Previous research has shown that red cell folate levels higher than 906 nmol/L (400 ng/mL) may be optimal for the prevention of folate-responsive neural tube defects. For folic acid supplement users, folate intakes of 450 μg per day and higher corresponded to these protective levels of red cell folate. In nonusers of supplements, intakes of more than 500 μg of folate per day from foods and folic acid-fortified cereals may be needed to attain red cell folate levels higher than 906 nmol/L (400 ng/mL). Red cell folate levels higher than 906 nmol/L (400 ng/mL) were primarily found in women who took folic acid supplements. Only 1 in 4 women had red cell folate levels higher than 906 nmol/L (400 ng/mL), while 1 in 8 had red cell folate levels indicative of a negative folate balance. Addition of a daily, 400-μg folic acid supplement to the usual diet would result in red cell folate levels over 906 nmol/L (400 ng/mL) in a majority of women in this study. Conclusions. —Supplementation of diets of women of childbearing potential with 400 μg of folic acid per day would effectively raise red cell folate to levels associated with a low risk of folate-responsive neural tube defects. Protective levels of red cell folate may also be obtained by ample consumption of vegetables, fruits, and folic acid-fortified breakfast cereals. Efforts to increase folic acid supplement use and folate consumption among women of childbearing potential must go beyond fortification of refined cereal and grain products and reach women within all educational and income groups.
On the Closure of Elliptic Wedge Operators

We prove a semi-Fredholm theorem for the minimal extension of elliptic operators on manifolds with wedge singularities and give, under suitable assumptions, a full asymptotic expansion of the trace of the resolvent.
Refined Black Hole Ensembles and Topological Strings

We formulate a refined version of the Ooguri-Strominger-Vafa (OSV) conjecture. The OSV conjecture that Z BH = |Z top |2 relates the BPS black hole partition function to the topological string partition function Z top. In the refined conjecture, Z BH is the partition function of BPS black holes counted with spin, or more precisely the protected spin character. Z top becomes the partition function of the refined topological string, which is itself an index. Both the original and the refined conjecture are examples of large N duality in the ’t Hooft sense. The refined conjecture applies to non-compact Calabi-Yau manifolds only, so the black holes are really BPS particles with large entropy, of order N 2. The refined OSV conjecture states that the refined BPS partition function has a large N dual which is captured by the refined topological string. We provide evidence that the conjecture holds by studying local Calabi-Yau threefolds consisting of line bundles over a genus g Riemann surface. We show that the refined topological string partition function on these geometries is computed by a two-dimensional TQFT. We also study the refined black hole partition function arising from N D4 branes on the Calabi-Yau, and argue that it reduces to a (q, t)-deformed version of two-dimensional SU(N ) Yang-Mills. Finally, we show that in the large N limit this theory factorizes to the square of the refined topological string in accordance with the refined OSV conjecture.
Production and application of synthetic precursors labeled with carbon-11 and fluorine-18

It is evident from this chapter that there is enormous flexibility both in the selection of the nature of the radioisotope and ways to generate it, as well as in the selection of the labeling precursor to appropriately attach that radioisotope to some larger biomolecule of interest. The arsenal of radiolabeling precursors now available to the chemist is quite extensive, and without a doubt will continue to grow as chemists develop new ones. However, the upcoming years will perhaps reflect a greater effort in refining existing methods for preparing some of those precursors that are already available to us. For example, the use of solid-phase reactions to accomplish in a single step what would normally take several using conventional solvent-based reactions has already been shown to work in many occasions. The obvious advantage here is that processes become more amenable to system automation thus affording greater reliability in day-to-day operations. There are perhaps other technologies in science that have yet to be realized by the chemist in the PET laboratory that could provide a similar or even a greater benefit. One only needs to be open to new ideas, and imaginative enough to apply them to the problems at hand.
The effects of frame rate and resolution on users playing first person shooter games

The rates and resolutions for frames rendered in a computer game directly impact the player performance, influencing both the overall game playability and the game's enjoyability. Insights into the effects of frame rates and resolutions can guide users in their choice for game settings and new hardware purchases, and inform system designers in their development of new hardware, especially for embedded devices that often must make tradeoffs between resolution and frame rate. While there have been studies detailing the effects of frame rate and resolution on streaming video and other multimedia applications, to the best of our knowledge, there have been no studies quantifying the effects of frame rate and resolution on user performance for computer games. This paper presents results of a carefully designed user study that measures the impact of frame rate and frame resolution on user performance in a first person shooter game. Contrary to previous results for streaming video, frame rate has a marked impact on both player performance and game enjoyment while resolution has little impact on performance and some impact on enjoyment.
Firm Formation And Regional Spillovers - Evidence From Germany

This paper studies the effect of regional spillovers on the rate of firm formation in two major West German industries for the time period from 1989 to 1993. 1 exploit regional variations in firm formation at the county level to identify the effects of historically given industry structure and employment structure on thc emergence of new firms. The results point to the existence of strong localization and urbanization effects. The emergence of high technology firms seems to be contingent on a heterogeneous historical industry structure, the existence of service providers, and in particular on a high employment share of scientists in universities and extra-university research laboratories.
Adaptive mode control: A static-power-efficient cache design

Lower threshold voltages in deep submicron technologies cause more leakage current, increasing static power dissipation. This trend, combined with the trend of larger/more cache memories dominating die area, has prompted circuit designers to develop SRAM cells with low-leakage operating modes (e.g., sleep mode). Sleep mode reduces static power dissipation, but data stored in a sleeping cell is unreliable or lost. So, at the architecture level, there is interest in exploiting sleep mode to reduce static power dissipation while maintaining high performance.Current approaches dynamically control the operating mode of large groups of cache lines or even individual cache lines. However, the performance monitoring mechanism that controls the percentage of sleep-mode lines, and identifies particular lines for sleep mode, is somewhat arbitrary. There is no way to know what the performance could be with all cache lines active, so arbitrary miss rate targets are set (perhaps on a per-benchmark basis using profile information), and the control mechanism tracks these targets. We propose applying sleep mode only to the data store and not the tag store. By keeping the entire tag store active the hardware knows what the hypothetical miss rate would be if all data lines were active, and the actual miss rate can be made to precisely track it. Simulations show that an average of 73p of I-cache lines and 54p of D-cache lines are put in sleep mode with an average IPC impact of only 1.7p, for 64 KB caches.
Modular product architecture

Abstract This paper presents an approach to architecting a product family that shares inter-changeable modules. Rather than a fixed product platform upon which derivative products are created through substitution of add-on modules, the approach here permits the platform itself to be one of several possible options. We first develop function structures for each product. After comparing function structures for common and unique functions, rules are applied to determine possible modules. This process defines possible architectures. Each architecture is represented using a matrix of functions versus products, with shared/unique function levels indicated. This provides a systematic approach to generating architectures.
Total synthesis of (+/-)-magnofargesin.

A convenient method for the preparation of 2,5-dihydrofurans by using the chemistry of alkynyl(phenyl)iodonium salts is reported. Treatment of 3-alkoxy-1-alkynyl(phenyl)iodonium triflates with sodium benzenesulfinate generates an alkylidenecarbene, which undergoes [1,5]-C-H insertion to form 2-substituted 4-benzenesulfonyl-2,5-dihydrofurans in reasonable yield. These cyclic vinyl sulfones are functionalized in such a way as to make them useful starting materials for the preparation of lignans. The application of this methodology to the first total synthesis of (±)-magnofargesin is disclosed.
Recent results from the Tevatron fixed target and collider experiments

We present a review of recent QCD related results from the Fermilab Tevatron fixed target and collider experiments. Topics include jet and boson production, W boson and top quark mass measurements, and studies of CP violation.
Prospects for the characterization and confirmation of transiting exoplanets via the rossiter-mclaughlin effect

The Rossiter-McLaughlin (RM) effect is the distortion of stellar spectral lines that occurs during eclipses or transits, due to stellar rotation. We assess the future prospects for using the RM effect to measure the alignment of planetary orbits with the spin axes of their parent stars, and to confirm exoplanetary transits. We compute the achievable accuracy for the parameters of interest, in general and for the five known cases of transiting exoplanets with bright host stars. We determine the requirements for detecting the effects of differential rotation. For transiting planets with small masses or long periods (as will be detected by forthcoming satellite missions), the velocity anomaly produced by the RM effect can be much larger than the orbital velocity of the star. For a terrestrial planet in the habitable zone of a Sunlike star found by the Kepler mission, it will be difficult to use the RM effect to confirm transits with current instruments, but it still may be easier than measuring the spectroscopic orbit.
Does inequality lead to a financial crisis

Abstract The recent global crisis has sparked interest in the relationship between income inequality, credit booms, and financial crises. Rajan (2010) and Kumhof and Ranciere (2011) propose that rising inequality led to a credit boom and eventually to a financial crisis in the US in the first decade of the 21st century as it did in the 1920s. Data from 14 advanced countries between 1920 and 2000 suggest these are not general relationships. Credit booms heighten the probability of a banking crisis, but we find no evidence that a rise in top income shares leads to credit booms. Instead, low interest rates and economic expansions are the only two robust determinants of credit booms in our data set. Anecdotal evidence from US experience in the 1920s and in the years up to 2007 and from other countries does not support the inequality, credit, crisis nexus. Rather, it points back to a familiar boom-bust pattern of declines in interest rates, strong growth, rising credit, asset price booms and crises.
The Lebost wind turbine laboratory tests and data analysis

Preliminary aerodynamic torque and power measurements and data analysis are presented for the Lebost Wind Turbine--a recently patented vertical-axis wind energy machine incorporating flow-focusing inlets fixed to a housing shroud surrounding blades rotating normal to the flow. Two laboratory-scale models were constructed, instrumented, and tested in a specially modified section of the NYU 30-m wind tunnel at freestream velocities (U/sub infinity/) of 0 to 15.4 m/s (0 to 34.5 mph) and blade diameter Reynolds numbers (Re/sub D/) of 0.5-3.7 x 10/sup 5/. At all U/sub infinity/ the shaft rotation rate decreased nearly linearly with applied load. However, the (no-load tip speed)/(U/sub infinity/) ratio X/sub 0/ and the torque coefficient at zero rotation were found to be Re/sub D/-dependent, with X/sub 0/ first decreasing for Re/sub D/ <2 x 10/sup 5/ and then increasing (presumably, X/sub 0/ levels off at about 1.0 at the end of the transitional regime). These results are consistent with the modified impulse turbine theory presented. Based on this theory, a parabolic correlation for the power coefficient based on projected blade frontal area is found. Results indicate an optimized high-Re/sub D/ prototype could generate X/sub 0/ greater than or equal to 1, corresponding to maximum power coefficientsmore » of CP/sub max/ greater than or equal to 0.6, roughly twice the CP/sub max/ of high-solidity horizontal-axis windmills and Darrieus windmills (X/sub 0/ approx. = 6) and three times the CP/sub max/ of Savonius windmills.« less
Stein’s method for concentration inequalities

We introduce a version of Stein’s method for proving concentration and moment inequalities in problems with dependence. Simple illustrative examples from combinatorics, physics, and mathematical statistics are provided.
Mist/steam cooling by a row of impinging jets

Abstract Mist/steam cooling has been studied to augment internal steam-only cooling for advanced turbine systems. Water droplets generally less than 10 μm are added to 1.3 bar steam and injected through a row of four round jets onto a heated surface. The Reynolds number is varied from 7500 to 22,500 and the heat flux varied from 3.3 to 13.4 kW/m2. The mist enhances the heat transfer along the stagnation line and downstream wanes in about 3 jet diameters. The heat transfer coefficient improves by 50–700% at the stagnation line for mist concentrations 0.75–3.5% by weight. Off-axis maximum cooling occurs in most of the mist/steam flow but not in the steam-only flow. CFD simulation indicates that this off-axis cooling peak is caused by droplets’ interaction with the target walls.
Nanostructured Pt-alloy electrocatalysts for PEM fuel cell oxygen reduction reaction

In this critical review, we present the current technological advances in proton exchange membrane (PEM) fuel cell catalysis, with a focus on strategies for developing nanostructured Pt-alloys as electrocatalysts for the oxygen reduction reaction (ORR). The achievements are reviewed and the major challenges, including high cost, insufficient activity and low stability, are addressed and discussed. The nanostructured Pt-alloy catalysts can be grouped into different clusters: (i) Pt-alloy nanoparticles, (ii) Pt-alloy nanotextures such as Pt-skins/monolayers on top of base metals, and (iii) branched or anisotropic elongated Pt or Pt-alloy nanostructures. Although some Pt-alloy catalysts with advanced nanostructures have shown remarkable activity levels, the dissolution of metals, including Pt and alloyed base metals, in a fuel cell operating environment could cause catalyst degradation, and still remains an issue. Another concern may be low retention of the nanostructure of the active catalyst during fuel cell operation. To facilitate further efforts in new catalyst development, several research directions are also proposed in this paper (130 references).
Robust Optical Richness Estimation with Reduced Scatter

Reducing the scatter between cluster mass and optical richness is a key goal for cluster cosmology from photometric catalogs. We consider various modifications to the red-sequence-matched filter richness estimator of Rozo et al. implemented on the maxBCG cluster catalog and evaluate the impact of these changes on the scatter in X-ray luminosity (L{sub X} ) at fixed richness, using L{sub X} from the ROSAT All-Sky Catalog as the best mass proxy available for the large area required. Most significantly, we find that deeper luminosity cuts can reduce the recovered scatter, finding that {sigma}{sub ln{sub L{sub x|{lambda}}}}=0.63{+-}0.02 for clusters with M{sub 500c} {approx}> 1.6 Multiplication-Sign 10{sup 14} h{sup -1}{sub 70} M{sub Sun }. The corresponding scatter in mass at fixed richness is {sigma}{sub lnM|{lambda}} Almost-Equal-To 0.2-0.3 depending on the richness, comparable to that for total X-ray luminosity. We find that including blue galaxies in the richness estimate increases the scatter, as does weighting galaxies by their optical luminosity. We further demonstrate that our richness estimator is very robust. Specifically, the filter employed when estimating richness can be calibrated directly from the data, without requiring a priori calibrations of the red sequence. We also demonstrate that the recovered richness is robust tomore » up to 50% uncertainties in the galaxy background, as well as to the choice of photometric filter employed, so long as the filters span the 4000 A break of red-sequence galaxies. Consequently, our richness estimator can be used to compare richness estimates of different clusters, even if they do not share the same photometric data. Appendix A includes 'easy-bake' instructions for implementing our optimal richness estimator, and we are releasing an implementation of the code that works with Sloan Digital Sky Survey data, as well as an augmented maxBCG catalog with the {lambda} richness measured for each cluster.« less
Crystalline molecular machines: Encoding supramolecular dynamics into molecular structure

Crystalline molecular machines represent an exciting new branch of crystal engineering and materials science with important implications to nanotechnology. Crystalline molecular machines are crystals built with molecules that are structurally programmed to respond collectively to mechanic, electric, magnetic, or photonic stimuli to fulfill specific functions. One of the main challenges in their construction derives from the picometric precision required for their mechanic operation within the close-packed, self-assembled environment of crystalline solids. In this article, we outline some of the general guidelines for their design and apply them for the construction of molecular crystals with units intended to emulate macroscopic gyroscopes and compasses. Recent advances in the preparation, crystallization, and dynamic characterization of these interesting systems offer a foothold to the possibilities and help highlight some avenues for future experimentation.
Two Paradoxes in the Theory of Capital Investment and Competition

AbstractThis paper considers two paradoxes concerning the relationship between capital investment decisions and competition. First, conventional capital budgeting methods imply that substantial infra-marginal surpluses are attained above the cost of capital, but this is inconsistent with the premise that returns on capital equal the cost of capital in competitive markets. Second, contrasts in the pharmaceutical industry between high reported returns on capital invested, the accounting treatment of research and development outlays, and inter-firm competition in research and development are explored.
Novel QCD effects in nuclear collisions

Abstract Heavy ion collisions can provide a novel environment for testing fundamental dynamical processes in QCD, including minijet formation and interactions, formation zone phenomena, color filtering, coherent co-mover interactions, and new higher twist mechanisms which could account for the observed excess production and anomalous nuclear target dependence of heavy flavor production. The possibility of using light-cone thermodynamics and a corresponding covariant temperature to describe the QCD phases of the nuclear fragmentation region is also briefly discussed.
Scintillating fiber detector performance, detector geometries, trigger, and electronics issues for scintillating fiber tracking

Abstract Scintillating fiber tracking technology has made great advances and has demonstrated great potential for high speed charged particle tracking and triggering. The small detector sizes and fast scintillation fluors available make them very promising for use at high luminosity experiments at today's and tomorrow's colliding and fixed target experiments where high rate capability is essential. This paper will discuss the current state of scintillating fiber performance and current Visual Light Photon Counter (VLPC) characteristics. The primary topic will be some of the system design and integration issues which should be considered by anyone attempting to design a scintillating fiber tracking system which includes a high speed tracking trigger. Design constraints placed upon the detector system by the electronics and mechanical sub-systems will be discussed. Seemingly simple and unrelated decisions can have far reaching effects on overall system performance. SDC and D0 example system designs will be discussed.
A dedekind finite borel set

In this paper we prove three theorems about the theory of Borel sets in models of ZF without any form of the axiom of choice. We prove that if $${B\subseteq 2^\omega}$$ is a G ?? -set then either B is countable or B contains a perfect subset. Second, we prove that if 2 ? is the countable union of countable sets, then there exists an F ?? set $${C\subseteq 2^\omega}$$ such that C is uncountable but contains no perfect subset. Finally, we construct a model of ZF in which we have an infinite Dedekind finite $${D\subseteq 2^\omega}$$ which is F ?? .
Synthesis of mixed sphere β-diketonate nickel(II) complexes

Abstract Complexes of the type [Ni(β-diketonate)(L L) 1,2 ] (LL = diphosphine, ( 2 ), en or dipy, ( 3 )) have been synthesized from [Ni(β-diketonate) 2 ] ( 1 ) and the free ligand under stoichiometric conditions in ethanol. Complexes 2 are square-planar species, while compounds 3 are hexacoordinate complexes, all being quite stable toward ligand disproportionation. The ligand-set {P 2 O 2 - } appears to be particularly stable in the nickel(II) coordination sphere and turns out to exert a fairly strong average ligand field.
Concurrency control and view notification algorithms for collaborative replicated objects

This paper describes algorithms for implementing a high-level programming model for synchronous distributed groupware applications. In this model, several application data objects may be atomically updated, and these objects automatically maintain consistency with their replicas using an optimistic algorithm. Changes to these objects may be optimistically or pessimistically observed by view objects by taking consistent snapshots. The algorithms for both update propagation and view notification are based upon optimistic guess propagation principles adapted for fast commit by using primary copy replication techniques. The main contribution of the paper is the synthesis of these two algorithmic techniques-guess propagation and primary copy replication-for implementing a framework that is easy to program to and is well suited for the needs of groupware applications.
Journal Club: Comparison of symptomatic and asymptomatic persons with Alzheimer disease neuropathology

Advances in neuroimaging, biomarkers, and clinical data have led to the hypothesis that the pathologic process of Alzheimer dementia begins decades prior to functional decline and diagnosis.1–3 High-profile clinical trial results have shown that biomarker changes can be made via pharmacologic intervention; however, the timing of this intervention has likely been too late to impact the cascade of neurodegenerative changes.4,5 In “Comparison of symptomatic and asymptomatic persons with Alzheimer disease neuropathology” by Monsell et al.,6 neuropathologic and clinical data were used to determine the risk of developing clinically significant cognitive impairment. This work represents a significant contribution because it examines a large cohort of autopsy data, which includes patients with Alzheimer dementia neuropathology who were clinically normal or diagnosed with mild cognitive impairment and Alzheimer-type dementia. The authors report a 3-fold increase in the risk of cognitive symptoms in association with quantifiable increases in neurofibrillary tangle pathology. Additionally, several other factors including APOE gene status, history of depression, and age impacted the clinical presentation. The ultimate goal of this investigation and similar studies is to facilitate the early and accurate identification of those at risk of developing Alzheimer dementia, such that potentially disease-modifying therapies may be considered.
General chiral gauge theories

Abstract Only requiring that Dirac operators decribing massless fermions on the lattice decompose into Weyl operators we arrive at a large class of them. After deriving general relations from spectral representations we study correlation functions of Weyl fermions for any value of the index, stressing the related conditions for basis transformations and getting the precise behaviors under gauge and CP transformations. Using the detailed structure of the chiral projections we also obtain a form of the correlation functions with a determinant in the general case.
Optimization of image processing algorithms on mobile platforms

This work presents a technique to optimize popular image processing algorithms on mobile platforms such as cell phones, net-books and personal digital assistants (PDAs). The increasing demand for video applications like context-aware computing on mobile embedded systems requires the use of computationally intensive image processing algorithms. The system engineer has a mandate to optimize them so as to meet real-time deadlines. A methodology to take advantage of the asymmetric dual-core processor, which includes an ARM and a DSP core supported by shared memory, is presented with implementation details. The target platform chosen is the popular OMAP 3530 processor for embedded media systems. It has an asymmetric dual-core architecture with an ARM Cortex-A8 and a TMS320C64x Digital Signal Processor (DSP). The development platform was the BeagleBoard with 256 MB of NAND RAM and 256 MB SDRAM memory. The basic image correlation algorithm is chosen for benchmarking as it finds widespread application for various template matching tasks such as face-recognition. The basic algorithm prototypes conform to OpenCV, a popular computer vision library. OpenCV algorithms can be easily ported to the ARM core which runs a popular operating system such as Linux or Windows CE. However, the DSP is architecturally more efficient at handling DFT algorithms. The algorithms are tested on a variety of images and performance results are presented measuring the speedup obtained due to dual-core implementation. A major advantage of this approach is that it allows the ARM processor to perform important real-time tasks, while the DSP addresses performance-hungry algorithms.
The bitter pill

Fundamentally new approaches to birth control--for example, a male pill, a once-a-month menses inducer, and an antifertility vaccine--cannot be realized before the next century, and then only if the virtual withdrawal of the pharmaceutical industry from this field can be reversed. Major changes in product liability would be the most significant incentive.
Farm technology and technical efficiency: Evidence from four regions in China

Abstract In this paper we fit stochastic frontier production functions to data of Chinese farms grouped into each of four regions—North, Northeast, East, and Southwest—over 1995–1999. These frontier production functions are shown to have statistically different structures, and the elasticities provide some evidence of diminished marginal products of chemical inputs in the East and capital services in the North and Southwest. Labor has a low elasticity except in the North. Standardized technical efficiency scores are estimated for the farms and are shown to have the same structure across regions and to be related to the age of the household head, land fragmentation, and the village migration ratio, controlling for year effects and village or regional fixed effects.
Čerenkov radiation and electromagnetic pulse produced by electron beams traversing a finite path in air

Abstract : Coherent Cerenkov radiation has been investigated previously in the time domain for an infinite path. The present calculations for a finite path length show an effect analogous to diffraction (in the frequency domain) in which radiation fields appear both at Cerenkov angles and at other angles. The latter have previously been named electromagnetic pulse fields. Keywords: Radiation Radio Frequency Emissions; Relativistic Electron Beams; Electrons in Air.
A simple iterative procedure for reducing stiffness and computer memory in reactive flow problems

Abstract An iterative procedure for the solution of one-dimensional reactive flow problems has been developed. This technique was used in conjunction with the method of lines although application to other finite difference algorithms is also possible. The system of ordinary differential equations (ODE) resulting from the method of lines is broken up into subsets of equations representing the spatial profile of a single species. Each subset is solved individually while holding all other variables constant. This procedure is performed iteratively until a converged solution is obtained. Important features of this technique include: 1. (1) a nonstiff ODE solver can be used, 2. (2) computer core memory is reduced, and 3. (3) computer core memory increases linearly rather than quadratically with increasing number of species or grids. This new algorithm is applied to the solution of low-pressure acetylene flames. Simulation results are in good agreement with results obtained by other methods.