cssi/SciSciGPT-SciSciNet huggingface dataset:
Mechanism of Hydrogen Formation in Solar Parabolic Trough Receivers

Solar parabolic trough systems for electricity production are receiving renewed attention, and new solar plants are under construction to help meet the growing demands of the power market in the Western United States. The growing solar trough industry will rely on operating experience it has gained over the last two decades. Recently, researchers found that trough plants that use organic heat transfer fluids (HTF) such as Therminol VP-1 are experiencing significant heat losses in the receiver tubes. The cause has been traced back to the accumulation of excess hydrogen gas in the vacuum annulus that surrounds the steel receiver tube, thus compromising the thermal insulation of the receiver. The hydrogen gas is formed during the thermal decomposition of the organic HTF that circulates inside the receiver loop, and the installation of hydrogen getters inside the annulus has proven to be insufficient for controlling the hydrogen build-up over the lifetime of the receivers. This paper will provide an overview of the chemical literature dealing with the thermal decomposition of diphenyl oxide and biphenyl, the two constituents of Therminol VP-1.
An improved forward algorithm for optimal control of a class of hybrid systems

Considers optimal control problems for a class of hybrid systems motivated by the structure of manufacturing environments that integrate process and operations control. We derive a new property of the optimal state trajectory structure which holds under a modified condition on the cost function. This allows us to develop a low-complexity, scalable algorithm for explicitly determining the optimal controls, which can be more efficient than the best algorithm to date, known as the forward algorithm. A numerical example is included to illustrate the efficacy of the proposed algorithm, and to compare it with the forward algorithm.
In the Beginning: The First Sources of Light and the Reionization of the Universe

Abstract The formation of the first stars and quasars marks the transformation of the universe from its smooth initial state to its clumpy current state. In popular cosmological models, the first sources of light began to form at a redshift z =30 and reionized most of the hydrogen in the universe by z =7. Current observations are at the threshold of probing the hydrogen reionization epoch. The study of high-redshift sources is likely to attract major attention in observational and theoretical cosmology over the next decade.
An Advantage of Newness: Vicarious Learning Despite Limited Absorptive Capacity

Entrants are often viewed as suffering from a "liability of newness"-at founding, they rarely possess the knowledge and capabilities necessary to compete and survive. They can overcome this liability by learning vicariously from the knowledge of incumbent firms. But how can entrants learn from external knowledge when they lack the prior related knowledge that forms the basis of absorptive capacity? We theorize that the process of internal experiential learning facilitates learning from external knowledge, particularly for entrants. To test this theory, we examine learning using a comprehensive set of U.S. commercial banking firms, including a full census of entrants. Our estimates suggest that the share of vicarious learning realized in the process of experiential learning is twice as large for entrants as for incumbents. In this sense, entrants enjoy an "advantage of newness" in learning.
Beneficial Mutation-Selection Balance and the Effect of Linkage on Positive Selection

When beneficial mutations are rare, they accumulate by a series of selective sweeps. But when they are common, many beneficial mutations will occur before any can fix, so there will be many different mutant lineages in the population concurrently. In an asexual population, these different mutant lineages interfere and not all can fix simultaneously. In addition, further beneficial mutations can accumulate in mutant lineages while these are still a minority of the population. In this article, we analyze the dynamics of such multiple mutations and the interplay between multiple mutations and interference between clones. These result in substantial variation in fitness accumulating within a single asexual population. The amount of variation is determined by a balance between selection, which destroys variation, and beneficial mutations, which create more. The behavior depends in a subtle way on the population parameters: the population size, the beneficial mutation rate, and the distribution of the fitness increments of the potential beneficial mutations. The mutation–selection balance leads to a continually evolving population with a steady-state fitness variation. This variation increases logarithmically with both population size and mutation rate and sets the rate at which the population accumulates beneficial mutations, which thus also grows only logarithmically with population size and mutation rate. These results imply that mutator phenotypes are less effective in larger asexual populations. They also have consequences for the advantages (or disadvantages) of sex via the Fisher–Muller effect; these are discussed briefly.
On the Initiation of High Explosives by Laser Radiation

The problem of laser initiation of high explosives in munitions is considered. In this situation, the laser illuminates a small spot on the casing, and lateral thermal transport affects the initiation temperature. We use a variational method to calculate the critical temperature for explosives' initiation as a function of the laser spot size for common high explosives. The effect of the dwelling time of the irradiation is then evaluated. We demonstrate that in typical situations the critical temperature is determined by the dwelling time rather than by the laser spot size.
Interactive policy learning through confidence-based autonomy

We present Confidence-Based Autonomy (CBA), an interactive algorithm for policy learning from demonstration. The CBA algorithm consists of two components which take advantage of the complimentary abilities of humans and computer agents. The first component, Confident Execution, enables the agent to identify states in which demonstration is required, to request a demonstration from the human teacher and to learn a policy based on the acquired data. The algorithm selects demonstrations based on a measure of action selection confidence, and our results show that using Confident Execution the agent requires fewer demonstrations to learn the policy than when demonstrations are selected by a human teacher. The second algorithmic component, Corrective Demonstration, enables the teacher to correct any mistakes made by the agent through additional demonstrations in order to improve the policy and future task performance. CBA and its individual components are compared and evaluated in a complex simulated driving domain. The complete CBA algorithm results in the best overall learning performance, successfully reproducing the behavior of the teacher while balancing the tradeoff between number of demonstrations and number of incorrect actions during learning.
An Enantiospecific Synthesis of Jiadifenolide

A Robinson annulation, van Leusen homologation, and a desymmetrizing CH oxidation enabled an enantiospecific synthesis of the neurotrophic natural product jiadifenolide. From a pulegone-derived building block, a key propellane intermediate was constructed through the use of simple reagents in a highly diastereoselective fashion. A short series of oxidations of this tricylic framework allowed progression to the natural product.
The Physical Nature of the Lyman Limit Systems

We analyze Keck HIRES observations of a Lyman-limit system at z = 2.652 toward Q2231-00. These observations afford the most comprehensive study of the physical properties of a Lyman-limit system to date. By comparing the ionic column densities for Fe+, Fe++, Si+, and Si3+ against calculations derived from the CLOUDY software package, we have strictly constrained the ionization state of this system. This has enabled us to calculate accurate abundances of a Lyman-limit system for the first time at z > 2, e.g., [Fe/H] = -0.5±0.1. We also derive a total hydrogen column density of log N(H) = 20.73 ± 0.2, which is comparable to values observed for the damped Lyα systems. The system is special for exhibiting C II* λ1335 absorption, allowing us to estimate the electron density, ne = 6.5 ± 1.3 × 10-2 cm-3. Coupling this measurement with our knowledge of the ionization state, we derive the following physical properties: (1) hydrogen volume density nH = 5.9 ± 1.2 × 10-2 cm-3, (2) path length l = 3 ± 1.6 kpc, and (3) ionizing intensity log J912 = -20.22 ± 0.21. We point out that a number of the physical properties (e.g., [Fe/H], N(H), nH) resemble those observed for the damped Lyα systems, which suggests that this system may be the photoionized analog of a damped system. The techniques introduced in this Letter should be applicable to a number of Lyman-limit systems and therefore enable a survey of their chemical abundances and other physical properties.
Mitrion-C Application Development on SGI Altix 350/RC100

This paper provides an evaluation of SGIreg RASC^TM RC100 technology from a computational science software developer's perspective. A brute force implementation of a two-point angular correlation function is used as a test case application. The computational kernel of this test case algorithm is ported to the Mitrion-C programming language and compiled, targeting the RC100 hardware. We explore several code optimization techniques and report performance results for different designs. We conclude the paper with an analysis of this system based on our observations while implementing the test case. Overall, the hardware platform and software development tools were found to be satisfactory for accelerating computationally intensive applications, however, several system improvements are desirable.
Assessing acculturation over time: A four-year prospective study of Asian American young adults.

Acculturation is commonly defined as a dynamic and multidimensional process in which individuals and groups change over time when coming into contact with another culture. Despite the emphasis on acculturation as a process of change over time, few researchers have directly assessed this hypothesis. The current study first identifies and then examines "stable" and "dynamic" dimensions of acculturation within a 4-year prospective study of 433 first- and second-generation Chinese- and Korean-American college students. Separate growth model analyses revealed significant linear change for first-generation students toward greater U.S. acculturation. In comparison, tests of linear and quadratic change for second-generation students were not significant. When stratifying by gender, acculturation increased for women but there was no significant change in acculturation for men. While all students reported increases in alcohol consumption over the study period, changes in acculturation predicted changes in alcohol consumption only for women. Chinese men showed greater increases in alcohol consumption than Korean men but there was no effect for ethnicity among women. There was significant individual variability in the models, which underscores the importance of examining change prospectively through within and between person analyses. The findings highlight the importance of examining acculturation changes over time for different migrant groups with implications for further development of acculturation measures, research methodologies, and health interventions. More prospective research designs of acculturation are needed to examine changes in health behavior and overall adaptation across migrant groups at varying stages of development.
Orbit-product representation and correction of Gaussian belief propagation

We present a new view of Gaussian belief propagation (GaBP) based on a representation of the determinant as a product over orbits of a graph. We show that the GaBP determinant estimate captures totally backtracking orbits of the graph and consider how to correct this estimate. We show that the missing orbits may be grouped into equivalence classes corresponding to backtrackless orbits and the contribution of each equivalence class is easily determined from the GaBP solution. Furthermore, we demonstrate that this multiplicative correction factor can be interpreted as the determinant of a backtrackless adjacency matrix of the graph with edge weights based on GaBP. Finally, an efficient method is proposed to compute a truncated correction factor including all backtrackless orbits up to a specified length.
Remote sensing of particle size and refractive index by varying the wavelength.

This is a numerical study to explore the feasibility of determining particle size and refractive index from the backscattered signal combined with a signal differentially scattered at one other angle. The wavelength of the radiation is varied over a broad range (in the particular example chosen, from λ = 0.5 μ to 1.5 μ). Three signatures of the particle size and refractive index are chosen: (1) deviation of the radiance from the inverse fourth power of the wavelength; (2) the first maximum of the variation of the angular intensity function with wavelength; and (3) the first two maxima of the variation of the phase difference of the amplitudes of the polarized radiances with wavelength. For monodisperse systems, these signatures will permit estimation of particle size in the fortyfold range of α = 0.033–1.29 μ (for m = 1.50).
Zambia's infrastructure : a continental perspective

Infrastructure improvements contributed 0.6 percentage points to Zambia's annual per capital GDP growth over the past decade, mostly because of exponential growth in information and communication services. The power sector, by contrast, pulled the growth rate down by more than 0.1 percentage points. Improving Zambia's infrastructure endowment could boost growth by up to 2 percentage points per year. Zambia's relatively high generation capacity and power consumption are accompanied by fewer power outages than elsewhere in the region. But Zambia's power sector emphasizes the mining industry, while household electrification is about half that in other resource-rich countries. Zambia's power tariffs, among the lowest in Africa, are less than half the level needed to accelerate electrification and keep pace with mining sector demands. In power as in just about every other aspect of infrastructure, rural Zambians lag well behind their African peers. In a country where 70 percent of the population depends on agriculture for its livelihood, this represents a huge drag on the economy. Zambia would need to spend an average of $1.6 billion a year over the decade 2006-15 to develop the infrastructure found in the rest of the developing world. This is equivalent to 20 percent of Zambia's GDP and about double the country's rate of investment in recent years. Closing the country's annual infrastructure funding gap of $500 million requires raising more funds, looking for more cost-effective ways to meet infrastructure targets, and eliminating the inefficiencies that cause the loss of $300 million annually.
Grid -Based Parallel Data Streaming implemented for the Gyrokinetic Toroidal Code

We have developed a threaded parallel data streaming approach using Globus to transfer multi-terabyte simulation data from a remote supercomputer to the scientists home analysis/visualization cluster, as the simulation executes, with negligible overhead. Data transfer experiments show that this concurrent data transfer approach is more favorable compared with writing to local disk and then transferring this data to be post-processed. The present approach is conducive to using the grid to pipeline the simulation with post-processing and visualization. We have applied this method to the Gyrokinetic Toroidal Code (GTC), a 3-dimensional particle-in-cell code used to study micro-turbulence in magnetic confinement fusion from first principles plasma theory.
Routine as resource for the design of learning systems

Even though the coordination of kids' activities is largely successful, the modern dual income family still regularly experiences breakdowns in their practices. Families often rely on routines to help them coordinate when plans prove less effective. Routines, however, are rarely documented, challenging to express in detail, and frequently evolving, making them cumbersome to manually describe and so largely unavailable to computational systems as input. This work proposes that this disconnect can be overcome, and argues that unsupervised models of family routine can be learned using a single, lightweight sensor. This way, the successful but tacit knowledge of the routine might be captured and exploited by learning systems, providing a new kind of information for families and computational systems alike. A method is proposed to develop a Bayesian Network to reason about the state of family coordination. This model relies on learned routines of pickup and drop-off at kids' activities.
Dynamics of three coupled van der Pol oscillators with application to circadian rhythms

Abstract In this work we study a system of three van der Pol oscillators. Two of the oscillators are identical, and are not directly coupled to each other, but rather are coupled via the third oscillator. We investigate the existence of the in-phase mode in which the two identical oscillators have the same behavior. To this end we use the two variable expansion perturbation method (also known as multiple scales) to obtain a slow flow, which we then analyze using the computer algebra system MACSYMA and the numerical bifurcation software AUTO. Our motivation for studying this system comes from the presence of circadian rhythms in the chemistry of the eyes. We model the circadian oscillator in each eye as a van der Pol oscillator. Although there is no direct connection between the two eyes, they are both connected to the brain, especially to the pineal gland, which is here represented by a third van der Pol oscillator.
M-MRAC backstepping for systems with unknown virtual control coefficients

The paper presents an over-parametrization free certainty equivalence state feedback backstepping adaptive control design method for systems of any relative degree with unmatched uncertainties and unknown virtual control coefficients. It uses a fast prediction model to estimate the unknown parameters, which is independent of the control design. It is shown that the system’s input and output tracking errors can be systematically decreased by the proper choice of the design parameters. The benefits of the approach is demonstrated in numerical simulations.
Legendrian links and the spanning tree model for Khovanov homology

The Khovanov homology has led to many interesting new developments in knot theory and related fields. See Lee [4; 5], Ng [6], Plamenevskaya [7] and Rasmussen [8] for examples. It is still very difficult to compute the Khovanov homology in general. Recently, A Champanerkar and I Kofman [2] and, independently, S Wehrli [11] constructed a spanning tree model for the Khovanov homology based on the spanning tree expansion of the Jones polynomial introduced by M Thistlethwaite in [10]. Though the spanning tree model does not completely determine the Khovanov homology, it does greatly simplify the Khovanov chain complex used to compute the Khovanov homology. In some cases, such simplifications are enough to deduce interesting results. For example, Lee’s result on the Khovanov homology of alternating knots is reproved in [2; 11] by the spanning tree model.
Unenhanced Helical CT of Ureterolithiasis: Value of the Tissue Rim Sign

The tissue rim sign-a rim or halo of soft-tissue attenuation seen around the circumference of an intraureteral calculus on unenhanced axial CT-has been described as useful in differentiating ureteral calculi from extraurinary abdominal or pelvic calcifications. The purpose of this study was to determine the prevalence of the tissue rim sign in patients with ureterolithiasis and extraurinary calcifications and to determine the relationship between the tissue rim sign, the size of a calculus, and the degree of urinary obstruction.Unenhanced helical CT studies followed by excretory urography were obtained in 59 patients with suspected acute ureterolithiasis. Each calcification along the expected course of the ureter seen on axial CT scans was categorized as a ureteral calculus or as an extraurinary calcification. Each categorization was based on CT, urographic, and clinical findings and the presence or absence of a tissue rim sign. When the outer wall of the ureter could not be seen because there was no clea...
A Broad Perspective on the Dynamics of Highly Confined Polymer Films

The manner in which the dynamics of a polymer are affected by thin film confinement is of technological significance, impacting thin film applications such as lubricants, adhesives, and chemically amplified photoresists. In this manuscript we use specular X-ray reflectivity (SXR), beam positron annihilation lifetime spectroscopy (PALS), and incoherent neutron scattering (INS) to study the influence of thin film confinement on the apparent glass transition temperature Tg and the thermal expansion coefficients of thin polycarbonate (PC) films. Both the SXR and PALS indicate a significant suppression of Tg when the film thickness becomes less than 200 A. However, the INS measurements suggest an increase in the apparent Tg below this same length scale. These disparate estimates of the thin film Tg seem to indicate that each technique is sensitive to slightly different aspects of the glass formation process. However, all three agree that thin film confinement results in reduced thermal motion, regardless of the precise temperature that is ‘designated’ as the thin film Tg.
Elasticity theory of a twisted stack of plates

We present an elastic model of B-form DNA as a stack of thin, rigid plates or base pairs that are not permitted to deform. The symmetry of DNA and the constraint of plate rigidity limit the number of bulk elastic constants contributing to a macroscopic elasticity theory of DNA to four. We derive an effective twist-stretch energy in terms of the macroscopic stretch \(\) along and relative excess twist \(\) about the DNA molecular axis. In addition to the bulk stretch and twist moduli found previously, we obtain a twist-stretch modulus with the following remarkable properties: 1) it vanishes when the radius of the helical curve following the geometric center of each plate is zero, 2) it vanishes with the elastic constant K23 that couples compression normal to the plates to a shear strain, if the plates are perpendicular to the molecular axis, and 3) it is nonzero if the plates are tilted relative to the molecular axis. This implies that a laminated helical structure carved out of an isotropic elastic medium will not twist in response to a stretching force, but an isotropic material will twist if it is bent into the shape of a helix.
Optimally learning social networks with activations and suppressions

In this paper we consider the problem of learning hidden independent cascade social networks using exact value injection queries. These queries involve activating and suppressing agents in the target network. We develop an algorithm that optimally learns an arbitrary social network of size n using O(n^2) queries, matching the information theoretic lower bound that we prove for this problem. We also consider the case when the target social network forms a tree and show that the learning problem takes @Q(nlog(n)) queries. We also give an approximation algorithm for finding an influential set of nodes in the network, without resorting to learning its structure. Finally, we discuss some limitations of our approach, and limitations of path-based methods, when non-exact value injection queries are used.
Numerical Study of Heterogeneous Reactions in an SOFC Anode with Oxygen Addition

Previous experimental studies have shown that addition of smallamounts of oxygen to a hydrocarbon fuel stream can controlcoking in the anode, while relatively large amounts of oxygenare present in the fuel stream in single-chamber SOFCs. Inorder to rationally design an anode for such use, it isimportant to understand the coupled catalytic oxidation /reforming chemistry and diffusion within the anode under SOFCoperating conditions. In this study, the heterogeneous catalyticreactions in the anode of an anode-supported SOFC running onmethane fuel with added oxygen are numerically investigated,using a model that accounts for catalytic chemistry, porousmedia transport, and electrochemistry at the anode/electrolyteinterface. Using an experimentally validated heterogeneousreaction mechanism for methane partial oxidation and reformingon nickel, we identify three distinct reaction zones atdifferent depths within the anode: a thin outer layer in whichoxygen is nearly fully consumed in oxidizing methane andhydrogen, followed by a reforming region, then a water-gas shiftregion deep within the anode. Based on these insights into thechemistry, the possibility of a composite anode with differentlayers of metal catalysts is also explored for the improvementof fuel cell performance.
A CASE FOR SUBVENTION OF PRIVATE LANDOWNERS IN THE LOUISIANA COASTAL ZONE

The Louisiana Coastal Zone (LCZ) is experiencing an unparalleled crisis of wetland loss, most of which (75%) is occurring on private lands. This paper use agricultural conservation policy as a comparative construct in a commentary that examines the rationale and methodology of providing economic incentives to subsidize wetland restoration on private lands in the LCZ.
Support Varieties and Representation Type of Small Quantum Groups

In this paper, we provide a wildness criterion for any finite dimensional Hopf algebra with finitely generated cohomology. This generalizes a result of Farnsteiner to not necessarily cocommutative Hopf algebras over ground fields of arbitrary characteristic. Our proof uses the theory of support varieties for modules, one of the crucial ingredients being a tensor product property for some special modules. As an application, we prove a conjecture of Cibils stating that small quantum groups of rank at least two are wild.
An Integrated Neighbor Discovery and MAC Protocol for Ad Hoc Networks Using Directional Antennas

Many MAC sub-layer protocols for supporting the usage of directional antennas in ad hoc networks have been proposed in literature. However, there remain two open issues that are yet to be resolved completely. First, in order to fully exploit the spatial diversity gains possible due to the use of directional antennas, it is essential to shift to the exclusive usage of directional antennas for the transmission and reception of all the MAC layer frames. This would facilitate maximal spatial reuse and will efface the phenomena of asymmetry in gain. Second, in the presence of mobility the MAC protocol should incorporate mechanisms by which a node can efficiently discover and track its neighbors. In this paper we propose PMAC, a new MAC protocol that addresses both the issues in an integrated way. PMAC incorporates an efficient mechanism for neighbor discovery, and a scheduling based medium sharing that allows for exclusive directional transmissions and receptions. We perform analysis and simulations to understand the performance of our scheme. We find that each node, on average, can achieve a per node utilization of about 80% in static and about 45% in mobile scenarios. In terms of throughput, our protocol is seen to outperform both the traditional IEEE 802.11 and previously proposed MAC protocols for use with directional antennas in ad hoc networks
Optimal number of annuli for maximizing the lifetime of sensor networks

The most effective way to maximize the lifetime of a wireless sensor network (WSN) is to allocate initial energy to sensors such that they exhaust their energy at the same time. The lifetime of a WSN as well as an optimal initial energy allocation are determined by a network design. The main contribution of the paper is to show that the lifetime of a WSN can be maximized by an optimal network design. We represent the network lifetime as a function of the number m of annuli and show that m has significant impact on network lifetime. We prove that if the energy consumed by data transmission is proportional to d α + c , where d is the distance of data transmission and α and c are some constants, then for a circular area of interest with radius R , the optimal number of annuli that maximizes the network lifetime is m = R ( ( α - 1 ) / c ) 1 / α for an arbitrary sensor density function. Maximize the lifetime of a wireless sensor network by optimal network design.Represent the network lifetime as a function of the number of annuli.Find an expression of the optimal number of annuli for an arbitrary sensor density function.
Synthesis of functionalized organotrifluoroborates via halomethyltrifluoroborates.

Potassium bromo- and iodomethyltrifluoroborates have been prepared via in situ reaction of n-BuLi with dibromo- and diiodomethane, respectively, in the presence of trialkyl borates, followed by treatment with KHF2. Moreover, a new synthetic method for the preparation of potassium organotrifluoroborates through nucleophilic substitution of the halide in these potassium halomethyltrifluoroborates is described.
Multilevel multidimensional item response model with a multilevel latent covariate

In a pre-test-post-test cluster randomized trial, one of the methods commonly used to detect an intervention effect involves controlling pre-test scores and other related covariates while estimating an intervention effect at post-test. In many applications in education, the total post-test and pre-test scores, ignoring measurement error, are used as response variable and covariate, respectively, to estimate the intervention effect. However, these test scores are frequently subject to measurement error, and statistical inferences based on the model ignoring measurement error can yield a biased estimate of the intervention effect. When multiple domains exist in test data, it is sometimes more informative to detect the intervention effect for each domain than for the entire test. This paper presents applications of the multilevel multidimensional item response model with measurement error adjustments in a response variable and a covariate to estimate the intervention effect for each domain.
Linear quadratic regulator loop shaping for high frequency compensation

This paper establishes a design technique that incorporates high-frequency design specifications into the framework of the LQG/LTR technique. This will be accomplished by augmenting plant input with extra dynamics. Singular perturbation techniques will be used to select input weighting functions for the LQR design. The change in nominal design due to the plant input augmentation will be quantified. An estimate of the change of the loop transfer function in the performance region will be determined.
Centralizers of the infinite symmetric group

We review and introduce several approaches to the study of centralizer algebras of the infinite symmetric group $S_{\infty}$. Our work is led by the double commutant relationship between finite symmetric groups and partition algebras; in the case of $S_{\infty}$, we obtain centralizer algebras that are contained in partition algebras. In view of the theory of symmetric functions in non-commuting variables, we consider representations of $S_{\infty}$ that are faithful and that contain invariant elements; namely, non-unitary representations on sequence spaces.
Export specialization and economic growth around the world

Abstract This paper empirically investigates the extent to which technological characteristics in exports affect the patterns of trade-led economic growth across countries. Data of the Balassa index, which captures a country's revealed comparative advantage, are obtained for industries classified by technological intensity. Regression results based on a sample of 71 countries since 1970 suggest that economies have tended to grow more rapidly when they have increasingly specialized in exporting high-technology as opposed to traditional or low-technology goods. The findings are robust to the presence of various control variables as well as the consideration of parameter heterogeneity and in the endogeneity of export structures.
Discrete Morse functions from lexicographic orders

This paper shows how to construct a discrete Morse function with a relatively small number of critical cells for the order complex of any finite poset with O and I from any lexicographic order on its maximal chains. Specifically, if we attach facets according to the lexicographic order on maximal chains, then each facet contributes at most one new face which is critical, and at most one Betti number changes; facets which do not change the homotopy type also do not contribute any critical faces. Dimensions of critical faces as well as a description of which facet attachments change the homotopy type are provided in terms of interval systems associated to the facets. As one application, the Mobius function may be computed as the alternating sum of Morse numbers. The above construction enables us to prove that the poset Π n /S λ of partitions of a set {1 λ 1,...,k λ k} with repetition is homotopy equivalent to a wedge of spheres of top dimension when A is a hook-shaped partition; it is likely that the proof may be extended to a larger class of A and perhaps to all A, despite a result of Ziegler (1986) which shows that Π n /S λ is not always Cohen-Macaulay.
An analysis and procedure for determining space environmental sink temperatures with selected computational results

The purpose of this paper is to analyze the heat transfer problem posed by the determination of spacecraft temperatures and to incorporate the theoretically derived relationships into a computational code. Subject code is based on a theoretical analysis of thermal radiative equilibrium in space, particularly in the Solar System. Starting with the solar luminosity, the code takes into account a number of key variables, namely; the spacecraft-to-Sun distance expressed in AU (Astronomical Units), with, 1 AU representing the average Sun-to-Earth distance of 149.6 million km; the angle (degrees of arc) at which solar radiation is incident on a spacecraft surface, the temperature of which is to be determined (i.e., a radiator or PV (photovoltaic) array); the absorptivity-to-emissivity ratio of the surface, /spl alpha///spl epsiv/, with respect to solar radiation; and the view factor of the surface to space.
Nanotechnology and in situ remediation: a review of the benefits and potential risks

In this review, we focus on environmental cleanup and provide a background and overview of current practice; research findings; societal issues; potential environment, health, and safety implications; and future directions for nanoremediation. We also discuss nanoscale zero-valent iron in detail. We searched the Web of Science for research studies and accessed recent publicly available reports from the U.S. Environmental Protection Agency and other agencies and organizations that addressed the applications and implications associated with nanoremediation techniques. We also conducted personal interviews with practitioners about specific site remediations. We aggregated information from 45 sites, a representative portion of the total projects under way, to show nanomaterials used, types of pollutants addressed, and organizations responsible for each site. Nanoremediation has the potential not only to reduce the overall costs of cleaning up large-scale contaminated sites but also to reduce cleanup time, eliminate the need for treatment and disposal of contaminated soil, and reduce some contaminant concentrations to near zero - all in situ.
Intergalactic baryon-rich regions at high redshift

Using a high-resolution cosmological simulation of reionization, we have examined the differing structures formed by gas and dark matter at a redshift of 5.1. Baryon-rich regions form a small number of filaments, which connect the largest galaxies in the simulation. More detailed examination of the 10 largest galaxies reveals long, slender gaseous filaments about five proper kpc in width radiating from the galaxy centers. Extending out from each filament are a few smooth, thin, nearly planar gaseous sheets. By contrast, the dark matter concentrates into quasi-spherical bodies. The results have implications for our understanding of structure formation in the early Universe and of the Lyman a forest.
Viscous-fluid reaction to a torsionally oscillating spheroid: Linearized steady-state weak-separation solution

The steady-state linearized problem of a prolate (oblate) spheroid torsionally oscillating in an infinite, viscous, incompressible fluid is considered. The use of spheroidal co-ordinates results in a separable partial differential equation whose solutions are orthogonal spheroidal functions. The solution of the boundary-value problem is then expressible as an infinite series of spheroidal functions. However, it is quite difficult to convert a spheroidal function series into a series in powers of the eccentricity. Here it is shown that with the use of a special «modified spheroidal» co-ordinate system the solution of the linearized Navier-Stokes equations can be obtained directly in the form of a perturbation expansion in powers of the square of the eccentricity. Both the azimuthal fluid velocity and resulting torsional reaction of the fluid on the spheroid are evaluated to all orders in the perturbation expansion. These results illustrate the usefulness of the «weak separation» method of solving certain partial-differential-equation boundary-value problems.
Algorithms for bispectra: Forecasting, optimal analysis, and simulation

We propose a factorizability ansatz for angular bispectra which permits fast algorithms for forecasting, analysis and simulation, yet is general enough to encompass many interesting cosmic microwave background (CMB) bispectra. We describe a suite of general algorithms which apply to any bispectrum which can be represented in factorizable form. First, we present algorithms for Fisher matrix forecasts and the related problem of optimizing the factorizable representation, giving a Fisher forecast for Planck as an example. We show that the CMB can give independent constraints on the amplitude of primordial bispectra of both local and equilateral shape as well as those created by secondary anisotropies. We also show that the integrated Sachs–Wolfe (ISW)-lensing bispectrum should be detected by Planck and could bias estimates of the local type of non-Gaussianity if not properly accounted for. Second, we implement a bispectrum estimator which is fully optimal in the presence of sky cuts and inhomogeneous noise, extends the generality of fast estimators which have been limited to a few specific forms of the bispectrum and improves the running time of existing implementations by several orders of magnitude. Third, we give an algorithm for simulating random, weakly non-Gaussian maps with prescribed power spectrum and factorizable bispectrum.
The National Ignition Facility: the path to a carbon-free energy future

The National Ignition Facility (NIF), the world's largest and most energetic laser system, is now operational at Lawrence Livermore National Laboratory. The NIF will enable exploration of scientific problems in national strategic security, basic science and fusion energy. One of the early NIF goals centres on achieving laboratory-scale thermonuclear ignition and energy gain, demonstrating the feasibility of laser fusion as a viable source of clean, carbon-free energy. This talk will discuss the precision technology and engineering challenges of building the NIF and those we must overcome to make fusion energy a commercial reality.
Synthesis of phosphatase-resistant analogues of phytic acid (InsP6)

Abstract Phytic acid is enzymatically catabolized to numerous inositol polyphosphates and subsequently to myo-inositol and inorganic phosphate. These conversions are important in energy metabolism, metabolic regulation, and signal transduction pathways. A concise synthesis of phosphatase-resistant analogues of phytic acid (InsP6) is described in which the P-1 phosphate has been replaced by phosphorothioate, phosphoroselenate, or methylphosphonate moieties. In addition, a new synthesis of P-1 tethered aminoalkyl InsP6 and the corresponding affinity resin are described.
A simple and versatile method for alkene epoxidation using aqueous hydrogen peroxide and manganese salophen catalysts

Abstract We describe a simple and versatile method for the catalytic epoxidation of a broad range of olefins (e.g., ketones, esters, and alkyl halides) with aqueous H2O2 using manganese salophen catalysts. Low catalyst loading, short reaction times, and a simple reaction setup (e.g., no pH buffer is required) are salient features of the system, which unites the benefits of H2O2 as an oxidant with the versatility and modularity of salen-based catalysts.
Laterally Driven Polysilicon Resonant Microstructures

Abstract Interdigitated finger (comb) structures are demonstrated to be effective for exciting electrostatically the resonance of polysilicon microstructures parallel to the plane of the substrate. Linear plates suspended by a folded-cantilever truss and torsional plates suspended by spiral and serpentine springs are fabricated from a 2 μm-thick phosphorus-doped low-pressure chemical-vapor-deposited (LPCVD) polysilicon film. Resonance is observed visually, with frequencies ranging from 18 kHz to 80 kHz and quality factors from 20 to 130. Simple beam theory is adequate for calculating the resonance frequencies, using a Young's modulus of 140 GPa and neglecting residual strain in the released structures.
How Insights from the “New” JDM Research Can Improve Auditor Judgment: Fundamental Research Questions and Methodological Advice

SUMMARY: We examine recent developments in judgment and decision-making (JDM) research to provide insight into how two big ideas in this area can be leveraged as overlapping frameworks to examine and improve auditor judgment. The ideas are (1) that human thinking and reasoning can be characterized by a dual-process model and (2) that conscious and nonconscious goals drive cognition. Despite that these ideas are well established in the broader JDM literature and have great promise for improving auditor judgment, we observe minimal use of them in the audit JDM literature. Thus, we briefly outline these ideas, and we develop fundamental, high-level research questions related to audit JDM research that are based on these ideas. Finally, we provide guidance for designing and evaluating experiments that effectively use these frameworks, whether in auditing or other rich decision-making contexts. The frameworks can help researchers improve audit quality by enhancing our understanding of auditors' judgment proces...
Stable wormholes on a noncommutative-geometry background admitting a one-parameter group of conformal motions

When Morris and Thorne first proposed the possible existence of traversable wormholes, they adopted the following strategy: maintain complete control over the geometry, thereby leaving open the determination of the stress–energy tensor. In this paper we determine this tensor by starting with a noncommutative-geometry background and assuming that the static and spherically symmetric spacetime admits conformal motions. We have shown that the wormhole obtained can be made stable to linearized radial perturbations.
Communication complexity of permutation-invariant functions

Motivated by the quest for a broader understanding of upper bounds in communication complexity, at least for simple functions, we introduce the class of "permutation-invariant" functions. A partial function f: {0, 1}n × {0, 1}n → {0, 1, ?} is permutation-invariant if for every bijection π: {1, . . ., n} → {1, . . ., n} and every x, y ∈ {0, 1}n, it is the case that f(x, y) = f(xπ, yπ). Most of the commonly studied functions in communication complexity are permutation-invariant. For such functions, we present a simple complexity measure (computable in time polynomial in n given an implicit description of f) that describes their communication complexity up to polynomial factors and up to an additive error that is logarithmic in the input size. This gives a coarse taxonomy of the communication complexity of simple functions. Our work highlights the role of the well-known lower bounds of functions such as Set-Disjointness and Indexing, while complementing them with the relatively lesser-known upper bounds for Gap-Inner-Product (from the sketching literature) and Sparse-Gap-Inner-Product (from the recent work of Canonne et al. [ITCS 2015]). We also present consequences to the study of communication complexity with imperfectly shared randomness where we show that for total permutation-invariant functions, imperfectly shared randomness results in only a polynomial blow-up in communication complexity after an additive O(log log n) overhead.
Microscopic theory of superconductivity

Key steps in the development of the microscopic understanding of superconductivity are discussed.
Buckling and its effect on the confined flow of a model capsule suspension

The rheology of confined flowing suspensions, such as blood, depends upon the dynamics of the components, which can be particularly rich when they are elastic capsules. Using boundary integral methods, we simulate a two-dimensional model channel through which flows a dense suspension of fluid-filled capsules. A parameter of principal interest is the equilibrium membrane perimeter, parameterized by ξ o, which ranges from round capsules with ξ o=1.0 to ξ o=3.0 capsules with a dog-bone-like equilibrium shape. It is shown that the minimum effective viscosity occurs for ξ o≈1.6, which forms a biconcave equilibrium shape, similar to a red blood cell. The rheological behavior changes significantly over this range; transitions are linked to specific changes in the capsule dynamics. Most noteworthy is an abrupt change in behavior for ξ o≈2.0, which correlates with the onset of capsule buckling. The buckled capsules have a more varied orientation and make significant rotational (rotlet) contributions to the capsule–capsule interactions.
Stability and complexity on a lattice: coexistence of species in an individual-based food web model

Abstract Theoretical studies of the stability of food webs have generally not incorporated space as a contingency affecting coexistence of species. Here, I considered the importance of spatial heterogeneity on the stability of an individual-based food web model. Individual agents diffused on a lattice of cells and interacted according to a set of probabilistic interaction coefficients. Simulations were run on both uniform and non-uniform lattices. The model had two modes: 1. a mean-field mode with global interactions, and 2. a spatially localized mode in which species interacted within local neighborhoods. Equilibrium number of species were compared among different simulations varying web connectance, interaction strength, and lattice heterogeneity. Local interactions resulted in more species rich webs, indicating greater stability. The addition of spatial heterogeneity to the lattice further altered relationships among species richness, web connectance, and interaction strength, and increased coexistence among species. The results did not support the stability criterion derived by May. However, an inverse relationship between web connectance and species richness was observed suggesting that the product of connectance and species richness may govern the stability of real, finite webs.
Wall Modeled Large Eddy Simulation of Airfoil Trailing Edge Noise

Large eddy simulation (LES) of airfoil trailing edge noise has largely been restricted to low Reynolds numbers due to prohibitive computational cost. Wall modeled LES (WMLES) is a computationally cheaper alternative that makes Reynolds numbers of practical importance accessible. A systematic investigation of trailing edge noise prediction using WMLES is conducted. Detailed comparisons are made with experimental data.