cssi/SciSciGPT-SciSciNet huggingface dataset:
Unanticipated Features of the Multidimensional G -Normal Distribution

In one dimension, the theory of the G-normal distribution is well-developed, and many results from the classical setting have a nonlinear counterpart. Significant challenges remain in multiple dimensions, and some of what has already been discovered is quite nonintuitive. By answering several classically-inspired questions concerning independence, covariance uncertainty, and behavior under certain linear operations, we continue to highlight the fascinating range of unexpected attributes of the multidimensional G-normal distribution.
Implementing a Wiki as a collaboration tool for group projects

A Wiki is a web-based tool that allows people to contribute, edit, and read content on a particular subject. Wikis are commonly used as repositories of information and technical notes in fields such as software applications development. This paper describes one professor’s experience using a free Wiki as a collaboration tool in an undergraduate course in project design and planning. In the past, students in this course worked together to produce a highly detailed project specification in printed format that was then used to create a significant project in a succeeding course. The Wiki was used to not only replace the printed document, but also as a tool to gather ideas, make decisions, and capture knowledge. Introduction A Wiki is a relatively new service that is readily available on the World Wide Web that allows for the creation and management of content by anyone who is able, and hopefully qualified, to contribute. Perhaps the best known Wiki is the Wikipedia (http://www.wikipedia.org), which is the Web's largest and most popular reference site. The Wikipedia, itself has become the subject of much debate in academe because of the means by which any person can contribute to the reference with no systematic editorial oversight or factchecking mechanism. However, if the Wikipedia can be upheld as a model for education one need not look at the legitimacy of its content, but in the ways in which it empowers individuals to supply and edit said content with little or no experience in Web authoring. As an assistant professor of media arts, I was curious to know if this model could serve as a means for collaboration and knowledge capture in my courses so I implemented a free Wiki into two courses during the '06-'07 academic year.
Explain: a tool for performing abductive inference

This paper describes a tool called Explain for performing abductive inference. Logical abduction is the problem of finding a simple explanatory hypothesis that explains observed facts. Specifically, given a set of premises Γ and a desired conclusion ϕ, abductive inference finds a simple explanation Ψ such that Γ Λ Ψ ⊢ ϕ, and Ψ is consistent with known premises Γ. Abduction has many useful applications in verification, including inference of missing preconditions, error diagnosis, and construction of compositional proofs. This paper gives a brief tutorial introduction to EXPLAIN and describes the basic inference algorithm.
An integral representation for the product of two parabolic cylinder functions having unrelated arguments

An integral representation is provided for the parabolic cylinder function product Dμ(x)Dμ(−y), where Reμ y are unrelated. A few simple consequences are given in the form of hyperbolic integrals and a sum rule.
Oxygen-Deficient Metabolism And Corneal Edema

Wear of low-oxygen-transmissible soft contact lenses swells the cornea significantly, even during open eye. Although oxygen-deficient corneal edema is well-documented, a self-consistent quantitative prediction based on the underlying metabolic reactions is not available. We present a biochemical description of the human cornea that quantifies hypoxic swelling through the coupled transport of water, salt, and respiratory metabolites. Aerobic and anaerobic consumption of glucose, as well as acidosis and pH buffering, are incorporated in a seven-layer corneal model (anterior chamber, endothelium, stroma, epithelium, postlens tear film, contact lens, and prelens tear film). Corneal swelling is predicted from coupled transport of water, dissolved salts, and especially metabolites, along with membrane-transport resistances at the endothelium and epithelium. At the endothelium, the Na+/K+ - ATPase electrogenic channel actively transports bicarbonate ion from the stroma into the anterior chamber. As captured by the Kedem–Katchalsky membrane-transport formalism, the active bicarbonate-ion flux provides the driving force for corneal fluid pump-out needed to match the leak-in tendency of the stroma. Increased lactate-ion production during hypoxia osmotically lowers the pump-out rate requiring the stroma to swell to higher water content. Concentration profiles are predicted for glucose, water, oxygen, carbon dioxide, and hydronium, lactate, bicarbonate, sodium, and chloride ions, along with electrostatic potential and pressure profiles. Although the active bicarbonate-ion pump at the endothelium drives bicarbonate into the aqueous humor, we find a net flux of bicarbonate ion into the cornea that safeguards against acidosis. For the first time, we predict corneal swelling upon soft-contact-lens wear from fundamental biophysico-chemical principles. We also successfully predict that hypertonic tear alleviates contact-lens-induced edema.
Mapping post-fire habitat characteristics through the fusion of remote sensing tools

Abstract Post-fire snags provide important resources for cavity nesting communities as well as being subject to timber removal through salvage logging practices. Tools that can characterize their distributions along with other features important as wildlife habitat, such as woody shrub cover, would be useful for research and management purposes. Three dimensional lidar data and Landsat time series disturbance products have both shown varying promise in their ability to characterize aspects of dead biomass and understory cover, but studies exploring the combination of the remote sensing datasets calibrated with field data to model difficult to map habitat components are limited. The purpose of this study was to 1) relate lidar and Landsat time series products to field-collected calibration data to produce maps of important post-fire wildlife habitat components including snags of varying sizes and the availability of a woody shrub layer; and 2) compare the individual performance of the Landsat and lidar datasets for predicting the distributions of these difficult to map forest habitat features. Using 164 field calibration plots and remote sensing predictors, we modeled and mapped the distributions of our response variables including snag classes (dbh ≥ 40 cm, ≥ 50 cm, and ≥ 75 cm) and woody shrub cover thresholds (≥ 30 and ≥ 50% cover) at 10 m resolutions. Remote sensing predictors included various lidar structure and topography variables and Landsat time series products representing the pre-fire forest, disturbance magnitude, and current forest condition. A model was chosen for mapping purposes using AIC model selection and then by comparing leave-one-out-cross-validation error matrices to choose among competing models. We were able to predict and map all response variables with moderate accuracies and variable sensitivity (true positive) and specificity (true negative) rates. All snag and shrub models were considered to have “good” predictive performance as indicated by area under the curve values (0.74–0.91), with percent correctly classified values ranging from 69–85% when a probability threshold is chosen that balances false positive and false negative errors. Landsat models performed marginally better than lidar structure models according to classification statistics. Landsat-only models had slightly less accuracy than models that included lidar and Landsat data, but often with greater errors than the combined model. The ability to map the response variables with moderate errors and acceptable accuracies for many applications was through the fusion of these remote sensing datasets.
The Maximum Independent Sets of de Bruijn Graphs of Diameter 3

The nodes of the de Bruijn graph $B(d,3)$ consist of all strings of length $3$, taken from an alphabet of size $d$, with edges between words which are distinct substrings of a word of length $4$. We give an inductive characterization of the maximum independent sets of the de Bruijn graphs $B(d,3)$ and for the de Bruijn graph of diameter three with loops removed, for arbitrary alphabet size. We derive a recurrence relation and an exponential generating function for their number. This recurrence allows us to construct exponentially many comma-free codes of length 3 with maximal cardinality.
Generalized Navier-Stokes equations for active suspensions

We discuss a minimal generalization of the incompressible Navier-Stokes equations to describe the complex steady-state dynamics of solvent flow in an active suspension. To account phenomenologically for the presence of an active component driving the ambient fluid flow, we postulate a generic nonlocal extension of the stress-tensor, conceptually similar to those recently introduced in granular flows. Stability and spectral properties of the resulting hydrodynamic model are studied both analytically and numerically for the two-dimensional (2D) case with periodic boundary conditions. Future generalizations of this theory could be useful for quantifying the shear properties of active suspensions.
Redetermination of CaMn2O4.

The title compound, calcium dimanganese tetraoxide, CaMn2O4, was synthesized hydro­thermally and is made up of edge-sharing Mn3+ distorted octahedral layers and eight-coordinate Ca2+ centered polyhedral layers.
Morse theory, Milnor fibers and minimality of hyperplane arrangements

Through the study of Morse theory on the associated Milnor fiber, we show that complex hyperplane arrangement complements are minimal. That is, the complement of any complex hyperplane arrangement has the homotopy type of a CW-complex in which the number of p-cells equals the p-th betti number. Combining this result with recent work of Papadima and Suciu, one obtains a characterization of when arrangement complements are Eilenberg-Mac Lane spaces.
Massive MIMO as a Big Data System: Random Matrix Models and Testbed

This paper has two parts. The first one deals with how to use large random matrices as building blocks to model the massive data arising from the massive (or large-scale) multiple-input, multiple-output (MIMO) system. As a result, we apply this model for distributed spectrum sensing and network monitoring. The part boils down to the streaming, distributed massive data, for which a new algorithm is obtained and its performance is derived using the central limit theorem that is recently obtained in the literature. The second part deals with the large-scale testbed using software-defined radios (particularly, universal software radio peripheral) that takes us more than four years to develop this 70-node network testbed. To demonstrate the power of the software-defined radio, we reconfigure our testbed quickly into a testbed for massive MIMO. The massive data of this testbed are of central interest in this paper. For the first time, we have modeled the experimental data arising from this testbed. To our best knowledge, there is no other similar work.
Flat-plate photovoltaics with solar-tracking origami micro-concentrator arrays

A new PV architecture combining the advantages of concentration and flat-plate PVs is shown. Using origami techniques, fabrication and solar tracking of micro-concentrators were achieved.
Search for RPV Scalar Leptons at Tevatron

We reviewed CDF and D0 searches for R-parity violation supersymmetry in leptons involved final states using up to 344 {+-} 21 pb{sup -1} Tevatron Run II data of p{bar p} collisions at {radical}s = 1.96 TeV. All the results were in good agreement with the Standard Model expectations. No evidence of new physics was observed. However, owing to the improvement on detectors, energy and luminosity from Run I to Run II, the limits for the existence of R-parity violation supersymmetry have been greatly advanced.
Possible New Resonance at the D *bar D * Threshold in e + e - Annihilation

We argue that the recent CLEO-c data on e+e- annihilation into pairs of charmed mesons at c.m. energy around 4.0 GeV are not well described by a single resonance ψ(4040), but can be better understood if there is an additional narrow resonance with mass within few MeV from the $D^*\bar D^*$ threshold.
Prediction markets, mechanism design, and cooperative game theory

Prediction markets are designed to elicit information from multiple agents in order to predict (obtain probabilities for) future events. A good prediction market incentivizes agents to reveal their information truthfully; such incentive compatibility considerations are commonly studied in mechanism design. While this relation between prediction markets and mechanism design is well understood at a high level, the models used in prediction markets tend to be somewhat different from those used in mechanism design. This paper considers a model for prediction markets that fits more straightforwardly into the mechanism design framework. We consider a number of mechanisms within this model, all based on proper scoring rules. We discuss basic properties of these mechanisms, such as incentive compatibility. We also draw connections between some of these mechanisms and cooperative game theory. Finally, we speculate how one might build a practical prediction market based on some of these ideas.
Resonances for steplike potentials: Forward and inverse results

We consider resonances associated to the one dimensional Schrodinger operator -d 2 d x 2 + V(x), where V(x) = V + if x > x M and V(x) = V- if x < -x M , with V + ≠ V_. We obtain asymptotics of the resonance-counting function for several regions. Moreover, we show that in several situations, the resonances, V + , and V- determine V uniquely up to translation.
Language Independent Word Spotting in Scanned Documents

Large quantities of scanned handwritten and printed documents are rapidly being made available for use by information storage and retrieval systems, such as for use by libraries. We present the design and performance of a language independent system for spotting handwritten/printed words in scanned document images. The technique is evaluated with three scripts: Devanagari (Sanskrit/Hindi), Arabic (Arabic/Urdu) and Latin (English). Three main components of the system are a word segmenter, a shape based matcher for words, and a search interface. The user gives a query which can be (i) A word image (to spot similar words from a collection of documents written in that script) or (ii) text (to look for the equivalent word images in the script). The candidate words that are searched in the documents are retrieved and ranked, where the ranking criterion is a similarity score between the query and the candidate words based on global word shape features. For handwritten English, a precision of 60% was obtained at a recall of 50%. An alternate approach comprising of prototype selection and word matching, that yields a better performance for handwritten documents is also discussed. For printed Sanskrit documents, a precision as high as 90% was obtained at a recall of 50%.
Language Constructs and Runtime Systems for Compositional Parallel Programming

In task-parallel programs, diverse activities can take place concurrently, and communication and synchronization patterns are complex and not easily predictable. Previous work has identified compositionality as an important design principle for task-parallel programs. In this paper, we discuss alternative approaches to the realization of this principle. We first provide a review and critical analysis of Strand, an early compositional programming language. We examine the strengths of the Strand approach and also its weaknesses, which we attribute primarily to the use of a specialized language. Then, we present an alternative programming language framework that overcomes these weaknesses. This framework uses simple extensions to existing sequential languages (C++ and Fortran) and a common runtime system to provide a basis for the construction of large, task-parallel programs. We also discuss the runtime system techniques required to support these languages on parallel and distributed computer systems.
A 10 kW DC-DC converter using IGBTs with active snubbers

A full bridge DC-DC power converter is described that employs zero voltage switching (ZVS) on one leg and zero current switching (ZCS) on the other. This technique produces exceptionally low IGBT switching losses through the use of an active snubber that recycles energy back to the source. Experimental results are presented for a 10 kW, 20 kHz converter. >
Hybrid particle-fluid modeling of plasmas

Summary form only given. Particle in Cell (PIC) methods enjoy great success in modeling devices that include moderately dense plasmas. However, as the plasma density becomes high in a large volume, the number of particles to track becomes computationally prohibitive. Reducing the number of particles by creating larger "macro particles" introduces significant numerical error. Alternatively, high-density plasmas in large volumes can be modeled using a dielectric fluid description. However, such a description is not accurate for non-Maxwellian energy distributions. Some physical processes, such as air breakdown phenomena, involve high-density plasmas with energy distributions that are partially Maxwellian but include a long, high-energy tail. The particles in the high-energy tail are those responsible for the majority of interactions that lead to a qualitative change in the physical behavior. Thus, a fluid description that neglects the high-energy tail fails to capture the physics of interest. A hybrid plasma description has the potential to capture the relevant physics in a tractable computational time. The hybrid description uses a fluid treatment for the particles that fall within the Maxwellian energy distribution, and uses PIC to model the particles in the high-energy tail. The computations are performed using the Improved Concurrent Electromagnetic Particle in Cell (ICEPIC) code. The PIC and fluid models have been tested both independently and in combination. In all cases, the computational techniques were able to accurately reproduce the theoretical curves for the dispersion relation and the transmitted power of electromagnetic plane waves incident on a plasma in a two dimensional box. Adding collisions of the plasma particles with a background gas will affect the transmission of electromagnetic radiation through a dense plasma. We wish to study this effect by adding collisions to ICEPIC; a modification that complicates the modeling because it requires that the fluid and particle treatments are consistent in the way they interact with the background gas. Consistency will ensure that changes in partial distributions of particles and fluid that make up the hybrid will not result in different predictions for the transmitted power. Future computations that involve a growth of the plasma density over many orders of magnitude will require several adjustments of the particle-fluid balance, so it is important to verify consistency. We test this by investigating the sensitivity of the collisional model to shifts in the particle-fluid balance.
Solar products for poor rural communities as a business: lessons from a successful project in Uttar Pradesh, India

Can sales of solar products and services be a commercially viable business in poor rural communities? Although enthusiasm for off-grid electrification among researchers and practitioners is widespread, the determinants of commercial success in this domain remain poorly understood. This article reports results and lessons from a successful field project in Uttar Pradesh, India. In collaboration with a local social enterprise, Boond Engineering and Development, a small investment of USD 5000 was made to establish an energy center in the Unnao district of the state. The energy center became profitable immediately and generated seven dollars of business in solar home systems for every dollar invested during the 6-month evaluation period. Factors contributing to the success of the project included robust marketing, a strong banking partnership, the high quality of products, and continuous evaluation of staff performance. Challenges to sales of solar products included a bias in sales toward large solar home systems, the limited access to finance for poor households, and access to working capital. Overall, the energy center model holds considerable promise for alleviating energy poverty in rural India on a large scale.
Effective Interactions in Soft Materials

Soft materials, such as colloidal suspensions, polymer solutions, and biological systems, are typically multicomponent mixtures of macromolecules and simpler components (e.g., microions, monomers, solvent) that can assemble into complex structures spanning broad length and time scales. Many characteristic traits of soft matter, e.g., mechanical fragility, sensitivity to external influence, and tunable thermal and optical properties, emerge from a mingling of microscopic and mesoscopic constituents. Large asymmetries in size and charge between macromolecules and microscopic components often make impractical the explicit modeling of all degrees of freedom over physically significant length and time scales. The complexity often can be reduced, however, by pre-averaging (coarse-graining) the degrees of freedom of some microscopic components, thus mapping the real system onto a simpler model of fewer components, but governed by effective interparticle interactions. This chapter reviews the statistical mechanical foundations of effective interactions in soft materials and discusses illustrative applications to charged colloids, polyelectrolytes, and colloid-polymer mixtures
Portage and Path Dependence

We examine portage sites in the U.S. South, Mid-Atlantic, and Midwest, including those on the fall line, a geomorphological feature in the southeastern U.S. marking the final rapids on rivers before the ocean. Historically, waterborne transport of goods required portage around the falls at these points, while some falls provided water power during early industrialization. These factors attracted commerce and manufacturing. Although these original advantages have long since been made obsolete, we document the continuing importance of these portage sites over time. We interpret these results as path dependence and contrast explanations based on sunk costs interacting with decreasing versus increasing returns to scale.
Projection-based model reduction for contact problems

Large scale finite element analysis requires model order reduction for computationally expensive applications such as optimization, parametric studies and control design. Although model reduction for nonlinear problems is an active area of research, a major hurdle is modeling and approximating contact problems. This manuscript introduces a projection-based model reduction approach for static and dynamic contact problems. In this approach, non-negative matrix factorization is utilized to optimally compress and strongly enforce positivity of contact forces in training simulation snapshots. Moreover, a greedy algorithm coupled with an error indicator is developed to efficiently construct parametrically robust low-order models. The proposed approach is successfully demonstrated for the model reduction of several two-dimensional elliptic and hyperbolic obstacle and self contact problems. ∗Corresponding author Email address: maciej.balajewicz@stanford.edu (Maciej Balajewicz) 1Postdoctoral Fellow 2Engineering Research Associate 3Vivian Church Hoff Professor of Aircraft Structures
Mid‐Ocean Ridges

The global mid-ocean ridge system is a primary focus for energy transfer from the Earth's interior to the lithosphere, biosphere, hydrosphere, and atmosphere. In a coordinated effort to understand the causes and predict the consequences of mantle-driven physical, chemical, and biological fluxes through the ridge-crest system, the RIDGE (Ridge Inter-Disciplinary Global Experiments) Initiative will launch in 1991 a series of integrated studies of the mid-ocean ridge “RIDGE Steering Committee, 1989”. Seafloor observatories will be developed for monitoring temporal variation in active hydrothermal and volcanic systems on a decadal scale. Innovative seafloor instrumentation and work systems will perform physical, chemical, and biological measurements and sampling to address covariation among magmatic, tectonic, hydrothermal, and water-column components of the ridge-crest system. Initial studies may be focused on the Northeast Pacific.
Studies of Mg-substituted Li4-xMgxTi5O12 spinel electrodes (0 ≤ x ≤ 1) for lithium batteries

Magnesium-substituted Li{sub 4-x}Mg{sub x}Ti{sub 5}O{sub 12} spinel electrodes (0<x {<=}1) have been investigated as insertion electrodes for lithium batteries. The substitution of divalent Mg ions for monovalent Li ions in the structure necessitates that the difference in charge must be compensated by a reduction of an equivalent number of Ti cations from Ti{sup 4+} to Ti{sup 3+} . The substitution increases the conductivity of the [Ti{sub 5/3}Li{sub 1/3}]O{sub 4} spinel framework by many orders of magnitude, from {sigma} <10{sup -13} S cm{sup -1} for insulating Li{sub 4}Ti{sub 5}O{sub 12} (x = 0), in which all the titanium ions are tetravalent, to {sigma} = 10{sup -2} S cm{sup -1} for Li{sub 3}MgTi{sub 5}O{sub 12} (x = 1.0), in which the average titanium oxidation state is 3.8. The improved conductivity decreases the area specific impedance of Li/Li{sub 4-x}Mg{sub x}Ti{sub 5}O{sub 12} cells and increases the rate capability of electrodes for small x, typically x = 0.25. The rechargeable capacity of Li{sub 4-x}Mg{sub x}Ti{sub 5}O{sub 12} electrodes, particularly those with x close to 1 (130 mAh/g), is inferior to that of unsubstituted Li{sub 4}Ti{sub 5}O{sub 12} electrodes (x = 0, 150 mAh/g); the smaller capacity is attributed to the partial occupation of tetrahedralmore » (8a) sites by Mg ions in the spinel structure.« less
Characteristics of black carbon aerosol from a surface oil burn during the Deepwater Horizon oil spill

[1] Black carbon (BC) aerosol mass mixing ratio and microphysical properties were measured from the NOAA P-3 aircraft during active surface oil burning subsequent to the Deepwater Horizon oil rig explosion in April 2010. Approximately 4% of the combusted material was released into the atmosphere as BC. The total amount of BC introduced to the atmosphere of the Gulf of Mexico via surface burning of oil during the 9-week spill is estimated to be (1.35 ± 0.72) × 106 kg. The median mass diameter of BC particles observed in the burning plume was much larger than that of the non-plume Gulf background air and previously sampled from a variety of sources. The plume BC particles were internally mixed with very little non-refractory material, a feature typical of fresh emissions from fairly efficient fossil-fuel burning sources and atypical of BC in biomass burning plumes. BC dominated the total accumulation-mode aerosol in both mass and number. The BC mass-specific extinction cross-section was 10.2 ± 4.1 and 7.1 ± 2.8 m2/g at 405 and 532 nm respectively. These results help constrain the properties of BC emissions associated with DWH and other large spills.
The generalized spectral kurtosis estimator

Due to its conceptual simplicity and its proven effectiveness in real-time detection and removal of radio frequency interference (RFI) from radio astronomy data, the spectral kurtosis (SK) estimator is likely to become a standard tool of a new generation of radio telescopes. However, the SK estimator in its original form must be developed from instantaneous power spectral density estimates, and hence cannot be employed as an RFI excision tool downstream of the data pipeline in existing instruments where any time averaging is performed. In this Letter, we develop a generalized estimator with wider applicability for both instantaneous and averaged spectral data, which extends its practical use to a much larger pool of radio instruments.
Trees and the dynamics of polynomials

Dans ce travail, nous etudions des revetements ramifies d'arbres metriques simpliciaux F: T → T qui sont obtenus a partir d'applications polynomiales f: C → C possedant un ensemble de Julia non connexe. Nous montrons que la collection de tous ces arbres, a un facteur d'echelle pres, forme un espace contractile PT D qui compactifie l'espace des modules des polynomes de degre D. Nous montrons aussi que F enregistre le comportement asymptotique des multiplicateurs de f et que toute famille meromorphe de polynomes definis sur Δ* peut etre completee par un unique arbre comme sa fibre centrale. Dans le cas cubique, nous donnons une enumeration combinatoire des arbres ainsi obtenus et montrons que PT 3 est lui-meme un arbre.
The potential role of organizational setting in creating "Entitled" employees: An investigation of the antecedents of equity sensitivity

Existing research suggests that the equity sensitivity construct has both theoretical significance and applied value. This study investigates the antecedents of equity sensitivity, focusing on the relationships among organizational setting, personal characteristics (age, sex, work experience), organization tenure, and equity sensitivity. Results based on survey data from 613 individuals employed in ten diverse organizations suggest that organizational setting influences equity sensitivity levels among employees, Evidence of a significant relationship between age and equity sensitivity is also found. However, the relationship between organizational tenure and equity sensitivity found in previous studies is not replicated when adequate controls are included. Theoretical and practical implications of the findings are discussed.
HEAT PIPE REACTORS FOR SPACE POWER APPLICATIONS

A family of heat pipe reactors design concepts has been developed to provide heat to a variety of electrical conversion systems. Three power plants are described that span the power range 1-500 kWe and operate in the temperature range 1200-1700 K. The reactors are fast, compact, heat-pipe cooled, high-temperature nuclear reactors fueled with fully enriched refractory fuels, UC-ZrC or UO2. Each fuel element is cooled by an axially located molybdenum heat pipe containing either sodium or lithium vapor. Virtues of the reactor designs are the avoidance of single-point failure mechanisms, the relatively high operating temperature, and the expected long lifetimes of the fuel element components.
A Decision-Theoretic Framework for Numerical Attribute Value Reconciliation

One of the major challenges of data integration is to resolve conflicting numerical attribute values caused by data heterogeneity. In addressing this problem, existing approaches proposed in prior literature often ignore such data inconsistencies or resolve them in an ad hoc manner. In this study, we propose a decision-theoretical framework that resolves numerical value conflicts in a systematic manner. The framework takes into consideration the consequences of incorrect numerical values and selects the value that minimizes the expected cost of errors for all data application problems under consideration. Experimental results show that significant savings can be achieved by adopting the proposed framework instead of ad hoc approaches.
Friends, foes, and fringe: norms and structure in political discussion networks

Online discussion groups have a network structure that emerges from the interactions of thousands of participants, writing in thousands of topical threads. This structure varies greatly according to the type of discussion group, such as technical, fan or support. Political groups have their own distinctive structure, organized around ideologically polarized clusters of participants. Whereas in some other groups, individuals who vehemently disagree with the mainstream might be ignored or ostracized, in political groups most participants preferentially interact with "opponents" and ignore "friends." And yet, there is a type of opponent whose ideas are so far from the field of debate as to be ignored by most or nearly all other participants. This difference is starkly apparent in network diagrams of discussion groups. The core of highly participative discussants contains opponents from different ideological clusters, tightly bound in debate. But fringe contributors, sometimes called "trolls", are relegated to peripheral positions by central actors' lack of interest in responding to their provocations or views. Network visualizations of this phenomenon illustrate how macro-level structure arises and is maintained by micro-level discursive choices.
Importance of small earthquakes for stress transfers and earthquake triggering

[1] We estimate the relative importance of small and large earthquakes for static stress changes and for earthquake triggering, assuming that earthquakes are triggered by static stress changes and that earthquakes are located on a fractal network of dimension D. This model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other earthquakes increase with m as similar to 10(Dm/2). The stronger the spatial clustering, the larger the influence of small earthquakes on stress changes at the location of a future event as well as earthquake triggering. If earthquake magnitudes follow the Gutenberg-Richter law with b > D/2, small earthquakes collectively dominate stress transfer and earthquake triggering because their greater frequency overcomes their smaller individual triggering potential. Using a southern California catalog, we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10(alpha m), where alpha = 1.05 +/- 0.05. We also find that the magnitude distribution of triggered earthquakes is independent of the triggering earthquake's magnitude m. When alpha approximate to b, small earthquakes are roughly as important to earthquake triggering as larger ones. We evaluate the fractal correlation dimension D of hypocenters using two relocated catalogs for southern California. The value of D measured for distances 0.1 < r < 5 km is D = 1.54 for the Shearer et al. catalog and D = 1.73 for the Hauksson et al. catalog. The value of D reflects both the structure of the fault network and the nature of earthquake interactions. By considering only those earthquake pairs with interevent times larger than 1000 days, we can largely remove the effects of short-term clustering. Then D approximate to 2, close to the value D = 2 alpha = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D approximate to 2b implies that small earthquakes are as important as larger ones for stress transfers between earthquakes and that considering stress changes induced by small earthquakes should improve models of earthquake interactions.
Thermal noise and bit error rate limits in nanoscale memories

Analysis of the effects of thermal noise in nanoscale memories is presented. A theoretical analysis of thermal noise is used to predict the number of bit errors per year caused by thermal noise.
Chemical Looping Technology and Its Fossil Energy Conversion Applications

The concept of chemical looping reactions has been widely applied in chemical industries, for example, the production of hydrogen peroxide (H2O2) from hydrogen and oxygen using 9,10-anthraquinone as the looping intermediate. Fundamental research on chemical looping reactions has also been applied to energy systems, for example, the splitting of water (H2O) to produce oxygen and hydrogen using ZnO as the looping intermediate. Fossil fuel chemical looping applications had been used commercially with the steam-iron process for coal from the 1900s to the 1940s and had been demonstrated at a pilot scale with the carbon dioxide acceptor process in the 1960s and 1970s. There are presently no chemical looping processes using fossil fuels in commercial operation. A key factor that hampered the continued use of these earlier processes for fossil energy operation was the inadequacy of the reactivity and recyclability of the looping particles. This factor led to higher costs for product generation using the chemical ...
The limitations of Slater's element-dependent exchange functional from analytic density-functional theory.

Our recent formulation of the analytic and variational Slater-Roothaan (SR) method, which uses Gaussian basis sets to variationally express the molecular orbitals, electron density, and the one-body effective potential of density-functional theory, is reviewed. Variational fitting can be extended to the resolution of identity method, where variationality then refers to the error in each two-electron integral and not to the total energy. However, a Taylor-series analysis shows that all analytic ab initio energies calculated with variational fits to two-electron integrals are stationary. It is proposed that the appropriate fitting functions be charge neutral and that all ab initio energies be evaluated using two-center fits of the two-electron integrals. The SR method has its root in Slater’s Xα method and permits an arbitrary scaling of the Slater-Gaspar-Kohn-Sham exchange-correlation potential around each atom in the system. The scaling factors are Slater’s exchange parameters α. Of several ways of choosi...
The effects of aniline impurities on monopropellant hydrazine thruster performance

Both a 0.45-N and a 0.9-N thruster representative of the designs being flown on 3-axis stabilized spacecraft were used in testing various grades of hydrazine for the phenomenon of monopropellant hydrazine thruster catalyst bed poisoning. Both designs employed Shell 405 ABSG spontaneous catalyst. It is found that pulse shape distortion can be minimized, if not eliminated, by using aniline-free hydrazine. The mechanisms for both steady-state and pulse-mode performance loss are associated with the formation of a catalyst coke similar to the polycyclic aromatic poisons encountered in the petroleum industry. These poisoning mechanisms are reversible, with high-temperature operation being required to drive off the aniline coke deposits. It is recommended that a purified-grade hydrazine be considered for any mission that imposes operational conditions on a thruster which can result in aniline-induced poisoning of the catalyst bed.
SYNTHESIS OF THE 8-PHOSPHABICYCLO[3.2.1]OCTA-2,6-DIENE RING SYSTEM

Abstract The 8-phosphabicyclo[3.2.1]octa-2,6-diene ring system is conveniently synthesized by the addition of chloro(diisopropylamino)phosphenium ion ((Cl)(i-Pr2N)P+,1) to cycloheptatriene. Hydrolysis of the primary adduct yields the corresponding phosphinamide (3). The NMR of 3 is discussed in terms of its structure, and the orientation at P is assigned by a combination of 2-D NMR techniques. The structure of 3 is also probed by model calculations at the MNDO level.
New properties from PLA-PEO-PLA hydrogels.

Polymeric materials are important in many medical applications. Regenerative medicine offers the potential to repair or replace damaged tissue and polymers are an essential component of many tissue engineering approaches. Hydrogels have many advantageous properties but, generally, lack robust mechanical properties. At the same time, mounting evidence points to the importance of the matrix modulus when constructing devices. In this context, triblock copolymers made from poly(L-lactide)–poly(ethylene glycol)–poly(L-lactide) have been prepared and formulated into hydrogels. Investigations into their mechanical properties found the elastic modulus to be greater than 10 kPa which is at least one order of magnitude stiffer than previously reported from macromolecules composed of similar monomers. Part of the reason is the presence of crystalline lactide domains. Creating hydrogels with tailored modulus across the kPa range will likely have important ramifications in regenerative medicine.
Can the universe be represented by a superposition of spacetime manifolds

Abstract In this article it is argued, that the universe cannot be modeled as a space-time manifold. A theorem of geometry provides that null geodesics on a space-time manifold which begin at the same point with the same initial tangent vector are unique. But in reality, light originating from a single point with a given initial direction does not travel along a unique null geodesic path when a massive object attracts it, in particular when the massive object is in an indefinite location. Therefore, the universe cannot be described as a space-time manifold. It is then argued that the universe is a superposition of space-time manifolds, where the manifolds form a Hilbert space over the complex numbers.
Synthesis of a polymer -bound iron Lewis acid and its utilization in Diels-Alder reactions

Abstract The first polymer-bound iron Lewis acid 3 was synthesized in two steps from (η5-vinylcyclopentadienyl)dicarbonylmethyliron. Preliminary studies for catalysis of Diels-Alder reactions by the polymer-bound iron Lewis acid 3 are also reported.
Imaging of oscillatory behavior in event-related MEG studies

Since event-related components in MEG (magnetoencephalography) studies are often buried in background brain activity and environmental and sensor noise, it is a standard technique for noise reduction to average over multiple stimulus-locked responses or “epochs”. However this also removes event-related changes in oscillatory activity that are not phase locked to the stimulus. To overcome this problem, we combine time-frequency analysis of individual epochs with corticallyconstrained imaging to produce dynamic images of brain activity on the cerebral cortex in multiple time-frequency bands. While the SNR in individual epochs is too low to see any but the strongest components, we average signal power across epochs to find event related components on the cerebral cortex in each frequency band. To determine which of these components are statistically significant within an individual subject, we threshold the cortical images to control for false positives. This involves testing thousands of hypotheses (one per surface element and time-frequency band) for significant experimental effects. To control the number of false positives over all tests, we must therefore apply multiplicity adjustments by controlling the familywise error rate, i.e. the probability of one or more false positive detections across the entire cortex. Applying this test to each frequency band produces a set of cortical images showing significant eventrelated activity in each band of interest. We demonstrate this method in applications to high density MEG studies of visual attention.
World-volume action of the M-theory five-brane

Abstract This paper presents a 6d world-volume action that describes the dynamics of the M-theory five-brane in a flat 11 d space-time background. The world-volume action has global 11d super-Poincare invariance, as well as 6d general coordinate invariance and kappa symmetry, which are realized as local symmetries. The paper mostly considers a formulation in which general coordinate invariance is not manifest in one direction. However, it also describes briefly an alternative formulation, due to Pasti, Sorokin, and Tonin, in which general coordinate invariance is manifest. The latter approach requires auxiliary fields and new gauge invariances.
Correlation Between Wave Slopes And Near-Surface Ocean Currents

Abstract The development of wind generated currents in the ocean was studied with simultaneous observations of mean wind speed, wind direction, surface wave parameters and near-surface ocean current. The measurements were carried out during February 23 - March 14, 1976 as part of a coastal ocean boundary layer and diffusion study off Long Island, New York in the Atlantic Ocean. The results show a high correlation between wave slope and near-surface current indicating the possibility of wave age playing a significant role in the generation of current. Wave age is known to cause variations in momentum transfer (Kraus 1972; SethuRaman, 1978). The wind generated current was found to have a broad spectral peak as compared with tidal currents. This peak was found to occur at approximately the same frequency as wind speed spectral peak. Integral time scales associated with wind and near-surface current were about the same, indicating the dominance of wind forcing near the ocean surface for this period of observations.
Do large abelian monopole loops survive the continuum limit

Abstract An analysis of the monopole loop length distribution is performed in Wilson-action SU(2) lattice gauge theory. A pure power law in the inverse length is found, at least for loops of length, l , less than the linear lattice size N . This power shows a definite β dependence, passing 5 around β = 2.9, and appears to have very little finite lattice size dependence. It is shown that when this power exceeds 5, no loops any finite fraction of the lattice size will survive the infinite lattice limit. This is true for any reasonable size distribution for loops larger than N. The apparent lack of finite size dependence in this quantity would seem to indicate that abelian monopole loops large enough to cause confinement do not survive the continuum limit. Indeed they are absent for all β > 2.9.
Labor Market Dynamics in the U.S. Food Sector

A simultaneous equation model is estimated to explain labor market phenomena (including wages, employment, and labor productivity) and food prices at manufacturing and retail levels of the U.S. food industry. Dynamic simulation results show that endogenizing input costs in a fully specified markup-pricing model leads to a complex long-run pattern of food price determination. Wage determination is found to play a central role linking general price levels to food sector prices and labor market behavior. Energy price changes are shown to significantly affect food prices. Food sector labor productivity is found to decline in response to exogenous commodity price shocks.
The role of tellurium and antimony in PtTe/Al2O3 and PtSb/Al2O3 reforming catalysts

Abstract PtTe Al 2 O 3 and PtSb Al 2 O 3 bimetallic catalysts were studied using the model n -hexane isomerization, aromatization, and hydrocracking reactions at 673 K and the cyclohexane dehydrogenation reaction at 573 K, under atmospheric pressure in a recirculation batch reactor. An increase in the selectivity for isomerization (and a corresponding decrease in hydrocracking selectivity) was found for all coimpregnated PtTe Al 2 O 3 and PtSb Al 2 O 3 catalysts compared to Pt Al 2 O 3 . The change in selectivity can be caused either by electronic effects, which increase the specific activities for isomerization, or by geometric effects, which reduce the rate of hydrocracking. The results of the kinetic experiments, along with FTIR spectroscopy of adsorbed CO using the isotopic dilution method, suggest that electronic effects can be identified with Te Pt alloying in catalysts of low ( Te Pt ) Te content, while geometric effects predominate in catalyst formulations more concentrated in the post-transition metal. The dehydrogenation turnover frequencies were also enhanced at low Te Pt ratio; in this respect the dehydrogenation and isomerization reactions are similar. Direct six-member ring closure, rather than ring expansion by way of an adsorbed methylcyclopentane intermediate, accounted for most of the production of benzene. PtTe Al 2 O 3 catalysts were also prepared by vapor deposition of Te onto Pt Al 2 O 3 . These catalysts exhibited selectivities which were influenced by the type of carrier gas used to deposit the tellurium. A carrier gas containing n -hexane improved the selectivity relative to hydrogen or helium carrier gases. The mechanism of this selectivity effect is unknown but possibly due to carbon incorporation into a PtTe alloy.