cssi/SciSciGPT-SciSciNet huggingface dataset:
Operationalizing Financial Covenants

We study the interplay between financial covenants and the operational decisions of a retailer that obtains financing through a secured, inventory-based lending contract. We characterize how leverage affects dynamic inventory decisions, and find that it can lead to surprising non-threshold policies, and perverse incentives such as sales under-reporting. We show that, under perfectly competitive lending, financial covenants are necessary and sufficient to restore channel optimality, and emerge as critical contract parameters. We characterize the optimal covenant terms in equilibrium, and perform comparative statics with respect to important operational details. Surprisingly, we find that retailers operating under higher demands, lower inventory depreciation rates or higher profit margins face more stringent covenants. Furthermore, we show that covenants are not substitutable by other contractual terms, such as interest rates and loan limits, even under a monopolistic lending market. We study the effect of additional operational flexibility, and show that it can impact covenant effectiveness in a surprising, non-monotonic way. Our results are well aligned with empirical findings in the finance and accounting literature, and also yield new insights that could be tested empirically.
Distance-dependent congestion pricing for downtown zones

Abstract A growing literature exploits macroscopic theories of traffic to model congestion pricing policies in downtown zones. This study introduces trip length heterogeneity into this analysis and proposes a usage-based, time-varying congestion toll that alleviates congestion while prioritizing shorter trips. Unlike conventional trip-based tolls the scheme is intended to align the fees paid by drivers with the actual congestion damage they do, and to increase the toll’s benefits as a result. The scheme is intended to maximize the number of people that finish their trips close to their desired times. The usage-based toll is compared to a traditional, trip-based toll which neglects trip length. It is found that, like trip-based tolls, properly designed usage-based tolls alleviate congestion. But they reduce schedule delay more than trip-based tolls and do so with much smaller user fees. As a result usage-based tolls leave most of those who pay with a large welfare gain. This may increase the tolls’ political acceptability.
The progenitors of subluminous type Ia supernovae

We find that spectroscopically peculiar subluminous SNe Ia come from an old population. Of the thirteen subluminous SNe Ia known, nine are found in E/S0 galaxies, and the remainder are found in early-type spirals. The probability that this is a chance occurrence is only 0.1%. The finding that subluminous SNe Ia are associated with an older stellar population indicates that for a sufficiently large lookback time (already accessible in current high redshift searches) they will not be found. Due to a scarcity in old populations, hydrogen and helium main sequence stars and He red giant stars that undergo Roche lobe overflow are unlikely to be the progenitors of subluminous SNe Ia. Earlier findings that overluminous SNe Ia (DELTA m{sub 15} (B) < 0.94) come from a young progenitor population are confirmed. The fact that subluminous SNe Ia and overluminous SNe Ia come from different progenitor populations and also have different properties is a prediction of the CO white dwarf merger progenitor scenario.
Recursive preferences and balanced growth

Abstract We study a class of utility functions that are defined recursively by an aggregator W x , y where u t = W c t , u t + 1 . In single-agent economies it is known that a sufficient condition for the existence of a balanced growth path is that utility should be homogenous of degree γ . In the context of a multi-agent economy we show that this restriction implies that either a balanced growth equilibrium fails to exist or all agents have the same constant discount factor. We suggest a generalization of recursive preferences wherein the intertemporal utility function is time dependent. Within this class we establish that there may exist a balanced growth equilibrium even if agents are different.
Finite Element Model for Hysteretic Friction Damping of Traveling Wave Vibration in Axisymmetric Structures

A finite element method is developed to treat the steady-state vibration of two axisymmetric structures-a base substructure and an attached damper substructure-that are driven by traveling wave excitation and that couple through a spatially distributed hysteretic friction interface. The base substructure is representative of a rotating brake rotor or gear, and the damper is a ring affixed to the base under preload and intended to control vibration through friction along the interface. In the axisymmetric approximation, the equation of motion of each substructure is reduced in order to the number of nodal degrees of freedom through the use of a propagation constant phase shift. Despite nonlinearity and with contact occurring at an arbitrarily large number of nodal points, the response during sticking, or during a combination of sticking and slipping motions, can be determined from a low-order set of computationally tractable nonlinear algebraic equations. The method is applicable to element types for longitudinal and bending vibration, and to an arbitrary number of nodal degrees of freedom in each substructure. In two examples, friction damping of the coupled base and damper is examined in the context of in-plane circumferential vibration (in which case the system is modeled as two unwrapped rods), and of out-of-plane vibration (alternatively, two unwrapped beams). The damper performs most effectively when its natural frequency is well below the base's natural frequency (in the absence of contact), and also when its natural frequency is well separated from the excitation frequency.
Rh-catalyzed desymmetrization of α-quaternary centers by isomerization-hydroacylation

We describe a Rh-catalyzed desymmetrization of all-carbon quaternary centers from α,α-bis(allyl)aldehydes by a cascade featuring isomerization and hydroacylation. This desymmetrization competes with two other novel olefin functionalizations that are triggered by C–H bond activation, including carboacylation and bisacylation. A BIPHEP ligand promotes enantioselective formation of α-vinylcyclopentanones. Mechanistic studies support irreversible and enantioselective olefin-isomerization followed by olefin-hydroacylation.
Self-field-induced chaotic electron motion in free electron lasers

It is shown that the inclusion of the equilibrium self-fields of the electron beam results in chaotic electron motion in the field configuration consisting of a constant-amplitude helical-wiggler magnetic field and a uniform axial guide field. The threshold value of the self-field parameter ϵ = ωpb2/4Ωc2 is determined for the onset of chaoticity in the Group-I and Group-II orbits for the parameter regime corresponding to moderately high beam current (and density). The time scale for self-field-induced changes in the particle orbits is found to be of the order of the beam-transit time through one wiggler period.
Powering Triton's recent geological activity by obliquity tides: Implications for Pluto geology

We investigate the origins of Triton’s deformed and young surface. Assuming Triton was captured early in solar system history, the bulk of the energy released during capture will have been lost, and cannot be responsible for its present-day activity. Radiogenic heating is sufficient to maintain a long-lived ocean beneath a conductive ice shell, but insufficient to cause convective deformation and yielding at the surface. However, Triton’s high inclination likely causes a significant ( 0.7) obliquity, resulting in large heat fluxes due to tidal dissipation in any subsurface ocean. For a 300 km thick ice shell, the estimated ocean heat production rate (0.3 TW) is capable of producing surface yielding and mobile-lid convection. Requiring convection places an upper bound on the ice shell viscosity, while the requirement for yielding imposes a lower bound. Both bounds can be satisfied with an ocean temperature 240 K for our nominal temperature-viscosity relationship, suggesting the presence of an antifreeze such as NH3. In our view, Triton’s geological activity is driven by obliquity tides, which arise because of its inclination. In contrast, Pluto is unlikely to be experiencing significant tidal heating. While Pluto may have experienced ancient tectonic deformation, we do not anticipate seeing the kind of young, deformed surfaces seen at Triton.
Inequality and Trade

We incorporate demand-side considerations in trade in a systematic but straightforward way. We do so by focusing on the role of inequality in the determination of trade flows and patterns. With nonhomothetic preferences, when countries are similar in all respects but asset inequality, we find that trade is driven by specialization in consumption ,n ot production. These assumptions allow us to generate some interesting international spillover effects of redistributive policies. We also look at the effects of combining inequality and endowment differences on trade flows, and see that this has implications for “the mystery of the missing trade.” We then study a model of monopolistic competition, and find a novel Vshaped relationship between the ratio of inter-industry to intra-industry trade and a country’s inequality. Finally, we look at how international differences in factor endowments affect this relationship between the ratio of inter- to- intra-industry trade and inequality. Our theory formalizes as well as modifies Linder’s conjecture about the relationship between intraindustry trade and the extent of similarity between trading partners.
Putting the “Con” into Constitutions: The Economics of Prison Gangs

This paper investigates the internal governance institutions of criminal enterprise by examining the law, economics, and organization of the La Nuestra Familia prison gang. To organize effectively within the confines of penitentiaries, the gang needs to provide a credible commitment for member safety to potential entrants and a means of preventing predation and misconduct within the gang. I analyze the governance structure outlined in the gang's written constitution and show how it solves the collective action problems associated with multilevel criminal enterprises. (JEL D23, K42, L23, P16) The Author 2008. Published by Oxford University Press on behalf of Yale University. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.
Identification of Panel Data Models with Endogenous Censoring

This paper analyzes the identification question in censored panel data models, where the censoring can depend on both observable and unobservable variables in arbitrary ways. Under some general conditions, we derive the tightest sets on the parameter of interest. These sets (which can be singletons) represent the limit of what one can learn about the parameter of interest given the model and the data in that every parameter that belongs to these sets is observationally equivalent to the true parameter. We consider two separate sets of assumptions, motivated by the previous literature, each controlling for unobserved heterogeneity with an individual specific (fixed) effect. The first imposes a stationarity assumption on the unobserved disturbance terms, along the �
Mitigation of 21st century Antarctic sea ice loss by stratospheric ozone recovery

[1] We investigate the effect of stratospheric ozone recovery on Antarctic sea ice in the next half-century, by comparing two ensembles of integrations of the Whole Atmosphere Community Climate Model, from 2001 to 2065. One ensemble is performed by specifying all forcings as per the Representative Concentration Pathway 4.5; the second ensemble is identical in all respects, except for the surface concentrations of ozone depleting substances, which are held fixed at year 2000 levels, thus preventing stratospheric ozone recovery. Sea ice extent declines in both ensembles, as a consequence of increasing greenhouse gas concentrations. However, we find that sea ice loss is ∼33% greater for the ensemble in which stratospheric ozone recovery does not take place, and that this effect is statistically significant. Our results, which confirm a previous study dealing with ozone depletion, suggest that ozone recovery will substantially mitigate Antarctic sea ice loss in the coming decades.
A method for taking models to the data

Abstract This paper develops a method for combining the power of a dynamic, stochastic, general equilibrium model with the flexibility of a vector autoregressive time-series model to obtain a hybrid that can be taken directly to the data. It estimates this hybrid model via maximum likelihood and uses the results to address a number of issues concerning the ability of a prototypical real business cycle model to explain movements in aggregate output and employment in the postwar US economy, the stability of the real business cycle model's structural parameters, and the performance of the hybrid model's out-of-sample forecasts.
A Convenient Synthesis of 2-(Alkylamino)pyridines

The synthesis of a series of 2-(alkylamino)pyridines (1) in three steps from 2-aminopyridine (4) is reported. The products were obtained in 67−91% overall yield from 4.
Individual Animal Selection Has the Potential to Improve Uniformity of Grazing on Foothill Rangeland

Uneven grazing distribution is a concern in rugged topography, because resources may be adversely impacted if livestock concentrate in gentle terrain near water. A study was conducted to determine if removing cattle with undesirable distribution patterns has the potential to increase uniformity of grazing. Before the study, 2 herds of cattle were observed by horseback observers during early mornings to establish terrain use patterns of individual animals. Cows were ranked on slope use and observed vertical and horizontal distance to water. Based on these rankings, cows were assigned to 1 of 2 treatments, hill climbers (observed on steeper slopes and farther from water) or bottom dwellers (used gentler slopes near water). Hill climber and bottom dweller cows grazed similar, but separate, pastures at 2 ranches during the 3-year study for a total of 8 comparisons. Based on a normalized and integrated index of terrain use from visual observations, hill climber cows used steeper and more distant areas from water (P = 0.06) than bottom dwellers. Hill climber cows tracked by global positioning system collars used steeper and more distant areas from water than bottom dwellers (P ≤ 0.09) during the first 4 weeks of the 6 weeks that pastures were grazed based on a normalized index of terrain use. Forage utilization was more uniform (P < 0.05) across slopes and varying horizontal distances to water in pastures grazed by hill climbers than by bottom dwellers. Stubble heights in riparian and coulee bottom areas were higher (P = 0.01) when grazed by hill climber cows (13.3 cm) than by bottom dwellers (8.1 cm). This study demonstrates that cattle with divergent grazing patterns when observed in the same pasture continue to use different terrain when separated, and it suggests that individual animal selection has the potential to increase uniformity of grazing.
Modeling the Effect of Injector Nozzle-Hole Layout on Diesel Engine Fuel Consumption and Emissions

Numerical simulations were used to study the effect of reduced nozzle-hole size and nozzle tip hole configuration on the combustion characteristics of a high speed direct injection diesel engine. The KIVA code coupled with the CHEMKIN chemistry solver was used for the calculations. The calculations were performed over wide ranges of equivalence ratio and injection timing. Three nozzle-hole layouts were considered: the base line conventional nozzle, and multi- and group-hole configurations. In the multihole case, the number of holes was doubled and the hole size was reduced, while keeping the same hole area as for the base line nozzle. The group-hole configuration used the same hole number and hole size as the multihole case, but pairs of holes were grouped with a close (0.2mm) spacing between the holes. The results of the mixture distributions showed that the group-hole configuration provides similar penetration and lower inhomogeneity to those of the base line large hole nozzle with the same nozzle flow area. Consequently, the fuel consumption and pollutant emissions, such as CO and soot, are improved by using the group-hole nozzle instead of the conventional hole nozzle over wide operating ranges. On the other hand, the multihole nozzle has advantages in its fuel consumption and CO emissions over the conventional hole layout at intermediate equivalence ratios (equivalence ratios from 0.56 to 0.84) and conventional injection timings (start of injection: 15deg before top dead center).
A KNOWLEDGE-BASED SYSTEM FOR THE IMAGE CORRESPONDENCE PROBLEM

The image correspondence problem has generally been considered the most difficult step in both stereo and temporal vision. Most existing approaches match area features or linear features extracted from an image pair. The approach described in this paper is novel in that it uses an expert system shell to develop an image correspondence knowledge-based system for the general image correspondence problem. The knowledge it uses consists of both physical properties and spatial relationships of the edges and regions in images for every edge or region matching. A computation network is used to represent this knowledge. It allows the computation of the likelihood of matching two edges or regions with logical and heuristic operators. Heuristics for determining the correspondences between image features and the problem of handling missing information will be discussed. The values of the individual matching results are used to direct the traversal and pruning of the global matching process. The problem of parallelizing the entire process will be discussed. Experimental results on real-world images show that all matching edges and regions have been identified correctly.
End User Development and Meta-Design: Foundations for Cultures of Participation

The first decade of the World Wide Web predominantly enforced a clear separation between designers and consumers. New technological developments, such as the participatory Web 2.0 architectures, have emerged to support social computing. These developments are the foundations for a fundamental shift from consumer cultures specialized in producing finished goods to cultures of participation in which all people can participate actively in personally meaningful activities. End-user development and meta-design provide foundations for this fundamental transformation. They explore and support new approaches for the design, adoption, appropriation, adaptation, evolution, and sharing of artifacts by all participating stakeholders. They take into account that cultures of participation are not dictated by technology alone: they are the result of incremental shifts in human behavior and social organizations. The design, development, and assessment of five particular applications that contributed to the development of our theoretical framework are described and discussed.
Native American Obesity: An Economic Model of the “Thrifty Gene” Theory

Native American obesity is hypothesized to result from three potential causes: (1) a genetic predisposition, or the “thrifty gene,” (2) a rational addiction to nutrients, and (3) dietary adjustment costs. These hypotheses are tested using a two-stage household production approach and scanner data from a panel of Native and non-Native supermarkets. Nutrient intake for both groups is strongly influenced by adjustment costs. Native Americans tend to place higher implicit valuations on protein relative to fats and carbohydrates compared to non-Natives. Consequently, reductions in real carbohydrate prices over time may be a cause of high incidence of Native American obesity.
Anion-Anion Bonding and Topology in Ternary Iridium Seleno-Stannides

The synthesis and physical properties of two new and one known Ir-Sn-Se compound are reported. Their crystal structures are elucidated with transmission electron microscopy and powder X-ray diffraction. IrSn0.45Se1.55 is a pyrite phase which consists of tilted corner-sharing IrX6 octahedra with randomly distributed (Sn-Se)(4-) and (Se-Se)(2-) dimers. Ir2Sn3Se3 is a known trigonally distorted skutterudite that consists of cooperatively tilted corner-sharing IrSn3Se3 octahedra with ordered (Sn-Se)2(4-) tetramers. Ir2SnSe5 is a layered, distorted β-MnO2 (pyrolusite) structure consisting of a double IrSe6 octrahedral row, corner sharing in the a direction and edge sharing in the b direction. This distorted pyrolusite contains (Se-Se)(2-) dimers and Se(2-) anions, and each double row is "capped" with a (Sn-Se)n polymeric chain. Resistivity, specific heat, and magnetization measurements show that all three have insulating and diamagnetic behavior, indicative of low-spin 5d(6) Ir(3+). Electronic structure calculations on Ir2Sn3Se3 show a single, spherical, nonspin-orbit split valence band and suggest that Ir2Sn3Se3 is topologically nontrivial under tensile strain due to inversion of Ir-d and Se-p states.
Bayesian optimization with exponential convergence

This paper presents a Bayesian optimization method with exponential convergence without the need of auxiliary optimization and without the δ-cover sampling. Most Bayesian optimization methods require auxiliary optimization: an additional non-convex global optimization problem, which can be time-consuming and hard to implement in practice. Also, the existing Bayesian optimization method with exponential convergence [1] requires access to the δ-cover sampling, which was considered to be impractical [1, 2]. Our approach eliminates both requirements and achieves an exponential convergence rate.
The axial ratio of hcp Fe and Fe–Ni–Si alloys to the conditions of Earth’s inner core

The Earth’s iron-rich inner core is seismically anisotropic, which may be due to the preferred orientation of Fe-rich hexagonal close packed (hcp) alloy crystals. Elastic anisotropy in a hexagonal crystal is related to its c / a axial ratio; therefore, it is important to know how this ratio depends on volume (or pressure), temperature, and composition. Experimental data on the axial ratio of iron and alloys in the Fe–Ni–Si system from 15 previous studies are combined here to parameterize the effects of these variables. The axial ratio increases with increasing volume, temperature, silicon content, and nickel content. When an hcp phase coexists with another structure, sample recovery and chemical analysis from each pressure-temperature point is one method for determining the phase’s composition and thus the position of the phase boundary. An alternate method is demonstrated here, using this parameterization to calculate the composition of an hcp phase whose volume, temperature, and axial ratio are measured. The hcp to hcp+B2 phase boundary in the Fe–FeSi system is parameterized as a function of pressure, temperature, and composition, showing that a silicon-rich inner core may be an hcp+B2 mixture. These findings could help explain observations of a layered seismic anisotropy structure in the Earth’s inner core.
Fees Eat Diversification's Lunch

Although diversification is often spoken of as the only free lunch in investing, the authors show that it is not free and that it must be considered in light of its costs. They also show that fees on diversifying asset classes are high relative to their risk-adjusted diversification benefit, with the more exotic asset classes carrying higher price tags. Because there is meaningful cross-sectional variation, fees need to be considered when making strategic asset allocation decisions.
Physical and electrochemical area determination of electrodeposited Ni, Co, and NiCo thin films

The surface area of electrodeposited thin films of Ni, Co, and NiCo was evaluated using electrochemical double-layer capacitance, electrochemical area measurements using the [Ru(NH $$_3$$ ) $$_6$$ ] $$^{3+}$$ /[Ru(NH $$_3$$ ) $$_6$$ ] $$^{2+}$$ redox couple, and topographic atomic force microscopy (AFM) imaging. These three methods were compared to each other for each composition separately and for the entire set of samples regardless of composition. Double-layer capacitance measurements were found to be positively correlated to the roughness factors determined by AFM topography. Electrochemical area measurements were found to be less correlated with measured roughness factors as well as applicable only to two of the three compositions studied. The results indicate that in situ double-layer capacitance measurements are a practical, versatile technique for estimating the accessible surface area of a metal sample.
Entropy, volume growth and SRB measures for Banach space mappings

We consider $$C^2$$ Frechet differentiable mappings of Banach spaces leaving invariant compactly supported Borel probability measures, and study the relation between entropy and volume growth for a natural notion of volume defined on finite dimensional subspaces. SRB measures are characterized as exactly those measures for which entropy is equal to volume growth on unstable manifolds, equivalently the sum of positive Lyapunov exponents of the map. In addition to numerous difficulties incurred by our infinite-dimensional setting, a crucial aspect to the proof is the technical point that the volume elements induced on unstable manifolds are regular enough to permit distortion control of iterated determinant functions. The results here generalize previously known results for diffeomorphisms of finite dimensional Riemannian manifolds, and are applicable to dynamical systems defined by large classes of dissipative parabolic PDEs.
Uniformly Moving Load on a Layered Half Plane

A problem of interest in studies of transmission of ground shock caused by a surface nuclear burst is that of the uniform motion of a steady pressure distribution over the surface of a half space. ...
Parallel and interacting stochastic approximation annealing algorithms for global optimisation

We present the parallel and interacting stochastic approximation annealing (PISAA) algorithm, a stochastic simulation procedure for global optimisation, that extends and improves the stochastic approximation annealing (SAA) by using population Monte Carlo ideas. The efficiency of standard SAA algorithm crucially depends on its self-adjusting mechanism which presents stability issues in high dimensional or rugged optimisation problems. The proposed algorithm involves simulating a population of SAA chains that interact each other in a manner that significantly improves the stability of the self-adjusting mechanism and the search for the global optimum in the sampling space, as well as it inherits SAA desired convergence properties when a square-root cooling schedule is used. It can be implemented in parallel computing environments in order to mitigate the computational overhead. As a result, PISAA can address complex optimisation problems that it would be difficult for SAA to satisfactory address. We demonstrate the good performance of the proposed algorithm on challenging applications including Bayesian network learning and protein folding. Our numerical comparisons suggest that PISAA outperforms the simulated annealing, stochastic approximation annealing, and annealing evolutionary stochastic approximation Monte Carlo.
Empirical Isoquants and Observable Optima: Cobb and Douglas at Seventy

The theory of production and derived demand for factor inputs seems abstract because of its dependence on unobservable marginal products. Seventy years ago, Charles Cobb and Paul Douglas showed that if the production function is linearly homogeneous, the theoretical propositions can be illustrated by observable wages and average products. This paper argues that economists can exploit this linkage between theory and observation to make production theory come alive in real-world data. A multicountry data set is used to illustrate how information on output per worker, output per unit of capital, and input prices can trace out theoretically defensible isoquants and labor demand curves. Choice of high capital-labor ratios are shown to be driven by relative wages across nations. Comparison of unit labor costs across nations demonstrates that high wages need not imply competitive disadvantage in international trade. Countries with inefficient input allocations are shown to be importers and/or highly protectionis, whereas countries with efficient input allocations are exporters. All these concepts are motivated by two-dimensional plots of real-world data that replicate textbook theoretical treatments with remarkable consistency. The paper closes with examples of how these plots have been used in classroom settings.
Geochemistry, thermal evolution, and cryovolcanism on Ceres with a muddy ice mantle

We present a model of the internal evolution of Ceres consistent with pre-Dawn observations and preliminary data returned by Dawn. We assume that Ceres accreted ice and both micron- and millimeter-sized rock particles and that micron-sized fines stayed suspended in liquid during differentiation. We conclude that aqueously altered grains were emplaced on Ceres's surface during the first tens of megayears of its evolution. Our geochemical simulations suggest that Ceres's unusual surface mineralogy is consistent with aqueous alteration of CM material, possibly by NH3-bearing fluid. Thermal evolution simulations including insulating fines yield present-day liquid at depth if Ceres has a small core or no core at all; otherwise, they yield temperatures at the core-mantle boundary of 240–250 K, just warm enough for chloride brines to persist and be freezing today. We hypothesize that ongoing freezing may overpressurize liquid or briny reservoirs, driving cryovolcanic outflow whose surface expression may have been observed by Dawn at Ceres's “bright spots.” These outflows may contribute to the water vapor being produced at Ceres.
Methodology of the RAND 2016 Presidential Election Panel Survey (PEPS)

The RAND 2016 Presidential Election Panel Survey (PEPS) uses the American Life Panel (ALP) to study voting intentions, public opinion, and voter behavior. The ALP is a scientifically recruited internet panel. Using the ALP allows us to contact the same people over time to study the evolution of their voting intentions, behavior and opinions. Furthermore, we follow previous RAND election polling by asking respondents about their voting intentions in probabilistic terms (percent chance), which improves forecasts. This document provides a detailed description of our methodology.
Learning in a Distributed Software Architecture for Large-Scale Neural Modeling

Progress on large-scale simulation of neural models depends in part on the availability of suitable hardware and software architectures. Heterogeneous hardware computing platforms are becoming increasingly popular as substrates for general-purpose simulation. On the other hand, recent work highlights that certain constraints on neural models must be imposed on neural and synaptic dynamics in order to take advantage of such systems. In this paper we focus on constraints related to learning in a simple visual system and those imposed by a new neural simulator for heterogeneous hardware systems, CogExMachina (Cog).
Pod learning: Student groups create podcasts to achieve economics learning goals

AbstractIn this article, the author describes a group project to create student-generated podcasts on economics topics. This project provides an innovative opportunity for students to demonstrate proficiency in skills required for the undergraduate economics major and valued in the professional marketplace. Results of a student self-assessment survey on the project reflect findings in the literature that collaborative assignments utilizing technology tools can provide opportunities for students to practice their economic proficiencies, for instructors to assess even the higher-level proficiencies, and for students to enjoy the learning process.
Remixing as a Pathway to Computational Thinking

Theorists and advocates of “remixing” have suggested that appropriation can act as a pathway for learning. We test this theory quantitatively using data from more than 2.4 million multimedia programming projects shared by more than 1 million users in the Scratch online community. First, we show that users who remix more often have larger repertoires of programming commands even after controlling for the numbers of projects and amount of code shared. Second, we show that exposure to computational thinking concepts through remixing is associated with increased likelihood of using those concepts. Our results support theories that young people learn through remixing, and have important implications for designers of social computing systems.
Atrioventricular Junction Ablation for Atrial Fibrillation

Atrioventricular junction (AVJ) ablation is an effective therapy in patients with symptomatic atrial fibrillation who are intolerant to or unsuccessfully managed with rhythm control or medical rate control strategies. A drawback is that the procedure mandates a pacing system. Overall, the safety and efficacy of AVJ ablation is high with a majority of the patients reporting significant improvement in symptoms and quality-of-life measures. Risk of sudden cardiac death after device implantation is low, especially with an appropriate postprocedure pacing rate. Mortality benefit with AVJ ablation has been shown in patients with heart failure and cardiac resynchronization therapy devices.
Association of Circulating Renin and Aldosterone With Osteocalcin and Bone Mineral Density in African Ancestry Families

Hypertension is associated with accelerated bone loss, and the renin-angiotensin-aldosterone system is a key regulator of blood pressure. Although components of this system are expressed in human bone cells, studies in humans are sparse. Thus, we studied the association of circulating renin and aldosterone with osteocalcin and bone mineral density. We recruited 373 African ancestry family members without regard to health status from 6 probands (mean family size: 62 and relative pairs: 1687). Participants underwent a clinical examination, dual-energy x-ray absorptiometry, and quantitative computed tomographic scans. Renin activity, aldosterone concentration, and osteocalcin were measured in fasting blood samples. Aldosterone/renin ratio was calculated as aldosterone concentration/renin activity. All models were analyzed using pedigree-based variance components methods. Full models included adjustment for age, sex, body composition, comorbidities, lifestyle factors, blood pressure, and antihypertensive medication. Higher renin activity was significantly associated with lower total osteocalcin and with higher trabecular bone mineral density (both P<0.01). There were also significant genetic correlations between renin activity and whole-body bone mineral density. There were no associations with aldosterone concentration in any model and results for aldosterone/renin ratio were similar to those for renin activity. This is the first study to report a significant association between renin activity and a marker of bone turnover and bone mineral density in generally healthy individuals. Also, there is evidence for significant genetic pleiotropy and, thus, there may be a shared biological mechanism underlying both the renin-angiotensin-aldosterone system and bone metabolism that is independent of hypertension.
Revenue and Incentive Effects of Basis Step-Up at Death: Lessons from the 2010 "Voluntary" Estate Tax Regime

Abstract In 2010, the U.S. estate tax expired and executors of wealthy decedents were not required to file estate tax returns. In the absence of the estate tax, beneficiaries received assets with carryover rather than stepped-up basis. Unrealized capital gains accounted for 44 percent of the fair market value of non-cash assets in estates that chose the carryover basis regime, and an even higher percentage for some asset categories. Many of the largest gains were on assets that had been held for at least two decades.
Microwave measurements of the tropolone-formic acid doubly hydrogen bonded dimer.

The microwave spectrum was measured for the doubly hydrogen bonded dimer formed between tropolone and formic acid. The predicted symmetry of this dimer was C2v(M), and it was expected that the concerted proton tunneling motion would be observed. After measuring 25 a- and b-type rotational transitions, no splittings which could be associated with a concerted double proton tunneling motion were observed. The calculated barrier to the proton tunneling motion is near 15 000 cm−1, which would likely make the tunneling frequencies too small to observe in the microwave spectra. The rotational and centrifugal distortion constants determined from the measured transitions were A = 2180.7186(98) MHz, B = 470.873 90(25) MHz, C = 387.689 84(22) MHz, DJ = 0.0100(14) kHz, DJK = 0.102(28) kHz, and DK = 13.2(81) kHz. The B3LYP/aug-cc-pVTZ calculated rotational constants were within 1% of the experimentally determined values.
Flexible Operation of Batteries in Power System Scheduling With Renewable Energy

The fast growing expansion of renewable energy increases the complexities in balancing generation and demand in the power system. The energy-shifting and fast-ramping capability of energy storage has led to increasing interests in batteries to facilitate the integration of renewable resources. In this paper, we present a two-step framework to evaluate the potential value of energy storage in power systems with renewable generation. First, we formulate a stochastic unit commitment approach with wind power forecast uncertainty and energy storage. Second, the solution from the stochastic unit commitment is used to derive a flexible schedule for energy storage in economic dispatch where the look-ahead horizon is limited. Analysis is conducted on the IEEE 24-bus system to demonstrate the benefits of battery storage in systems with renewable resources and the effectiveness of the proposed battery operation strategy.
Environmental management for the future

The field of cleaner technology continues to represent the major new direction for environmental management. Defining cleaner technology or pollution prevention is difficult because the context for use is very diverse. However, a typical definition is ‘All efforts closely related to or influencing manufacturing, that also reduce chemical loss or waste generation.’ Other definitions are described in this paper, as well as a history of pollution prevention in the United States. Economics remain a major driving force for the development and use of pollution prevention alternatives in industries providing goods and services. The tools for achieving cleaner technology are discussed to better understand the challenges to industry in implementing cleaner technology concepts.
Rhodium-catalyzed B-H activation of 1,2-azaborines: synthesis and characterization of BN isosteres of stilbenes.

The first example of catalytic B–H activation of azaborines leading to a new family of stilbene derivatives through dehydrogenative borylation is reported. Ten 1,2-azaborine-based BN isosteres of stilbenes have been synthesized using this method, including a BN isostere of a biologically active stilbene. It is demonstrated that BN/CC isosterism in the context of stilbenes can lead to significant changes in the observed photophysical properties such as higher quantum yield and a larger Stokes shift. Direct comparative analysis of BN stilbene 3g and its carbonaceous counterpart 6g is consistent with a stronger charge-transfer character of the excited state exhibited by 3g in which the 1,2-azaborine heterocycle serves as a better electron donor than the corresponding arene.
Imaging of turbulent buoyant jet mixing

This paper presents quantitative imaging measurements of jet fluid mole fraction fields in turbulent buoyant jets of helium issuing into air. The measurements use planar laser Rayleigh scattering. Signal levels are low, necessitating a novel approach to background subtraction in the signal processing. The jet flows considered are classified as momentum-driven, meaning that buoyancy effects are presumed to be confined to the small scales of the flow. We focus here on the near-nozzle, developing region of the jet, which is of particular interest to flows with combustion. The results suggest that buoyancy affects the details of the evolution of the mixing field even while the mean field maintains scaling properties consistent with non-buoyant jets. Specifically, the mean jet fluid mole fraction profiles show a sharper jet/ambient fluid interface relative to non-buoyant jets. The mole fraction fluctuations within the jet are also weaker than those reported in non-buoyant jets. These results will inform ongoing efforts to model the mixing process in flows with density differences, such as combustion systems.Copyright © 2006 by ASME
Access to Diverse Oxygen Heterocycles via Oxidative Rearrangement of Benzylic Tertiary Alcohols

A facile method for the synthesis of challenging medium-sized cyclic ethers has been developed via a novel oxidative rearrangement of benzylic tertiary alcohols. The reaction provides access to cyclic acetals with diverse substitution at both C2 and the aromatic ring. The unique reactivity is enabled by poly(cationic) hypervalent iodine reagents and represents the first synthetic application of this underexplored class of compounds.
Improving Financial Reports by Revealing the Accuracy of Prior Estimates

Several researchers (e.g., Lundholm 1999; Ryan 1997; Petroni, Ryan, and Wahlen 2000) have proposed a reporting mechanism to enhance the reliability of estimates and other forward-looking information in financial reports. Their proposals require companies to report reconciliations of prior-year estimates to actual realizations as supplemental information in their financial reports. Such disclosures would enable investors to distinguish between accurate and opportunistic reporting behavior, and, arguably, should create incentives for companies to estimate accurately in the first place. Our study provides evidence on these proposals. Specifically, we conduct two experiments within the context of an important intangible asset requiring estimation - software development costs. Our results show that the proposed reporting mechanism is effective in communicating information about the accuracy of financial estimates. We find, however, that not all disclosures are equally useful. The most effective disclosures explicitly describe the implications of misestimation (if any) on both the balance sheet and on earnings, thereby reducing the computational complexity associated with less explicit disclosures. Furthermore, our results show that when the disclosures explicitly describe the implications of misestimation, investors reward accurate estimators but do not explicitly punish those who are inaccurate. We conclude that information about previous estimate accuracy is useful to investors and that regulators should consider the type of disclosure, because not all disclosures may be equally effective in creating management incentives for accurate estimation. Moreover, the competitive advantage conferred on firms that provide accurate estimates arguably should create incentives for all companies to estimate accurately in the future.
Airship Buoyancy Control Using Inflatable Vacuum Chambers

Buoyancy control is identified as a significant problem in airships, past and present. An existing proposal to enhance the control of buoyancy in lighter-than-air aircraft is reviewed, and a new method of buoyancy control (the inflatable vacuum chamber) is proposed. The differences between the existing proposal and new proposal are highlighted, including the new possibility of an airship that lands vertically onto the ground without a mooring mast, a ground handling party, or a runway. Theory of lightweight stiff inflatable structures is discussed and a specific design and construction method is proposed. The design is optimized and confirmed elastically stable; design specifications are given. A typical operation cycle (including liftoff, flight, and touchdown) is detailed. An area of potential theoretical advancement is identified.
Neoglycoconjugates from synthetic tetra- and hexasaccharides that mimic the terminus of the O-PS of Vibrio cholerae O:1, serotype Inaba

A glycosyl acceptor and a glycosyl donor having the N-3-deoxy-L-glycero-tetronic acid side chain already attached have been prepared and used for the synthesis of the di- through to the hexasaccharide that mimic the upstream terminus of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Inaba. The target tetra- and the hexasaccharide, which were obtained in the form of 5-methoxycarbonylpentyl glycosides, were linked to BSA using squaric acid diester chemistry. The conjugation reactions were monitored by surface enhanced laser desorption ionization-time of flight mass spectrometry (SELDI-TOF MS). This allowed the progression of the conjugation of the synthetic oligosaccharides in a controlled way and termination of the reaction when the desired molar hapten/BSA ratio had been reached, yielding neoglycoconjugates with predetermined carbohydrate/carrier ratios. The ability to monitor the conjugation by the SELDI-TOF MS technique made it possible to prepare, from one hapten in a one-pot reaction, several neoglycoconjugates having different, predetermined carbohydrate/carrier ratios.
Synthetic Studies of Quinone Antitumor Antibiotics

Total syntheses of the nitrogen-containing quinone antitumor antibiotics saframycin B (2), cyanocycline A (3), and mitomycin C (6) are described. Brief retrosynthetic analyses of these challenging molecules are provided to show our basic synthetic strategy.
Coupling of Crystal Structure and Magnetism in the Layered, Ferromagnetic Insulator CrI3

We have examined the crystallographic and magnetic properties of single crystals of CrI3, an easily cleavable, layered and insulating ferromagnet with a Curie temperature of 61 K. Our X-ray diffraction studies reveal a first-order crystallographic phase transition occurring near 210–220 K upon warming, with significant thermal hysteresis. The low-temperature structure is rhombohedral (R3, BiI3-type) and the high-temperature structure is monoclinic (C2/m, AlCl3-type). We find evidence for coupling between the crystallographic and magnetic degrees of freedom in CrI3, observing an anomaly in the interlayer spacing at the Curie temperature and an anomaly in the magnetic susceptibility at the structural transition. First-principles calculations reveal the importance of proper treatment of the long-ranged interlayer forces, and van der Waals density functional theory does an excellent job of predicting the crystal structures and their relative stability. Calculations also suggest that the ferromagnetic order f...
Optimization of Refueling Schedule for Light-Water Reactors

A stagewise optimization of the refueling schedule for light-water reactors has been developed with emphasis on the nuclear model. The decision variables to be determined are end-of-cycle (EOC) rea...
Ruthenium-BINAP Catalyzed Alcohol C–H tert-Prenylation via 1,3-Enyne Transfer Hydrogenation: Beyond Stoichiometric Carbanions in Enantioselective Carbonyl Propargylation

The chiral ruthenium complex formed in situ from (TFA)2Ru(CO)(PPh3)2 and (R)-BINAP is found to catalyze the enantioselective C–C coupling of diverse primary alcohols with the 1,3-enyne, TMSC≡CC(Me)═CH2, to form secondary homopropargyl alcohols bearing gem-dimethyl groups. All reagents for this byproduct-free coupling are inexpensive and commercially available, making this protocol a practical alternative to stoichiometric carbanions in enantioselective carbonyl reverse prenylation.