cssi/SciSciGPT-SciSciNet huggingface dataset:
A modified gas-kinetic scheme for turbulent flow

The implementation of a turbulent gas-kinetic scheme into a finite-volume RANS solver is put forward, with two turbulent quantities, kinetic energy and dissipation, supplied by an allied turbulence model. This paper shows a number of numerical simulations of flow cases including an interaction between a shock wave and a turbulent boundary layer, where the shock-turbulent boundary layer is captured in a much more convincing way than it normally is by conventional schemes based on the Navier-Stokes equations. In the gas-kinetic scheme, the modeling of turbulence is part of the numerical scheme, which adjusts as a function of the ratio of resolved to unresolved scales of motion. In so doing, the turbulent stress tensor is not constrained into a linear relation with the strain rate. Instead it is modeled on the basis of the analogy between particles and eddies, without any assumptions on the type of turbulence or flow class. Conventional schemes lack multiscale mechanisms: the ratio of unresolved to resolved scales – very much like a degree of rarefaction – is not taken into account even if it may grow to non-negligible values in flow regions such as shocklayers. It is precisely in these flow regions, that the turbulent gas-kinetic scheme seems to provide more accurate predictions than conventional schemes.
Optimal estimation of several linear parameters in the presence of Lorentzian thermal noise

In a previous paper, we developed an approach to the optimal (minimum variance, unbiased) statistical estimation technique for the equilibrium displacement of a damped, harmonic oscillator in the presence of thermal noise. Here, we expand that work to include the optimal estimation of several linear parameters from a continuous time series. We show that working in the basis of the thermal driving force both simplifies the calculations and provides additional insight into why various approximate (not optimal) estimation techniques perform as they do. To illustrate this point, we compare the variance in the optimal estimator that we derive for thermal noise with those of two approximate methods which, like the optimal estimator, suppress the contribution to the variance that would come from the irrelevant, resonant motion of the oscillator. We discuss how these methods fare when the dominant noise process is either white displacement noise or noise with power spectral density that is inversely proportional to the frequency (1/f noise). We also construct, in the basis of the driving force, an estimator that performs well for a mixture of white noise and thermal noise. To find the optimal multi-parameter estimators for thermal noise, we derive and illustrate a generalization of traditional matrix methods for parameter estimation that can accommodate continuous data. We discuss how this approach may help refine the design of experiments as they allow an exact, quantitative comparison of the precision of estimated parameters under various data acquisition and data analysis strategies.
The Roles of Reconnected Flux and Overlying Fields in CME Speeds

Researchers have reported i) correlations of coronal mass ejection (CME) speeds and the total photospheric magnetic flux swept out by flare ribbons in flare-associated eruptive events, and, separately, ii) correlations of CME speeds and more rapid decay, with height, of magnetic fields in potential-field coronal models above eruption sites. Here, we compare the roles of both ribbon fluxes and the decay rates of overlying fields in a set of 16 eruptive events. We confirm previous results that higher CME speeds are associated with both higher ribbon fluxes and more rapidly decaying overlying fields. We find the association with ribbon fluxes to be weaker than a previous report, but stronger than the dependence on the decay rate of overlying fields. Since the photospheric ribbon flux is thought to approximate the amount of coronal magnetic flux reconnected during the event, the correlation of speeds with ribbon fluxes suggests that reconnection plays some role in accelerating CMEs. One possibility is that reconnected fields that wrap around the rising ejection produce an increased outward hoop force, thereby increasing CME acceleration. The correlation of CME speeds with more rapidly decaying overlying fields might be caused by greater downward magnetic tension in stronger overlying fields, which could act as a source of drag on rising ejections.
Duality and conditional expectations in the Nakajima-Mori-Zwanzig formulation

We develop a new operator algebraic formulation of the Nakajima-Mori-Zwanzig (NMZ) method of projections. The new theory is built upon rigorous mathematical foundations, and it can be applied to both classical and quantum systems. We show that a duality principle between the NMZ formulation in the space of observables and in the state space can be established, analogous to the Heisenberg and Schrodinger pictures in quantum mechanics. Based on this duality we prove that under natural assumptions, the projection operators appearing in the NMZ equation must be conditional expectations. The proposed formulation is illustrated in various examples.
Accelerating our understanding of supernova explosion mechanism via simulations and visualizations with GenASiS

Core-collapse supernovae are among the most powerful explosions in the Universe, releasing about 1053 erg of energy on timescales of a few tens of seconds. These explosion events are also responsible for the production and dissemination of most of the heavy elements, making life as we know it possible. Yet exactly how they work is still unresolved. One reason for this is the sheer complexity and cost of a self-consistent, multi-physics, and multi-dimensional core-collapse supernova simulation, which is impractical, and often impossible, even on the largest supercomputers we have available today. To advance our understanding we instead must often use simplified models, teasing out the most important ingredients for successful explosions, while helping us to interpret results from higher fidelity multi-physics models. In this paper we investigate the role of instabilities in the core-collapse supernova environment. We present here simulation and visualization results produced by our code GenASiS.
Lattice gases with a point source

We study diffusive lattice gases with local injection of particles, namely we assume that whenever the origin becomes empty, a new particle is immediately injected into the origin. We consider two lattice gases: a symmetric simple exclusion process and random walkers. The interplay between the injection events and the positions of the particles already present implies an effective collective interaction even for the ostensibly non-interacting random walkers. We determine the average total number of particles entering into the initially empty system. We also compute the average total number of distinct sites visited by all particles, and discuss the shape of the visited domain and the statistics of visits.
Robust Sub-Gaussian Principal Component Analysis and Width-Independent Schatten Packing

We develop two methods for the following fundamental statistical task: given an $\epsilon$-corrupted set of $n$ samples from a $d$-dimensional sub-Gaussian distribution, return an approximate top eigenvector of the covariance matrix. Our first robust PCA algorithm runs in polynomial time, returns a $1 - O(\epsilon\log\epsilon^{-1})$-approximate top eigenvector, and is based on a simple iterative filtering approach. Our second, which attains a slightly worse approximation factor, runs in nearly-linear time and sample complexity under a mild spectral gap assumption. These are the first polynomial-time algorithms yielding non-trivial information about the covariance of a corrupted sub-Gaussian distribution without requiring additional algebraic structure of moments. As a key technical tool, we develop the first width-independent solvers for Schatten-$p$ norm packing semidefinite programs, giving a $(1 + \epsilon)$-approximate solution in $O(p\log(\tfrac{nd}{\epsilon})\epsilon^{-1})$ input-sparsity time iterations (where $n$, $d$ are problem dimensions).
Emergence of gravity from spinfoams

We find a nontrivial regime of spinfoam quantum gravity that reproduces classical Einstein equations. This is the double scaling limit of small Immirzi parameter (gamma), large spins (j) with physical area (gamma times j) constant. In addition to quantum corrections in the Planck constant, we find new corrections in the Immirzi parameter due to the quantum discreteness of spacetime. The result is a strong evidence that the spinfoam covariant quantization of general relativity possesses the correct classical limit.
The Effects of Crustal Magnetic Fields and Solar EUV Flux on Ionopause Formation at Mars

We study the ionopause of Mars using a database of 6,893 ionopause detections obtained over 11 years by the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) experiment. The ionopause, in this work, is defined as a steep density gradient that appears in MARSIS remote sounding ionograms as a horizontal line at frequencies below 0.4 MHz. We find that the ionopause is located on average at an altitude of $363 \pm 65$ km. We also find that the ionopause altitude has a weak dependence on solar zenith angle and varies with the solar extreme ultraviolet (EUV) flux on annual and solar cycle time scales. Furthermore, our results show that very few ionopauses are observed when the crustal field strength at 400 km is greater than 40 nT. The strong crustal fields act as mini-magnetospheres that alter the solar wind interaction and prevent the ionopause from forming.
Determining Exoplanetary Oblateness Using Transit Depth Variations

The measurement of an exoplanet's oblateness and obliquity provides insights into the planet's internal structure and formation history. Previous work using small differences in the shape of the transit light curve has been moderately successful, but was hampered by the small signal and extreme photometric precision required. The measurement of changes in transit depth, caused by the spin precession of an oblate planet, was proposed as an alternative method. Here, we present the first attempt to measure these changes. Using Kepler photometry, we examined the brown dwarf Kepler-39b and the warm Saturn Kepler-427b. We could not reliably constrain the oblateness of Kepler-39b. We find transit depth variations for Kepler-427b at significance () consistent with a precession period of and an oblateness of . This oblateness is comparable to solar system gas giants and would raise questions about the dynamics and tidal synchronization of Kepler-427b.
Atmospheric Dispersion Effects in Weak Lensing Measurements

The wavelength dependence of atmospheric refraction causes elongation of finite-bandwidth images along the elevation vector, which produces spurious signals in weak gravitational lensing shear measurements unless this atmospheric dispersion is calibrated and removed to high precision. Because astrometric solutions and point spread function (PSF) characteristics are typically calibrated from stellar images, differences between the reference stars' spectra and the galaxies' spectra will leave residual errors in both the astrometric positions () and in the second moment (width) of the wavelength-averaged PSF (ΔV) for galaxies. We estimate the level of ΔV that will induce spurious weak lensing signals in PSF-corrected galaxy shapes that exceed the statistical errors of the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST) cosmic-shear experiments. We also estimate the signals that will produce unacceptable spurious distortions after stacking of exposures taken at different air masses and hour angles. Using standard galaxy and stellar spectral templates we calculate the resultant errors in the griz bands and find that atmospheric dispersion shear systematics, left uncorrected, are up to 6 and 2 times larger in g and r bands, respectively, than the thresholds at which they become significant contributors to the DES error budget, but can be safely ignored in i and z bands. For the stricter LSST requirements, the factors are about 30, 10, and 3 in g, r, and i bands, respectively. These shear systematic errors scale with observed zenith angle z as tan2z, for which we take a nominal value of unity—simulations of DES and LSST suggest 0.6-1.0. We find that a simple correction linear in galaxy color is accurate enough to reduce dispersion shear systematics to insignificant levels in the r band for DES and i band for LSST, but still as much 5× above the threshold of significance for LSST r-band observations. More complex approaches to correction of the atmospheric dispersion signal will likely be able to reduce the systematic cosmic shear errors below statistical errors for LSST r band. But g-band dispersion effects remain large enough that it seems likely that induced systematics will dominate the statistical errors of both surveys, and cosmic-shear measurements should rely on the redder bands.
On the subgraph query problem

Given a fixed graph H, a real number p (0, 1) and an infinite Erdos–Renyi graph G ∼ G(∞, p), how many adjacency queries do we have to make to find a copy of H inside G with probability at least 1/2? Determining this number f(H, p) is a variant of the subgraph query problem introduced by Ferber, Krivelevich, Sudakov and Vieira. For every graph H, we improve the trivial upper bound of f(H, p) = O(p−d), where d is the degeneracy of H, by exhibiting an algorithm that finds a copy of H in time O(p−d) as p goes to 0. Furthermore, we prove that there are 2-degenerate graphs which require p−2+o(1) queries, showing for the first time that there exist graphs H for which f(H, p) does not grow like a constant power of p−1 as p goes to 0. Finally, we answer a question of Feige, Gamarnik, Neeman, Racz and Tetali by showing that for any δ < 2, there exists α < 2 such that one cannot find a clique of order α log2 n in G(n, 1/2) in nδ queries.
Observational Diagnostics of Gas Flows: Insights from Cosmological Simulations

Galactic accretion interacts in complex ways with gaseous halos, including galactic winds. As a result, observational diagnostics typically probe a range of intertwined physical phenomena. Because of this complexity, cosmological hydrodynamic simulations have played a key role in developing observational diagnostics of galactic accretion. In this chapter, we review the status of different observational diagnostics of circum-galactic gas flows, in both absorption (galaxy pair and down-the-barrel observations in neutral hydrogen and metals; kinematic and azimuthal angle diagnostics; the cosmological column density distribution; and metallicity) and emission (Lyα; UV metal lines; and diffuse X-rays). We conclude that there is no simple and robust way to identify galactic accretion in individual measurements. Rather, progress in testing galactic accretion models is likely to come from systematic, statistical comparisons of simulation predictions with observations. We discuss specific areas where progress is likely to be particularly fruitful over the next few years.
MAGNETOHYDRODYNAMIC SLOW MODE WITH DRIFTING He++: IMPLICATIONS FOR CORONAL SEISMOLOGY AND THE SOLAR WIND

The MHD slow mode wave has application to coronal seismology, MHD turbulence, and the solar wind where it can be produced by parametric instabilities. We consider analytically how a drifting ion species (e.g. He{sup ++}) affects the linear slow mode wave in a mainly electron-proton plasma, with potential consequences for the aforementioned applications. Our main conclusions are as follows. 1. For wavevectors highly oblique to the magnetic field, we find solutions that are characterized by very small perturbations of total pressure. Thus, our results may help to distinguish the MHD slow mode from kinetic Alfven waves and non-propagating pressure-balanced structures, which can also have very small total pressure perturbations. 2. For small ion concentrations, there are solutions that are similar to the usual slow mode in an electron-proton plasma, and solutions that are dominated by the drifting ions, but for small drifts the wave modes cannot be simply characterized. 3. Even with zero ion drift, the standard dispersion relation for the highly oblique slow mode cannot be used with the Alfven speed computed using the summed proton and ion densities, and with the sound speed computed from the summed pressures and densities of all species. 4. The ions can drivemore » a non-resonant instability under certain circumstances. For low plasma beta, the threshold drift can be less than that required to destabilize electromagnetic modes, but damping from the Landau resonance can eliminate this instability altogether, unless T{sub e} /T{sub p} >> 1.« less
Nuclear Forensics using Gamma-ray Spectroscopy

Much of George Dracoulis’s research career was devoted to utilising gamma-ray spectroscopy in fundamental studies in nuclear physics. This same technology is useful in a wide range of applications in the area of nuclear forensics. Over the last several years, our research group has made use of both high- and low-resolution gamma-ray spectrometers to: identify the first sample of plutonium large enough to be weighed; determine the yield of the Trinity nuclear explosion; measure fission fragment yields as a function of target nucleus and neutron energy; and observe fallout in the U. S. from the Fukushima nuclear reactor accident.
On the isomorphism problem for generalized Baumslag–Solitar groups

Generalized Baumslag–Solitar groups (GBS groups) are groups that act on trees with infinite cyclic edge and vertex stabilizers. Such an action is described by a labeled graph (essentially, the quotient graph of groups). This paper addresses the problem of determining whether two given labeled graphs define isomorphic groups; this is the isomorphism problem for GBS groups. There are two main results and some applications. First, we find necessary and sufficient conditions for a GBS group to be represented by only finitely many reduced labeled graphs. These conditions can be checked effectively from any labeled graph. Then we show that the isomorphism problem is solvable for GBS groups whose labeled graphs have first Betti number at most one.
Scalar Multi-Solitons on the Fuzzy Sphere

We study solitons in scalar theories with polynomial interactions on the fuzzy sphere. Such solitons are described by projection operators of rank k, and hence the moduli space for the solitons is the grassmannian Gr(k,2j+1). The gradient term of the action provides a non-trivial potential on Gr(k,2j+1), thus reducing the moduli space. We construct configurations corresponding to well-separated solitons, and show that although the solitons attract each other, the attraction vanishes in the limit of large j. In this limit, it is argued that the moduli space is (1)⊗k/k k. For the k-soliton bound state, the moduli space is simply 1, all other moduli being lifted. We find that the moduli space of multi-solitons is smooth and that there are no singularities as several solitons coalesce. When the fuzzy S2 is flattened to a noncommutative plane, we find agreement with the known results, modulo some operator-ordering ambiguities. This suggests that the fuzzy sphere is a natural way to regulate the noncommutative plane both in the ultraviolet and infrared.
Physics of Luminous Transient Light Curves: A New Relation between Peak Time and Luminosity

Simplified analytic methods are frequently used to model the light curves of supernovae and other energetic transients and to extract physical quantities, such as the ejecta mass and amount of radioactive heating. The applicability and quantitative accuracy of these models, however, have not been clearly delineated. Here we carry out a systematic study comparing certain analytic models to numerical radiation transport calculations. We show that the neglect of time-dependent diffusion limits the accuracy of common Arnett-like analytic models, and that the widely-applied Arnett's rule for inferring radioactive mass does not hold in general, with an error that increases for models with longer diffusion times or more centralized heating. We present new analytic relations that accurately relate the peak time and luminosity of an observed light curve to the physical ejecta and heating parameters. We further show that recombination and the spatial distribution of heating modify the peak of the light curve and that these effects can be accounted for by varying a single dimensionless parameter in the new relations. The results presented should be useful for estimating the physical properties of a wide variety of transient phenomena.
Nuclear Environments Inspection with Micro Aerial Vehicles: Algorithms and Experiments

In this work, we address the estimation, planning, control and mapping problems to allow a small quadrotor to autonomously inspect the interior of hazardous damaged nuclear sites. These algorithms run onboard on a computationally limited CPU. We investigate the effect of varying illumination on the system performance. To the best of our knowledge, this is the first fully autonomous system of this size and scale applied to inspect the interior of a full scale mock-up of a Primary Containment Vessel (PCV). The proposed solution opens up new ways to inspect nuclear reactors and to support nuclear decommissioning, which is well known to be a dangerous, long and tedious process. Experimental results with varying illumination conditions show the ability to navigate a full scale mock-up PCV pedestal and create a map of the environment, while concurrently avoiding obstacles.
Voter Verification of BMD Ballots Is a Two-Part Question: Can They? Mostly, They Can. Do They? Mostly, They Don't

The question of whether or not voters actually verify ballots produced by ballot marking devices (BMDs) is presently the subject of some controversy. Recent studies (e.g., Bernhard et al. 2020) sug...
Quantifying Interference-Assisted Signal Strength Surveillance of Sound Vibrations

A malicious attacker could, by taking control of internet-of-things devices, use them to capture received signal strength (RSS) measurements and perform surveillance on a person’s vital signs, activities, and sound in their environment. This article considers an attacker who looks for subtle changes in the RSS in order to eavesdrop sound vibrations. The challenge to the adversary is that sound vibrations cause very low amplitude changes in RSS, and RSS is typically quantized with a significantly larger step size. This article contributes a lower bound on an attacker’s monitoring performance as a function of the RSS step size and sampling frequency so that a designer can understand their relationship. Our bound considers the little-known and counter-intuitive fact that an adversary can improve their sinusoidal parameter estimates by making some devices transmit to add interference power into the RSS measurements. We demonstrate this capability experimentally. As we show, for typical transceivers, the RSS surveillance attacker can monitor sound vibrations with remarkable accuracy. New mitigation strategies will be required to prevent RSS surveillance attacks.
“Judge me by my size (noun), do you?” YodaLib: A Demographic-Aware Humor Generation Framework

The subjective nature of humor makes computerized humor generation a challenging task. We propose an automatic humor generation framework for filling the blanks in Mad Libs® stories, while accounting for the demographic backgrounds of the desired audience. We collect a dataset consisting of such stories, which are filled in and judged by carefully selected workers on Amazon Mechanical Turk. We build upon the BERT platform to predict location-biased word fillings in incomplete sentences, and we fine-tune BERT to classify location-specific humor in a sentence. We leverage these components to produce YodaLib, a fully-automated Mad Libs style humor generation framework, which selects and ranks appropriate candidate words and sentences in order to generate a coherent and funny story tailored to certain demographics. Our experimental results indicate that YodaLib outperforms a previous semi-automated approach proposed for this task, while also surpassing human annotators in both qualitative and quantitative analyses.
The Price of Anarchy for Instantaneous Dynamic Equilibria

We consider flows over time within the deterministic queueing model and study the solution concept of instantaneous dynamic equilibrium (IDE) in which flow particles select at every decision point a currently shortest path. The length of such a path is measured by the physical travel time plus the time spent in queues. Although IDE have been studied since the eighties, the efficiency of the solution concept is not well understood. We study the price of anarchy for this model and show an upper bound of order \(\mathcal {O}(U\cdot \tau )\) for single-sink instances, where U denotes the total inflow volume and \(\tau \) the sum of edge travel times. We complement this upper bound with a family of quite complex instances proving a lower bound of order \(\varOmega (U\cdot \log \tau )\).
Technologies for trapped-ion quantum information systems

Scaling up from prototype systems to dense arrays of ions on chip, or vast networks of ions connected by photonic channels, will require developing entirely new technologies that combine miniaturized ion trapping systems with devices to capture, transmit, and detect light, while refining how ions are confined and controlled. Building a cohesive ion system from such diverse parts involves many challenges, including navigating materials incompatibilities and undesired coupling between elements. Here, we review our recent efforts to create scalable ion systems incorporating unconventional materials such as graphene and indium tin oxide, integrating devices like optical fibers and mirrors, and exploring alternative ion loading and trapping techniques.
Exploring the turbulent velocity gradients at different scales from the perspective of the strain-rate eigenframe

Expressing the evolution equations for the filtered velocity gradient tensor (FVGT) in the strain-rate eigenframe provides an insightful way to disentangle and understand various processes such as strain self-amplification, vortex stretching and tilting, and to consider their properties at different scales in the flow. Using data from direct numerical simulation of the forced Navier–Stokes equation, we consider the relative importance of local and non-local terms in the FVGT eigenframe equations across the scales using statistical analysis. The eigenframe rotation rate (that drives vorticity tilting) is shown to exhibit highly non-Gaussian fluctuations even at large scales due to kinematic effects, but dynamically, the anisotropic pressure Hessian plays a key role. The anisotropic pressure Hessian conditioned on the eigenvalues and principal vorticity components exhibits highly nonlinear behaviour at low values of normalized local gradients, with important modelling implications. We derive a generalization of the Lumley triangle that allows us to show that the pressure Hessian has a preference for two-component axisymmetric configurations at small scales, with a transition to a more isotropic state at larger scales. Correlations between the sub-grid stress and other terms in the eigenframe equations are considered, highlighting the coupling between the sub-grid and nonlinear amplification terms, with the sub-grid term playing an important role in regularizing the system. These results provide useful guidelines for improving Lagrangian models of the FVGT, since current models fail to capture a number of subtle features observed in our results.
Global Effect of Non-Conservative Perturbations on Homoclinic Orbits

We study the effect of time-dependent, non-conservative perturbations on the dynamics along homoclinic orbits to a normally hyperbolic invariant manifold. We assume that the unperturbed system is Hamiltonian, and the normally hyperbolic invariant manifold is parametrized via action-angle coordinates. The homoclinic excursions can be described via the scattering map, which gives the future asymptotic of an orbit as a function of its past asymptotic. We provide explicit formulas, in terms of convergent integrals, for the perturbed scattering map expressed in action-angle coordinates. We illustrate these formulas for perturbations of both uncoupled and coupled rotator-pendulum systems.
“Active Investors, LBOs, and the Privatization of Bankruptcy*”

In this testimony to the House Ways and Means Committee on February 1, 1989 (when LBOs and other highly leveraged transactions were under fierce attack by politicians and the media), the author identified “LBO associations” such as KKR and Forstmann Little as a valuable innovation in organizational form—a new model of management and governance that was competing directly with the headquarters of large public corporations, especially conglomerates. In the author's words, LBOs “substitute incentives provided by compensation and ownership plans for the direct monitoring and often centralized decision-making in the typical corporate bureaucracy.” In illustrating his point, the author noted that whereas the CEOs of U.S. companies during the '70s and '80s saw their personal wealth go up by only about $3 for every $1,000 increase in firm value, the average CEO in an LBO experienced a change of $64 per $1,000—and for the partners of the LBO firm, the closest equivalent to a conglomerate CEO, the change was about $200 per $1,000. Based on the performance of the first wave of LBOs to return to public ownership, such dramatic concentrations of equity ownership appear to have produced large gains in operating efficiency. (And since the author's testimony, these findings have been confirmed by subsequent studies of later periods and in other countries.) The heavy debt loads in these transactions, besides making possible the concentration of equity ownership, also perform an important control function, intensifying the search for efficiencies and discouraging reinvestment in low-return projects. For those LBOs that have trouble servicing their debt loads, the author argues that the costs of insolvency should turn out to be significantly lower than for traditional public companies because LBOs provide strong incentives to keep the process of reorganizing troubled companies out of the bankruptcy court (a prediction that, although proving wrong in the early‘90s, has turned out to be true of the most recent wave of private equity deals).
Location of foreign research and development in China

This study examines the location of foreign research and development activities within China, using the 2004 China Economic Census data, published in 2006. The study reveals that the scale of foreign R&D in China is significant and involves a few thousand of foreign enterprises, much broader than what has been reported before. It also finds that foreign R&D activities in China are highly concen- trated in a few costal provinces and cities including Guangdong, Jiangsu, Shanghai, Zhejiang, Fujian and Beijing, though the degree of concentration in Beijing is significantly lower than what was reported before. The results of the analyses demonstrate that proxim- ity to foreign manufacturing investment dictates the location of foreign R&D. Also important is the quality of local technological infrastructure, which is a composite measurement of availability of quality labor and their creativity. However, labor costs and infrastructure do not show consistent or significant impacts.
Dissipative relativistic fluid dynamics for nuclear collisions

In the context of the Muller-Israel-Stewart second-order theory for dissipative fluids due to Grad, we analyze the effects of thermal conduction and viscosity in heavy ion collisions. We contrast the results to those of the first-order theory due to Eckart and to Landau and Lifshitz and to those of perfect (ideal) fluid due to Euler. We study the energy density and entropy density evolution of a pion gas produced in the heavy ion collisions. The truncated version of the second-order theory is used to find the dissipative quantities.
The price of doing good: Executive compensation in nonprofit organizations

This article examines foundational assumption that nonprofit organizations operate under a non-distribution constraint, which prohibits the paying out of excess earnings and requires instead their ...
Limiting Death: Maryland’s New Death Penalty Law

In this Article, I describe and analyze the State of Maryland's 2009 death penalty law. This law adds three new death-eligibility criteria to the pre-existing law. These new evidentiary criteria supplement the pre-existing substantive death-eligibility criteria. As a result, Maryland now has one of the most restrictive death penalties in the country.
Choice Construction versus Preference Construction: The Instability of Preferences Learned in Context:

Abstract Preference consistency implies that people have learned their willingness to trade off attributes. The authors argue that this is not necessarily the case. Instead, they show that when people learn preferences in context (e.g., through repeated choices made from a trinary choice set that includes an asymmetrically dominated decoy), they learn a context-specific choice heuristic (e.g., they always choose the asymmetrically dominating option), which leads to less consistent preferences across contexts. In contrast, repeated choices from sets containing only two options impel people to learn their subjective attribute weights, yielding preferences that are consistent across contexts. The difference between choice construction and preference construction is of importance to marketing managers because repeat purchase is typically interpreted as a signal of customer preference. The authors show that this “preference” might just be a learned solution to the choice problem and that as soon as the competi...
Theoretically Framing Relational Framing

Our research program on relational framing leaves many process and normative-prescriptive issues unresolved. We agree with the three commentators on the usefulness of (a) experimental work that probes the cognitive and affective processes underlying relational-framing effects, (b) ethnographic work that probes the cultural and historical processes that can shift the boundaries of acceptable commercial transactions, and (c) philosophical analyses that probe the views of rationality that guide whether the research community sees human judgments as biased and in need of correction.
Transparency of outside options in bargaining

Abstract We study the effect of the transparency of outside options in bilateral bargaining. A seller posts prices to screen a buyer over time, and the buyer may receive an outside option at a random time. We consider two information regimes: one in which the arrival of the outside option is public and one in which the arrival is private. A public arrival of the outside option works as a commitment device that forces the buyer to opt out immediately. This effect leads to a generically unique equilibrium in which the Coase conjecture holds. In contrast, a private arrival of the outside option may lead to additional delay and equilibrium multiplicity. The Coase conjecture fails in some equilibria. The buyer's preference about transparency is time-inconsistent: she prefers to commit to making arrivals public, but she is unwilling to disclose her outside option after the arrival. Moreover, the seller benefits from having the buyer privately observe her outside option.
The Legal Structure of American Freedom and the Provenance of the Antitrust Immunities

It is a reflection of the subtle relationship between legal doctrine and the larger social context it regulates that, on occasion, some humble point of mere theory proves to be the lynchpin of a serious social problem. Often the most pernicious aspect of such a situation will be the very obscuriyy that causes courts to overlook it. That is emphatically the case with the issue addressed in this paper. Confusion persists over the seemingly academic question whether the so-called "Noerr-Pennington" or "petitioning" immunity, a doctrine in antitrust law which protects persons from being sued when they seek action from their government is: (1) a construction of the antitrust statutes, or (2) an application of a First Amendment right which is said to protect the "petition of government for redress of grievances." The prevalent view, driven mainly by dicta in one Supreme Court opinion, is that the immunity is a direct application of the First Amendment. However, the problem is usually either ignored or said to be academic at best. In fact, this issue is terribly significant. Mistakes here necessarily confuse other First Amendment doctrines, in ways that most observers do not take the time to consider, and ultimately infect the larger legal theory of American political freedom. The paper argues that the immunity should be understood as a rule of statutory construction, or else a range of negative consequences follow, including most significantly a serious donation of public political power into private hands. The contrary argument has nothing going for it but good intentions and a scattered collection of ambiguous dicta.
Retail Competition Percolating Through to Suppliers and the Use of Vertical Integration, Tying, and Vertical Restraints To Stop It

Conventional wisdom presumes that a supplier in a monopolistic market, or in an oligopolistic market that is not perfectly competitive, has the power to charge a supra-competitive wholesale price. In contrast, elaborating on recent economics studies, this Article shows that the supplier of an intermediate product may not be able to charge a supra-competitive wholesale price. This is because the supplier has the incentive to grant a marginal price concession to one buyer, in exchange for a fixed payment, at the expense of competing buyers. This Article demonstrates how vertical integration, tying and vertical restraints (particularly imposition of minimum or maximum resale prices, selling to a sole buyer, designation of exclusive territories to buyers, and using most-favored-consumer clauses) can be used to remove the supplier's incentive to grant such concessions, and thus restore the supplier's market power. This reveals an anticompetitive explanation for vertical integration and vertical restraints that has been neglected by legal commentators, courts, and agencies. The Article also reveals an anticompetitive explanation for tying that has not been identified by either the economics or the legal literature, or by the case law. Moreover, filling the void left by the current economics literature on the subject, the Article shows how imposition of maximum resale prices is anticompetitive even when it does not completely eliminate buyers' profits from sales. The Article further shows how the supplier's incentive to grant concessions renders the double marginalization and input substitution efficiencies of vertical integration less important than conventionally thought. In addition, more antitrust concerns are raised when the supplier is contractually bound to enforce minimum resale prices or exclusive dealerships. As the Article reveals, however, in contrast to recent economics literature, even if these restraints do not bind the supplier to enforce them, they are anticompetitive, as they aid the supplier in developing a reputation for not making concessions. Finally, the statutory ban on second degree price discrimination helps the supplier commit to charging a supra-competitive wholesale price. However, the Article exposes how buyer liability under this statutory ban erodes the effectiveness of the statute and fuels the supplier's urge to make concessions.
Beyond the Article I Horizon: Congress’s Enumerated Powers and Universal Jurisdiction Over Drug Crimes

In March 2007, the United States Coast Guard boarded a suspicious Panamanian vessel that had been spotted by a surveillance plane.1 The boarding resulted in the largest maritime cocaine seizure to date: over forty-two thousand pounds uncut.2 Fourteen crewmembers were arrested, and the eleven nonPanamanian detainees were brought to Florida for prosecution.3 Yet the seizure did not take place in U.S. waters.4 It took place in Panamanian territorial waters, approximately one thousand nautical miles from Miami.5 Moreover, none of the
Constitutionalizing forfeiture law - the german example

This article demonstrates how German criminal law has made forfeiture of objects used in crime consistent with constitutional guarantees.
Capital controls and foreign direct investment

Abstract This paper examines the effect of three types of capital control policies on FDI: (a) the existence of multiple exchange rates; (b) restrictions on capital account, and (c) restrictions on the repatriation of export proceeds. We find that the impact of capital controls on FDI varies by region and has changed over time. In the 1970s and 1980s, none of the policies had a significant impact on FDI. In the 1990s, all three were significant. Furthermore, capital controls have no effect on FDI to sub-Saharan Africa and the Middle East, but affects FDI to East Asia and Latin America adversely.
Traditional Trust Measurement and the Risk Confound: An Experiment in Rural Paraguay ?

Abstract Play in the traditional trust experiment depends both on trust beliefs and on levels of risk aversion. We ran two experiments with a diverse set of subjects in 15 villages of rural Paraguay, the traditional trust experiment and a new experiment measuring only risk aversion. We find that risk attitudes are highly predictive of play in the trust game. In addition, omitting risk aversion as a regressor in trust regressions significantly changes the coefficients of important explanatory variables such as gender and wealth.
JOB FLOWS AND PRODUCTIVITY DYNAMICS: EVIDENCE FROM U.S. MANUFACTURING

Through their influence on the cross-sectional distribution of productivity across firms and workers, job creation and destruction likely have an impact on the rate at which aggregate productivity changes over time. However, the nature of this effect is not, a priori, clear. Although a broad consensus has emerged suggesting that job destruction enhances productivity by eliminating inefficient production units, theories disagree with regard to the effect of job creation. If job flows represent the reallocation of labor from low- to high-productivity positions, job creation would boost productivity growth. If, instead, they represent changes in employment along a primarily low-skill dimension, the effect would be negative. This paper estimates the influence of job creation and destruction on total factor productivity (TFP) growth using annual data on four-digit U.S. manufacturing. As expected, the results reveal a positive association between job destruction and changes in TFP. Yet, they also indicate that job creation tends to have a negative effect on productivity growth.
Powering America: The impact of ethanol production in the Corn Belt states

This paper investigates the impact of ethanol production in the Corn Belt states (Iowa, Indiana, Illinois, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, Ohio, South Dakota, and Wisconsin). Employing data at the county level, from 2005 to 2006, we investigate the effect of ethanol production on employment and wages. Our empirical results show that ethanol production has a positive significant effect on employment and wages, but this effect is of insignificant magnitude. We also find that counties with high and medium levels of ethanol production capacity show higher levels of employment and wages than those counties that do not produce ethanol. Counties with low levels of ethanol production do not show any significant difference in employment and wages than non-producing ethanol counties.
Translating Local Knowledge at Organizational Peripheries

This article theorizes about the kinds of knowing present in organizations that share both a structural similarity in the organization of work and work practices – a ‘double periphery’ in which a community of practitioners acts across both a horizontal, geographic periphery and a vertical, hierarchical periphery – and a common mode of practice – translating across these peripheral borders. In principle, these workers develop knowledge in interaction with clients and customers that could be valuable to the organization, were it but to learn from them. Instead, the ‘local knowledge’ they learn in acting across these peripheries is discounted, if not disparaged, by more centrally-located managers and executives. The article theorizes about the nature of translating local knowledge concerning organizational practices and about the structural character of local versus ‘expert’ knowledge.
Estimation of a transformation model with truncation, interval observation and time‐varying covariates

Summary Abrevaya (1999b) considered estimation of a transformation model in the presence of left truncation. This paper observes that a cross-sectional version of the statistical model considered in Frederiksen et al. (2007) is a generalization of the model considered by Abrevaya (1999b) and the generalized model can be estimated by a pairwise comparison version of one of the estimators in Frederiksen et al. (2007). Specifically, our generalization will allow for discretized observations of the dependent variable and for piecewise constant time-varying explanatory variables.
Electricity transmission pricing and performance-based regulation

Performance-based regulation (PBR) is influenced by the Bayesian and non-Bayesian incentive mechanisms. While Bayesian incentives are impractical for direct implementation, the insights from their properties can be combined with practical non-Bayesian mechanisms for application to transmission pricing. This combination suggests an approach based on the distinction between ultra-short, short and long periods. Ultra-short periods are marked by real-time pricing of point-to-point transmission services. Pricing in short periods involves fixed fees and adjustments via price-cap formulas or profit sharing. Productivity-enhancing incentives have to be tempered by long-term commitment considerations, so that profit sharing may dominate pure price caps. Investment incentives require long-term adjustments based on rate-of-return regulation with a "used and useful" criterion.
Is Disinflation Good for the Stock Market

The stock market appreciates by an average of 24 percent in real dollar terms when countries attempt to stabilize annual inflation rates that are greater than 40 percent. In contrast, the average market response is 0 when the pre–stabilization rate of inflation is less than 40 percent. These results suggest that the potential long–run benefits of stabilization may dominate short–run costs at high levels of inflation, but at low to moderate levels of inflation, benefits may be offset by costs in a present value sense. Stock market responses also help predict the change in inflation and output in the year following all 81 stabilization efforts.
Risking Other People's Money: Gambling, Limited Liability, and Optimal Incentives

We consider optimal incentive contracts when managers can, in addition to shirking or diverting funds, increase short term profits by putting the firm at risk of a low probability "disaster." To avoid such risk-taking, investors must cede additional rents to the manager. In a dynamic context, however, because managerial rents must be reduced following poor performance to prevent shirking, poorly performing managers will take on disaster risk even under an optimal contract. This risk taking can be mitigated if disaster states can be identified ex-post by paying the manager a large bonus if the firm survives. But even in this case, if performance is sufficiently weak the manager will forfeit eligibility for a bonus, and again take on disaster risk. When effort costs are convex, reductions in effort incentives are used to limit risk taking, with a jump to high powered incentives in the gambling region. Our model can explain why suboptimal risk taking can emerge even when investors are fully rational and managers are compensated optimally.