cssi/SciSciGPT-SciSciNet huggingface dataset:
Smoothed particle hydrodynamics continuous boundary force method for Navier-Stokes equations subject to a Robin boundary condition

A Robin boundary condition for the Navier-Stokes equations is used to model slip conditions at the fluid-solid boundaries. A novel continuous boundary force (CBF) method is proposed for solving the Navier-Stokes equations subject to the Robin boundary condition. In the CBF method, the Robin boundary condition is replaced by the homogeneous Neumann boundary condition and a volumetric force term added to the momentum conservation equation.Smoothed particle hydrodynamics (SPH) method is used to solve the resulting Navier-Stokes equations. We present solutions for two- and three-dimensional flows subject to various forms of the Robin boundary condition in domains bounded by flat and curved boundaries. The numerical accuracy and convergence are examined through comparison of the SPH-CBF results with the solutions of finite difference or finite-element method. Considering the no-slip boundary condition as a special case of the slip boundary condition, we demonstrate that the SPH-CBF method accurately describes both the no-slip and slip conditions.
Effects of thermal cycling on thermal expansion and mechanical properties of SiC fiber-reinforced reaction-bonded Si3N4 composites

Thermal expansion curves for SiC fibre-reinforced reaction-bonded Si3N4 matrix composites (SiC/RBSN) and unreinforced RBSN were measured from 25 to 1400 °C in nitrogen and in oxygen. The effects of fibre/matrix bonding and cycling on the thermal expansion curves and room-temperature tensile properties of unidirectional composites were determined. The measured thermal expansion curves were compared with those predicted from composite theory. Predicted thermal expansion curves parallel to the fibre direction were between the measured curves for the strongly- and weakly-bonded composites, but those normal to the fibre direction for both bonding cases were similar to that of the unreinforced RBSN. Thermal cycling in nitrogen for both bonding cases resulted in no net dimensional changes at room temperature and no loss in tensile properties from the as-fabricated condition. In contrast, thermal cycling in oxygen for both composites caused volume expansion primarily due to internal oxidation of RBSN. Cyclic oxidation affected the mechanical properties of the weakly-bonded SiC/RBSN composites the most, resulting in loss of strain capability beyond matrix fracture and catastrophic, brittle fracture. Increased bonding between the SiC fibre and RBSN matrix due to oxidation of the carbon-rich fibre surface coating and an altered residual stress pattern in the composite due to internal oxidation of the matrix are the main reasons for the poor mechanical performance of these composites.
Unusual phase transitions in ferroelectric nanodisks and nanorods

Bulk ferroelectrics undergo structural phase transformations at low temperatures, giving multi-stable (that is, multiple-minimum) degenerate states with spontaneous polarization. Accessing these states by applying, and varying the direction of, an external electric field is a key principle for the operation of devices such as non-volatile ferroelectric random access memories (NFERAMs). Compared with bulk ferroelectrics, low-dimensional finite ferroelectric structures promise to increase the storage density of NFERAMs 10,000-fold. But this anticipated benefit hinges on whether phase transitions and multi-stable states still exist in low-dimensional structures. Previous studies have suggested that phase transitions are impossible in one-dimensional systems, and become increasingly less likely as dimensionality further decreases. Here we perform ab initio studies of ferroelectric nanoscale disks and rods of technologically important Pb(Zr,Ti)O3 solid solutions, and demonstrate the existence of previously unknown phase transitions in zero-dimensional ferroelectric nanoparticles. The minimum diameter of the disks that display low-temperature structural bistability is determined to be 3.2 nm, enabling an ultimate NFERAM density of 60 x 10(12) bits per square inch-that is, five orders of magnitude larger than those currently available. Our results suggest an innovative use of ferroelectric nanostructures for data storage, and are of fundamental value for the theory of phase transition in systems of low dimensionality.
Calculations of Soft Auroral Bremsstrahlung and K alpha Line Emission at Satellite Altitude.

Abstract Satellite altitude (835km) fluxes of 0.1–10 keV auroral X-rays are calculated for some typical forms of incident electron spectra. Both bremsstrahlung and K ga line emission are included. These calculations indicate that K α emission can increase the observable intensity of satellite altitude auroral X-rays by up to 100 times, thereby making soft X-rays an ideal medium for producing images of the auroral morphology.
Adventures in Creating an Outdoor Leadership Challenge Course for an Emba Program

This article documents the evolution of an outdoor-based experiential leadership training event within an Executive MBA (EMBA) program. The purpose of this article is to encourage other EMBA faculty and directors to consider adding a similar event to their leadership development initiatives and to learn from our experiences. After 3 years of experience with this approach, we improved continuously each year and now offer a potentially transformative capstone personal growth experience that focuses on Kouzes and Posner’s (1995) leadership practices inventory.
Queuing Network Modeling of Driver Workload and Performance

Drivers overloaded with information significantly increase the chance of vehicle collisions. Driver workload, which is a multidimensional variable, is measured by both performance-based and subjective measurements and affected by driver age differences. Few existing computational models are able to cover these major properties of driver workload or simulate subjective mental workload and human performance at the same time. We describe a new computational approach in modeling driver performance and workload-a queuing network approach based on the queuing network theory of human performance and neuroscience discoveries. This modeling approach not only successfully models the mental workload measured by the six National Aeronautic and Space Administration Task Load Index workload scales in terms of subnetwork utilization but also simulates the driving performance, reflecting mental workload from both subjective- and performance-based measurements. In addition, it models age differences in workload and performance and allows us to visualize driver mental workload in real time. Further usage and implementation of the model in designing intelligent and adaptive in-vehicle systems are discussed.
Concise Synthesis of Spirocyclic, Bridged γ-Butyrolactones via Stereospecific, Dyotropic Rearrangements of β-Lactones Involving 1,2-Acyl and δ-Lactone Migrations

Dyotropic processes involving unprecedented 1,2-acyl migrations provide access to novel spirocyclic, bridged keto-γ-lactones from a series of fused, tricyclic-β-lactones, available via biscyclization of ketoacids including a new asymmetric variant. In addition, a spirocyclic bis-γ-lactone was generated via a dyotropic process involving a 1,2-β-lactone/δ-lactone interchange. Overall, this sequence provides a simple, two-step process for conversion of diketoacids to complex spiro[5.n]alkanes bearing a contiguous tertiary carbon center, a quaternary carbon center, and a tertiary alcohol in the form of a bridging γ-lactone.
Mechanism of plasma assisted oxidation and ignition of ethylene–air flows by a repetitively pulsed nanosecond discharge

Abstract The paper presents results of plasma assisted combustion experiments using high-voltage, nanosecond pulse duration, high pulse repetition rate discharge and kinetic modeling calculations. In the experiments, two different operation regimes have been identified, (i) oxidation regime with relatively low fuel fractions oxidized in the absence of visible flame, and (ii) ignition regime, with large fuel fraction burned, large amounts of CO and CO 2 generated, and flame detected in the reactor. Ignition occurred at air flow temperatures as low as 300 °C (before adding fuel). In both regimes, significant plasma temperature rise is detected in air–fuel flows, up to Δ T = 300 °C. Comparing these results with temperatures and dissociated fuel fractions in nitrogen–fuel flows demonstrates that the temperature rise in air–fuel flows is due to exothermic plasma chemical fuel oxidation process, which results in ignition when the flow temperature approaches autoignition temperature. This conclusion was confirmed by kinetic modeling calculations, which also demonstrated that ignition temperature is significantly reduced by the presence of radicals in the flow. Calculations showed that the model correctly predicts oxidized fuel fractions and resultant temperature rise in the plasma in the oxidation regime but significantly overpredicts burned fuel fractions in the ignition regime. Transition from the oxidation to the ignition regime predicted by the model is consistent with the experiment. Finally, the model poorly predicts some product species concentrations (CO 2 , CH 2 O, and C 2 H 2 ), even in the oxidation regime. Comparison of product species concentrations predicted utilizing two widely used hydrocarbon reaction mechanisms showed significant differences. Since these mechanisms have not been validated at near-room temperatures, this suggests that they may be inapplicable at the present conditions. This demonstrates the need for development of an accurate low-temperature plasma chemical fuel oxidation reaction mechanism.
How general relativity and Lorentz covariance arise from the spatially-covariant effective field theory of the transverse, traceless graviton

Traditional derivations of general relativity (GR) from the graviton degrees of freedom assume spacetime Lorentz covariance as an axiom. In this paper, we survey recent evidence that GR is the unique spatially-covariant effective field theory of the transverse, traceless graviton degrees of freedom. The Lorentz covariance of GR, having not been assumed in our analysis, is thus plausibly interpreted as an accidental or emergent symmetry of the gravitational sector. From this point of view, Lorentz covariance is a necessary feature of low-energy graviton dynamics, not a property of spacetime. This result has revolutionary implications for fundamental physics.
Static and Dynamic Characteristics for a Pressure-Dam Bearing

Measured rotordynamic force coefficients (stiffness, damping, and added mass) and static characteristics (eccentricity and attitude angle) of a pressure-dam bearing are presented and compared to predictions from a Reynolds-equation model, using an isothermal and isoviscous laminar analysis. The bearing's groove dimensions are close to the optimum predictions of Nicholas and Allaire (1980, "Analysis of Step Journal Bearings-Infinite Length and Stability," ASLE Trans., 22, pp. 197-207) and are consistent with current field applications. Test conditions include four shaft speeds (4000 rpm, 6000 rpm, 8000 rpm, and 10000 rpm) and bearing unit loads from 0 kPa to 1034 kPa (150 psi). Laminar flow was produced for all test conditions. A finite-element algorithm was used to generate solutions to the Reynolds-equation model. Excellent agreement was found between predictions and measurements for the eccentricity ratio and attitude angles. Predictions of stiffness and damping coefficients are in reasonable agreement with measurements. However, experimental results show that the bearing has significant added mass of about 60 kg at no-load conditions, versus zero mass for predictions from the Reynolds-equation model and 40 kg using Reinhardt and Lund's (1975, "The Influence of Fluid Inertia on the Dynamic Properties of Journal Bearings, " ASME J. Lubr. Technol., 97, pp. 159-167) extended Reynolds-equation model for a plain journal bearing. The added mass quickly drops to zero as the load increases. Measured results also show a whirl frequency ratio near 0.36 at no-load conditions; however, a zero whirl frequency ratio was obtained at all loaded conditions, indicating an inherently stable bearing from a rotordynamics viewpoint.
Numerical solution of differential equations

The problem of finding solutions to various types of differential equations has intrigued mathematicians from a theoretical point of view for many years. It has also plagued many applied scientists for an equally long period of time. Except for the relatively few equations whose solutions are available in closed form, the best one can do is to obtain approximate solutions.
Ultraviolet InAlGaN multiple‐quantum‐well laser diodes

The Guest Editors of the Proceedings of the 5th International Conference on Nitride Semiconductors (ICNS-5), Hiroshi Amano and Takashi Udagawa, have nominated the contributed presentation by Michael Kneissl et al. [1] as Editor's Choice of the present issue of physica status solidi (a). This paper is a report on ultraviolet InGaN, GaN and InAlGaN multiple-quantum-well (MQW) laser diodes with emission wavelengths between 368 and 378 nm, continuous-wave operation and a differential quantum efficiency of up to 4.2% which is remarkably high for these laser diodes grown directly on sapphire. The cover picture is a scheme of an InAlGaN MQW laser diode on sapphire substrate. Michael Kneissl is a Member of the Research Staff at the Palo Alto Research Center. He is responsible for device design, MOCVD growth, fabrication, and characterization of GaN-based short-wavelength laser diodes. The full Proceedings of the 5th International Conference on Nitride Semiconductors (ICNS-5) are published in physica status solidi (c) – conferences and critical reviews, Vol. 0, No. 7 (November 2003) (ISBN 3-527-40489-9). Conference papers can also be found in phys. stat. sol. (b) 240, No. 2 (2003).
Conduction-band states and the 5d-4f laser transition of rare-earth ion dopants

We discuss how the interactions of the 5d orbital with the conduction band of the host medium play a crucial role in determining whether rare earth containing materials can serve as useful laser materials, based on their 5d-4f transition. To explore this issue, we examine the pump-probe spectra of Sm2+, Eu2+, and Ce3+ dopants in various fluoride and chloride crystals. In addition we suggest that the luminescence properties are also profoundly impacted by this interaction. The outstanding UV laser performance achieved by the Ce:LiSrAlF6 crystal is rationalized in terms of the reduced overlap of conduction band states with the cerium ions.
Contingent Earnouts in Acquisitions of Privately Held Targets

Prior research has devoted significant attention to ownership choices when firms make market-entry decisions (e.g., equity alliance versus acquisition). This article emphasizes the importance of studying firms' contractual choices as well as the potential relationships between their contractual and ownership choices. This study of acquisitions examines the incidence and determinants of contingent earnouts, which are contracts that specify deferred variable payments to the target. The evidence indicates that the usage of such contracts increases with information asymmetries surrounding mergers and acquisitions, in particular when privately held targets are young or possess knowledge bases that are dissimilar from those of the acquirers. The article also presents evidence that firms' contractual choices (i.e., earnouts) and ownership choices (i.e., equity alliances) can substitute for one another.
Law and the American State

Although classical theories of the state and key texts of historical institutionalism and American political development (APD) defined the American state as a fundamentally legal entity, contemporary studies of the American state show a range of roles for law and courts, from no role at all, to a constraint or obstacle, to a positive force for state development. This review maps these varying roles, showing that law and courts are most absent or play negative roles in studies of the growth of the national administrative welfare state. It highlights new studies in this area that show the American state as a legal state and surveys growing numbers of historical institutionalist and APD studies of the state and economic and social regulation, where law and courts are more prominent. It points to the important but mostly neglected subjects of criminal and tort law as areas for future study that unite law and the state. Finally, it concludes by showing how concepts from the sociology of law—legal mobilization,...
No smoking gun: findings from a national survey of office-based cosmetic surgery adverse event reporting

Background. Because of recent press reports of adverse outcomes, office-based cosmetic surgery has come under intense scrutiny and associated legislative regulatory action. Objective. To assess the safety of office-based cosmetic surgery through a national survey of state agencies that collect information on adverse patient outcomes. Methods. Medical boards or other responsible authorities were contacted in 48 states to obtain records on adverse outcomes from cosmetic surgery procedures performed in an office-based setting. Results. Five states were able to provide complete information regarding 13 cases of adverse outcomes that resulted from office-based cosmetic surgery procedures. Thirteen states had incomplete information or were unable to provide information. The remaining states reported no adverse outcomes. Information collected by state agencies varies greatly and is inadequate to define the safety of office-based cosmetic surgery practice. Conclusions. The need to regulate physician office surgery on the basis of hospital privileges and office certification is not supported by current data. Mandatory reporting of adverse outcomes from office-based surgery is warranted to identify modifiable risk factors and to reduce the risk of adverse outcomes.
A method for determining high-resolution activation time delays in unipolar cardiac mapping

Presents a method for determining activation time delays in unipolar cardiac mapping data to resolutions considerably smaller than the sample interval. The method involves taking two filtered, differentiated electrograms and computing the Hilbert transform of their cross correlation, which exhibits a negative-to-positive zero crossing at the delay time between the signals. Simultaneous endocardial/epicardial recordings of sinus rhythm were made in the swine right atrium using identical, precisely superpositioned electrode arrays. Data were amplified, lowpass filtered, and digitized at 1000 Hz. A window of data was chosen around each electrogram in an endocardial/epicardial electrogram pair. The windowed electrograms were differentiated and highpass filtered, and the Hilbert transform of the cross correlation between the electrograms was computed. The activation time delay was taken to be the first negative-to-positive zero crossing. Average activation time delays (/spl plusmn/SD) were computed for 4-s sinus rhythm recordings from each endocardial/epicardial electrode pair. For a representative site, the average transmural activation time delay was 0.71/spl plusmn/0.06 ms (n=10 electrograms). Time delays estimated using the Hilbert transform method were compared with time delays estimated using the maximum negative slope criterion. The Hilbert transform results exhibited much smaller standard deviations, indicating that the Hilbert transform method may produce more accurate time delay estimates than the maximum negative slope method.
A model for adaptable systems for transaction processing

Adaptability is an essential tool for managing escalating software costs and to build high-reliability, high-performance systems. Algorithmic adaptability, which supports techniques for switching between classes of schedulers in distributed transaction systems, is modeled. RAID, an experimental system implemented to support experimentation in adaptability, is discussed. Adaptability features in RAID, including algorithmic adaptability, fault tolerance, and implementation techniques for an adaptable server-based design, are modeled. >
A single hollow-beam optical trap for cold atoms

We present an optical trap for atoms which we have developed for precision spectroscopy measurements. Cold atoms are captured in a dark region of space inside a blue-detuned hollow laser beam formed by an axicon. We analyse the light potential in a ray optics picture and experimentally demonstrate trapping of laser-cooled metastable xenon atoms.
Scheduling in Wireless Networks under Uncertainties: A Greedy Primal-Dual Approach

This paper proposes a dynamic primal-dual type scheduling algorithm in wireless networks, which achieves optimal throughput even with uncertain parameters. In wireless networks, such uncertain parameters are generated by complicated stochastic dynamics, such as random packet arrivals, channel fading, and node mobilities. The algorithm is a generalization of the well-known max-weight scheduling algorithm proposed by Tassiulas et al., where the only uncertain parameters are the packet arrival rates. Using the technique of fluid limits, sample path convergence result of the algorithm to an arbitrarily close to optimal solution is proved, under the assumption that the Strong Law of Large Numbers (SLLN) applies to the random processes which generate these uncertain parameters. The performance of the algorithm is further verified by simulation results. This method may potentially be applied to other cross-layer optimization problems, where dynamic algorithms for convex problems with uncertain parameters are needed.
Antibacterials from the sea.

The ocean contains a host of macroscopic life in a great microbial soup. Unlike the terrestrial environment, an aqueous environment provides perpetual propinquity and blurs spatial distinctions. Marine organisms are under a persistent threat of infection by resident pathogenic microbes including bacteria, and in response they have engineered complex organic compounds with antibacterial activity from a diverse set of biological precursors. The diluting effect of the ocean drives the construction of potent molecules that are stable to harsh salty conditions. Members of each class of metabolite—ribosomal and non-ribosomal peptides, alkaloids, polyketides, and terpenes—have been shown to exhibit antibacterial activity. The sophistication and diversity of these metabolites points to the ingenuity and flexibility of biosynthetic processes in Nature. Compared with their terrestrial counterparts, antibacterial marine natural products have received much less attention. Thus, a concerted effort to discover new antibacterials from marine sources has the potential to contribute significantly to the treatment of the ever increasing drug-resistant infectious diseases.
Group path formation

When people make choices within a group, they are frequently influenced by the choices made by others. We have experimentally explored the general phenomenon of group behavior where an early action facilitates subsequent actions. Our concrete instantiation of this problem is group path formation where people travel between destinations with the travel cost for moving onto a location inversely related to the frequency with which others have visited the location. We compare the resulting paths to optimal solutions [minimal Steiner trees (MSTs)] and the "Active Walker" model of pedestrian motion from biophysics. There were systematic deviations from beeline pathways in the direction of MST. These deviations showed asymmetries (people took different paths from A to B than they did from B to A) and varied as a function of the topology of the destinations, the duration of travel, and the absolute scale of the world. The Active Walker model accounted for many of these results, in addition to correctly predicting the approximate spatial distribution of steps
An improved query for the hidden subgroup problem

The Hidden Subgroup Problem (HSP) is at the forefront of problems in quantum algorithms. In this paper, we introduce a new query, the character query, generalizing the well-known phase kickback trick that was first used successfully to efficiently solve Deutsch's problem. An equal superposition query with 〈0〉 in the response register is typically used in the "standard method" of single-query algorithms for the HSP. The proposed character query improves over this query by maximizing the success probability of subgroup identification under a uniform prior, for the HSP in which the oracle functions take values in a finite abelian group. We apply our results to the case when the subgroups are drawn from a set of conjugate subgroups and obtain a success probability greater than that found by Moore and Russell.
Optical Analog Solutions Of Partial Differential And Integral Equations

Confocal feedback systems exist in a variety of forms and can solve a wide range of partial differential equations (PDEs) and integral equations (lEs). In this paper we describe several of these feedback systems and how they can be applied to provide optical analog solutions to PDEs of constant coefficients (e.g., diffusion, Poisson's, and wave equations), PDEs of variable coefficients (e.g., modified Helmholtz equations), three-dimensional PDEs, four-dimen-sional PDEs, and IEs (e.g., Fredholm and Volterra equations). The important advantage of obtaining the solutions by optical analog methods rather than digital methods is speed. The disadvantage is solution accuracy, although the accuracy obtainable with optical feedback is better than without feedback. To further improve solution accuracy, we suggest the replacement of simple spherical mirrors by Mangin mirrors and the incorporation of coherent image amplification by photorefractive crystals (e.g., BaTiO3 or BSO) in the confocal systems.
Geodesic Object Representation and Recognition

This paper describes a shape signature that captures the intrinsic geometric structure of 3D objects. The primary motivation of the proposed approach is to encode a 3D shape into a one-dimensional geodesic distribution function. This compact and computationally simple representation is based on a global geodesic distance defined on the object surface, and takes the form of a kernel density estimate. To gain further insight into the geodesic shape distribution and its practicality in 3D computer imagery, some numerical experiments are provided to demonstrate the potential and the much improved performance of the proposed methodology in 3D object matching. This is carried out using an information-theoretic measure of dissimilarity between probabilistic shape distributions.
An Input-Output Construction of Finite State $\rho/\mu$ Approximations for Control Design

We consider discrete-time plants that interact with their controllers via fixed discrete alphabets. For this class of systems, and in the absence of exogenous inputs, we propose a general, methodical approach for constructing a sequence of finite state approximate models starting from finite length sequences of input and output signal pairs. We explicitly derive conditions under which the proposed construct, used in conjunction with a particular generalized structure, satisfies desirable properties ofρ/µapproximations thereby leading to nominal deterministic finite state machine models that can be used in certified-by-design controller synthesis. We also show that the cardinality of the min- imal disturbance alphabet that can be used in this setting equals that of the sensor output alphabet. Finally, we show that the pro- posed construct satisfies a relevant semi-completeness property.
Informal accountability, credible actions, and democratization in Taiwan

How does informal government accountability relate to democratization? In this paper, we use multiple methodologies to show the relation between informal government accountability and democratization in Taiwan. Three results are relevant: First, a game-theoretic model reveals that both informal government accountability and formal democratization are pursued when economic conditions are weak to improve support for the government and extract political concessions for citizens. In particular, the game-theoretic model depicts informal accountability and democratization as outcomes from strategic interaction between the government and citizens where the timing of their preferences and credibility motivate the outcomes. Second, the descriptive studies and statistical analyses corroborate that informal government accountability and democratization occur when economic performance is weak; they also show that informal government accountability is precursory to the democratization process in Taiwan. Third, the evidence supports that informal government accountability leads to formal democratization when political tenure is jeopardized if the constituency-base is not expanded. The findings provide for a predictive model of political development that specifies how informal government accountability feasibly leads to democratization in Taiwan.
Velocity dispersion profiles of seven dwarf spheroidal galaxies

We present stellar velocity dispersion profiles for seven Milky Way dwarf spheroidal (dSph) satellite galaxies. We have measured 8394 line-of-sight velocities (±2.5 km s-1) for 6804 stars from high-resolution spectra obtained at the Magellan and MMT telescopes. We combine these new data with previously published velocities to obtain the largest available kinematic samples, which include more than 5500 dSph members. All the measured dSphs have stellar velocity dispersion of order 10 km s-1 that remains approximately constant with distance from the dSph center, out to and in some cases beyond the radius at which the mean surface brightness falls to the background level. Assuming dSphs reside within dark matter halos characterized by the NFW density profile, we obtain reasonable fits to the empirical velocity dispersion profiles. These fits imply that, among the seven dSphs, Mvir ~ 108-109 M☉. The mass enclosed at a radius of 600 pc, the region common to all data sets, lies in the range (2-7) × 107 M☉.
SPIKE PENETRATION IN BLAST-WAVE-DRIVEN INSTABILITIES

The problem of interest is the unstable growth of structure at density transitions affected by blast waves, which arise in natural environments such as core-collapse supernovae and in laboratory experiments. The resulting spikes of dense material, which penetrate the less dense material, develop broadened tips, but the degree of broadening varies substantially across both experiments and simulations. The variable broadening presumably produces variations in the drag experienced by the spike tips as they penetrate the less dense material. The present work has used semianalytic theory to address the question of how the variation in drag might affect the spike penetration, for cases in which the post-shock interface deceleration can be described by a power law in a normalized time variable. It did so by following the evolution of structure on the interface through the initial shock passage, the subsequent small-amplitude phase of Rayleigh-Taylor instability growth, and the later phase in which the spike growth involves the competition of buoyancy and drag. In all phases, the expansion of the system during its evolution was accounted for and was important. The calculated spike length is strongly affected by the drag attributed to spike tip broadening. One finds from such a calculation that it is not unreasonable for narrow spikes to keep up with the shock front of the blast wave. The implication is that the accuracy of prediction of spike penetration and consequent structure by simulations very likely depends on how accurately they treat the broadening of the spike tips and the associated drag. Experimental validation of spike morphology in simulations would be useful.
From Group Member to Democratic Citizen: How Deliberating with Fellow Jurors Reshapes Civic Attitudes

This investigation assesses the attitudinal impact of one of America’s most distinctive and famous group activities—jury deliberation. Tocqueville and the U.S. Supreme Court have both reasoned that jury service can promote civic engagement and recent research supports this view. The present study examines whether the attitudinal impact of jury deliberation depends on the quality of one’s jury experience. Two panel surveys of 2,410 total jurors tested the reciprocal relationship between the subjective experience of deliberation and the changes in civic attitudes toward oneself, fellow citizens, and public institutions. Principal results of structural equation models showed multiple effects of jury deliberation on attitudes, but there were no effects on one’s civic identity and political self-efficacy. Reciprocally, every civic attitude except faith in fellow citizens was predictive of deliberative experience in at least one of the two studies. Overall, the study bolsters the claim of deliberative democratic theorists that the experience of consequential face-to-face talk can make private individuals into public citizens by reinforcing their confidence in fellow citizens and public institutions.
Profiling Grid Data Transfer Protocols and Servers

The trend of data intensive grid applications has brought grid storage protocols and servers into focus. The objective of this study is to gain an understanding of how time is spent in the storage protocols and servers. The storage protocols have a variety of tuning parameters. Some parameters improve single client performance at the expense of increased server load, thereby limiting the number of served clients. What ultimately matters is the throughput of the whole system. Some parameters increase the flexibility or security of the system at some expense. The objective of this study is to make such trade-offs clear and enable easy full system optimization.
Measurement analogies: comparisons of behavioral and physical measures*

Two examples of behavioral measurement are explored—utility theory and a global psychophysical theory of intensity—that closely parallel the foundations of classical physical measurement in several ways. First, the qualitative attribute in question can be manipulated in two independent ways. Second, each method of manipulation is axiomatized and each leads to a measure of the attribute that, because they are order preserving, must be strictly monotonically related. Third, a law-like constraint, somewhat akin to the distribution property underlying, e.g., mass measurement, links the two types of manipulation. Fourth, given the numerical measures that result from each manipulation, the linking law between them can be recast as a functional equation that establishes the connection between the two measures of the same attribute. Fifth, a major difference from most physical measurement is that the resulting measures are themselves mathematical functions of underlying physical variables—of money and probability in the utility case and of physical intensity and numerical proportions in the psychophysical case. Axiomatizing these functions, although still problematic, appears to lead to interesting results and to limit the degrees of freedom in the representations.
Investigation of the Diffuser Flow Quality in an Icing Research Wind Tunnel

In this paper, the flow in the diffuser section of the Icing Research Tunnel at the NASA Lewis Research Center is both numerically and experimentally investigated. To accomplish the numerical portion of the work, and existing computer code is utilised. The code, known as PARC3D, is based on the Beam-Warming algorithm applied to the strong conservation law form of the complete Navier-Stokes equations. Following a brief description of the diffuser geometry, the measured flow characteristics are described. A brief discussion of the code work is also provided. The flow measurements show a highly nonuniform velocity profile across the diffuser exit with boundary-layer growth more prevalent near the centres of the walls rather than in the corners of the diffuser. Predicted velocity profiles at the centreline are similar to those measured; however, the code did not accurately predict the boundary-layer behaviour near the corners.
Asymmetric synthesis of (-)-dihydroxanthatin by the stereoselective Oshima-Utimoto reaction.

The catalytic stereoselective Oshima−Utimoto reaction is useful for the construction of five-membered oxacycles from simple starting materials and was employed for the preparation of the lactone group in the asymmetric synthesis of (−)-11α,13-dihydroxanthatin. Completion of the synthesis is facilitated by ring-closing enyne metathesis and alkene cross metathesis reactions.
Twisted geometric Satake equivalence via gerbes on the factorizable grassmannian

The geometric Satake equivalence of Ginzburg and Mirkovic– Vilonen, for a complex reductive group G, is a realization of the tensor category of representations of its Langlands dual group LG as a category of “spherical” perverse sheaves on the affine grassmannian GrG = G(C((t)))/G(C[[t]]). Since its original statement it has been generalized in two directions: first, by Gaitsgory, to the Beilinson–Drinfeld or factorizable grassmannian, which for a smooth complex curve X is a collection of spaces over the powers Xn whose general fiber is isomorphic to GrG but with the factors “fusing” as they approach points with equal coordinates, allowing a more natural description of the structures and properties even of the Mirkovic–Vilonen equivalence. The second generalization, due recently to Finkelberg–Lysenko, considers perverse sheaves twisted in a suitable sense by a root of unity, and obtains the category of representations of a group other than the Langlands dual. This latter result can be considered as part of “Langlands duality for quantum groups”. In this work we obtain a result simultaneously generalizing all of the above. We consider the general notion of twisting by a gerbe and define the natural class of “factorizable” gerbes by which one can twist in the context of the Satake equivalence. These gerbes are almost entirely described by the quadratic forms on the weight lattice of G. We show that a suitable formalism exists such that the methods of Mirkovic–Vilonen can be applied directly in this general context virtually without change and obtain a Satake equivalence for twisted perverse sheaves. In addition, we present new proofs of the properties of their structure as an abelian tensor category.
Instability and transition to turbulence in a free shear layer affected by a parallel magnetic field

Instability and transition to turbulence in a temporally evolving free shear layer of an electrically conducting fluid affected by an imposed parallel magnetic field is investigated numerically. The case of low magnetic Reynolds number is considered. It has long been known that the neutral disturbances of the linear problem are three-dimensional at sufficiently strong magnetic fields. We analyse the details of this instability solving the generalized Orr–Sommerfeld equation to determine the wavenumbers, growth rates and spatial shapes of the eigenmodes. The three-dimensional perturbations are identified as oblique waves and their properties are described. In particular, we find that at high hydrodynamic Reynolds number, the effect of the strength of the magnetic field on the fastest growing perturbations is limited to an increase of their oblique angle. The dimensions and spatial shape of the waves remain unchanged. The transition to turbulence triggered by the growing oblique waves is investigated in direct numerical simulations. It is shown that initial perturbations in the form of superposition of two symmetric waves are particularly effective in inducing three-dimensionality and turbulence in the flow.
The Approval Process for Biosimilar Erythropoiesis-Stimulating Agents

A biosimilar drug or follow-on biologic drug is defined by the Public Health Service Act as a product that is “highly similar to the reference product notwithstanding minor differences in clinically active components and there are no clinically meaningful differences between the biologic product and the reference product in terms of the safety, purity and potency of the product.” The advantage of biosimilar drugs is that they are significantly less expensive than the reference products, allowing for increased accessibility and cost savings. Recognizing these advantages, the US Congress passed the Biologics Price Competition and Innovation Act in 2009 as part of health care reform. The Biologics Price Competition and Innovation Act allows sponsors of biosimilar agents to seek approval by showing structural and functional similarity to the reference agent, with the extent of required clinical studies to be determined on the basis of the degree of biosimilarity with the reference product. The goal is to bring biosimilar agents to the market more efficiently while still protecting the safety of the public. The European Union has had such a process in place for a number of years. Two biosimilar epoetin agents have been approved in the European Union since 2007, and their companies are conducting trials to seek approval in the United States, because Amgen’s patent protection for epoetin alfa expires in 2014. Trials completed for European Union approval of both agents showed similar efficacy and safety to the reference epoetin alfa. As with all biologics, immunogenicity concerns may persist because of the fragility of the manufacturing process and the worldwide experience with pure red cell aplasia as a result of epoetin therapy. The uptake of biosimilar epoetins after approval in the United States will depend on the balance of cost advantage against safety concerns. Competition in the marketplace will likely decrease the cost of the reference agent as well.
Control of an unstable reaction-diffusion PDE with long input delay

A Smith Predictor-like design for compensation of arbitrarily long input delays is available for general, controllable, possibly unstable LTI finite-dimensional systems. Such a design has not been proposed previously for problems where the plant is a PDE. We present a design and stability analysis for a prototype problem, where the plant is a reaction-diffusion (parabolic) PDE, with boundary control. The plant has an arbitrary number of unstable eigenvalues and arbitrarily long delay, with an unbounded input operator. The predictor-based feedback design extends fairly routinely, within the framework of infinite-dimensional backstepping. However, the stability analysis contains interesting features that do not arise in predictor problems when the plant is an ODE. The unbounded character of the input operator requires that the stability be characterized in terms of the H 1 (rather than the usual L 2 ) norm of the actuator state. The analysis involves an interesting structure of interconnected PDEs, of parabolic and first-order hyperbolic types, where the feedback gain kernel for the undelayed problem becomes an initial condition in a PDE arising in the compensator design for the problem with input delay. Space and time variables swap their roles in an interesting manner throughout the analysis.
The effect of hysteresis on equilibrium selection in coordination games

Abstract One of the fundamental problems in both economics and organization is to understand how individuals coordinate. The widely used minimum-effort coordination game has served as a simplified model to better understand this problem. This paper first presents theoretical results that give conditions under which the minimum-effort coordination game exhibits hysteresis. It then uses these theoretical results to develop and confirm some experimental hypotheses using human subjects in the laboratory. The main insight is that play in a given game is heavily dependent on the history of parameters leading up to that game. For example, the experiments show that when cost c = 0.5 in the minimum-effort coordination game, there is significantly more high effort if the cost has increased to c = 0.5 compared to when the cost has decreased to c = 0.5. One implication of this is that a temporary change in parameters may be able move the economic system from a bad equilibrium to a good equilibrium.
Abnormal Audit Fees and Audit Quality: The Importance of Considering Managerial Incentives in Tests of Earnings Management

SUMMARY: Are high audit fees a signal that the auditor exerted more effort or a signal that the auditor may be losing her independence? Prior literature offers conflicting evidence. In this paper, we reexamine the issue on a sample of clients who have both the incentive and the ability to use discretionary accruals to meet or beat the consensus earnings forecast. We find a negative relationship between the level of abnormal audit fees paid by the client and the likelihood of using discretionary accruals to meet or beat the consensus analyst forecast. The evidence is consistent with the notion that abnormal audit fees are indicative of greater effort on the engagement. In other words, the results suggest a positive relationship between abnormal audit fees and audit quality. We show that the conflicting evidence in prior research was caused by research designs that did not consider the incentives of the manager. JEL Classifications: M42; M41. Data Availability: All data are available from public sources quo...
Machine learning of generic and user-focused summarization

A key problem in text summarization is finding a salience function which determines what information in the source should be included in the summary. This paper describes the use of machine learning on a training corpus of documents and their abstracts to discover salience functions which describe what combination of features is optimal for a given summarization task. The method addresses both "generic" and user-focused summaries.
Integrating vehicle design and human factors: minimizing elderly driving constraints

With a projected rise in the number of elderly, most of whom have also relied primarily on the private automobile for their mobility, it is likely that future adaptations in vehicle design will be linked in some part to the physical infirmities often faced by the elderly. This paper oAers a bridge between medical research on the physical impairments of the elderly and automobile design and driving safety. We describe recent findings on the driving-related physical and cognitive impairments faced by the elderly. We then propose two major types of vehicle design and infrastructure adaptations: (1) modifications for private vehicles, and (2) intelligent technology and support services for private vehicles, which can help to minimize the driving- related eAects of these impairments. For example, we present a range of modest vehicle design adaptations for components such as seats and doorways, handles, knobs, and steering wheels, and seat belts. We find that many of these improvements can be made to standard passenger vehicles with little additional design eAort, and that the adaptations should also increase overall vehicle marketability. Finally, we argue that while most, if not all, of our proposed adaptations would be made to largely benefit the elderly, they will nevertheless support and improve driving across all age groups. " 2001 Elsevier Science Ltd. All rights reserved.