cssi/SciSciGPT-SciSciNet huggingface dataset:
Inertial range turbulence in kinetic plasmas

The transfer of turbulent energy through an inertial range from the driving scale to dissipative scales in a kinetic plasma followed by the conversion of this energy into heat is a fundamental plasma physics process. A theoretical foundation for the study of this process is constructed, but the details of the kinetic cascade are not well understood. Several important properties are identified: (a) The conservation of a generalized energy by the cascade; (b) the need for collisions to increase entropy and realize irreversible plasma heating; and (c) the key role played by the entropy cascade—a dual cascade of energy to small scales in both physical and velocity space—to convert ultimately the turbulent energy into heat. A strategy for nonlinear numerical simulations of kinetic turbulence is outlined. Initial numerical results are consistent with the operation of the entropy cascade. Inertial range turbulence arises in a broad range of space and astrophysical plasmas and may play an important role in the th...
Frobenius modules and Hodge asymptotics

We exhibit a direct correspondence between the potential defining the H1,1 small quantum module structure on the cohomology of a Calabi-Yau manifold and the asymptotic data of the A-model variation of Hodge structure. This is done in the abstract context of polarized variations of Hodge structure and Frobenius modules.
Overlap Dirac operator, eigenvalues and random matrix theory

Abstract The properties of the spectrum of the overlap Dirac operator and their relation to random matrix theory are studied. In particular, the predictions from chiral random matrix theory in topologically non-trivial gauge field sectors are tested.
Measuring Primordial Non-Gaussianity in the Cosmic Microwave Background

We derive a fast way for measuring primordial non-Gaussianity in a nearly full-sky map of the cosmic microwave background. We find a cubic combination of sky maps combining bispectrum configurations to capture a quadratic term in primordial fluctuations. Our method takes only N3/2 operations rather than N5/2, as taken by the bispectrum analysis (1000 times faster for l = 512), retaining the same sensitivity. A key component is a map of the underlying primordial fluctuations, which can be more sensitive to the primordial non-Gaussianity than a temperature map. We also derive a fast and accurate statistic for measuring non-Gaussian signals from foreground point sources. The statistic is 106 times faster than the full bispectrum analysis and can be used to estimate contamination from the sources. Our algorithm has been successfully applied to the Wilkinson Microwave Anisotropy Probe sky maps by Komatsu and coworkers.
Fourier Series and Approximation on Hexagonal and Triangular Domains

Several problems on Fourier series and trigonometric approximation on regular hexagonal and triangular domains are studied. The results include Abel and Cesaro summability of Fourier series, degree of approximation, and best approximation by trigonometric functions with both direct and inverse theorems. One of the objectives of this study is to demonstrate that Fourier series on spectral sets enjoy a rich structure that permits an extensive theory for Fourier series and approximation.
Supersymmetric, cold and lukewarm black holes in cosmological Einstein-Maxwell theory

Abstract In asymptotically flat (AF) space, the extreme Reissner-Nordstrom (RN) black hole is distinguished by its coldness (vanishing Hawking temperature) and its supersymmetry. We examine RN solutions to Einstein-Maxwell theory with a cosmological constant Λ, classifying the cold black holes and, for positive Λ, the “lukewarm” black holes at the same temperature as the de Sitter thermal background. For negative Λ, we classify the supersymmetric solutions within the context of N = 2 gauged supergravity. One finds supersymmetric analogues of AF-space extreme RN black holes, which for nonzero Λ differ from the cold black holes. In addition, these is an exotic class of supersymmetric solutions which cannot be continued to asymptotically flat space, since the magnetic charge becomes infinite in that limit.
The effect of neglecting correlations when propagating uncertainty and estimating the population distribution of risk.

Interest in examining both the uncertainty and variability in environmental health risk assessments has led to increased use of methods for propagating uncertainty. While a variety of approaches have been described, the advent of both powerful personal computers and commercially available simulation software have led to increased use of Monte Carlo simulation. Although most analysts and regulators are encouraged by these developments, some are concerned that Monte Carlo analysis is being applied uncritically. The validity of any analysis is contingent on the validity of the inputs to the analysis. In the propagation of uncertainty or variability, it is essential that the statistical distribution of input variables are properly specified. Furthermore, any dependencies among the input variables must be considered in the analysis. In light of the potential difficulty in specifying dependencies among input variables, it is useful to consider whether there exist rules of thumb as to when correlations can be safely ignored (i.e., when little overall precision is gained by an additional effort to improve upon an estimation of correlation). We make use of well-known error propagation formulas to develop expressions intended to aid the analyst in situations wherein normally and lognormally distributed variables are linearly correlated.
JNI light: an operational model for the core JNI

Through foreign function interfaces (FFIs), software components in different programming languages interact with each other in the same address space. Recent years have witnessed a number of systems that analyse FFIs for safety and reliability. However, lack of formal specifications of FFIs hampers progress in this endeavour. We present a formal operational model, Java Native Interface (JNI) light (JNIL), for a subset of a widely used FFI – the Java Native Interface (JNI). JNIL focuses on the core issues when a high-level garbage-collected language interacts with a low-level language. It proposes abstractions for handling a shared heap, cross-language method calls, cross-language exception handling, and garbage collection. JNIL can directly serve as a formal basis for JNI tools and systems. We demonstrate its utility by proving soundness of a system that checks native code in JNI programs for type-unsafe use of JNI functions. The abstractions in JNIL are also useful when modelling other FFIs, such as the Python/C interface and the OCaml/C interface.
Generalized localized atomic orbitals

Recent publications concerning localized atomic orbitals (LAOs) for atoms in closed shell molecules showed a number of LAO properties to be highly transferable insofar as the atom experienced equivalent bonding environments in a series of molecules. Assuming that transferability of LAO properties (such as interorbital angles and Mulliken populations) portends a concurrent transferability of LAO structure, we here deduce a set of average hybrids, or generalized LAOs (GLAOs). The GLAOs may, in principle, serve the same purpose as the familiar spn (n = 1, 2, 3,) orbitals; however, the former evidence a number of desireable trends not represented in the latter. For instance, GLAOs allow hybridization to vary in response to alterations in both degree of unsaturation (e.g., –C– vs C = vs = C = vs. –C≡) and atomic number (e.g., –C– vs. N– vs –O– vs F– ). This is in accord with experimental data such as bond angles, which tend to vary in conjunction with the same sorts of phenomena. It is important to note...
Adsorption as a Method of Doping 3‐mol%‐Yttria‐Stabilized Zirconia Powder with Copper Oxide

The adsorption behavior of Cu[sup 2+] on 3-mol%-yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) powder was studied. There is a window of pH values (10 < pH < 11) where adsorption may be used as a method of doping 3Y-TZP with Cu[sup 2+]. The maximum mole percent of the CuO additions is determined by the specific surface area of the 3Y-TZP powder; a powder with a specific surface area of 16.1 m[sup 2]/g is limited to about 1 mol% CuO. Compacts made from powders doped with CuO using this method exhibited an enhancement in superplasticity comparable to that observed in other studies using samples doped with CuO by attrition milling.
TiO2 nanocrystals grown on graphene as advanced photocatalytic hybrid materials

A graphene/TiO2 nanocrystals hybrid has been successfully prepared by directly growing TiO2 nanocrystals on graphene oxide (GO) sheets. The direct growth of the nanocrystals on GO sheets was achieved by a two-step method, in which TiO2 was first coated on GO sheets by hydrolysis and crystallized into anatase nanocrystals by hydrothermal treatment in the second step. Slow hydrolysis induced by the use of EtOH/H2O mixed solvent and addition of H2SO4 facilitates the selective growth of TiO2 on GO and suppresses growth of free TiO2 in solution. The method offers easy access to the GO/TiO2 nanocrystals hybrid with a uniform coating and strong interactions between TiO2 and the underlying GO sheets. The strong coupling gives advanced hybrid materials with various applications including photocatalysis. The prepared graphene/TiO2 nanocrystals hybrid has superior photocatalytic activity to other TiO2 materials in the degradation of rhodamine B, showing an impressive three-fold photocatalytic enhancement over P25. It is expected that the hybrid material could also be promising for various other applications including lithium ion batteries, where strong electrical coupling to TiO2 nanoparticles is essential.
Coase, competition, and compensation

Abstract I show that the Pigovian solution to a simple externalities problem and a particular Coasian solution can be viewed as competitive equilibria from different initial endowments. I also describe the “compensation mechanism,” a mechanism that implements either the Coasian or Pigovian solution as the outcome of an economically natural bargaining game.
HyRec: A fast and highly accurate primordial hydrogen and helium recombination code

We present a state-of-the-art primordial recombination code, HYREC, including all the physical effects that have been shown to significantly affect recombination. The computation of helium recombination includes simple analytic treatments of hydrogen continuum opacity in the He I ${2}^{1}{P}^{o}\ensuremath{-}{1}^{1}S$ line, the He I] ${2}^{3}{P}^{o}\ensuremath{-}{1}^{1}S$ line, and treats feedback between these lines within the on-the-spot approximation. Hydrogen recombination is computed using the effective multilevel atom method, virtually accounting for an infinite number of excited states. We account for two-photon transitions from $2s$ and higher levels as well as frequency diffusion in Lyman-$\ensuremath{\alpha}$ with a full radiative transfer calculation. We present a new method to evolve the radiation field simultaneously with the level populations and the free electron fraction. These computations are sped up by taking advantage of the particular sparseness pattern of the equations describing the radiative transfer. The computation time for a full recombination history is $\ensuremath{\sim}2$ seconds. This makes our code well suited for inclusion in Monte Carlo Markov chains for cosmological parameter estimation from upcoming high-precision cosmic microwave background anisotropy measurements.
The Mild Cleavage of 2-Amino-2-deoxy-d-glucoside Methoxycarbonyl Derivatives

The conversion of methyl carbamate to the corresponding free amine is described for a series of 2-amino-2-deoxy-d-glucosamine derivatives. Cleavage of methoxycarbonyl moiety with MeSiCl3 and triethylamine in dry THF at 60 °C and subsequent aqueous hydrolysis yields the free amine in 54 to 93% yields. The selective cleavage of methyl carbamates with MeSiCl3 in the presence of a 2,2,2-trichloroethoxycarbonyl group or 2-azido glycosides affords selectively, orthogonal N-deprotected carbohydrates.
Scale determination using the static potential with two dynamical quark flavors

Abstract We study the static potential using gauge configurations that include the effects of two flavors of dynamical Kogut-Susskind quarks. The configurations, generated by the MILC collaboration, and used to study the spectrum and heavy-light decay constants, cover a range 5.3 ⪯ 6 g 2 ⪯ 5.6 . There are at least four quark masses for each coupling studied. Determination of r 0 from the potential can be used to set a scale. This alternative scale is useful to study systematic errors on the spectrum and decay constants.
The classical limit for a class of quantum baker’s maps

We show that the class of quantum baker's maps defined by Schack and Caves have the proper classical limit provided the number of momentum bits approaches infinity. This is done by deriving a semi-classical approximation to the coherent-state propagator.
Satellite augmentation of cellular type mobile radio telephone systems

Abstract NASA's ATS-6 satellite relayed voice bandwidth communications between five trucks and the trucking company dispatchers as the trucks traveled throughout the north-eastern quarter of the contiguous United States. The experiment, conducted over a seven month period, demonstrated that propagation characteristics are much different for the satellite-mobile links than for terrestrial-mobile links. A properly designed satellite system can provide high quality, reliable voice and data communications except where the vehicle-satellite path is shadowed by a structure or terrain feature. Mobile equipment in the experiment was adapted from commercial mobile radios. The vehicle antennas were 75 cm tall, 2 cm diam. Another experiment proved the feasibility of vehicle position surveillance using active two-way tone-code ranging through ATS-6 to provide one line of position and passive one-way ranging by measuring the time-of-arrival of a signal from an independent satellite. A position fix was printed out at an earth station 1 sec after it sent the interrogation signal to the distant vehicle, a towboat on the Mississippi River. The line of position from ATS-6 was accurate to 0.1 nautical mile using a voice bandwidth ranging signal. The line of position from the NOAA GOES satellite was accurate to 2 miles, using 100 Hz signal bandwidth. If the signal from the independent satellite had the same bandwidth and signal-to-noise ratio as ATS-6, the fixes would have been accurate to about 0.1 nautical mile. A concept study concluded that satellites might be a cost effective augmentation of terrestrial cellular type mobile radio telephone systems. The satellites would serve thinly populated areas where terrestrial systems are not cost effective. In the United States, the satellites would serve about 90% of the land area where 20% of the population resides. A multibeam satellite with many channels in each beam would be compatible with the urban terrestrial systems and together they would provide a nearly ubiquitous mobile radio telephone service.
CytoSolve: A Scalable Computational Method for Dynamic Integration of Multiple Molecular Pathway Models

A grand challenge of computational systems biology is to create a molecular pathway model of the whole cell. Current approaches involve merging smaller molecular pathway models’ source codes to create a large monolithic model (computer program) that runs on a single computer. Such a larger model is difficult, if not impossible, to maintain given ongoing updates to the source codes of the smaller models. This paper describes a new system called CytoSolve that dynamically integrates computations of smaller models that can run in parallel across different machines without the need to merge the source codes of the individual models. This approach is demonstrated on the classic Epidermal Growth Factor Receptor (EGFR) model of Kholodenko. The EGFR model is split into four smaller models and each smaller model is distributed on a different machine. Results from four smaller models are dynamically integrated to generate identical results to the monolithic EGFR model running on a single machine. The overhead for parallel and dynamic computation is approximately twice that of a monolithic model running on a single machine. The CytoSolve approach provides a scalable method since smaller models may reside on any computer worldwide, where the source code of each model can be independently maintained and updated.
GETTING THE WORDS IN

T HE AUTHOR Of a very good first-year text in a foreign language has this bit of advice for the user of his book: "If you are a typical foreignlanguage student.., .you probably tend to worry a great deal about vocabulary. Please don't, because it is the least important aspect of your study ... ."1 This bit of doctrine has been preached to students for half a century, but I doubt that anyone but a first-year dropout has ever been convinced by it. The faithful, after struggling on for three or four years, know very well what they have had to spend the most time on-the brute mastery of hundreds of terms for not quite familiar segmentations of reality as it is seen by people in a culture different from their own. It is probably true that in the initial stages one learns better by concentrating on other things, but in the long run the heaviest investment is in words. If the language teacher puts words last, what does the linguist do ? Take the classical version of transformational grammar. It pictures, underlying each sentence, a deep structure in which the top roles are given to elements such as NP and VP, leading down a structure tree to other elements such as determiners, nouns, verbs, and adverbials, and ending up, at the bottom, with a series of slots each of which is headed by a list of features: +Animate, +Common, -Count, -Emphatic, to name a few. As a final step, into each slot there is plugged a word, one selected from the lexicon in such a way as not to violate the conditions set forth in the list of features. As with the
Enantioselective Catalytic α-Alkylation of Aldehydes via an SN1 Pathway

Primary aminothiourea derivatives are shown to catalyze enantioselective alkylation of alpha-arylpriopionaldehdyes with diarylbromomethane. Evidence for a stepwise, S(N)1 mechanism in the substitution reaction induced by anion binding to the catalyst is provided by catalyst structure-activity studies, kinetic isotope effects, linear free-energy relationship studies, and competition experiments.
Hydrogen shifts in cyclohexylcarbenes. Spatial dependence of activating power and of primary deuterium isotope effects

Abstract The conformationally biased ketones 4-t-butyl-cis-2-methylcyclohexanone (1c) and 4-t-butyl-cis-2-trans-6-dimethylcyclohexanone (7a; and its 2,6-dideuterio derivative 7c) were converted into p-toluenesulfonylhydrazone Li salts. Thermolysis or photolysis generated putative singlet carbenes, which underwent competitive axial vs equatorial H shift (or D shift in the case of 7c) to give alkenes. Product analysis showed that a bystander Meeq substituent promotes a geminal H shift several times more efficiently than does a bystander Meax. This geometry-dependent activating power parallels behavior noted earlier for OMe and Ph bystander groups; but as Me groups are rotationally symmetric and possess no lone pair or π electrons this phenomenon cannot be attributed solely to rotameric considerations or to effects involving mobile electron clouds. For the trans-dimethylcarbenes 10a and 10c the primary deuterium isotope effect (kH/kD) for axial migration (Iax) was determined to be ca. 1.5 times larger than that for equatorial migration (Ieq). This finding invalidates the common assumption that Iax = Ieq and suggests that published data on deuterium isotope effects and on Hax/Heq migration selectivities need to be adjusted.
The Stellar Kinematic Fields of NGC 3379

We have measured the stellar kinematic profiles of NGC 3379 along four position angles, using absorption lines in spectra obtained with the Multiple Mirror Telescope. We derive a far more detailed description of the kinematic fields through the main body of the galaxy than could be obtained from previous work. Our data extend 90'' from the center, at essentially seeing-limited resolution out to 17''. The derived mean velocities and dispersions have total errors (internal and systematic) better than ?10 km s-1, and frequently better than 5 km s-1, out to 55''. We find very weak (3 km s-1) rotation on the minor axis interior to 12'' and no detectable rotation above 6 km s-1 from 12'' to 50'' or above 16 km s-1 out to 90'' (95% confidence limits). However, a Fourier reconstruction of the mean velocity field from all four sampled PAs does indicate a ~5? twist of the kinematic major axis, in the direction opposite to the known isophotal twist. The h3 and h4 parameters are found to be generally small over the entire observed region. The azimuthally averaged dispersion profile joins smoothly at large radii with the velocity dispersions of planetary nebulae. Unexpectedly, we find sharp bends in the major axis rotation curve, also visible (though less pronounced) on the diagonal position angles. The outermost bend closely coincides in position with other sharp kinematic features: an abrupt flattening of the dispersion profile, and local peaks in h3 and h4. All of these features are in a photometrically interesting region in which the surface brightness profile departs significantly from an r1/4 law. Features such as these are not generally known in elliptical galaxies owing to a lack of data at comparable resolution. Very similar behavior, however, is seen the kinematics of the edge-on S0 galaxy NGC 3115. We discuss the suggestion that NGC 3379 could be a misclassified S0 galaxy; preliminary results from dynamical modeling indicate that it may be a flattened, weakly triaxial system seen in an orientation that makes it appear round.
Oriented open - closed string theory revisited

Abstract String theory on D-brane backgrounds is open-closed string theory. Given the relevance of this fact, we give details and elaborate upon our earlier construction of oriented open-closed string field theory. In order to incorporate explicitly closed strings, the classical sector of this theory is open strings with a homotopy associativeA∞algebraic structure. We build a suitable Batalin–Vilkovisky algebra on moduli spaces of bordered Riemann surfaces, the construction of which involves a few subtleties arising from the open string punctures and cyclicity conditions. All vertices coupling open and closed strings through disks are described explicitly. Subalgebras of the algebra of surfaces with boundaries are used to discuss symmetries of classical open string theory induced by the closed string sector, and to write classical open string field theory on general closed string backgrounds. We give a preliminary analysis of the ghost-dilaton theorem.
An Interhemispheric Four-Box Model of the Meridional Overturning Circulation

Abstract The authors introduce a four-box interhemispheric model of the meridional overturning circulation. A single box represents high latitudes in each hemisphere, and in contrast to earlier interhemispheric box models, low latitudes are represented by two boxes—a surface box and a deep box—separated by a thermocline in which a balance is assumed between vertical advection and vertical diffusion. The behavior of the system is analyzed with two different closure assumptions for how the low-latitude upwelling depends on the density contrast between the surface and deep low-latitude boxes. The first is based on the conventional assumption that the diffusivity is a constant, and the second on the assumption that the energy input to the mixing is constant. There are three different stable equilibrium states that are closely analogous to the three found by Bryan in a single-basin interhemispheric ocean general circulation model. One is quasi-symmetric with downwelling in high latitudes of both hemispheres, a...
Pictorial data transmission from a space vehicle

Space communications pose a unique set of problems in line-of-sight transmission. Major ones include nonstationary terminals, the astronomical distances involved, and bandwidth restrictions consistent with power restrictions. There are also conflicting requirements of maximum reliability and minimum weight of equipment.
A new spin on magnetic memories

Solid-state memory devices with all-electrical read and write operations might lead to faster, cheaper information storage.
An Elliptic Problem Arising from the Unsteady Transonic Small Disturbance Equation

Abstract We prove a theorem on existence of a weak solution of the Dirichlet problem for a quasilinear elliptic equation with a degeneracy on one part of the boundary. The degeneracy is of a type (“Keldysh type”) associated with singular behavior—blow-up of a derivative—at the boundary. We define an associated operator which is continuous, pseudo-monotone and coercive and show that a weak solution displaying singular behavior at the boundary exists.
Harnessing energy from marine productivity using bioelectrochemical systems

Over the past decade, studies have shown that devices called microbial fuel cells (MFCs) can harness electricity from microbially mediated degradation of organic carbon, in both lab cultures and natural environments. Other studies have shown that MFCs can harness power from coastal and deep ocean sediments, as well as from plankton, without any fuel supplementation or microbial inoculation. The fuel for these systems is organic matter resulting from oceanic primary productivity. Models suggest that MFCs may operate for decades on endogenous organic carbon. In light of their capacity to generate power in natural milieus by tapping into biogeochemical cycles, MFCs may one day provide an efficient means of generating power (or high value biofuels) directly from marine productivity.
Bayesian Gaussian Copula Factor Models for Mixed Data

Gaussian factor models have proven widely useful for parsimoniously characterizing dependence in multivariate data. There is rich literature on their extension to mixed categorical and continuous variables, using latent Gaussian variables or through generalized latent trait models accommodating measurements in the exponential family. However, when generalizing to non-Gaussian measured variables, the latent variables typically influence both the dependence structure and the form of the marginal distributions, complicating interpretation and introducing artifacts. To address this problem, we propose a novel class of Bayesian Gaussian copula factor models that decouple the latent factors from the marginal distributions. A semiparametric specification for the marginals based on the extended rank likelihood yields straightforward implementation and substantial computational gains. We provide new theoretical and empirical justifications for using this likelihood in Bayesian inference. We propose new default pri...
Low-Thrust Eccentricity-Constrained Orbit Raising

The problem of zero-eccentricity-constrained orbit raising in circular orbit in the presence of shadowing is analyzed using both numerical and analytical methods. Given the shadow arclength, piecewise constant pitch angles are selected analytically, and the location along the orbit where the pitch angle switches is optimized to effect the largest change in semimajor axis per revolution. Two strategies yielding near-optimal performance are presented, differing in whether or not a pitch reorientation maneuver is carried out inside the shadow arc. These analyticresultsarealso compared withtheexacteccentricity-constrainednumericalsolutions,whichuseoptimally varying continuous pitch proe les to maximize the change in semimajor axis after each revolution. The suboptimal analytic strategies arealmost as effectiveastheoptimal strategy especially in higherorbit. Thesestrategiesremove theneedforcontinuouslyreorienting thespacecraftattitudein pitch,providing robustreal-timeon-boardguidance capability for electric orbit transfer vehicle orbit raising applications.
Synthesis of ceratinamine and moloka'iamine: Antifouling agents from the marine sponge Pseudoceratina purpurea

Abstract Syntheses of the title compounds ( 4 and 5 , respectively) are described together with a biogenetic hypothesis that rationalizes the origin of ceratinamine's unique cyanoformamide functionality.
Modeling Self-subtraction in Angular Differential Imaging: Application to the HD?32297 Debris Disk

We present a new technique for forward-modeling self-subtraction of spatially extended emission in observations processed with angular differential imaging (ADI) algorithms. High-contrast direct imaging of circumstellar disks is limited by quasi-static speckle noise, and ADI is commonly used to suppress those speckles. However, the application of ADI can result in self-subtraction of the disk signal due to the disk's finite spatial extent. This signal attenuation varies with radial separation and biases measurements of the disk's surface brightness, thereby compromising inferences regarding the physical processes responsible for the dust distribution. To compensate for this attenuation, we forward model the disk structure and compute the form of the self-subtraction function at each separation. As a proof of concept, we apply our method to 1.6 and 2.2 μm Keck adaptive optics NIRC2 scattered-light observations of the HD 32297 debris disk reduced using a variant of the "locally optimized combination of images" algorithm. We are able to recover disk surface brightness that was otherwise lost to self-subtraction and produce simplified models of the brightness distribution as it appears with and without self-subtraction. From the latter models, we extract radial profiles for the disk's brightness, width, midplane position, and color that are unbiased by self-subtraction. Our analysis of these measurements indicates a break in the brightness profile power law at r ≈ 110 AU and a disk width that increases with separation from the star. We also verify disk curvature that displaces the midplane by up to 30 AU toward the northwest relative to a straight fiducial midplane.
Do firms plan

The late F. A. Hayek is remembered for the argument that the decentralized price system has enormous advantages over planned systems in the critical areas of information transmission and the use of knowledge. In many minds, the recent fall of the Soviet-style economies in Eastern Europe has decisively made that case. But not all are persuaded. The model of central planning that originally impressed Lenin—the modern business corporation—remains in many minds a formidable piece of empirical evidence in favor of the possibility and desirability of centralized administrative control. This paper argues that Hayek's theory of spontaneous order can in fact include the case of such apparently purposive and extramarket forms as the business firm. It picks up a number of suggestions in Hayek's evolutionary theory of social institutions and uses them to draw a picture of the firm that is somewhat different from what one finds on the easel of neoclassical transaction-cost analysis. In the Hayekian picture, firms and markets are both systems of rules of conduct. And both are systems for economizing on knowledge in the face of economic change, albeit quite different kinds of knowledge and change. In the end, the firm is not a model for political planning for one very simple reason: the firm does not plan.
The impact of contact

Abstract Scenarios of the impact on human society of radio contact with an extraterrestrial civilization vary widely between paranoid projections that contact with advanced extraterrestrials would quickly devastate the human spirit, and pronoid predictions that the extraterrestrials would be so advanced that they would swiftly and benevolently lead us into a golden age. Such extreme pronouncements exaggerate the probable speed and magnitude of the impact of radio contact in that they conflate technical and cultural understanding, and ignore the problem of inter-civilizational comprehension. Judging from the record of cultural misunderstanding between closely related human groups, comprehending a totally different civilization light years away, and absorbing the meaning of whatever messages were sent, would be a slow and tedious process calling for the efforts of specialists from many disciplines as well as the SETI scientists now engaged in the search.
Electro-optical silicon isolator

We demonstrate the first non-magnetic CMOS-compatible optical isolator on a silicon chip. The isolator is based on indirect interband photonic transition, created by electrically-driven dynamic refractive index modulation on a two-mode waveguide. We observe a strong contrast (up to 3dB) in the transmission coefficient along the forward and backward directions.
Money market pressure in emerging economies: International contagion versus domestic determinants

Abstract Recent market turmoil has again raised the threat of banking crises worldwide. Might these crises be contagious internationally, or are fundamentals more likely to be responsible? This study creates monthly indices of “money market pressure” (MMP) for 20 emerging markets from 2002 to 2010, before using Vector Autoregressive (VAR) methods to test for various spillovers among money and foreign exchange markets. We find that MMP Granger-causes exchange market pressure (EMP) in most countries, but that causality does not run the other direction. Secondly, MMP seems to be more contagious in Southeast Asia than in Latin America or among large emerging markets globally, and the most financially open economies are most susceptible to “direct” spillovers that do not operate through exchange markets. Finally, when examining domestic influences in large emerging markets, output drops are most likely to increase MMP.
The Business Value of IT: A Synthesis and Framework of Archival Research

ABSTRACT: This paper synthesizes recent empirical archival research investigating the link between information technology investment and business value. It examines (1) financial and nonfinancial measures to represent different elements of business value, (2) IT investment measures and links with firm performance, (3) IT and business complementarities that affect firm performance, and (4) the impact of business context and IT alignment with business strategy on resulting performance. The review of prior research is guided by a balanced scorecard framework that places IT in a business context and highlights the role of potential drivers and contextual factors that impact the association between IT and firm value. The paper concludes by proposing several broad avenues of future research that may be of particular interest to archival accounting information systems researchers.
Quantitative Magneto-Optical Imaging for Superconducting Thick Films and Tapes

Practical superconducting thick films and tapes, manufactured in an industrial process, have microscopic inhomogeneities. Quantitative magneto-optical imaging (MOI) is one of the most desirable techniques and provides both local and global information on defects, flux pinning, critical current density J c, and current distribution. We present, herein, a comparative magneto-optical imaging study of the flux profile in YBa2Cu3O7−δ (YBCO) thick films prepared in two different processes, the laboratory versus the industrial scalable process. The remarkably different flux propagation patterns are the manifestation of their different defect landscapes within these films. A method of determining J c near zero applied field is also given for locally nonuniform superconducting films, using the quantitative MOI technique.
MIDCOURSE GUIDANCE FOR A SHORT-RANGE ATTACK MISSILE USING ERROR COMPENSATION

A midcourse guidance law is developed for a short range attack missile of the SRAM I1 class which has a very high thrust-teweight ratio. The optimal control formulation is to minimize the flight time from a low altitude, subsonic launch to a fixed ground target 100 300 nm from the launch aircraft at any azimuth. An approximate optimal guidance law is developed by neglecting the aerodynamics and creating burnout conditions which enable the zero angle of attack coast to get close to the target. Simultaneously, error compensation terms are included in the state differential equations and final conditions that lead to a control law which can be tuned to improve the performance of the missile and enable it to hit the target. The error compensation weights are obtained by solving the true optimal control problem numerically. In practice, weights could be stored for each target range and azimuth and obtained from a table.
Unstable density stratification of miscible fluids in a vertical Hele-Shaw cell: influence of variable viscosity on the linear stability

The influence of viscosity variations on the density-driven instability of two miscible fluids in a vertical Hele-Shaw cell is investigated by means of a linear stability analysis. Dispersion relations are presented for different Rayleigh numbers, viscosity ratios and interfacial thickness parameters of the base concentration profile. The analysis employs the three-dimensional Stokes equations, and the results are compared with those obtained from the variable density and viscosity Hele-Shaw equations. While the growth rate does not depend on which of the two fluids is the more viscous, the maxima of the eigenfunctions are always seen to shift towards the less viscous fluid. For every parameter combination, the dominant instability mode is found to be three-dimensional. With increasing viscosity ratio, the instability is uniformly damped. For a fixed viscosity ratio, both the growth rate and the most unstable wavenumber increase monotonically with the Rayleigh number, until they asymptotically reach a plateau.Surprising findings are obtained regarding the effects of varying the interface thickness. At higher viscosity ratios the largest growth rates and unstable wavenumbers are observed for intermediate thicknesses. This demonstrates that for variable viscosities thicker interfaces can be more unstable than their thinner counterparts, in contrast to the constant viscosity case. The reason behind this behaviour can be traced to the influence of the gap width on the vertical extent of the perturbation eigenfunctions. For thick interfaces, the eigenfunction can reside almost entirely within the interfacial region. In that way, the perturbation maximum is free to shift towards the less viscous fluid, i.e. into a locally more unstable environment. In contrast, for thin interfaces, the eigenfunction is forced to extend far into the viscous fluid, which leads to an overall stabilization. While the Hele-Shaw analysis also captures this ‘optimal’ growth for intermediate interface thicknesses, the growth rates differ substantially from those obtained from the full Stokes equations. Compared to the Hele-Shaw results, growth rates obtained from the modified Brinkman equation are seen to yield better quantitative agreement with the Stokes results.
Space Internet architectures and technologies for NASA enterprises

NASA's future space communication needs and requirements will be addressed through a space communications network that mirrors the terrestrial Internet in its capabilities and flexibility. NASA's needs and requirements for future data gathering and distribution by this Space Internet have been obtained from NASA's Earth Science Enterprise (ESE), the Human Exploration and Development in Space (HEDS), and the Space Science Enterprise (SSE). To address NASA's future needs, we propose and describe an integrated communications infrastructure based on Internet technologies, the architectures within the infrastructure, and the elements that make up the architectures. The architectures meet the requirements of the enterprises beyond 2010 with Internet compatible technologies and functionality. The elements of an architecture include the backbone, access, inter-spacecraft, and proximity communication parts. From the architectures, technologies have been identified which have the most impact and are critical for the implementation of the architectures. Published in 2002 by John Wiley & Sons, Ltd.
On Kinematic Substructure in the Sextans Dwarf Spheroidal Galaxy

We present multifiber echelle radial velocity results for 551 stars in the Sextans dwarf spheroidal galaxy and identify 294 stars as probable Sextans members. The projected velocity dispersion profile of the binned data remains flat to a maximum angular radius of 30. We introduce a nonparametric technique for estimating the projected velocity dispersion surface and use this to search for kinematic substructure. Our data do not confirm previous reports of a kinematically distinct stellar population at the Sextans center. Instead we detect a region near the Sextans core radius that is kinematically colder than the overall Sextans sample with 95% confidence. Subject headings: galaxies: dwarf — galaxies: individual (Sextans) — galaxies: kinematics and dynamics — Local Group
Cohen-Macaulayness of Special Fiber Rings

Abstract Let (R, &#x1d52a;) be a Noetherian local ring and let Ibe an R-ideal. Inspired by the work of Hubl and Huneke, we look for conditions that guarantee the Cohen-Macaulayness of the special fiber ring ℱ = ℛ/&#x1d52a;ℛ of I, where ℛ denotes the Rees algebra of I. Our key idea is to require ‘good’ intersection properties as well as ‘few’ homogeneous generating relations in low degrees. In particular, if Iis a strongly Cohen-Macaulay R-ideal with G land the expected reduction number, we conclude that ℱ is always Cohen-Macaulay. We also obtain a characterization of the Cohen-Macaulayness of ℛ/Kℛ for any &#x1d52a;-primary ideal K. This result recovers a well-known criterion of Valabrega and Valla whenever K = I. Furthermore, we study the relationship between the Cohen-Macaulay property of the special fiber ring ℱ and the Cohen-Macaulay property of the Rees algebra ℛ and the associated graded ring &#x1d4a2; of I. Finally, we focus on the integral closedness of &#x1d52a;I. The latter question is motivated by the theory of evolutions. Dedicated t...
Coming into Money: The Impact of Foreign Aid on Leader Survival

Donors are more likely to send aid to leaders facing elevated risks of losing power, but targets’ ability to benefit from this assistance is conditioned by regime type and political processes. The institutionalization of winning coalitions’ loyalty across regime type follows opposite patterns, supporting opposite temporal dynamics across regime types. Democratic leaders’ coalitions are firmest immediately after taking office, and aid is of most assistance to them at that time. As competition and dissatisfaction grow, aid becomes a political liability. In small winning coalition systems, however, coalitions become more solid over time, facilitating increasing benefits from aid. Without a firm coalition, however, external resources are destabilizing to autocratic leaders. Analysis of 4,692 leader years from 1960 to 2001 using a censored probit model supports these expectations.
State space modeling and robust reduced-order control of combustion instabilities

Abstract Thermoacoustic instabilities in combustion processes can have adverse effects on system performance. In this paper we formulate the problem of active control of combustion instabilities in a form that lends itself to the application of robust feedback control design. Using an uncertain state-space combustion system model, the parameter-dependent Lyapunov function framework for robust fixed-order controller design developed by Haddad and Bernstein is used to design high-performance reduced-order robust controllers for suppressing thermoacoustic oscillations in combustion chambers.
Is Geriatric Care Associated with Less Emergency Department Use

Objectives: To determine whether community-dwelling individuals and nursing home (NH) residents treated by a geriatrician were less likely to use the emergency department (ED) than individuals treated by other physicians. Design: Retrospective cohort study using data from a national sample of older adults with a history of cardiovascular disease. Setting: Ambulatory care or NH. Participants: Fee-for-service Medicare beneficiaries aged 66 and older diagnosed with one or more geriatric conditions from 2004 to 2007 and followed for up to 3 years. Measurements: Emergency department use was measured in Medicare inpatient and outpatient claims; geriatric care was measured as geriatrician visits in ambulatory or NH settings coded in physician claims. Results: Multivariable analyses controlled for observed and unobserved subject characteristics that were constant during the study period. For community-dwelling participants, one or more nonhospital geriatrician visits in a 6-month period were associated with 11.3% lower ED use the following month (95% confidence interval (CI) = 7.5�15.0, N = 287,259). Participants who received primary care from geriatricians were less likely to have ED use than those who had traditional primary care. Results for participants who received consultative care from geriatricians were similar to those for participants who received primary care from geriatricians. Results for NH residents (N = 66,551) were similar to those for community-dwelling participants. Conclusion: Geriatric care was associated with an estimated 108 fewer ED visits per 1,000 community-dwelling residents and 133 fewer ED visits per 1,000 NH residents per year. Geriatric consultative care in collaboration with primary care providers may be as effective in reducing ED use as geriatric primary care. Increased provision of collaborative care could allow the existing supply of geriatricians to reach a larger number of individuals.
Approximation of contractible valued correspondences by functions

Abstract Let X and Y be absolute neighborhood retracts (this is a large class of spaces) with X compact, and let F : X → Y be an upper hemicontinuous correspondence whose values are compact and contractible. It is shown that any neighborhood of the graph of F contains the graph of a continuous function f : X → Y . The relevance of this result to fixed point theory is indicated. It is also shown that if X is ‘locally infinite’, then F can be approximated in the stronger sense of the graph of f being close to the graph of F and every point in the graph of F being close to some point in the graph of f . A conjectured generalization of the main result is stated.
Complexity and organizational architecture

This paper examines how architectural features of organizations, that are made up of individuals screening projects, afiect organizational screening performance. The paper explores consequences for organizational design of a theorem of Von Neumann, Moore, and Shannon on how to build reliable networks using unreliable components. The paper shows that screening performance is sigmoid in individual screening performance for hierarchies of polyarchies and for polyarchies of hierarchies. This property is also satisfled by a cognitive model that allows for individuals’ own screening to be in∞uenced by screening decisions of superiors and of subordinates. The paper examines the implications of such features for the limits to organizational performance. JEL classiflcation codes: D200, D230. Keywords: organizations, project evaluation, screening, organizational architecture, complexity, composition, social networks in flrms. Reliability.