cssi/SciSciGPT-SciSciNet huggingface dataset:
Joint Power Minimization in Wireless Relay Channels

Energy-constrained multihop wireless links are considered, where the total power consumption is minimized under given requirements on the end-to-end bit error rate (BER). As multihop transmissions are known to be able to save transmission energy in a wireless environment, we study the optimal power scheduling schemes over intermediate hops when the source- relays-destination link can be modeled as cascaded binary symmetric channels. The problem is formulated with an end- to-end BER constraint, and the resulting power consumption is compared with that of the individual link requirement strategy where each hop assigns power under a per-link BER constraint. Results show that the proposed joint power scheduling strategy can achieve a maximum power reduction factor of M in an M-hop route.
Are there three peaks in the power spectra of GX 339−4 and Cyg X-1?

Among the variability behaviours exhibited by neutron star systems are the so-called ‘horizontal branch oscillations’ (HBO, with frequencies ≈50 Hz), the ‘lower-frequency kHz quasi-periodic oscillation’ (QPO) and the ‘upper-frequency kHz QPO’, with the latter two features being separated in frequency by an amount comparable to, but varying slightly from, the suspected spin-frequency of the neutron star. Recently, Psaltis, Belloni & van der Klis have suggested that there exists a correlation between these three frequencies that, when certain identifications of variability features are made, even encompasses black hole sources. We consider this hypothesis by reanalysing a set of GX 339−4 observations. The power spectral density (PSD) constructed from a composite of seven separate, but very similar, observations shows evidence for three broad peaks in the PSD. If the peak frequencies of these features are identified with QPO, then their frequencies approximately fit the correlations suggested by Psaltis, Belloni, & van der Klis. We also reanalyse a Cyg X-1 observation and show that the suggested QPO correlation may also hold, but that complications arise when the QPOs (which, in reality, are fairly broad features) are considered as a function of energy band. These fits suggest the existence of at least three separate, independent physical processes in the accretion flow, a hypothesis that is also supported by consideration of the Fourier frequency-dependent time lags and coherence function between variability in different energy bands. If these variability features have a common origin in neutron star and black hole systems, then ‘beat frequency models’ of kHz QPO in neutron star systems are called into question.
A Decision Procedure for Linear Big O Equations

Let F be the set of functions from an infinite set, S, to an ordered ring, R. For f, g, and h in F, the assertion f = g + O(h) means that for some constant C, |f(x) ? g(x)| ?C |h(x)| for every x in S. Let L be the first-order language with variables ranging over such functions, symbols for 0, +, ?, min , max , and absolute value, and a ternary relation f = g + O(h). We show that the set of quantifier-free formulas in this language that are valid in the intended class of interpretations is decidable and does not depend on the underlying set, S, or the ordered ring, R. If R is a subfield of the real numbers, we can add a constant 1 function, as well as multiplication by constants from any computable subfield. We obtain further decidability results for certain situations in which one adds symbols denoting the elements of a fixed sequence of functions of strictly increasing rates of growth.
A convenient one-pot, organoaluminum mediated vinylsilane synthesis from non-enolizable ketones via the Peterson protocol

Vinylsilanes serve as convenient vinyl anion equivalents which have gained popularity over decades. A variety of non-enolizable aromatic ketones are converted to the corresponding vinylsilanes in a one-pot procedure involving the addition of (trimethylsilylmethyl)lithium to aromatic ketones followed by addition of diethylaluminum chloride and then small amounts of water. Halide and alkoxide substituents are tolerated, and this trans-stereoselective (broad generalization; the most sterically bulky group on the double bond is trans to the trimethylsilyl group) reaction affords vinylsilanes in good yield.
Time-resolved studies of hypervelocity vertical impacts into porous particulate targets: Effects of projectile density on early-time coupling and crater growth

The depth and duration of energy and momentum coupling in an impact shapes the formation of the crater. The earliest stages of crater growth (when the projectile transfers its energy and momentum to the target) are unrecoverable when the event is described by late stage parameters, which collapse the initial conditions of the impact into a singular point in time and space. During the coupling phase, the details of the impact are mapped into the ejecta flow field. In this experimental study, we present new experimental and computational measurements of the ejecta distribution and crater growth extending from early times into main-stage ballistic flow for hypervelocity impacts over a range of projectile densities. Specifically, we assess the effect of projectile density on coupling depth and location in porous particulate (sand) targets. A non-invasive high-speed imaging technique is employed to capture the velocity of individual ejecta particles very early in the cratering event as a function of both time and launch position. These data reveal that the effects of early-stage coupling, such as non-constant ejection angles, manifest not only in early-time behavior but also extend to main-stage crater growth. Time-resolved comparisons with hydrocode calculations provide both benchmarking and insight into the parameters controlling the ejection process. Measurements of the launch position and metrics for the transient diameter to depth ratio as a function of time demonstrate non-proportional crater growth throughout much of excavation. Low-density projectiles couple closer to the surface, thereby leading to lower ejection angles and larger effective diameter to depth ratios. These results have implications for the ballistic emplacement of ejecta on planetary surfaces, and are essential to interpreting temporally resolved data from impact missions.
Integral-equation methods in steady and unsteady subsonic, transonic, and supersonic aerodynamics for interdisciplinary design

Abstract This paper reviews the NASA Langley Research Center program for development of integral-equation aerodynamic methods with emphasis on application in computer-aided multidisciplinary design processes as well as in aerodynamic design and stand-alone analysis. The accomplishments, status, and outlook of the program are discussed in order to highlight the scope, generality, versatility, and attractive features of this methodology.
Memory-efficient displacement-based internal friction for wave propagation simulation

The characterization of anelastic losses due to material internal friction has become increasingly important in geophysical exploration and other seismological applications, as these losses greatly affect the amplitude and dispersion of seismic waves. Anelasticity is usually specified in terms of the material’s quality factor, Q. Different viscoelastic models have been used to represent Q as a function of frequency. Most of these models are defined in terms of stresses and strains as the primary variables. Thus, in three dimensions, a separate model needs to be associated with each of the six strain components. We introduce an internal friction model that uses, instead, displacements as primary variables. For a fiber, the proposed model consists of a set of three distinct elements in parallel with different relaxation mechanisms: namely, two elements that consist of a spring and a dashpot in series (Maxwell) and a third element that consists of a spring and a dashpot in parallel (Voigt). In addition to sa...
Dark-matter QCD-axion searches

In the late 20th century, cosmology became a precision science. Now, at the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. There’s no known such elementary particle, so the strong presumption is the dark matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10−(6–3) eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. However, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. This article is a selective overview of the current generation of sensitive axion searches. Not all techniques and experiments are discussed, but I hope to give a sense of the current experimental landscape of the search for dark-matter axions.
An Apologia for Firewalls

We address claimed alternatives to the black hole firewall. We show that embedding the interior Hilbert space of an old black hole into the Hilbert space of the early radiation is inconsistent, as is embedding the semi-classical interior of an AdS black hole into any dual CFT Hilbert space. We develop the use of large AdS black holes as a system to sharpen the firewall argument. We also reiterate arguments that unitary non-local theories can avoid firewalls only if the non-localities are suitably dramatic.
New H2 Collision-induced Absorption and NH3 Opacity and the Spectra of the Coolest Brown Dwarfs

We present new cloudy and cloudless model atmospheres for brown dwarfs using recent ab initio calculations of the line list of ammonia (NH3) and of the collision-induced absorption of molecular hydrogen (H2). We compare the new synthetic spectra with models based on an earlier description of the H2 and NH3 opacities. We find a significant improvement in fitting the nearly complete spectral energy distribution of the T7p dwarf Gliese 570D and in near-infrared color-magnitude diagrams of field brown dwarfs. We apply these new models to the identification of NH3 absorption in the H-band peak of very late T dwarfs and the new Y dwarfs and discuss the observed trend in the NH3-H spectral index. The new NH3 line list also allows a detailed study of the medium-resolution spectrum of the T9/T10 dwarf UGPS J072227.51–054031.2 where we identify several specific features caused by NH3.
Design and analysis of transmit-beamforming based on limited-rate feedback

This paper deals with design and performance analysis of transmit beamformers for multiple-input multiple-output (MIMO) systems based on bandwidth-limited information that is fed back from the receiver to the transmitter. By casting the design of transmit beamforming based on limited-rate feedback as an equivalent sphere vector quantization (SVQ) problem, multiantenna beamformed transmissions through independent and identically distributed (i.i.d.) Rayleigh fading channels are first considered. The rate-distortion function of the vector source is upper-bounded, and the operational rate-distortion performance achieved by the generalized Lloyd's algorithm is lower-bounded. Although different in nature, the two bounds yield asymptotically equivalent performance analysis results. The average signal-to-noise ratio (SNR) performance is also quantified. Finally, beamformer codebook designs are studied for correlated Rayleigh fading channels, and a low-complexity codebook design that achieves near-optimal performance is derived.
Dead-Time Compensation for Wave/String PDEs

Smith predictorlike designs for compensation of arbitrarily long input delays are commonly available only for finite-dimensional systems. Only very few examples exist, where such compensation has been achieved for partial differential equation (PDE) systems, including our recent result for a parabolic (reaction-diffusion) PDE. In this paper, we address a more challenging wave PDE problem, where the difficulty is amplified by allowing all of this PDE’s eigenvalues to be a distance to the right of the imaginary axis. Antidamping (positive feedback) on the uncontrolled boundary induces this dramatic form of instability. We develop a design that compensates an arbitrarily long delay at the input of the boundary control system and achieves exponential stability in closed-loop. We derive explicit formulae for our controller’s gain kernel functions. They are related to the open-loop solutions of the antistable wave equation system over the time period of input delay (this simple relationship is the result of the design approach).
Corporate IT Standardization: Product Compatibility, Exclusive Purchase Commitment, and Competition Effects

When companies purchase information technology (IT) products for their employees, departments, or divisions, whether to standardize on one product or to allow the users to make their own choices is an important decision for IT managers to make. By consolidating demand and committing to buy from a single seller, standardization ensures product compatibility within the corporation and has a potential to induce intense price competition among sellers, but this potential is subject to whether competing products are compatible and the relative competitive advantages of the sellers. This paper studies when it is optimal for an employer to commit to exclusive purchase from a single seller to enforce standardization and sellers' incentives to invest in mutual compatibility. Our results suggest that the employer is more likely to make such a commitment when the competing products are compatible, less vertically differentiated, and/or more horizontally differentiated. We also find that the sellers agree to cooperate and invest in mutual compatibility only when the gap between their competitive advantages is moderate, but the availability of third party converters that enable partial compatibility can induce more collaboration among the sellers.
On the choice of regions for generalized belief propagation

Generalized belief propagation (GBP) has proven to be a promising technique for approximate inference tasks in AI and machine learning. However, the choice of a good set of clusters to be used in GBP has remained more of an art then a science until this day. This paper proposes a sequential approach to adding new clusters of nodes and their interactions (i.e. "regions") to the approximation. We first review and analyze the recently introduced region graphs and find that three kinds of operations ("split", "merge" and "death") leave the free energy and (under some conditions) the fixed points of GBP invariant. This leads to the notion of "weakly irreducible" regions as the natural candidates to be added to the approximation. Computational complexity of the GBP algorithm is controlled by restricting attention to regions with small "region-width". Combining the above with an efficient (i.e. local in the graph) measure to predict the improved accuracy of GBP leads to the sequential "region pursuit" algorithm for adding new regions bottom-up to the region graph. Experiments show that this algorithm can indeed perform close to optimally.
Real-time trajectory generation for differentially flat systems

This paper considers the problem of real-time trajectory generation and tracking for nonlinear control systems. We employ a two-degree-of-freedom approach that separates the nonlinear tracking problem into real-time trajectory generation followed by local (gain-scheduled) stabilization. The central problem which we consider is how to generate, possibly with some delay, a feasible state space and input trajectory in real time from an output trajectory that is given online. We propose two algorithms that solve the real-time trajectory generation problem for differentially flat systems with (possibly non-minimum phase) zero dynamics. One is based on receding horizon point to point steering, the other allows additional minimization of a cost function. Both algorithms explicitly address the tradeoff between stability and performance and we prove convergence of the algorithms for a reasonable class of output trajectories. To illustrate the application of these techniques to physical systems, we present experimental results using a vectored thrust flight control experiment built at Caltech. A brief introduction to differentially flat systems and its relationship with feedback linearization is also included. © 1998 John Wiley & Sons, Ltd.
Dynamic primitives of motor behavior

We present in outline a theory of sensorimotor control based on dynamic primitives, which we define as attractors. To account for the broad class of human interactive behaviors--especially tool use--we propose three distinct primitives: submovements, oscillations, and mechanical impedances, the latter necessary for interaction with objects. Owing to the fundamental features of the neuromuscular system--most notably, its slow response--we argue that encoding in terms of parameterized primitives may be an essential simplification required for learning, performance, and retention of complex skills. Primitives may simultaneously and sequentially be combined to produce observable forces and motions. This may be achieved by defining a virtual trajectory composed of submovements and/or oscillations interacting with impedances. Identifying primitives requires care: in principle, overlapping submovements would be sufficient to compose all observed movements but biological evidence shows that oscillations are a distinct primitive. Conversely, we suggest that kinematic synergies, frequently discussed as primitives of complex actions, may be an emergent consequence of neuromuscular impedance. To illustrate how these dynamic primitives may account for complex actions, we brieflyreviewthree typesof interactivebehaviors: constrained motion, impact tasks, and manipulation of dynamic objects.
The entrainment behavior of a turbulent axisymmetric jet in a viscous host fluid

Although turbulent jets have been studied extensively, one configuration that has not received much attention is the viscosity-stratified jet, wherein a turbulent jet of lower viscosity issues into a density-matched host liquid of higher viscosity. We present experimental data for scalar dispersion and two-dimensional velocity measurements in the axial plane of a turbulent axisymmetric jet with a Reynolds number (Re) of 2,000 issuing into a viscous host liquid at viscosity ratios (m) ranging from 1 to 55. The presence of a strong viscosity discontinuity across the jet edge results in a significant decrease in the scalar spread rate. We attribute this to the rapid reduction in turbulence intensity and the suppression of large engulfing eddies at the jet edge. The velocity profile, on the other hand, indicates that the velocity width and mass flux reduce with increasing m up to about 20, but then increase for higher values of m. This non-monotonic variation is explained by the growing influence of viscous stress for m>20. The scalar spread rate, the velocity spread rate, the centerline velocity decay rate, and the jet mass flux are all minimized for m≈20 for Re=2,000.
Generalized Lattices Express Parallel Distributed Concept Learning

Concepts have been expressed mathematically as propositions in a distributive lattice. A more comprehensive formulation is that of a generalized lattice, or category, in which the concepts are related in hierarchical fashion by lattice-like links called concept morphisms. A concept morphism describes how a more abstract concept is used within a more specialized concept, as the color "red" is used in describing "apples". Often, an abstract concept can be used in a more specialized concept in more than one way as with "color", which can appear in "apples" as either "red", "yellow" or "green". Further, "color" appears in "apples" because it appears in "red", "yellow" and "green", which in turn appear in "apples", expressed via the composition of concept morphisms. Using categorical constructs based upon composition together with structure-preserving mappings that preserve compositional structure, a recently-developed semantic theory shows how abstract and specialized concepts are learned by a neural network.
An overview of the new test stand for H⁻ ion sources at FNAL.

A new test stand at Fermi National Accelerator Laboratory (FNAL) is being constructed to carry out experiments to develop and upgrade the present magnetron-type sources of H− ions of up to 80 mA at 35 keV in the context of the Proton Improvement Plan. The aim of this plan is to provide high-power proton beams for the experiments at FNAL. The technical details of the construction and layout of this test stand are presented, along with a prospective set of diagnostics to monitor the sources.
Transmission Spectra of Three-Dimensional Hot Jupiter Model Atmospheres

We compute models of the transmission spectra of planets HD 209458b, HD 189733b, and generic hot Jupiters. We examine the effects of temperature, surface gravity, and metallicity for the generic planets as a guide to understanding transmission spectra in general. We find that carbon dioxide absorption at 4.4 and 15 μm is prominent at high metallicity, and is a clear metallicity indicator. For HD 209458b and HD 189733b, we compute spectra for both one-dimensional and three-dimensional model atmospheres and examine the differences between them. The differences are usually small, but can be large if atmospheric temperatures are near important chemical abundance boundaries. The calculations for the three-dimensional atmospheres, and their comparison with data, serve as constraints on these dynamical models that complement the secondary eclipse and light curve data sets. For HD 209458b, even if TiO and VO gases are abundant on the dayside, their abundances can be considerably reduced on the cooler planetary limb. However, given the predicted limb temperatures and TiO abundances, the model's optical opacity is too high. For HD 189733b we find a good match with some infrared data sets and constrain the altitude of a postulated haze layer. For this planet, substantial differences can exist between the transmission spectra of the leading and trailing hemispheres, which are an excellent probe of carbon chemistry. In thermochemical equilibrium, the cooler leading hemisphere is methane-dominated, and the hotter trailing hemisphere is CO-dominated, but these differences may be eliminated by non-equilibrium chemistry due to vertical mixing. It may be possible to constrain the carbon chemistry of this planet, and its spatial variation, with James Webb Space Telescope.
Cavity method for force transmission in jammed disordered packings of hard particles.

The force distribution of jammed disordered packings has always been considered a central object in the physics of granular materials. However, many of its features are poorly understood. In particular, analytic relations to other key macroscopic properties of jammed matter, such as the contact network and its coordination number, are still lacking. Here we develop a mean-field theory for this problem, based on the consideration of the contact network as a random graph where the force transmission becomes a constraint satisfaction problem. We can thus use the cavity method developed in the past few decades within the statistical physics of spin glasses and hard computer science problems. This method allows us to compute the force distribution P(f) for random packings of hard particles of any shape, with or without friction. We find a new signature of jamming in the small force behavior P(f) ∼ fθ, whose exponent has attracted recent active interest: we find a finite value for P(f = 0), along with θ = 0. Furthermore, we relate the force distribution to a lower bound of the average coordination number minc(μ) of jammed packings of frictional spheres with coefficient μ. This bridges the gap between the two known isostatic limits c (μ = 0) = 2D (in dimension D) and c(μ → ∞) = D + 1 by extending the naive Maxwell's counting argument to frictional spheres. The theoretical framework describes different types of systems, such as non-spherical objects in arbitrary dimensions, providing a common mean-field scenario to investigate force transmission, contact networks and coordination numbers of jammed disordered packings.
If multi-agent learning is the answer, what is the question?

The area of learning in multi-agent systems is today one of the most fertile grounds for interaction between game theory and artificial intelligence. We focus on the foundational questions in this interdisciplinary area, and identify several distinct agendas that ought to, we argue, be separated. The goal of this article is to start a discussion in the research community that will result in firmer foundations for the area.
Cost-constrained selection of strand diameter and number in a litz-wire transformer winding

Design of litz-wire windings subject to cost constraints is analyzed. An approximation of normalized cost is combined with analysis of proximity effect losses to find combinations of strand number and diameter that optimally trade off cost and loss. The relationship between wire size, normalized cost, and normalized loss is shown to have a general form that applies to a wide range of designs. A practical design procedure is provided, Applied to an example design, it leads to less than half the original loss at lower than the original cost, or, alternatively, under one fifth the original cost with the same loss as the original design.
Molding the flow of light on the nanoscale: from vortex nanogears to phase-operated plasmonic machinery.

Efficient delivery of light into nanoscale volumes by converting free photons into localized charge-density oscillations (surface plasmons) enables technological innovation in various fields from biosensing to photovoltaics and quantum computing. Conventional plasmonic nanostructures are designed as nanoscale analogs of radioantennas and waveguides. Here, we discuss an alternative approach for plasmonic nanocircuit engineering that is based on molding the optical powerflow through ‘vortex nanogears’ around a landscape of local phase singularities ‘pinned’ to plasmonic nanostructures. We show that coupling of several vortex nanogears into transmission-like structures results in dramatic optical effects, which can be explained by invoking a hydrodynamic analogy of the ‘photon fluid’. The new concept of vortex nanogear transmissions (VNTs) provides new design principles for the development of complex multi-functional phase-operated photonics machinery and, therefore, generates unique opportunities for light generation, harvesting and processing on the nanoscale.
Reinventing Phenanthroline Ligands − Chiral Derivatives for Asymmetric Catalysis?

Over the last three decades, the rational design of chiral ligands for asymmetric catalysis has increasingly replaced the trial-and-error approach. A well-known analytical reagent, 1,10-phenanthroline, is now being employed as a template for the development of chiral ligands. In most cases these heterocyclic ligands have been functionalized in the peripheral region utilizing three prevailing ligand templates. Chiral groups are either introduced in the 2-, 3-, 8- and/or 9-position (I, II) or are incorporated by ring fusion to phenanthroline (III). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Hierarchical Exploration for Accelerating Contextual Bandits

Contextual bandit learning is an increasingly popular approach to optimizing recommender systems via user feedback, but can be slow to converge in practice due to the need for exploring a large feature space. In this paper, we propose a coarse-to-fine hierarchical approach for encoding prior knowledge that drastically reduces the amount of exploration required. Intuitively, user preferences can be reasonably embedded in a coarse low-dimensional feature space that can be explored efficiently, requiring exploration in the high-dimensional space only as necessary. We introduce a bandit algorithm that explores within this coarse-to-fine spectrum, and prove performance guarantees that depend on how well the coarse space captures the user's preferences. We demonstrate substantial improvement over conventional bandit algorithms through extensive simulation as well as a live user study in the setting of personalized news recommendation.
Probabilistic ensembles for improved inference in protein-structure determination.

Protein X-ray crystallography — the most popular method for determining protein structures — remains a laborious process requiring a great deal of manual crystallographer effort to interpret low-quality protein images. Automating this process is critical in creating a high-throughput protein-structure determination pipeline. Previously, our group developed ACMI, a probabilistic framework for producing protein-structure models from electron-density maps produced via X-ray crystallography. ACMI uses a Markov Random Field to model the three-dimensional (3D) location of each non-hydrogen atom in a protein. Calculating the best structure in this model is intractable, so ACMI uses approximate inference methods to estimate the optimal structure. While previous results have shown ACMI to be the state-of-the-art method on this task, its approximate inference algorithm remains computationally expensive and susceptible to errors. In this work, we develop Probabilistic Ensembles in ACMI (PEA), a framework for leveraging multiple, independent runs of approximate inference to produce estimates of protein structures. Our results show statistically significant improvements in the accuracy of inference resulting in more complete and accurate protein structures. In addition, PEA provides a general framework for advanced approximate inference methods in complex problem domains.
The Impact of Union Corruption on Union Membership

This paper examines the relationship between union corruption actions and union membership. State-level data from the Office of Labor-Management Standards, and other sources, are utilized over two study periods (1974-2000 and 2001- 2008) to test three hypotheses, including the union corruption hypothesis, as pos­sible explanations for the decline in union membership in the United States over time. Although our initial findings suggest a negative relationship exists between union corruption and membership, after removing the possibility of simultaneous equations bias, we find that changes in corruption do not influence changes in union membership in our sample.
Practical, asymmetric synthesis of aromatic-substituted bulky and hydrophobic tryptophan and phenylalanine derivatives

Abstract Aromatic ring substituted tryptophans and phenylalanines can provide valuable tools in developing highly potent and selective peptide ligands with specific structural features in addition to providing a large lipophilic surface for binding to receptors and for crossing membrane barriers. An efficient method for the synthesis of these novel amino acids has been developed. In the approach, asymmetric hydrogenations of α-enamides using Burk's DuPHOS-based Rh (I) catalysts generated high enantiomerically pure α-amino acid derivatives, which subsequently underwent Suzuki cross couplings with boronic acid derivatives to afford these aromatic substituted amino acids in high yields and high enantioselectivity. The method can allow for the preparation of such amino acids in large scales for extensive structure–activity studies.
Polymer Diaphragm Based Fiber Optic Fabry-Perot Acoustic Sensor

This paper presents a polymer diaphragm based Fabry-Perot (F-P) sensor system for aeroacoustic measurement in air. The diaphragm of a novel polymer material poly phthalazinone ether sulfone ketone (PPESK) is used as the sensing element. The effective dimension of the diaphragm is 1.0mm in diameter and 6μm in thickness. Thanks to the good mechanical feature of the material and the interferometric-intensity demodulation mechanism, the sensor diaphragm shift sensitivity of 0.72 nm/Pa, correspond to an acoustic pressure to voltage sensitivity of 5.56mV/Pa has been achieved. Experimental results showed that the characteristics of the sensor system is comparable with traditional electrical microphone in frequency range 100Hz to 1kHz and the sensor has the potential to be used as an optical microphone.
A note on Lascar strong types in simple theories

Let T be a countable, small simple theory. In this paper, we prove that for such T, the notion of Lascar strong type coincides with the notion of strong type, over an arbitrary set.
JavaTA: A Logic-based Debugger for Java

Department of Computer Science and EngineeringUniversity at Buﬀalo, The State University of New YorkBuﬀalo, NY 14260, USA{hzgirgis,bharat}@cse.buffalo.eduhttp://www.cse.buffalo.eduAbstract. This paper presents a logic based approach to debuggingJava programs. In contrast with traditional debugging we propose a de-bugging methodology for Java programs using logical queries on indi-vidual execution states and also over the history of execution. Thesequeries were arrived at by a systematic study of errors in object-orientedprograms in our earlier research. We represent the salient events duringthe execution of a Java program by a logic database, and implementthe queries as logic programs. Such an approach allows us to answer anumber of useful and interesting queries about a Java program, such asthe calling sequence that results in a certain outcome, the state of anobject at a particular execution point, etc. Our system also provides theability to compose new queries during a debugging session. We believethat logic programming oﬀers a signiﬁcant contribution to the art ofobject-oriented programs debugging.
Tropical forest backscatter anomaly evident in SeaWinds scatterometer morning overpass data during 2005 drought in Amazonia

Abstract A severe drought occurred in southwestern Amazonia in the dry season (June–September) of 2005. We analyzed 10 years (7/99–10/09) of SeaWinds active microwave Ku-band backscatter data collected over the Amazon Basin, developing monthly means and anomalies from those means in an effort to detect landscape responses to this drought. We compared these to seasonal accumulating water deficit anomalies generated using Tropical Rainfall Monitoring Mission (TRMM) precipitation data (1999–2009) and 100 mm mo− 1 evapotranspiration demand as a water deficit threshold. There was significant interannual variability in dry-season monthly mean backscatter only for morning (c. 06:00 LST) overpass data, and little interannual variability in dry-season monthly mean backscatter for afternoon (c. 18:00 LST) overpass data. Strong negative anomalies in both morning-overpass backscatter and accumulating water deficit developed during July–October 2005, centered on the southwestern Amazon Basin, with a strong spatial correlation between morning-overpass backscatter anomalies and water deficit anomalies in September. This is the first reporting of tropical forest seasonal drought detection by active microwave scatterometry. Based on the differences between early-morning and late-afternoon backscatter variability, we hypothesize that as the drought persisted over several months, the forest canopy was increasingly unable to recover full leaf moisture content over night, resulting in anomalously low early-morning overpass backscatter.
A model for magnetic recording channels with signal dependent noise

This paper presents a model that includes both signal dependent and signal independent noises. A method for extracting statistics of the coefficients of the noise expansion from measured covariances is described. The paper also suggests how to take advantage of the signal dependence of the noise in the detection process. >
Do Business School Professors Make Good Executive Managers

Despite suggestions that business school professors do not understand what actually accounts for the performance of business organizations, the evidence is anecdotal at best. We review past work, develop expectations, and provide large-scale evidence for examining the validity of such suggestions. We accessed extensive data provided by Dun & Bradstreet and procured detailed information from 765 leading public and private North American businesses. Analysis of 215 closely matched pairs showed that companies with former business school professors as executives generated significantly greater revenues per employee than counterparts with non-former professors as executives. Companies with former professors in vice-president positions had the best performance in the sample, signifying the value of correspondence between academic expertise and functional business area. Companies with executives who had exited academic careers early performed better than companies with late career exit counterparts. The performa...
Phthalocyanines and porphyrins as materials

Several recent studies of phthalocyanines and porphyrins as materials in emerging technologies are reviewed here. Emphasis is placed on the use of these materials as components in building materials where the symmetry, optical and electrical properties of the molecule are important. Aggregates or polymers of these molecules have been known for some time to possess interesting electrical conductivities, and more recently interesting optical properties. Their optical properties as isolated species in condensed phases have also recently become interesting, and their ability to form new hybrid materials, by mixing or by thin film deposition, with other molecules with different electron affinities and ionization potentials, now appears to be extremely attractive. Device technologies in which we can anticipate these molecules appearing in the near future include organic light-emitting diodes, organic field effect transisitors, organic photovoltaics, optical limiters and optically based chemical sensors.
Silicon photonics: The inside story

The electronic chip industry embodies the height of technological sophistication and economics of scale. Fabricating inexpensive photonic components by leveraging this mighty manufacturing infrastructure has fueled intense interest in silicon photonics. If it can be done economically and in an energy efficient manner, empowering silicon with optical functionality will bring optical communications to the realm of computers where limitations of metallic interconnects are threatening the industrypsilas future. The field is making stunning progress and stands to have a bright future, as long as the community recognizes the real challenges, and maintains an open mind with respect to its applications. This talk will review recent dasiagame changingpsila developments and discuss promising applications beyond data communication. It will conclude with recent observation of extreme-value statistical behavior in silicon photonics, a powerful example of how scientific discoveries can unexpectedly emerge in the course of technology development.
Reducing Multi-Valued Algebraic Operations to Binary

Algebraic operations were developed for binary logic synthesis and extended later to apply to multi-valued (MV) logic. Operations in the MV domain were considered more complex and slower. This paper shows that the MV algebraic operations are essentially as easy as bunary ones, with only a slight overhead (linear in the size of the expression) in transformation into and out of the binary domain. By introducing co-singleton sets as a new basis, any MV sum-of-products expression can be rewritten and passed to a binary logic synthesizer for fast execution; the optimized results can be directly interpreted in the MV domain. This process, called EBD, reduces MV algebraic operations to binary. A pure MV operation differs mainly from its corresponding EBD one in that the former possesses "semi-algebraic" generality, which has not been implemented for the binary logic. Experiments show that the proposed methods are significantly faster, with little or no loss in quality when run in comparable scripts of sequences of logic synthesis operations.
Participation and Development: Perspectives from the Comprehensive Development Paradigm

This paper investigates the relationship between economic and social development. Contrary to the view of those who believe in the existence of a tradeoff between democracy and growth, the paper contends that consensus-building, open dialog and the promotion of an active civil society are key ingredients to longterm sustainable development. Development is a participatory process. “Best practices” or reforms that are imposed on a country through conditionality may very well fail to produce lasting change. They will tend to undermine people’s incentives to develop their own capacities and weaken their confidence in using their own intelligence. Success in a knowledge-based economy requires a highly-educated citizenry, involved in the process of shaping and adapting ideas and policies. Participation and democracy in turn call for greater transparency and accountability in both the corporate and government sectors.
Three-dimensional magnetic reconnection through a moving magnetic null

Abstract. A computational study of three-dimensional magnetic reconnection between two flux ropes through a moving reconnection site is presented. The configuration is considered in the context of two interacting spheromaks constrained by a perfectly conducting cylindrical boundary and oriented to form a single magnetic field null at its center. The initial magnetic field configuration is embedded into a uniform thermal plasma and is unstable to tilting. As the spheromaks tilt, their magnetic fields begin to reconnect at the null, subsequently displacing both the null and the reconnection site. The motion of the reconnection region and the magnetic null are shown to be correlated, with stronger correlation and faster reconnection observed in plasmas with lower thermal to magnetic pressure ratio. It is also shown that ion inertial effects allow for yet faster reconnection, but do not qualitatively change the dynamics of the process. Implications of the coupling between moving magnetic nulls and reconnection sites, as well as of possible mechanisms for fast reconnection through a moving reconnection region, are discussed. The simulations are conducted using both single-fluid and Hall MHD plasma models within the HiFi multi-fluid modeling framework.
Education in Production: Measuring Labor Quality and Management

Production function studies have used the education of the head of the household or the average education of farm workers to assess the contribution of schooling to farm efficiency. In this paper I critically examine the information content of these measures by developing a team production model which suggests separate education measures to approximate labor quality and managerial skills. Empirical analyses based on Chinese farm household data show that the new measures are statistically superior to the existing alternatives. There is evidence of centralized decision making on the farms where the highest schooling contributes the most to production efficiency.
Efficiency loss in revenue optimal auctions

We study efficiency loss in Bayesian revenue optimal auctions. We quantify this as the worst case ratio of loss in the realized social welfare to the social welfare that can be realized by an efficient auction. Our focus is on auctions with single-parameter buyers and where buyers' valuation sets are finite. For binary valued single-parameter buyers with independent (not necessarily identically distributed) private valuations, we show that the worst case efficiency loss ratio (ELR) is no worse than it is with only one buyer; moreover, it is at most 1/2. Moving beyond the case of binary valuations but restricting to single item auctions, where buyers' private valuations are independent and identically distributed, we obtain bounds on the worst case ELR as a function of number of buyers, cardinality of buyers' valuation set, and ratio of maximum to minimum possible values that buyers can have for the item.
Organomanganese‐Mediated Radical Reactions

Free radical reactions offer functional group compatibility which complements that of carbanion reagents. A variety of synthetically useful transformations proceeding via free radicals, including reductions, carbonylations, reductive additions, cyclizations and polymerizations, may be induced by organomanganese reagents. These generate carbon-centered radicals from organic halides; photolysis with dimanganese decacarbonyl leads to halogen atom abstraction, or triorganomanganate reagents effect electron transfer followed by loss of halide ion. Synthetic methods employing these reagents are reviewed, with emphasis on carbon-carbon bond construction, stereoselectivity, and applications in natural product synthesis. Reductive dehalogenation, Wurtz coupling, intermolecular radical additions and carbonylations, radical cyclizations including atom transfer methods, and radical addition to imino compounds are discussed in the context of recent developments using organomanganese reagents. Keywords: reduction; radical addition; cyclization; carbonylation; amine synthesis; imines; hydrazones; stereoselectivity
Mobility in Rural Credit Markets: A Honduran Case Study

In this paper I analyze mobility in rural credit markets. A panel data set of rural Honduran households is used to study credit market transitions; specifically, the dynamic evolution of formal and informal sector participation. Mobility patterns among four different credit market states are analyzed, namely those who have formal sector participation, informal sector participation, participation in both sectors and nonparticipation in rural credit markets. I use a random effects dynamic multinomial logit model which can accommodate unobserved heterogeneity. The main findings are that state dependence plays a significant role in ones ability to borrow.
Nitrogen superfractionation in dense cloud cores

We report new calculations of interstellar 15N-fractionation. Previously, we have shown that large enhancements of 15N/14N can occur in cold, dense gas where CO is frozen out, but that the existence of an NH + N channel in the dissociative recombination of N2H+ severely curtails the fractionation. In the light of recent experimental evidence that this channel is in fact negligible, we have reassessed the 15N chemistry in dense cloud cores. We consider the effects of temperatures below 10 K, and of the presence of large amounts of atomic nitrogen. We also show how the temporal evolution of gas-phase isotope ratios is preserved as spatial heterogeneity in ammonia ice mantles, as monolayers deposited at different times have different isotopic compositions. We demonstrate that the upper layers of this ice may have 15N/14N ratios an order of magnitude larger than the underlying elemental value. Converting our ratios to δ-values, we obtain δ15N > 3000 ‰ in the uppermost layer, with values as high as 10 000 ‰ in some models. We suggest that this material is the precursor to the 15N ‘hotspots’ recently discovered in meteorites and IDPs.