cssi/SciSciGPT-SciSciNet huggingface dataset:
Flow tracing fidelity of scattering aerosol in laser Doppler velocimetry

An experimental method for the determination of the flow-tracing fidelity of a scattering aerosol used in laser Doppler velocimeters was developed with particular reference to the subsonic turbulence measurements. The method employs the measurement of the dynamic response of a flow-seeding aerosol excited by acoustic waves. The amplitude and frequency of excitation were controlled in order to simulate the corresponding values of fluid turbulence components. Experimental results are presented on the dynamic response of aerosols over the size range from 0.1 to 2.0 microns in diam and over the frequency range 100 Hz to 100 kHz. It was observed that unit-density spherical scatterers with diameters of 0.2 micron followed subsonic air turbulence frequency components up to 100 kHz with 98% fidelity.
Measuring the initial transient: reflected brownian motion

We analyze the convergence to equilibrium of one-dimensional reflected Brownian motion (RBM) and compute a number of related initial transient formulae. These formulae are of interest as approximations to the initial transient for queueing systems in heavy traffic, and help us to identify settings in which initialization bias is significant. We conclude with a discussion of mean square error for RBM. Our analysis supports the view that initial transient effects for RBM and related models are typically of modest size relative to the intrinsic stochastic variability, unless one chooses an especially poor initialization.
The Economic Value of Minimum-Variance Hedges

The present article examines the potential economic gains from "better" minimum-variance hedge (MVH) estimates, focusing on the assumptions that yield MVHs consistent with expected-utility maximization. It is found that the economic value of "better" MVH estimates is negligible, and that optimal hedges are substantially different from MVHs when the usual MVH restrictions are relaxed. Among other things, findings suggest that the hedging research's recent emphasis on "better" MVHs has been a waste of resources. Investigating the consequences of relaxing the standard MVH assumptions seems to be much more important than recent literature contributions.
Bone histomorphometry: Standardization of nomenclature, symbols and units (summary of proposed system)

Abstract The American Society of Bone and Mineral Research appointed a committee to devise a unified system of terminology for bone histomorphometry, whose report was recently published in the society's journal (Parfitt et al., 1987). In the interests of scientific communication the editors of Bone, Calcified Tissue International, and Bone and Mineral have each agreed to publish a summary of the new system, which has been adopted as part of the instructions to authors by all four journals. This summary is intended to make the system intelligible to the general readership of the journal; the complete version should be consulted by those preparing manuscripts reporting bone histomorphometric data.
A new approach for reconstructing SUSY particle masses with a few fb−1 at the LHC

We describe a new cascade mass reconstruction approach to allow reconstruction of SUSY particle masses in long cascades (five or more particles) at the LHC with integrated luminosity as low as a few fb−1. This approach is based on a consecutive use of the endpoint method, an event filter and a combinatorial mass reconstruction method. The endpoint method gives a preliminary estimate of light sparticle masses. An event filter combining the maximum likelihood distributions for all events in the data sample allows suppression of backgrounds and gives a preliminary estimate of heavy sparticle masses. Finally, SUSY particle masses are reconstructed by a search for a maximum of a combined likelihood function constructed for each possible combination of five events in the data sample. SUSY data sample sets for the SU3 model point containing 80k events each were generated, corresponding to an integrated luminosity of 4.2 fb−1. These events were passed through the AcerDET detector simulator, which parametrized the response of a detector. To demonstrate the stability and precision of the approach five different 80k event data sets were considered. Masses were reconstructed with a precision of about 10% for heavy sparticles and 10–20% for light sparticles.
Central city school administrative policy: systematically passing undeserving students

Abstract Local public schools must satisfy the electorate to pass tax levies and re-elect school board members. Central city schools seem to pursue these goals differently than suburban or non-metropolitan schools. While something about Ohio's central city schools depresses standardized test scores, that same something raises graduation rates, all else constant. This paper argues that social promotion may be the cause. It therefore seems that central city school districts perform poorly independent of school and neighborhood factors, yet they consciously choose to pass students through the system. The results are obtained using both weighted least squares and 2SLS analysis. [ JEL D73, H40, I21]
BISTABLE EQUILIBRIUM POINTS OF MERCURY BODY BURDEN

In the last century, mercury levels in the global environment have tripled as a result of increased pollution from industrial, occupational, medicinal and domestic uses. Glutathione is known to be the main agent responsible for the excretion of mercury (Refs. 2 to 4). It has also been shown that mercury inhibits glutathione synthetase (an enzyme acting in the synthesization of glutathione), therefore leading to decreased glutathione levels (Refs. 5 to 7). Mercury also interferes with the production of heme in the porphyrin pathway. Heme is needed for biological energy production and ability to detox organic toxins via the P450 enzymes. The purpose of this paper is to show that the body’s response to mercury exposure is hysteretic, i.e. when this feedback of mercury on its main detoxifying agents is strong enough, then mercury body burden has two points of equilibrium: one with normal abilities to detoxify and low levels of mercury and one with inhibited abilities to detoxify and high levels of mercury. Furthermore, a small increase of the body’s mercury burden may not be sufficient to trigger observable neurotoxic effects but it may be sufficient to act as a switch leading to an accumulation of mercury in the body through environmental exposure until its toxicity is manifested.
The second-order bias and mean squared error of estimators in time-series models

We develop analytical results on the second-order bias and mean squared error of estimators in time-series models. These results provide a unified approach to developing the properties of a large class of estimators in linear and nonlinear time-series models and they are valid for both normal and nonnormal samples of observations, and where the regressors are stochastic. The estimators included are the generalized method of moments, maximum likelihood, least squares, and other extremum estimators. Our general results are applied to four time-series models. We investigate the effects of nonnormality on the second-order bias results for two of these models, while for all four models, the second-order bias and mean squared error results are given under normality. Numerical results for some of these models are also presented.
Wavelength independent Faraday isolator.

A wavelength independent Faraday isolator has been built using an optically active rotator to compensate the dispersion of a 45° Faraday rotator. Its isolation is better than 30 dB from 735 to 870 nm. Over this wavelength range the measured transmission in the forward direction is better than 80%. Dispersion, temperature, angular tolerance, and other factors affecting the isolation and forward transmission are discussed.
Efficient Normal-Form Parsing for Combinatory Categorial Grammar

Under categorial grammars that have powerful rules like composition, a simple n-word sentence can have exponentially many parses. Generating all parses is inefficient and obscures whatever true semantic ambiguities are in the input. This paper addresses the problem for a fairly general form of Combinatory Categorial Grammar, by means of an efficient, correct, and easy to implement normal-form parsing technique. The parser is proved to find exactly one parse in each semantic equivalence class of allowable parses; that is, spurious ambiguity (as carefully defined) is shown to be both safely and completely eliminated.
Some Effects of Applying Sonic Boom Minimization to Supersonic Cruise Aircraft Design

This paper presents a discussion of an aircraft shaping method to control sonic boom overpressure levels along with the analysis of wind tunnel data which validated the method. The results indicate that the sonic boom minimization method can guide the design team choices of aircraft planform and component arrangement toward a low-boom-level configuration while permitting sufficient freedom and flexibility to satisfy other design criteria. Further, it is shown that off-design flight conditions do not drastically change the overpressure sonic boom shape and strength.
A Spectral Graph Uncertainty Principle

The spectral theory of graphs provides a bridge between classical signal processing and the nascent field of graph signal processing. In this paper, a spectral graph analogy to Heisenberg's celebrated uncertainty principle is developed. Just as the classical result provides a tradeoff between signal localization in time and frequency, this result provides a fundamental tradeoff between a signal's localization on a graph and in its spectral domain. Using the eigenvectors of the graph Laplacian as a surrogate Fourier basis, quantitative definitions of graph and spectral “spreads” are given, and a complete characterization of the feasibility region of these two quantities is developed. In particular, the lower boundary of the region, referred to as the uncertainty curve, is shown to be achieved by eigenvectors associated with the smallest eigenvalues of an affine family of matrices. The convexity of the uncertainty curve allows it to be found to within e by a fast approximation algorithm requiring O(e-1/2) typically sparse eigenvalue evaluations. Closed-form expressions for the uncertainty curves for some special classes of graphs are derived, and an accurate analytical approximation for the expected uncertainty curve of Erd-s-Renyi random graphs is developed. These theoretical results are validated by numerical experiments, which also reveal an intriguing connection between diffusion processes on graphs and the uncertainty bounds.
Binocular shading and visual surface reconstruction

Abstract Zero-crossing or feature-point based stereo algorithms can, by definition, determine explicit depth information only at particular points in the image. To compute a complete surface description, this sparse depth map must be interpolated. A computational theory of this interpolation or reconstruction process, based on a surface consistency constraint, has previously been proposed, implemented, and tested. In order to provide stronger boundary conditions for the interpolation process, other visual cues to surface shape are examined in this paper. In particular, it is shown that in theory, shading information from the two views can be used to determine the orientation of the surface normal along the feature-point contours, provided the photometric properties of the surface material are known. This computation can be performed by using a simple modification of existing photometric stereo algorithms. It is further shown that these photometric properties need not be known a priori, but can be computed directly from image irfadiance information for a particular class of surface materials. The numerical stability of the resulting equations is also examined.
Thrifty algorithms for multistage robust optimization

We consider a class of multi-stage robust covering problems, where additional information is revealed about the problem instance in each stage, but the cost of taking actions increases. The dilemma for the decision-maker is whether to wait for additional information and risk the inflation, or to take early actions to hedge against rising costs. We study the "k-robust" uncertainty model: in each stage i=0, 1, …, T, the algorithm is shown some subset of size ki that completely contains the eventual demands to be covered; here k1>k2>⋯>kT which ensures increasing information over time. The goal is to minimize the cost incurred in the worst-case possible sequence of revelations. For the multistage k-robust set cover problem, we give an O(logm+logn)-approximation algorithm, nearly matching the $\Omega\left(\log n+\frac{\log m}{\log\log m}\right)$ hardness of approximation [4] even for T=2 stages. Moreover, our algorithm has a useful "thrifty" property: it takes actions on just two stages. We show similar thrifty algorithms for multi-stage k-robust Steiner tree, Steiner forest, and minimum-cut. For these problems our approximation guarantees are O( min { T, logn, logλmax }), where λmax is the maximum inflation over all the stages. We conjecture that these problems also admit O(1)-approximate thrifty algorithms.
Vortex Counting and Lagrangian 3-manifolds

To every 3-manifold M one can associate a two-dimensional N=(2,2) supersymmetric field theory by compactifying five-dimensional N=2 super-Yang–Mills theory on M. This system naturally appears in the study of half-BPS surface operators in four-dimensional N=2 gauge theories on one hand, and in the geometric approach to knot homologies, on the other. We study the relation between vortex counting in such two-dimensional N=(2,2) supersymmetric field theories and the refined BPS invariants of the dual geometries. In certain cases, this counting can also be mapped to the computation of degenerate conformal blocks in two-dimensional CFT’s. Degenerate limits of vertex operators in CFT receive a simple interpretation via geometric transitions in BPS counting.
Controlling the speed of light pulses

Recent experiments have demonstrated that light pulses can be made to propagate `superluminally' or, at the opposite extreme, to come to a complete stop. Some of the basic physics underlying these studies and their antecedents are reviewed.
Democracy and Legitimacy in the European Union Revisited: Input, Output and ‘Throughput’

Scholars of the European Union have analyzed the EU's legitimacy mainly in terms of two normative criteria: output effectiveness for the people and input participation by the people. This article argues that missing from this theorization is what goes on in the ‘black box’ of governance between input and output, or ‘throughput’. Throughput consists of governance processes with the people, analyzed in terms of their efficacy, accountability, transparency, inclusiveness and openness to interest consultation. This article defines and discusses this third normative criterion as well as the interaction effects of all three normative criteria. It does so by considering EU scholars' institutional and constructivist analyses of EU legitimacy as well as empirical cases of and proposed solutions to the EU's democracy problems. The article also suggests that unlike input and output, which affect public perceptions of legitimacy both when they are increased or decreased, throughput tends to be most salient when negat...
Analysis of traffic flow with mixed manual and semi-automated vehicles

The paper analyzes the effects on traffic flow characteristics and environment when semi-automated vehicles with automatic vehicle following capability (in the same lane) operate together with manually driven vehicles. We show that semi-automated vehicles do not contribute to the slinky effect phenomenon observed in today's highway traffic when the lead manual vehicle performs smooth acceleration manoeuvres. We demonstrate that semi-automated vehicles smooth traffic flow by filtering the response of rapidly accelerating lead vehicles. Using simulations we show that the fuel consumption and pollution levels present in manual traffic simulated using a car following model that models the slinky effect behavior observed in manual driving can be reduced during rapid acceleration transients by 7.3% and 3.8%-47.3% respectively, due to the presence of 10% semi-automated vehicles. The data obtained are qualitatively valid and demonstrate the beneficial effect of semi-automated vehicles in mixed traffic in improving air quality and fuel consumption.
On the relative time of adaptive processes

Adaptive control systems can be classified according to the response time of the adaptive loop T a relative to that of the main servo loop T m . The response time T a cannot be smaller than the time needed for making the required measurement on which the adjustments are based. In a slow adaptive system, T_{a}\ggT_{m} , and the adjustments are made according to the estimated situation (statistical parameters of the inputs changing plant parameters, etc.) or the estimated performance (error, cost, intermediate parameters etc.). If T_{a}\llT_{m} , usually a reference model is chosen and the system is forced to conform to the reference model. Sometimes the reference model is dimensionless so that the fastest response can be obtained. In both cases, T_{a}\ggT_{m} and T_{a}\llT_{m} , the system can be analyzed by introducing suitable approximations. The condition of stability for the adaptive loop is derived in general terms. If T_{a}\approxT_{m} , both analysis and synthesis become difficult. The concept of "dual control" is introduced, but not developed in the paper.
Metalorganic chemical vapor deposition of aluminum oxide on silicon nitride

Thin films of aluminum oxide were deposited on silicon nitride thin films using trimethylaluminum and oxygen at 0.5 Torr and 300 °C. Fourier transform infrared (FTIR) and x-ray photoelectron spectroscopic (XPS) analyses of these films showed no aluminum silicate phase at the film-substrate interface. The O/Al ratio in the deposited film was found to be higher than that in stoichiometric Al2O3 indicating the presence of excess oxygen. FTIR spectroscopy and XPS of the annealed samples did not show any formation of silicon oxide, oxynitride or silicate at the aluminum oxide/silicon nitride interface. In contrast to aluminum oxide on clean silicon substrates, using ultrathin silicon nitride as a barrier layer could prevent excess oxygen migration towards the Si substrate and formation of any interfacial layers.
Disordering transitions in vortex matter: peak effect and phase diagram

Using numerical simulations of magnetically interacting vortices in disordered layered superconductors we obtain the static vortex phase diagram as a function of magnetic field and temperature. For increasing field or temperature, we find a transition from ordered straight vortices to disordered decoupled vortices. This transition is associated with a peak effect in the critical current. For samples with increasing disorder strength the field at which the decoupling occurs decreases. Long range, nonlinear interactions in the c-axis are required to observe the effect.
High power impulse magnetron sputtering and related discharges: Scalable plasma sources for plasma-based ion implantation and deposition

High power impulse magnetron sputtering (HIPIMS) and related self-sputtering techniques are reviewed from a viewpoint of plasma-based ion implantation and deposition (PBII&D). HIPIMS combines the classical, scalable sputtering technology with pulsed power, which is an elegant way of ionizing the sputtered atoms. Related approaches, such as sustained self-sputtering, are also considered. The resulting intense flux of ions to the substrate consists of a mixture of metal and gas ions when using a process gas, or of metal ions only when using `gasless? or pure self-sputtering. In many respects, processing with HIPIMS plasmas is similar to processing with filtered cathodic arc plasmas, though the former is easier to scale to large areas. Both ion implantation and etching (high bias voltage, without deposition) and thin film deposition (low bias, or bias of low duty cycle) have been demonstrated.
The nature and origin of low‐redshift O vi absorbers

The O VI ion observed in quasar absorption-line spectra is the most accessible tracer of the cosmic metal distribution in the low-redshift ( z< 0.5) intergalactic medium (IGM). We explore the nature and origin of O VI absorbers using cosmological hydrodynamic simulations including galactic outflows with a range of strengths. We consider the effects of ionization background variations, non-equilibrium ionization and cooling, uniform metallicity and small-scale (subresolution) turbulence. Our main results are as follows. (1) IGM O VI is predominantly photoionized with T ≈ 10 4.2±0.2 K. A key reason for this is that O VI absorbers preferentially trace overenriched (by ∼× 5) regions of the IGM at a given density, which enhances metal-line cooling such that absorbers can cool to photo-ionized temperatures within a Hubble time. As such, O VI is not a good tracer of the warm-hot intergalactic medium. (2) The predicted O VI properties fit observables if and only if sub-resolution turbulence is added, regardless of any other model variations. The required turbulence increases with O VI absorber strength. Stronger absorbers arise from more recent outflows, so qualitatively this can be understood if IGM turbulence dissipates on the order of a Hubble time. The amount of turbulence is consistent with other examples of turbulence observed in the IGM and galactic haloes. (3) Metals traced by O VI and H I do not trace exactly the same baryons, but reside in the same large-scale structure. Our simulations reproduce observed alignment statistics between O VI and H I, yet aligned absorbers typically have O VI arising from cooler gas, and for stronger absorbers lower densities, than H I. Owing to peculiar velocities dominating the line structure, coincident absorption often arises from spatially distinct gas. (4) Photo-ionized O VI traces gas in a variety of environments, and is not directly associated with the nearest galaxy, though is typically nearest to ∼0.1L∗ galaxies. Weaker O VI components trace some of the oldest cosmic metals. (5) Very strong absorbers (EW 100 mA) are more likely to be collisionally ionized, tracing more recent enrichment (2 Gyr) within or near galactic haloes.
Fabrication of 10-nm Gratings Using STM Chemical Vapor Deposition

Using STM assisted chemical vapor deposition (STM-CVD), we have successfully fabricated what we believe are the finest gratings to date. Our best grating consists of half-micron long evenly spaced lines which have a width of 10 nm and a 10 nm interspacing. The gratings were fabricated on passivated p-type silicon using trimethylaluminum (TMA) as a precursor gas. Although the composition of the nanostructures is not exactly known at this time, we believe that the lines are partially metallic. We made some systematic investigations to optimize the resolution, including studies of the effect of tunneling current, tip speed, tip-sample biasing voltage, and the effect of formation of very fine TMA whiskers on the tip.
Educational Ethics and the DESD: Considering Trade-offs

The United Nation's Decade of Education for Sustainable Development (DESD) aims to prepare students for pressing economic and environmental problems. In this article, I argue that an exclusive emphasis on an ambiguous goal, sustainable development, raises important questions for educational ethics. Specifically, I argue that DESD mission statements and curricula often fail to account for trade-offs that are inevitable in environmental decision-making. Further, I argue that DESD aims don't adequately focus on the development of agency, decision-making skills, and ethical empowerment. I conclude by suggesting that ESD curricula should critically and constructively recognize the inevitability of trade-offs.
Image Registration for Interventional MRI Guided Procedures: Interpolation Methods, Similarity Measurements, and Applications to the Prostate

Nuclear medicine can detect and localize tumor in the prostate not reliably seen in MR. We are investigating methods to combine the advantages of SPECT with interventional MRI (iMRI) guided radiofrequency thermal ablation of the prostate. Our approach is to first register the low-resolution functional images with a high resolution MR volume. Then, by combining the high-resolution MR image with live-time iMRI acquisitions, we can, in turn, include the functional data and high-resolution anatomic information into the iMRI system for improved tumor targeting. In this study, we investigated registration methods for combining noisy, thick iMRI image slices with high-resolution MR volumes. We compared three similarity measures, i.e., normalized mutual information, mutual information, and correlation coefficient; and three interpolation methods, i.e., re-normalized sinc, tri-linear, and nearest neighbor. Registration experiments showed that transverse slice images covering the prostate work best with a registration error of ≈ 0.5 mm as compared to our volume-to-volume registration that was previously shown to be quite accurate for these image pairs.
A parameterless scale-space approach to find meaningful modes in histograms — Application to image and spectrum segmentation

In this paper, we present an algorithm to automatically detect meaningful modes in a histogram. The proposed method is based on the behavior of local minima in a scale-space representation. We show that the detection of such meaningful modes is equivalent in a two classes clustering problem on the length of minima scale-space curves. The algorithm is easy to implement, fast and does not require any parameter. We present several results on histogram and spectrum segmentation, grayscale image segmentation and color image reduction.
A quasi three-dimensional distributed electromagnetic model for complex power distribution networks

This paper describes a systematic methodology for the electromagnetic modeling of complex power distribution networks. The proposed methodology uses locally three-dimensional (3D) modifications to an otherwise two-dimensional (2D) description of the behavior of electromagnetic fields between power/ground plane pairs, to model correctly the field behavior at discontinuities such as vias, pins, and splits in the power/ground plane structure. Furthermore, a systematic synthesis methodology is presented for the direct generation of a SPICE-compatible multiport macro-model for the power distribution network from its discrete quasi 3D model. The proposed modeling and equivalent circuit synthesis methodologies are validated through a specific numerical simulation study of the transient electromagnetic analysis of a power/ground plane pair during switching.
Resolution and accuracy of resonances in R-matrix cross sections

We investigate the effect of resonances in photoionization and recombination cross sections computed using the R-matrix method. Photoionization and recombination rates derived from high-resolution cross sections for oxygen ions are compared with earlier works with less resolution and accuracy, such as in the widely used Opacity Project data. We find significant differences in photoionization rates for O II metastable states, averaged over Planck functions corresponding to ionizing radiation fields, with respect to the intrinsic accuracy of the calculations and improved resolution. Furthermore, for highly charged ions other physical effects are also important. Recombination rate coefficients, averaged over a Maxwellian distribution, are extremely sensitive to the position and resolution of near-threshold resonances and radiation damping, in (e + O VII) ⟷ O VI + hν. Surprisingly, however, the effect on the monochromatic and the mean Rosseland and Planck bound-free opacities is relatively small, but may be potentially significant.
Electric-Magnetic Duality And The Geometric Langlands Program

The geometric Langlands program can be described in a natural way by compactifying on a Riemann surface C a twisted version of N=4 super Yang-Mills theory in four dimensions. The key ingredients are electric-magnetic duality of gauge theory, mirror symmetry of sigma-models, branes, Wilson and 't Hooft operators, and topological field theory. Seemingly esoteric notions of the geometric Langlands program, such as Hecke eigensheaves and D-modules, arise naturally from the physics.
Aid effectiveness in Africa: the unfinished agenda

Africa is the world’s most aided major region. Yet economic growth has been disappointingly low there. A number of factors explain the poor outcomes and limited sustainability of and in Africa. But the organisation and management of the aid relationship is a particularly important one, including the dependence of Africans on that aid. The currently popular nostrums for solving the problem of the effectiveness in Africa — selectivity, ownership, sector investment programme and more aid — are as yet inadequate and often contradictory. Much more work and honest debate needs to occur before the problem of aid effectiveness can be tackled in Africa.
System implications of information privacy

Recent advances in computer time-sharing technology promise information systems which will permit simultaneous on-line access to many users at remotely located terminals. In such systems, the question naturally arises of protecting one user's stored programs and data against unauthorized access by others. Considerable work has already been done in providing protection against accidental access due to hardware malfunctions or undebugged programs. Protection against deliberate attempts to gain access to private information, although recently discussed from a philosophical point of view, has attracted only fragmentary technical attention. This paper presents a discussion of the threat to information privacy in non-military information systems, applicable countermeasures, and system implications of providing privacy protection.
Intrinsic MOSFET parameter fluctuations due to random dopant placement

Intrinsic fluctuations in threshold voltage, subthreshold swing, saturation drain current and subthreshold leakage of ultrasmall-geometry MOSFETs due to random placement of dopant atoms in the channel are examined using novel physical models and a Monte Carlo simulator. These fluctuations are shown to pose severe barriers to the scaling of supply voltage and channel length and thus, to the minimization of power dissipation and switching delay in multibillion transistor chips of the future. In particular, using the device technology and the level of integration projections of the National Technology Roadmap for Semiconductors for the next 15 years, standard and maximum deviations of threshold voltage, drive current, subthreshold swing and subthreshold leakage are shown to escalate to 40 and 600 mV, 10 and 100%, 2 and 20 mV/dec, and 10 and 10/sup 8/%, respectively, in the 0.07 /spl mu/m, 0.9 V complementary metal-oxide-semiconductor (CMOS) technology generation with 1.3-64 billion transistors on a chip in 2010. While these deviations can be reduced to some degree by selecting optimal values of channel width, the associated penalties in dynamic and static power, and in packing density demand improved MOSFET structures aimed at minimizing parameter deviations.
Posture control of a cockroach-like robot

As legged robots become more animal-like, it is likely that these robots will have many complex limbs with redundant degrees of freedom (DOF). This is especially true when we desire them to move like an animal. Animals are capable of spontaneous and non-stereotyped locomotion, such as turning, swaying, twisting, deliberately falling, jumping, climbing, and running, Therefore, it becomes difficult to provide joint space trajectories, in real-time, for these complex movements when many limbs are simultaneously involved, and when some or all of these limbs contain redundant DOF. When locomotion takes place rapidly, it has been suggested that there is a feedforward control component that involves a proactive, higher level computation in the nervous system. We suggest and demonstrate an intuitive and computationally simple algorithm for controlling the posture of a complex, multileg robot with many redundant DOF. The algorithm avoids inverse kinematics by issuing feedforward force commands to both maintain static posture and generate body motion. In so doing, it is also shown that the multileg mechanics of postural control can be reduced to a simple center-of-pressure representation, or equivalently, an instantaneous virtual leg model.
Decomposition Algorithms for Stochastic Programming on a Computational Grid

We describe algorithms for two-stage stochastic linear programming with recourse and their implementation on a grid computing platform. In particular, we examine serial and asynchronous versions of the L-shaped method and a trust-region method. The parallel platform of choice is the dynamic, heterogeneous, opportunistic platform provided by the Condor system. The algorithms are of master-worker type (with the workers being used to solve second-stage problems), and the MW runtime support library (which supports master-worker computations) is key to the implementation. Computational results are presented on large sample-average approximations of problems from the literature.
Four-D blood flow patterns in the thoracic aorta in patients with CAD compared to age-matched normal subjects

Cardiac gated three directional time resolved velocity data obtained with MR velocity encoded phase contrast sequences were used. Normal subjects of different ages were studied earlier. Age-matched normal subjects were compared with 15 patients with CAD. Systolic forward velocities were much more rapid in the normal subjects compared to the patients with CAD. Retrograde velocities were more rapid in the patients and particles took longer time to travel from the aortic valve to mid-descending aorta in patients compared with normal subjects. We believe that there is also a factor in the aorta that contributes to cardiac ischemia by allowing less blood flow into the coronary arteries.
Does Bat Day Make Cents? The Effect of Promotions on the Demand for Major League Baseball

A primary objective of sport marketers in the professional sport setting is to develop strategies to increase game attendance. Historically, one of the strategies to accomplish this goal has been the utilization of special promotions. This paper studied the impact of promotions on attendance at professional sport games. Specifically, this research examines (a) the overall effect of promotions on attendance, and (b) the marginal impact on attendance of additional promotional days. Using a data set containing 1,500 observations, we find that a promotion increases single game attendance by about 14%. Additionally, increasing the number of promotions has a negative effect on the marginal impact of each promotion. The loss from this watering down effect, however, is outweighed by the gain from having an extra promotion day.
Almost everywhere positivity of the lyapunov exponent for the doubling map

We show that discrete one-dimensional Schrodinger operators on the half-line with ergodic potentials generated by the doubling map on the circle, V θ (n)=f(2 n θ), may be realized as the half-line restrictions of a non-deterministic family of whole-line operators. As a consequence, the Lyapunov exponent is almost everywhere positive and the absolutely continuous spectrum is almost surely empty.
Every Matrix is a Product of Toeplitz Matrices

We show that every $$n\,\times \,n$$n×n matrix is generically a product of $$\lfloor n/2 \rfloor + 1$$?n/2?+1 Toeplitz matrices and always a product of at most $$2n+5$$2n+5 Toeplitz matrices. The same result holds true if the word `Toeplitz' is replaced by `Hankel,' and the generic bound $$\lfloor n/2 \rfloor + 1$$?n/2?+1 is sharp. We will see that these decompositions into Toeplitz or Hankel factors are unusual: We may not, in general, replace the subspace of Toeplitz or Hankel matrices by an arbitrary $$(2n-1)$$(2n-1)-dimensional subspace of $${n\,\times \,n}$$n×n matrices. Furthermore, such decompositions do not exist if we require the factors to be symmetric Toeplitz or persymmetric Hankel, even if we allow an infinite number of factors.
How Have the World's Poorest Fared since the Early 1980s?

This article offers a new assessment of progress in reducing poverty over 1981–2001 using more consistent data and methods, closely following the methods underlying the Attacking Poverty (World Bank 2000) numbers, which had been based on Chen and Ravallion (2000). In common with our past estimates, the authors draw on nationally representative surveys as much as possible. The article reviews the methods of measuring poverty from those surveys and notes any changes from past estimates, though the authors refer readers to other sources for further discussion of our methods and alternatives. The new estimates presented here supersede all our previous estimates in that the authors recalculate everything back in time on a consistent basis incorporating the new data. The authors summarize our results in a standard regional tabulation following previous work. However, the authors have also created a Web-based interactive tool, PovcalNet, that allows users to access the primary distributions and so estimate poverty measures for alternative country groupings or for a selected set of individual countries (http:/ /iresearch.worldbank.org/povcalnet). The article first describes the coverage of the survey data. It then discusses the poverty line and exchange rates, followed by the measures of poverty, and then presents the main results.
MODULI SPACES OF FRAMED SHEAVES ON CERTAIN RULED SURFACES OVER ELLIPTIC CURVES

Fix a ruled surface S obtained as the projective completion of a line bundle L on a complex elliptic curve C; we study the moduli problem of parametrizing certain pairs consisting of a sheaf ℰ on S and a map of ℰ to a fixed reference sheaf on S. We prove that the full moduli stack for this problem is representable by a scheme in some cases. Moreover, the moduli stack admits an action by the group C*, and we determine its fixed-point set, which leads to explicit formulas for the rational homology of the moduli space.
A pole-placement design approach for systems with multiple operating conditions

The author proposes design procedures based on state-space pole-placement techniques for systems with multiple operating conditions. This is the so-called simultaneous pole-placement problem. First, the full state feedback problem is studied, in which a nonlinear local pole-placement solution is proposed. The design condition is formulated in terms of the rank condition of a multimode controllability matrix. Then, the output feedback problem is approached using a multimodel controller design, which is an extension of the observer design to multimode systems. The design is decomposed into separated global pole-placement subproblems and a local pole-placement subproblem. For a system with some operating conditions having modes on the j omega -axis, but no modes at the origin in the open right-half of the complex plane, stabilizability and detectability conditions for the design of an asymptotically stabilizing control are established, without any restriction on the number of inputs or outputs. Relations of this approach to other simultaneous control design approaches are pointed out. >
On the Partition Function and Random Maximum A-Posteriori Perturbations

In this paper we relate the partition function to the max-statistics of random variables. In particular, we provide a novel framework for approximating and bounding the partition function using MAP inference on randomly perturbed models. As a result, we can use efficient MAP solvers such as graph-cuts to evaluate the corresponding partition function. We show that our method excels in the typical "high signal - high coupling" regime that results in ragged energy landscapes difficult for alternative approaches.
Plasma Surface Modification of Polymer Backsheets: Origins of Future Interfacial Barrier/Backsheet Failure

Flexible polymer substrates coated with inorganic oxide moisture barriers are a potential replacement for glass backsheets in thin-film PV (photovoltaic) modules. Silicon oxynitride (SiOxNy ) deposited by plasma enhanced chemical vapor deposition (PECVD) on polyethylene terephthalate (PET) represents one potential new backsheet candidate. Barrier deposition runs at NREL have included a nitrogen-rich plasma pretreatment prior to barrier deposition with the intention of cleaning the PET surface and enhancing adhesion of the SiO xNy barrier film to PET; however, test coupons of PET/barrier/EVA/TPE failed after damp-heat exposure. (EVA is ethylene vinyl acetate and TPE is Tedlar-PET-EVA). PET substrates exposed to plasma conditions similar to those used in pretreatment were examined by X-ray photoelectron spectroscopy (XPS) to reveal that new low molecular weight PET fragments were created at the PET surface. These fragments are responsible for barrier/PET interfacial failure and barrier transfer to the EVA encapsulant side following damp heat exposure
LINEAR-QUADRATIC-REGULATOR POINTING CONTROL SYSTEM FOR A HIGH-ALTITUDE BALLOON PAYLOAD

A pointing control system design for the science package of a NASA high-altitude research balloon is described. The balloon assembly consists of a single helium balloon connected to a payload recovery parachute, payload gondola, and ballast hopper. Pointing of the scientific payload is accomplished via an arrangement of drive motors and a flywheel. Linear quadratic regulator (LQR) synthesis techniques are employed to produce the azimuth and elevation controller designs. The use of LQR synthesis is motivated by the azimuthal dynamic coupling encountered between the balloon and gondola. Two control devices are employed in azimuth, one of which is a decoupler motor and the other a flywheel. The decoupler motor is intended to isolate the gondola from the balloon such that the flywheel can be accelerated or decelerated about a steady-state angular velocity to provide precise azimuthal pointing. The multiple-input/multiple-output nature of the azimuth pointing problem is best handled in a matrix synthesis procedure such as LQR. The controller design methodology is explained, and a combination of time responses and singular value analyses are used to analytically evaluate the performance of the control system. 11 refs., 17 figs.
Early warning signals: The charted and uncharted territories

The realization that complex systems such as ecological communities can collapse or shift regimes suddenly and without rapid external forcing poses a serious challenge to our understanding and management of the natural world. The potential to identify early warning signals that would allow researchers and managers to predict such events before they happen has therefore been an invaluable discovery that offers a way forward in spite of such seemingly unpredictable behavior. Research into early warning signals has demonstrated that it is possible to define and detect such early warning signals in advance of a transition in certain contexts. Here, we describe the pattern emerging as research continues to explore just how far we can generalize these results. A core of examples emerges that shares three properties: the phenomenon of rapid regime shifts, a pattern of “critical slowing down” that can be used to detect the approaching shift, and a mechanism of bifurcation driving the sudden change. As research has expanded beyond these core examples, it is becoming clear that not all systems that show regime shifts exhibit critical slowing down, or vice versa. Even when systems exhibit critical slowing down, statistical detection is a challenge. We review the literature that explores these edge cases and highlight the need for (a) new early warning behaviors that can be used in cases where rapid shifts do not exhibit critical slowing down; (b) the development of methods to identify which behavior might be an appropriate signal when encountering a novel system, bearing in mind that a positive indication for some systems is a negative indication in others; and (c) statistical methods that can distinguish between signatures of early warning behaviors and noise.
Male labor force participation and social security in Mexico

Labor-force participation among Mexican males in their early retirement years (60 to 64 years of age) has decreased in recent decades, from 94.6 percent in 1960 to 65.2 percent in 2010. Similar trends are evident elsewhere in Latin America, and have occurred in the developed world. Such trends pose challenges to financial sustainability of social security systems as working-age populations decrease and those in retirement increase both because of demographic trends and decisions to take early retirement. In this study, we find that the Mexican social security system provides incentives to retire early. The retirement incentives of the Mexican social security system affect retirement behavior, and may be one of the main contributors to early retirement decisions, particularly for lower-income populations. We simulated the effect of the reform from a Pay-As-You-Go (PAYG) to the new Personal Retirement Accounts (PRA) system and we find that the PRA system also provides incentives to early retirement. Further analysis is needed to assess the financial sustainability of the social security system and financial security in old age for the largest cohorts in Mexico that will begin to retire by 2040.
Benchmarking the effective literacy rate

Abstract Several authors have identified an externality accruing to proximate illiterates, that is, illiterate people with access to a literate person. The standard literacy rate ignores this externality; measures of effective literacy are sensitive to it. Nearly all measures of effective literacy appearing in the literature are greater than or equal to R . In fact, the best known of these, the Basu–Foster measure L ∗ , is strictly greater in virtually every case (see Basu and Foster [Basu, Kaushik, Foster, James, 1998. On measuring literacy. Economic Journal 108 (451), 1733–1749]). Although the inequality L ∗ ≥ R is an unintended consequence of their construction, it amounts to setting a benchmark for the effective literacy rate. This note examines Basu and Foster’s framework and offers an alternative benchmark.
Development of a microwave cusp accelerator driven by electron cyclotron resonance

A microwave ion source is presented that employs a plasma discharge driven by distributed electron cyclotron resonance absorption (ECR) in a magnetic field cusp geometry. Ions are accelerated out of the cusp at controllable energies by a combination of magnetic mirror forces and an applied anode voltage. Previous experiments have demonstrated the ability to create controllable potential differences in an ECR cusp plasma and induce ion beam emission1. However, the axial profile of the accelerating potential has, up to this point, remained largely unmapped. As a result, the interaction of the ion production zone (where ECR occurs) and the acceleration zone (where the accelerating potential drop occurs) is not well understood.