cssi/SciSciGPT-SciSciNet huggingface dataset:
Frictional vibration transmission from a laterally moving surface to a traveling beam

Abstract As the density of information stored in automated magnetic tape libraries continues to increase, greater requirements are placed on the precision of mechanical positioning in order to successfully read and write data bits. The location of the read/write head in the direction across the tape's width (termed the lateral direction) is actively controlled in order to maintain alignment between the head and data tracks, even in the presence of the tape's lateral vibration. However, during repositioning, vibration is undesirably transmitted from the laterally moving head structure to the axially moving tape because of frictional contact between the two adjacent surfaces. As an analog of that interaction, a model is developed here to describe frictional vibration transmission from a surface having prescribed lateral motion to a tensioned beam that travels and slides over it. For a transport speed that is high when compared to the lateral vibration velocity, Coulomb friction between the surface and the beam can be well-approximated by an equivalent form of viscous damping. The beam is divided into contiguous regions corresponding to free spans and the beam's portion that contacts the surface. A critical engagement length between the beam and the surface exists for which vibration transmission at a particular natural frequency can be substantially reduced, and for a given mode, that length depends weakly on the surface's position along the beam's span. By contouring the surface to have portions of differing radii of curvature, the extent of vibration transmission can be reduced over a broad range of frequency.
Density Matrix Approach to Local Hilbert Space Reduction

We present a density matrix approach for treating systems with a large or infinite number of degrees of freedom per site with exact diagonalization or the density matrix renormalization group. The method is demonstrated on the 1D Holstein model of electrons coupled to Einstein phonons. In this system, two or three optimized phonon modes per site give results as accurate as with 10--100 bare phonon levels per site.
Highly diastereoselective and enantioselective C-H functionalization of 1,2-dihydronaphthalenes: a combined C-H activation/Cope rearrangement followed by a retro-Cope rearrangement.

The Rh2(S-DOSP)4-catalyzed reaction of vinyldiazoacetates with dihydronaphthalenes results in a highly enantioselective (91−99.6% ee) and diastereoselective (>98% de) C−H functionalization. The apparent intermolecular C−H insertion was demonstrated to be a combined C−H activation/Cope rearrangement followed by a retro-Cope rearrangement.
Polarity inversion of donor-acceptor cyclopropanes: disubstituted δ-lactones via enantioselective iridium catalysis.

The coupling of carbonyl electrophiles at the donor position of donor–acceptor cyclopropanes is described, representing an inversion of polarity with respect to conventional reactivity modes displayed by these reagents. Specifically, upon exposure of donor–acceptor cyclopropanes to alcohols in the presence of a cyclometalated iridium catalyst modified by (S)-BINAP, catalytic C–C coupling occurs, providing enantiomerically enriched products of carbonyl allylation. Identical products are obtained upon isopropanol-mediated transfer hydrogenation of donor–acceptor cyclopropanes in the presence of aldehydes. The reaction products are directly transformed to cis-4,5-disubstituted δ-lactones.
From the Earth to the Moon: A Freshman Seminar

The seminar course for first-year undergraduate students, From the Earth to the Moon, deals with both technical and non-technical aspects of space flight, with particular reference to lunar voyages. The goals of the course are to establish a framework for understanding technology and its applications, to present fundamental principles of science and program management, and to motivate students to learn more about the many facets of engineering. As such, the course introduces numerous issues of systems engineering in a broad context, presenting not only science, technology, and mathematics but also the reasons that these subjects are important. Typically, all of the students in the course have studied physics and/or calculus in high school, though half plan to major in the humanities. Thus, the course has dual roles in exposing liberal arts students to details of technology and engineering students to societal impacts of technology.
A Symplectic Test of the L-Functions Ratios Conjecture

Recently Conrey, Farmer and Zirnbauer [8, 9] conjectured formulas for the averages over a family of ratios of products of shifted L-functions. Their L-functions Ratios Conjecture predicts both the main and lower order terms for many problems, ranging from n-level correlations and densities to mollifiers and moments to vanishing at the central point. There are now many results showing agreement between the main terms of number theory and random matrix theory; however, there are very few families where the lower order terms are known. These terms often depend on subtle arithmetic properties of the family, and provide a way to break the universality of behavior. The L-functions Ratios Conjecture provides a powerful and tractable way to predict these terms. We test a specific case here, that of the 1-level density for the symplectic family of quadratic Dirichlet characters arising from even fundamental discriminants d ≤ X. For test functions supported in (−1/3, 1/3) we calculate all the lower order terms up to size O (X −½+ɛ ) and observe perfect agreement with the conjecture (for test functions supported in (−1, 1) we show agreement up to errors of size O (X −ɛ ) for any ɛ). Thus for this family and suitably restricted test functions, we completely verify the Ratios Conjecture's prediction for the 1-level density.
Portable whiteboard system with vision input

We present a novel whiteboard system that uses one or more active input devices. The system is especially suitable for situations in which several users provide input on a large writing surface which also serves as a projection surface. That surface can have general orientation. We have implemented a system that uses an inexpensive, infrared-emitting stylus and an off-the-shelf videoconferencing camera fitted with an IR transmitting/visible blocking filter to capture handwritten strokes. The system uses a calibration method that uses projective mapping thus allowing off-axis camera placement. We also propose a self-calibrating system in which the capture device shares its optical system with the projector. In a system with multiple local users the question of 'who wrote what' becomes relevant. Therefore, we address the question of attaching identify to stroke information.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Hydrogen and methane plasma assisted ignition by NS discharge behind reflected shock wave

The kinetics of ignition in lean H 2 :O 2 :Ar and CH 4 :O 2 :Ar mixtures has been studied experimentally and numerically after a high-voltage nanosecond discharge. The ignition delay time behind a reflected shock wave was measured with and without the discharge when detecting OH* radiation. It was shown that the initiation of the discharge with a specific deposited energy of 10 – 30 mJ/cm3 leads to an order of magnitude decrease in the ignition delay time. Discharge processes and following chain chemical reactions with energy release were simulated. The generation of atoms, radicals and excited and charged particles was numerically simulated using the measured time - resolved discharge current and electric field in the discharge phase. The calculated densities of the active particles were used as input data to simulate plasma-assisted ignition. Good agreement was obtained between the calculated ignition delay times and the experimental data. It was shown that ignition delay time is difficult to measure in too lean mixtures. Possible approaches to solve this problem were discussed.
Optimal SAM defense system: An application of optimal control concept to operations research

An operations research problem concerning the optimal surface-to-air-missile (SAM) firing pattern to defend a surface target is solved via applications of the concept of closed-loop (feedback) and open-loop optimal control. The SAM defense problem is formulated as a Markov decision process with the number of SAM's in each salvo as the decision variable. Interesting cases, including the presence of imperfect sensor observation and a bound on the number of SAM's available are considered. The principle of dynamic programming and the technique of nonlinear integer programming are applied to reach closed-loop and open-loop solutions. Numerical examples are given for illustration.
Product Variety and Economic Growth: Empirical Evidence for the OECD Countries

This paper uses panel data for 19 OECD countries and finds support for the hypothesis that a greater degree of product variety relative to the United States helps to explain relative per capita GDP levels. The empirical work relies upon some direct measures of product variety calculated from 6-digit OECD export and import data. Although the issue is still far from being settled, the emerging conclusion is that the index of relative product variety across countries is significantly correlated with relative per capita income levels.
Manipulation with soft fingers: contact force control

The issue of controlling contact forces generated when the fingers of a dextrous device first close on an object is addressed. The use of active fingertips is proposed to enhance the system performance and avoid contact instability problems resulting from noncollocated sensors and actuators. A first step towards exploring this issue is the study of an idealized controllable fingertip making contact with an object. The authors provide analytical and simulation studies to identify ideal fingertip characteristics to achieve a desired performance for a simple contact problem. An investigation of the performance of more realistic fingers with limited controllability follows. Preliminary experimental results for a prototype semi-active fingertip that uses an electrorheological fluid to achieve active damping control are provided. A brief summary of future experimental plans to implement such active fingertips in simple manipulation tasks is presented. >
Electron bunch length diagnostic with coherent Smith-Purcell radiation

We have designed a new technique for measuring subpicosecond electron bunch lengths using coherent Smith-Purcell radiation. This new diagnostic technique involves passing the electron beam in close proximity of a grating with period comparable to the electron bunch length. The emitted Smith-Purcell radiation will have a coherent component whose angular position and distribution are directly related to the electron bunch length and longitudinal profile, respectively. This new diagnostic technique is inherently simple, inexpensive and non-intercepting. We show that the new technique is also scaleable to femtosecond regime.
Oriented Active Shape Models

Active shape models (ASM) are widely employed for recognizing anatomic structures and for delineating them in medical images. In this paper, a novel strategy called oriented active shape models (OASM) is presented in an attempt to overcome the following five limitations of ASM: 1) lower delineation accuracy, 2) the requirement of a large number of landmarks, 3) sensitivity to search range, 4) sensitivity to initialization, and 5) inability to fully exploit the specific information present in the given image to be segmented. OASM effectively combines the rich statistical shape information embodied in ASM with the boundary orientedness property and the globally optimal delineation capability of the live wire methodology of boundary segmentation. The latter characteristics allow live wire to effectively separate an object boundary from other nonobject boundaries with similar properties especially when they come very close in the image domain. The approach leads to a two-level dynamic programming method, wherein the first level corresponds to boundary recognition and the second level corresponds to boundary delineation, and to an effective automatic initialization method. The method outputs a globally optimal boundary that agrees with the shape model if the recognition step is successful in bringing the model close to the boundary in the image. Extensive evaluation experiments have been conducted by utilizing 40 image (magnetic resonance and computed tomography) data sets in each of five different application areas for segmenting breast, liver, bones of the foot, and cervical vertebrae of the spine. Comparisons are made between OASM and ASM based on precision, accuracy, and efficiency of segmentation. Accuracy is assessed using both region-based false positive and false negative measures and boundary-based distance measures. The results indicate the following: 1) The accuracy of segmentation via OASM is considerably better than that of ASM; 2) The number of landmarks can be reduced by a factor of 3 in OASM over that in ASM; 3) OASM becomes largely independent of search range and initialization becomes automatic. All three benefits of OASM ensue mainly from the severe constraints brought in by the boundary-orientedness property of live wire and the globally optimal solution found by the 2-level dynamic programming algorithm.
Stability Analysis of Switched Dynamical Systems with State-Space Dilation and Contraction

This paper considers switched dynamical systems with state-space dilation and contraction formed by concatenating the states of a set of local dynamical systems or semi-flows on state spaces with different dimensions at specified time-instants. These systems arise naturally in many aerospace applications such as multi-body dynamic systems involving changes in the degrees of freedom, and systems composed of multiple spacecraft with docking and undocking capabilities flying in formation. The notions of stability of invariant sets in the sense of Lyapunov for usual dynamical systems are extended to this class of switched dynamical systems. Also the notion of finite-time stability with specified bounds is introduced. Sufficient stability conditions are established for a special class of switched dynamical systems with state-space dilation and contraction. Their application to spacecraft formation stability analysis is discussed.
Consumer Learning and Hybrid Vehicle Adoption

We study the effect of differences in product quality on new technology diffusion. We propose a model in which heterogeneity in perceived product quality affects consumer adoption. If consumers experientially infer the quality of a technology, an increase in initial exposure to a low-quality product may inhibit subsequent diffusion. Incentives intended to speed up adoption may in fact have the opposite effect, if they propagate low-quality signals. We examine the predictions of the model using sales data for 11 hybrid-vehicle models between 2000 and 2006. Consistent with press reports that the first-generation Insight was perceived to be of lower quality than the first-generation Prius, we find that, conditional on overall hybrid vehicle adoption in the first 2 years, locations with a relatively high Prius market share experienced faster subsequent adoption than states with a relatively high Insight market share. We estimate the elasticity of new hybrid sales with respect to the Prius penetration rate is 0.30–0.58, while the elasticity with respect to the Insight penetration rate is $$-$$ 0.14 to $$-$$ 0.44.
Evolution of the Constitution

An 'analytic narrative' is the presentation of crucial historical events, using the intuitions of rational choice theory, to clarify the motivations and beliefs of the principal actors. This article attempts to understand a dilemma embedded in the Declaration of Independence: the expected costs of war against Britain far exceeded any possible benefits, if these are construed simply as the removal of colonial taxation. Furthermore, war against Britain necessitated an alliance with a potential aggressive power, France. An analysis is presented indicating that the benefits also included the enormous reward of the west and the 'costs' incorporated possible future aggression by France and Spain. The narrative is extended to the Ratification of the Constitution in 1787, to suggest that the Federalists, and Madison, justifiably feared Spanish aggression in the Mississippi Valley. In the 1790s, consensus (about credible threats by the European powers) fragmented, and this led to entirely different policy preferences by Federalists and Jeffersonian Republicans. Napoleon's imperial intentions in Louisiana were, however, thwarted by the defeat of the French forces in Haiti in 1802-03. The result was the Louisiana Purchase of 1803-04.While the necessary causes of these various constitutional transformations can be appreciated, there appears to be an element of contingency, or happenstance, embedded in the sufficient causes. The purpose of the exercise is to attempt to understand the possibly chaotic basis of rapid institutional change.
Inferring Evolutionary History from DNA Sequences

One of the longstanding problems in computational molecular biology is the Character Compatibility Problem, which is concerned with the construction of phylogenetic trees for species sets, where the species are defined by characters. The character compatibility problem is NP-Complete in general. In this paper an $O(n^2 k)$ time algorithm is described for the case where the species are described by quaternary characters. This algorithm can be used to construct phylogenetic trees from DNA sequences.
Mortgage Lending in Korea : An Example of a Countercyclical Macroprudential Approach

Regulatory regimes are actively discussing macroprudential policy. Korea pursued a countercyclical macroprudential approach to prevent the overheating of mortgage lending and to minimize the risk of loan default. The Korean financial supervisory authority made adjustments in response to both the condition of the housing market and trends in mortgage loans. The lessons learned from the Korean experience are applicable to other situations. First, regulations regarding loan-to-value and debt-to-income ratios and other restrictions on mortgage lending can be employed as an important part of a countercyclical framework. Next, measures need to be applied in a timely manner and according to the specific conditions of each country. Finally, authorities should preemptively prepare macroprudential instruments before banks enter a period of rapid mortgage lending to avoid reckless mortgage lending operations and weaken any speculative motive in the housing market.
Approximating the little Grothendieck problem over the orthogonal and unitary groups

The little Grothendieck problem consists of maximizing $$\sum _{ij}C_{ij}x_ix_j$$źijCijxixj for a positive semidefinite matrix C, over binary variables $$x_i\in \{\pm 1\}$$xiź{±1}. In this paper we focus on a natural generalization of this problem, the little Grothendieck problem over the orthogonal group. Given $$C\in \mathbb {R}^{dn\times dn}$$CźRdn×dn a positive semidefinite matrix, the objective is to maximize $$\sum _{ij}{\text {tr}}\left( C^T_{ij}O_iO_j^T\right) $$źijtrCijTOiOjT restricting $$O_i$$Oi to take values in the group of orthogonal matrices $$\mathcal {O}_d$$Od, where $$C_{ij}$$Cij denotes the (ij)-th $$d\times d$$d×d block of C. We propose an approximation algorithm, which we refer to as Orthogonal-Cut, to solve the little Grothendieck problem over the group of orthogonal matrices $$\mathcal {O}_d$$Od and show a constant approximation ratio. Our method is based on semidefinite programming. For a given $$d\ge 1$$dź1, we show a constant approximation ratio of $$\alpha _{\mathbb {R}}(d)^2$$źR(d)2, where $$\alpha _{\mathbb {R}}(d)$$źR(d) is the expected average singular value of a $$d\times d$$d×d matrix with random Gaussian $$\mathcal {N}\left( 0,\frac{1}{d}\right) $$N0,1d i.i.d. entries. For $$d=1$$d=1 we recover the known $$\alpha _{\mathbb {R}}(1)^2=2/\pi $$źR(1)2=2/ź approximation guarantee for the classical little Grothendieck problem. Our algorithm and analysis naturally extends to the complex valued case also providing a constant approximation ratio for the analogous little Grothendieck problem over the Unitary Group $$\mathcal {U}_d$$Ud. Orthogonal-Cut also serves as an approximation algorithm for several applications, including the Procrustes problem where it improves over the best previously known approximation ratio of $$\frac{1}{2\sqrt{2}}$$122. The little Grothendieck problem falls under the larger class of problems approximated by a recent algorithm proposed in the context of the non-commutative Grothendieck inequality. Nonetheless, our approach is simpler and provides better approximation with matching integrality gaps. Finally, we also provide an improved approximation algorithm for the more general little Grothendieck problem over the orthogonal (or unitary) group with rank constraints, recovering, when $$d=1$$d=1, the sharp, known ratios.
Meditation States and Traits: EEG, ERP, and Neuroimaging Studies.

Neuroelectric and imaging studies of meditation are reviewed. Electroencephalographic measures indicate an overall slowing subsequent to meditation, with theta and alpha activation related to proficiency of practice. Sensory evoked potential assessment of concentrative meditation yields amplitude and latency changes for some components and practices. Cognitive event-related potential evaluation of meditation implies that practice changes attentional allocation. Neuroimaging studies indicate increased regional cerebral blood flow measures during meditation. Taken together, meditation appears to reflect changes in anterior cingulate cortex and dorsolateral prefrontal areas. Neurophysiological meditative state and trait effects are variable but are beginning to demonstrate consistent outcomes for research and clinical applications. Psychological and clinical effects of meditation are summarized, integrated, and discussed with respect to neuroimaging data.
A compactness theorem of n-harmonic maps

Abstract For n ⩾ 3 , let Ω ⊂ R n be a bounded domain and N ⊂ R L be a compact smooth Riemannian submanifold without boundary. Suppose that { u n } ⊂ W 1 , n ( Ω , N ) are weak solutions to the (perturbed) n-harmonic map equation (1.2), satisfying (1.3), and u k → u weakly in W 1 , n ( Ω , N ) . Then u is an n-harmonic map. In particular, the space of n-harmonic maps is sequentially compact for the weak- W 1 , n topology.
Managerial openness and the adoption of distributed group support systems: the case of WebWide participation

The full involvement of designated participants in a meeting process is a well-recognized standard of group effectiveness, yet most face-to-face meetings are undertaken without the presence of every group member. The problem of total participation in asynchronous meetings convened with distributed group support systems has been noted frequently but investigated rarely. This paper describes a portion of a large field study of government and non-profit agencies using the distributed group support system WebWide Participation in which explanations for meeting involvement (and non-involvement) were explored. In particular, four WebWide meetings with varying levels of participation were selected, and surveys were sent to all designated participants. The hypothesis was that non-participants have less openness (i.e., one of the key personality dimensions in Big Five personality theory) than active participants in the targeted meetings Using two indices of managerial openness, a discriminant analysis was undertaken that correctly distinguished over four of every five participants and non-participants. The important of this finding for advancing the adoption of other information technologies is discussed.
Intrinsic and extrinsic galaxy alignment

We show with analytic models that the assumption of uncorrelated intrinsic ellipticities of target sources that is usually made in searches for weak gravitational lensing arising from large-scale mass inhomogeneities (‘field lensing’) is unwarranted. If the orientation of the galaxy image is determined either by the angular momentum or by the shape of the halo in which it forms, then the image should be aligned preferentially with the component of the tidal gravitational field perpendicular to the line of sight. Long-range correlations in the tidal field will thus lead to long-range ellipticity–ellipticity correlations that mimic the shear correlations arising from weak gravitational lensing. We calculate the ellipticity–ellipticity correlation expected if halo shapes determine the observed galaxy shape, and we discuss uncertainties (which are still considerable) in the predicted amplitude of this correlation. The ellipticity–ellipticity correlation induced by angular momenta should be smaller. We consider several methods for discriminating between the weak-lensing (extrinsic) and intrinsic correlations, including the use of redshift information. An ellipticity–tidal-field correlation also implies the existence of an alignment of images of galaxies near clusters. Although the intrinsic alignment may complicate the interpretation of field-lensing results, it is inherently interesting as it may shed light on galaxy formation as well as on structure formation.
Charging spectrum of a small Wigner crystal island

Abstract Charging of a clean two-dimensional island is studied in the regime of small concentration of electrons when they form the Wigner crystal. The number of electrons in the island is assumed to be not too large (N ≤ 100). It is shown that the total energy of the island as a function of N has a quasiperiodic component of a universal shape that is independent of the form of electron-electron interactions. These oscillations are caused by the combination of the geometric effects associated with packing of the triangular lattice into the circular island. These effects are the shell effect, associated with starting a new crystalline row, and the so-called confinement polaronic effect. In the presence of close metallic gates, which eliminate the long-range part of the electronelectron interactions, the oscillations of the energy bring about simultaneous entering of the dot by a few electrons.
A Synthesis of Research on Psychological Types of Gifted Adolescents

In this study, the author synthesizes results of studies about personality types of gifted adolescents. Fourteen studies were coded with 19 independent samples. The total number of identified participants in original studies was 5,723. The most common personality types among gifted adolescents were “intuitive” and “perceiving.” They were higher on the Introversion, Intuition, Thinking, and Perceiving dimensions of the personality scales of the Myers-Briggs Type Indicator (MBTI) when compared to general high school students. Also, gifted adolescents differed within the group by gender and by ability. Based on the findings, the author discusses teaching practices for gifted students according to their personality preferences.
Scaling question answering to the web

The wealth of information on the web makes it an attractive resource for seeking quick answers to simple, factual questions such as “who was the first American in space?” or “what is the second tallest mountain in the world?” Yet today's most advanced web search services (e.g., Google and AskJeeves) make it surprisingly tedious to locate answers to such questions. In this paper, we extend question-answering techniques, first studied in the information retrieval literature, to the web and experimentally evaluate their performance.First we introduce Mulder, which we believe to be the first general-purpose, fully-automated question-answering system available on the web. Second, we describe Mulder's architecture, which relies on multiple search-engine queries, natural-language parsing, and a novel voting procedure to yield reliable answers coupled with high recall. Finally, we compare Mulder's performance to that of Google and AskJeeves on questions drawn from the TREC-8 question answering track. We find that Mulder's recall is more than a factor of three higher than that of AskJeeves. In addition, we find that Google requires 6.6 times as much user effort to achieve the same level of recall as Mulder.
Phase mixing in time-independent Hamiltonian systems

Everything you ever wanted to know about what has come to be known as ``chaotic mixing:'' This paper describes the evolution of localised ensembles of initial conditions in 2- and 3-D time-independent potentials which admit both regular and chaotic orbits. The coarse-grained approach towards an invariant, or near-invariant, distribution was probed by tracking (1) phase space moments through order 4 and (2) binned reduced distributions f(Z_a,Z_b,t) for a,b=x,y,z,p_x,p_y,p_z, computed at fixed time intervals. For ``unconfined'' chaotic orbits in 2-D systems not stuck near islands by cantori, the moments evolve exponentially: Quantities like the dispersion in p_x, which start small and eventually asymptote towards a larger value, initially grow exponentially in time at a rate comparable to the largest short time Lyapunov exponent. Quantities like | |, that can start large but eventually asymptote towards zero, decrease exponentially. With respect to a discrete L^p norm, reduced distributions f(t) generated from successive decay exponentially towards a near-invariant f_{niv}, although a plot of Df(t)=||f(t)-f_{niv}|| can exhibit considerable structure. Regular ensembles behave very differently, both moments and Df evolving in a fashion better represented by a power law time dependence. ``Confined'' chaotic orbits, initially stuck near regular islands because of cantori, exhibit an intermediate behaviour. The behaviour of ensembles evolved in 3-D potentials is qualitatively similar, except that, in this case, it is relatively likely to find one direction in configuration space which is ``less chaotic'' than the other two, so that quantities like L_{ab} depend more sensitively on which phase space variables one tracks.
Optimizing instrumentation when measuring jet engine blade vibration

An analytical model of bladed disk vibration is used to calculate the statistical variations in blade amplitudes that can occur in mistuned turbomachinery blading. The results provide a basis for evaluating alternative strategies for instrumenting the stage. This approach is illustrated by applying it to an unshrouded fan stage. It is found for this stage that the best strategy is to instrument blades that have frequencies near the tuned system frequency. A procedure is proposed for establishing how gages should be allocated from stage to stage throughout the engine.Copyright © 1991 by ASME
Monte-Carlo simulation of electromagnetic scattering from a heterogeneous two-component medium

A numerical solution for scattering from a random collection of long vertical cylinders and spheres above a ground plane is developed to examine the validity of radiative transfer theory when applied to vegetation canopies. Numerical simulations, while frequently computationally intensive, give detailed statistical information, including the phase-coherence, directly related to the scattered fields themselves. Electromagnetic scattering properties of the heterogeneous medium, such as the backscattering coefficient and phase-statistics, are determined including interactions up to second order. The second-order, near-field, and sphere-cylinder interaction has been computed for nonuniform illumination of one particle by its pair using a novel technique based on reciprocity. The application of this reciprocity-based approach is validated using the method of moments. The Monte-Carlo simulation results are compared with corresponding analytical solutions obtained from radiative transfer (RT) theory for the purpose of examining the significance of limitations in the underlying assumptions of RT in formulating solutions for EM scattering from vegetation media. >
Experimental Studies in Fluid Mechanics and Materials Science Using Acoustic Levitation

Ground-based and short-duration low gravity experiments have been carried out with the use of ultrasonic levitators to study the dynamics of freely suspended liquid drops under the influence of predominantly capillary and acoustic radiation forces. Some of the effects of the levitating field on the shape as well as the fluid flow fields within the drop have been determined. The development and refinement of measurement techniques using levitated drops with size on the order of 2 mm in diameter have yielded methods having direct application to experiments in microgravity. In addition, containerless melting, undercooling, and freezing of organic materials as well as low melting metals have provided experimental data and observations on the application of acoustic positioning techniques to materials studies.
The Nobel Memorial Prize for Daniel Kahneman

In an essay on his web page, Paul Krugman recommends as his first rule of research to young economists that they "Listen to the Gentiles.... Pay attention to what intelligent people are saying, even if they do not have your customs or speak your analytical language." His own context for applying this principle was in understanding that international-trade economists should pay attention to the field of geography: "Geographers and regional scientists have amassed a great deal of evidence on the nature and importance of localized external economies, and organized that evidence intelligently if not rigorously." To urge an academic discipline to listen to its critics, and to embrace the insights of another discipline even when the language and conceptual differences between the disciplines invite dismissal, is excellent advice. It is rarely followed. But it is even rarer for critics from one discipline to persistently and intelligently insinuate themselves into another discipline by making an effort to use a common language and to minimize conceptual differences. Yet this is what two brilliant psychologists, Daniel Kahneman and Amos Tversky, have done since the early 1970s. It is surely one of the biggest boons to the social sciences in recent decades that they have launched this research program so relevant for economics, doing so with an ability and willingness to address economists in economic language and venues, and with an emphasis on the implications of their research for economic questions. In recognition of these contributions, Daniel Kahneman was awarded The Bank of Sweden Prize in Economic Science in Memory of Alfred Nobel in October 2002.'
Aeroelastic Behavior of Low-Aspect-Ratio Metal and Composite Blades

The aeroelastic stability of titanium and composite blades of low aspect ratio is examined over a range of design parameters, using a Rayleigh-Ritz formulation. The blade modes include a plate-type mode to account for chordwise bending. Chord-wise flexibility is found to have a significant effect on the unstalled supersonic flutter of low-aspect-ratio blades, and also on the stability of tip sections of shrouded fan blades. For blades with a thickness of less than approximately 4 percent of chord, the chordwise, second bending, and first torsion branches are all unstable at moderately high supersonic Mach numbers. For composite blades, the important structural coupling between bending and torsion cannot be modeled properly unless chordwise bending is accounted for. Typically, aft fiber sweep produces beneficial bending-torsion coupling that is stabilizing, whereas forward fiber sweep has the opposite effect. By using crossed-ply laminate configurations, critical aeroelastic modes can be stabilized.
Involvement of Cellular Membranes and their Lipids in Nucleation of Stone Forming Crystals

More than 80% of human kidney stones consist of calcium oxalate and/or calcium phosphate. Human urine is generally metastable with respect to these salts and their nucleation is heterogeneous. Based on: 1. ultrastructural and immunohistochemical studies of stones in which cellular degradation products and lipids were commonly seen in association with calcific crystals and 2. in vivo studies of nephrolithiasis in rat models where calcium oxalate (CaOx) and calcium phosphate (CaP) crystals almost always formed and seen in association with cell membranes, we proposed that membranes and their lipids are involved in crystallization of these salts. To test our hypothesis we isolated organic matrix of kidney stones, its lipid contents and membrane vesicles from epithelial cells of rat kidney and incubated them in metastable solution of CaOx. Both membrane vesicles and matrix from the stones supported crystallization of CaOx and crystals formed in association with the membranes. Lipids of the stone matrix appeared better nucleators than whole matrix. Urine spends only minutes within the kidneys thus any nucleation which can lead to stone formation has to occur rapidly. In studies described here, we demonstrate that under specific circumstances relevant to conditions in the kidney, membrane vesicle- supported CaOx crystallization can occur within seconds, demonstrating the possibility of such events happening in the kidneys. We also studied CaOx monohydrate (COM) precipitation at Langmuir monolayers of dipalmitoylphosphatidylglecerol (DPPG), dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylserine (DPPS) showed precipitation to be heterogeneous and selective with a majority of crystals orienting with the 101 face of COM facing the monolayer. Our results show that membrane lipids can initiate nucleation of calcium oxalate crystals in solutions similar to those present in the kidneys. In addition these crystals form within the time urine spends inside the renal tubules demonstrating for the first time the likelihood of occurrence of such a phenomenon in the kidneys during stone formation.
Robust continuous-time adaptive control by parameter projection

The problem of adaptive control of a continuous-time plant of arbitrary relative degree, in the presence of bounded disturbances as well as unmodeled dynamics, is addressed. The adaptation considered is the usual gradient update law with parameter projection, the latter being the only robustness enhancement modification employed. It is shown that if the unmodeled dynamics, which consists of multiplicative as well as additive system uncertainty, is small enough, then all the signals in the closed-loop system are bounded. This shows that extra modifications are not necessary for robustness with respect to bounded disturbances and small unmodeled dynamics. In the nominal case, where unmodeled dynamics and disturbances are absent, the asymptotic error in tracking a given reference signal is zero. Moreover, the performance of the adaptive controller is also robust. >
Morita classes in the homology of automorphism groups of free groups

Using Kontsevich's identification of the homology of the Lie algebra l1 with the co- homology of Out(Fr), Morita defined a sequence of 4k-dimensional classesk in the unstable rational homology of Out(F2k+2). He showed by a computer calculation that the first of these is non-trivial, so coincides with the unique non-trivial rational ho- mology class for Out(F4). Using the "forested graph complex" introduced in (2), we reinterpret and generalize Morita's cycles, obtaining an unstable cycle for every con- nected odd-valent graph. (Morita has independently found similar generalizations of these cycles.) The description of Morita's original cycles becomes quite simple in this interpretation, and we are able to show that the second Morita cycle also gives a non- trivial homology class. Finally, we view things from the point of view of a different chain complex, one which is associated to Bestvina and Feighn's bordification of outer space. We construct cycles which appear to be the same as the Morita cycles constructed in the first part of the paper. In this setting, a further generalization becomes apparent, giving cycles for objects more general than odd-valent graphs. Some of these cycles lie in the stable range. We also observe that these cycles lift to cycles for Aut(Fr). AMS Classification numbers Primary: 20J06 Secondary: 20F65, 20F28
The Yellowstone magmatic system from the mantle plume to the upper crust

The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in the world. An understanding of its properties is key to enhancing our knowledge of volcanic mechanisms and corresponding risk. Using a joint local and teleseismic earthquake P-wave seismic inversion, we revealed a basaltic lower-crustal magma body that provides a magmatic link between the Yellowstone mantle plume and the previously imaged upper-crustal magma reservoir. This lower-crustal magma body has a volume of 46,000 cubic kilometers, ~4.5 times that of the upper-crustal magma reservoir, and contains a melt fraction of ~2%. These estimates are critical to understanding the evolution of bimodal basaltic-rhyolitic volcanism, explaining the magnitude of CO2 discharge, and constraining dynamic models of the magmatic system for volcanic hazard assessment.
Computer pattern recognition of printed music

A major area of concentration of pattern recognition research has been the design of computer programs to recognize two-dimensional visual patterns. These patterns may be divided into two classes: patterns representing objects in the real world (e.g., landscapes, blood cells) and patterns representing conventionalized symbols (e.g., printed text, maps). The standard notation used to specify most instrumental and vocal music forms a conventionalized, two-dimensional, visual pattern class.
Are hedge fund managers systematically misreporting? Or not? ☆

A discontinuity, or kink, at zero in the hedge fund net return distribution has been interpreted as evidence of managers manipulating returns to avoid showing small losses. Instead, we propose alternative explanations for this phenomenon. In particular, we show that incentive fees can mechanistically create a kink in the net return distribution. This mechanism accounts for almost the entire kink observed in the large, liquid Long-Short Equity style. Furthermore, we show that asset illiquidity and the bounding of yields at zero can generate distribution discontinuities as well. Therefore, we conclude that the observed hedge fund return discontinuities are not direct proof of manipulation.
Low-energy dynamics of spinor condensates

We present a derivation of the low-energy Lagrangian governing the dynamics of the spin degrees of freedom in a spinor Bose condensate for any phase in which the average magnetization vanishes. This includes all phases found within mean-field treatments except for the ferromagnet for which the low-energy dynamics has been discussed previously. The Lagrangian takes the form of a sigma model for the rotation matrix describing the local orientation of the spin state of the gas.
Improvement in doppler navigator performance through spectral compression

A Doppler navigation radar for space applications must be at least 30 db more sensitive than present Doppler sensors but still maintain the same (or better) error tolerances. Yet, solution of the problem (if at all attainable) by conventional approaches is severely hampered by the prohibitive space and power limitations of present spacecraft. This paper will show that proper frequency modulation of the microwave transmitter can code the ground scatterer return in such a way that considerable signal bandwidth reduction (40-50 times) can be effected [referenced to the normal continuous-wave (CW) bandwidth] with an attendant increase in peak spectral power and a reduction of certain critical error sources.
Price Impacts of Small Firm Entry in US Manufacturing

There has been little prior research into whether there are differing effects of entry by size of entrants. This study examines the annual data for the decade of the 1990s, and virtually all three-digit SIC industries; entry and expansion by firms in different employment size categories are examined and the econometric analysis seeks to find differential impacts on producer prices. The results presented here, although limited by data availability, confirm previous work suggesting an important market-disciplining role of small-firm entry. Industries experiencing greater rates of small-firm entry show smaller price increases, after controlling for cost, demand, and exchange rate pressures.
Online Collaborative Filtering on Graphs

Existing approaches to designing recommendation systems with user feedback focus on settings where the number of items is small and/or admit some underlying structure. It is unclear, however, if these approaches extend to applications like social network news feeds and content-curation platforms, which have large and unstructured content pools and constraints on user-item recommendations. To this end, we consider the design of recommendation systems in content-rich setting—where the number of items and the number of item-views by users are of a similar order and an access graph constrains which user is allowed to see which item. In this setting, we propose recommendation algorithms that effectively exploit the access graph, and characterize how their performance depends on the graph topology. Our results demonstrate the importance of serendipity in exploration and how recommendation improves when the access graph has higher expansion; they also suggest reasons behind the success of simple algorithms like ...
FINITE REPRESENTATIONS OF REAL PARAMETRIC CURVES AND SURFACES

Algebraic curves and surfaces are commonly used in geometric modeling. Parametric curves and surfaces are those that can be represented using rational parametric equations, and are particularly important. In geometric modeling applications, the parametric equations are restricted to some bounded portion of the domain, yielding a segment of a curve or a patch of a surface. However, the algebraic curve or surface is an image of the entire infinite parameter domain. Attempting to map the entire curve or surface using very large regions of the parameter domain is not a solution because some finite points may be images of infinite parameter values.
Isolation and analysis of ginseng: advances and challenges

Ginseng occupies a prominent position in the list of best-selling natural products in the world. Because of its complex constituents, multidisciplinary techniques are needed to validate the analytical methods that support ginseng’s use worldwide. In the past decade, rapid development of technology has advanced many aspects of ginseng research. The aim of this review is to illustrate the recent advances in the isolation and analysis of ginseng, and to highlight their new applications and challenges. Emphasis is placed on recent trends and emerging techniques. The current article reviews the literature between January 2000 and September 2010.
Kinetics and mechanisms of the gas‐phase reactions of the NO3 radical with aromatic compounds

The kinetics and nitrated products of the gas-phase reactions of the NO3 radical with methoxybenzene, 1,2-, 1,3-, and 1,4-dimethoxybenzene, dibenzofuran and dibenzo-p-dioxin have been investigated at 297 ± 2 K and in the presence of one atmosphere of air. A relative rate method was used for the kinetic measurements. No reactions of methoxybenzene or dibenzofuran with the NO3 radical were observed. The dimethoxybenzenes were observed to react by H-atom abstraction and NO3 radical addition to the aromatic ring, while dibenzo-p-dioxin reacted by NO3 radical addition to the aromatic rings. For these compounds, the NO3 radical addition pathways were observed to be reversible. At the NO2 concentrations employed, the NO3-aromatic adducts reacted with NO2 and the observed rate constants increased with increasing NO2 concentration. However, for dibenzo-p-dioxin the observed rate constant became independent of the NO2 concentration for concentrations ≥ 4.8 × 1013 molecule cm−3, and under these conditions the rate constant of 6.8 × 10−14 cm3 molecule−1 s−1 was taken to be that for addition of the NO3 radical to the aromatic rings. The proposed NO3 radical reaction mechanisms are discussed. © 1994 John Wiley & Sons, Inc.