cssi/SciSciGPT-SciSciNet huggingface dataset:
Force chains as the link between particle and bulk friction angles in granular material

From sediment transport in rivers to landslides, predictions of granular motion rely on a Mohr-Coulomb failure criterion parameterized by a friction angle. Measured friction angles are generally large for single grains, smaller for large numbers of grains, and no theory exists for intermediate numbers of grains. We propose that a continuum of friction angles exists between single-grain and bulk friction angles due to grain-to-grain force chains. Physical experiments, probabilistic modeling, and discrete element modeling demonstrate that friction angles decrease by up to 15° as the number of potentially mobile grains increases from 1 to ~20. Decreased stability occurs as longer force chains more effectively dislodge downslope “keystone” grains, implying that bulk friction angles are set by the statistics of single-grain friction angles. Both angles are distinct from and generally larger than grain contact-point friction, with implications for a variety of sediment transport processes involving small clusters of grains.
Myxoma of the jaw bones

Myxoma is a peculiar and rare bone tumor of the jaws. During the last 50 years, 10 such cases were treated in the Memorial-Sloan Kettering Cancer Center. Six were in the mandible and four in the maxilla. During that period, 8,723 primary bone tumors were treated in this hospital. Although this tumor is histologically benign, it has the potentiality of local invasion of the bone. Excision of the underlying bone whenever involved by the tumor should be done.
Smart-grid policies: an international review

The electric power systems of many industrialized nations are challenged by the need to accommodate distributed renewable generation, increasing demands of a digital society, growing threats to infrastructure security, and concerns over global climate disruption. The ‘smart grid’—with a two-way flow of electricity and information between utilities and consumers—can help address these challenges, but various financial, regulatory, and technical obstacles hinder its rapid deployment. An overview of experiences with smart-grid policies in pioneering countries shows that many governments have designed interventions to overcome these barriers and to facilitate grid modernization. Smart-grid policies include a new generation of regulations and finance models such as regulatory targets, requirements for data security and privacy, renewable energy credits, and various interconnection tariffs and utility subsidies.
Fractionated stereotactic radiotherapy for acoustic neuromas.

Abstract Purpose: When compared with radiosurgery, fractionated stereotactic radiotherapy for acoustic neuroma (AN) offers escalation of the tumor dose and potential sparing of auditory and facial nerve functions. Methods and Materials: Between 1996 and 2001, 249 consecutive patients have received fractionated stereotactic radiotherapy for AN. One hundred twenty-five patients had follow-up >1 year and were the subject of this report. A noninvasive, repeat-fixation mask allowed simulation by way of spiral CT. Two distinct schedules for total dose and fractionation were used. For an AN 3 ), patients received 25 Gy given in 5 consecutive daily fractions of 5 Gy (111 patients), and for ANs ≥3.0 cm (volume 8.1 ± 1.2 cm 3 ), patients received 30 Gy given in 10 fractions of 3 Gy (14 patients). Results: The percentage of decrease in tumor size was 12% ± 2% (range 0–100%) vs. 13% ± 3% (range 0–38%) for the 25 Gy vs. 30 Gy regimens, respectively. No patient had growth of the AN or developed facial weakness. Two patients developed transient decreases in facial sensation. The rates of hearing preservation were similar for the larger and smaller tumors. Conclusion: Fractionated stereotactic radiotherapy may preserve normal function and control both small and large ANs.
ONE-LOOP N-POINT HELICITY AMPLITUDES IN (SELF-DUAL) GRAVITY

Abstract We present an ansatz for all one-loop amplitudes in pure Einstein gravity for which the n external gravitons have the same outgoing helicity. These loop amplitudes, which are rational functions of the momenta, also arise in the quantization of self-dual gravity in four-dimensional Minkowski space. Our ansatz agrees with explicit computations via D -dimensional unitarity cuts for n ≤6. It also has the expected analytic behavior, for all n , as a graviton becomes soft, and as two momenta become collinear. The gravity results are closely related to analogous amplitudes in (self-dual) Yang-Mills theory.
BPS spectrum of Argyres-Douglas theory via spectral network

We study the BPS spectrum of four-dimensional $ \mathcal{N} $ = 2 superconformal field theory of Argyres-Douglas type, obtained via twisted compactification of six-dimensional A N −1 (2, 0) theory on a sphere with an irregular puncture, by using spectral networks. We give strong evidence of the equivalence of $ \mathcal{N} $ = 2 superconformal field theories from sixdimensional theories of different ranks by systematically comparing the chamber structure and wall-crossing phenomena.
Classification of protein localization patterns obtained via fluorescence light microscopy

Describes a method of classifying cellular protein localization patterns based on their appearance in fluorescence light microscope images. Images depicting cellular protein localization were obtained using immunofluorescence microscopy. After collection, the images were processed and subject to feature extraction. Zernike moments were calculated for each image and used as inputs to one of two classification schemes: a classification tree or a neural network. Of the two classifiers, the neural network demonstrated better performance, correctly classifying 84% of previously unseen images. This work has application as a novel approach to protein description, as a means of automating microscopes, and as part of a new approach to gene discovery.
The aza-Robinson annulation: an application to the synthesis of iso-A58365A

Abstract Annulation of diazomethylvinylketone (4a) with a variety of secondary thiolactams provides a novel route to dihydro-γ-pyridones. This approach has been applied to the synthesis of iso-A58365A (2), the γ-pyridone analog of the ACE inhibitor, A58365A (1).
A world trade model based on comparative advantage with m regions, n goods, and k factors

Abstract This paper describes the World Trade Model, a linear program that determines world prices, scarcity rents, and international trade flows based on comparative advantage in a world economy with m regions, n goods, and k factors. The new model generalizes the World Model of Leontief et al. (1977) in ways that make it particularly useful for analyzing scenarios about sustainable development. Major properties of the model are demonstrated, and sources of the gains from trade are identified for the world as a whole and for individual regions. Illustrative results are reported for a 10-region, 8-good, 3-factor model of the world economy.
Dynamics of Proteins

A brief outline of theoretical approaches to the internal motions of protein is presented. The magnitudes and time-scale of the calculated fluctuations around the average structure are given and their biological importance indicated.
Masculinized or Marginalized: Decentralization and Women's Status in Regional Polish Institutions

Research on gendered institutions reveals that women often face a dilemma of being masculinized or marginalized. Female politicians downplay gender differences to fit in or risk sanction for highlighting women's issues. Sub‐national institutions are closer and less prestigious, so decentralization may facilitate women's participation and gender equality. Examining Poland's 1998 decentralization, I analyze 40 semi‐structured interviews with male and female regional political elites using a mixed‐methods approach to test five hypotheses about gender attitudes. Women initially respond “no gender inequalities” but change their answers; many support the notion of more women in politics, but not quotas or women's policy machinery. The author wishes to thank Lisa Baldez, Sunita Parikh, Kathleen Montgomery, Irfan Nooruddin, Mona Lena Krook, Candice Ortbals, John Carey, Gary Miller, Erica Townsend Bell, Celeste Montoya, the editors and two anonymous reviewers for their suggestions; the Eisenhower Institute for sup...
Digital Control for Improved Efficiency and Reduced Harmonic Distortion Over Wide Load Range in Boost PFC Rectifiers

This paper focuses on efficiency improvements and harmonic distortion reductions in digitally controlled single-phase boost power-factor-correction (PFC) rectifiers operating over wide load range. Based on a discontinuous conduction mode (DCM) detection circuit, a predictive current control law is modified to improve current shaping in both DCM and continuous conduction mode (CCM). Adaptive switching and adaptive frequency control techniques are introduced to reduce switching losses and improve efficiency at light loads. Experimental results are shown for a 300 W boost PFC rectifier.
Probing Embryonic Stem Cell Autocrine and Paracrine Signaling Using Microfluidics

Although stem cell fate is traditionally manipulated by exogenously altering the cells' extracellular signaling environment, the endogenous autocrine and paracrine signals produced by the cells also contribute to their two essential processes: self-renewal and differentiation. Autocrine and/or paracrine signals are fundamental to both embryonic stem cell self-renewal and early embryonic development, but the nature and contributions of these signals are often difficult to fully define using conventional methods. Microfluidic techniques have been used to explore the effects of cell-secreted signals by controlling cell organization or by providing precise control over the spatial and temporal cellular microenvironment. Here we review how such techniques have begun to be adapted for use with embryonic stem cells, and we illustrate how many remaining questions in embryonic stem cell biology could be addressed using microfluidic technologies.
Faster Generation of Random Spanning Trees

In this paper, we set forth a new algorithm for generating approximately uniformly random spanning trees in undirected graphs. We show how to sample from a distribution that is within a multiplicative $(1+\delta)$ of uniform in expected time $\TO(m\sqrt{n}\log 1/\delta)$. This improves the sparse graph case of the best previously known worst-case bound of $O(\min \{mn, n^{2.376}\})$, which has stood for twenty years. To achieve this goal, we exploit the connection between random walks on graphs and electrical networks, and we use this to introduce a new approach to the problem that integrates discrete random walk-based techniques with continuous linear algebraic methods. We believe that our use of electrical networks and sparse linear system solvers in conjunction with random walks and combinatorial partitioning techniques is a useful paradigm that will find further applications in algorithmic graph theory.
More on Subjective Executive Appraisal: An Empirical Study

A case study designed to examine the degree of congruence in management attitudes and socioeconomic background factors between executive superiors and executive subordinates, tested the hypothesis ...
Time-resolved measurements of the polarization state of four-wave mixing signals from GaAs multiple quantum wells

The complete polarization state of the degenerate four-wave mixing signal from a GaAs/AlxGa1-xAs multiple quantum well is determined by time resolution of all four of its Stokes parameters as a function of the relative angle between the two linear input polarizations. The degree of ellipticity and the orientation of the polarization ellipse are both observed to vary dramatically in time, and the temporal evolution is found to depend strongly on the orientation of the input polarizations. These time-resolved results are shown to be consistent with previous measurements of the time-integrated Stokes parameters and to provide new constraints for physical models. The results are shown to be qualitatively consistent with a phenomenological model requiring the inclusion of both many-body interactions and biexcitonic effects.
Heegaard gradient and virtual fibers

We show that if a closed hyperbolic 3-manifold has infinitely many finite covers of bounded Heegaard genus, then it is virtually fibered. This generalizes a theorem of Lackenby, removing restrictions needed about the regularity of the covers. Furthermore, we can replace the assumption that the covers have bounded Heegaard genus with the weaker hypotheses that the Heegaard splittings for the covers have Heegaard gradient zero, and also bounded width, in the sense of Scharlemann-Thompson thin position for Heegaard splittings.
Photon damping of waves in accretion disks

MHD turbulence is generally believed to have two important functions in accretion disks: it transports angular momentum outward, and the energy in its shortest wavelength modes is dissipated into the heat that the disks radiate. In this paper we examine a pair of mechanisms that may play an important role in regulating the amplitude and spectrum of this turbulence: photon diffusion and viscosity. We demonstrate that in radiation pressure-dominated disks, photon damping of compressive MHD waves is so rapid that it likely dominates all other dissipation mechanisms.
A linear algorithm for motion estimation using straight line correspondences

A linear algorithm is presented for determining 3-D motion parameters of a rigid object based on straightline correspondences. The algorithm requires a minimum number of thirteen-line correspondences over three frames. It comprises three steps: three intermediate matrices are computed; several candidate solutions of the rotation matrices and translation vectors are obtained from the intermediate matrices; and motion parameters are uniquely determined by the physical constraints of the 3-D rotations and translations. Some simulation results are given. >
A Process for Assessing NASA's Capability in Aircraft Noise Prediction Technology

An acoustic assessment is being conducted by NASA that has been designed to assess the current state of the art in NASA s capability to predict aircraft related noise and to establish baselines for gauging future progress in the field. The process for determining NASA s current capabilities includes quantifying the differences between noise predictions and measurements of noise from experimental tests. The computed noise predictions are being obtained from semi-empirical, analytical, statistical, and numerical codes. In addition, errors and uncertainties are being identified and quantified both in the predictions and in the measured data to further enhance the credibility of the assessment. The content of this paper contains preliminary results, since the assessment project has not been fully completed, based on the contributions of many researchers and shows a select sample of the types of results obtained regarding the prediction of aircraft noise at both the system and component levels. The system level results are for engines and aircraft. The component level results are for fan broadband noise, for jet noise from a variety of nozzles, and for airframe noise from flaps and landing gear parts. There are also sample results for sound attenuation in lined ducts with flow and the behavior of acoustic lining in ducts.
To Sample or not to Sample: Self-Triggered Control for Nonlinear Systems

Feedback control laws have been traditionally implemented in a periodic fashion on digital hardware. Although periodicity simplifies the analysis of the mismatch between the control design and its digital implementation, it also leads to conservative usage of resources such as CPU utilization in the case of embedded control. We present a novel technique that abandons the periodicity assumption by using the current state of the plant to decide the next time instant in which the state should be measured, the control law computed, and the actuators updated. This technique, termed self-triggered control, is developed for two classes of nonlinear control systems, namely, state-dependent homogeneous systems and polynomial systems. The wide applicability of the proposed results is illustrated in two well known physical examples: a jet engine compressor and the rigid body.
Self-starting phase conjugation with liquid crystals

Summary form only given. Liquid crystals are technologically important electro-optical materials, as they possess many unique physical and electro-optical properties. They have also been shown to be technologically important nonlinear optical materials. Extraordinarily large optical nonlinearities are exhibited over the entire visible-near infrared-infrared spectrum; nonlinear optical responses to CW, microsecond, nanosecond and picosecond lasers have been documented. Among the various physical mechanisms, perhaps the most noteworthy ones are those associated with temperature and director axis (orientational) fluctuations. As a result of molecular correlation effects, and the critical behavior of the order parameter near the phase transition temperatures T nematic liquid crystals exhibit the by now well known property of large thermal index gradients Another property of the nematic phase is the large susceptibility of the crystal axis to weak external field, i.e., orientational fluctuations can be easily induced. In this presentation, the author describes how these thermal and orientational fluctuations may be fruitfully utilized in some noise initiated self-starting coherent nonlinear optical devices. >
Intersection homology Künneth theorems

Cohen, Goresky, and Ji showed that there is a Kunneth theorem relating the intersection homology groups \({I^{\bar p}H_*(X\times Y)}\) to \({I^{\bar p}H_*(X)}\) and \({I^{\bar p}H_*(Y)}\) , provided that the perversity \({\bar p}\) satisfies rather strict conditions. We consider biperversities and prove that there is a Kunneth theorem relating \({I^{\bar p,\bar q}H_*(X\times Y)}\) to \({I^{\bar p}H_*(X)}\) and \({I^{\bar q}H_*(Y)}\) for all choices of \({\bar p}\) and \({\bar q}\) . Furthermore, we prove that the Kunneth theorem still holds when the biperversity p, q is “loosened” a little, and using this we recover the Kunneth theorem of Cohen–Goresky–Ji.
Asymmetric synthesis of diastereomeric diaminoheptanetetraols. A proposal for the configuration of (+)-zwittermicin a.

A proposed absolute configuration for the 7 stereocenters in (+)-zwittermicin A is described based on asymmetric synthesis of six diastereomeric 2,6-diamino-1,3,5,7-heptanetetraols corresponding to the C9−C15 segment, pairwise 13C NMR chemical shift difference analysis of the models with the natural product, interpretation of enantiospecificity of the serine loading domain of the zwittermicin A biosynthetic gene cluster, and degradation of the natural product.
Sensitivity of Antenna Arrays for Long-Wavelength Radio Astronomy

A number of new and planned radio telescopes will consist of large arrays of low-gain antennas operating at frequencies below 300 MHz. In this frequency regime, Galactic noise can be a significant or dominant contribution to the total noise. This, combined with mutual coupling between antennas, makes it difficult to predict the sensitivity of these instruments. This paper describes a system model and procedure for estimating the system equivalent flux density (SEFD)-a useful and meaningful metric of the sensitivity of a radio telescope-that accounts for these issues. The method is applied to LWA-1, the first “station” of the Long Wavelength Array (LWA) interferometer. LWA-1 consists of 512 bowtie-type antennas within a 110 × 100 m elliptical footprint, and is designed to operate between 10 MHz and 88 MHz using receivers having noise temperature of about 250 K. It is shown that the correlation of Galactic noise between antennas significantly desensitizes the array for beam pointings which are not close to the zenith. It is also shown that considerable improvement is possible using beamforming coefficients which are designed to optimize signal-to-noise ratio under these conditions. Mutual coupling is found to play a significant role, but does not have a consistently positive or negative influence. In particular, we demonstrate that pattern multiplication (assuming the behavior of single antennas embedded in the array is the same as those same antennas by themselves) does not generate reliable estimates of SEFD.
A charge-coupled infrared imaging array with Schottky-barrier detectors

An IR sensitive, charge-coupled linear imaging array using palladium-silicide Schottky-barrier detectors has been designed, fabricated, and tested. Thermal scenes as low in temperature as 110° C were imaged. It was shown theoretically that in the vidicon mode of operation, nonuniformities in the transfer process and in detector capacitance do not degrade the video signal. Good uniformity was indeed obtained in this mode. A scheme for removing the background signal from the detectors before loading into the charge-coupled device (CCD) was incorporated into the design of the chip, and operation in this mode was also demonstrated. This imager, though made with a single level of metallization with gaps, had reasonably good transfer efficiency and is free of smearing and blooming.
Microellipsometer with radial symmetry

We report on a novel microellipsometer that uses a spatially filtered high-numerical-aperture (NA) lens for large-angle ellipsometric illumination and high spatial resolution. A radially symmetric ellipsometric signal is achieved with two half-wave plates to produce a pure polarization rotation and a birefringent cube as a radial analyzer. This radial symmetry offers a better signal-to-noise ratio compared with other microellipsometer techniques. Ellipsometric measurement with a spatial resolution of 0.5 microm is performed with a He-Ne (632.8-nm) laser source and an objective lens with an NA of 0.8. Experimental data on SiO2 samples with different thicknesses are in good agreement with spectroscopic ellipsometer results. We acquired ellipsometric images of photoresist microstructure through scanning the sample. Surface profiles of the photoresist microstructure are derived from the ellipsometric data and compared with the results from a stylus profiler.
Uncertainty Analysis of the Standard Delay-and-Sum Beamformer and Array Calibration

Beamforming has become an ubiquitous task in aeroacoustic noise measurements for source localization and power estimation. The standard delay-and-sum (DAS) beamformer is the most commonly used beamforming algorithm due to its simplicity and robustness and also serves as the basis for more sophisticated algorithms, such as the deconvolution approach for the mapping of acoustic sources (DAMAS). The DAS data reduction equation is a function of many parameters including the microphone locations, microphone transfer functions, temperature and the cross spectral matrix (CSM), where each one of these parameters has a unique uncertainty associated with it. This paper provides a systematic uncertainty analysis of the DAS beamformer and Dougherty’s widely used calibration procedure under the assumption that the underlying mathematical model of incoherent, monopole sources is correct. An analytical multivariate method based on a flrst-order Taylor series expansion and a numerical Monte-Carlo method based on assumed uncertainty distributions for the input variables are considered. The uncertainty of calibration is analyzed using the Monte-Carlo method, whereas the uncertainty of the DAS beamformer is analyzed using both the complex multivariate and the Monte-Carlo methods. It is shown that the multivariate uncertainty analysis method fails when the perturbations are relatively large and/or the output distribution is non-Gaussian, and therefore the Monte-Carlo analysis should be used in the general case. The calibration procedure is shown to greatly reduce the uncertainties in the DAS power estimates. In particular, 95% confldence intervals for the DAS power estimates are presented with simulated data for various scenarios. Moreover, the 95% confldence intervals for the integrated DAS levels at difierent frequencies are computed using experimental data. It is shown that with experimental data, the 95% confldence intervals for the integrated power levels are within §1 dB of the mean levels when the component uncertainties are set at low but achievable values.
Quantum cascade laser-based free space optical communications

The advent of the quantum cascade laser (QCL) with emission wavelengths available in the infrared range from 3 µm through more than 100 µm opens up the possibility of exploiting infrared atmospheric transparency windows for free space optical communications. In an effort to establish the efficacy of using directly modulated QCLs for free space communications we have conducted a series of investigations that demonstrate the potential advantages of this technology. In these experiments we first establish that the QCL has very high modulation bandwidth. We then implement a practical free space communications link that under conditions of atmospheric fog, dust and other obscurants offers significant transparency advantage when compared with near infrared wavelength sources presently used in commercial free space optical communications links.
Deformations of Lifshitz holography

The simplest gravity duals for quantum critical theories with z = 2 ‘Lifshitz’ scale invariance admit a marginally relevant deformation. Generic black holes in the bulk describe the field theory with a dynamically generated momentum scale Λ as well as finite temperature T. We describe the thermodynamics of these black holes in the quantum critical regime where T ≫ Λ2. The deformation changes the asymptotics of the spacetime mildly and leads to intricate UV sensitivities of the theory which we control perturbatively in Λ2/T .
Gamma guidance of trajectories for coplanar, aeroassisted orbital transfer

The optimization and guidance of trajectories for coplaner, aeroassisted orbital transfer (AOT) from high Earth orbit (HEO) to low Earth orbit (LEO) are examined. In particular, HEO can be a geosynchronous Earth orbit (GEO). It is assumed that the initial and final orbits are circular, that the gravitational field is central and is governed by the inverse square law, and that at most three impulses are employed: one at HEO exit, one at atmospheric exit, and one at LEO entry. It is also assumed that, during the atmospheric pass, the trajectory is controlled via the lift coefficient. The presence of upper and lower bounds on the lift coefficient is considered. First, optimal trajectories are computed by minimizing the total velocity impulse (hence, the propellant consumption) required for AOT transfer. The sequential gradient-restoration algorithm (SGRA) is used for optimal control problems. The optimal trajectory is shown to include two branches: a relatively short descending flight branch (branch 1) and a long ascending flight branch (branch 2). Next, attention is focused on guidance trajectories capable of approximating the optimal trajectories in real time, while retaining the essential characteristics of simplicity, ease of implementation, and reliability. For the atmospheric pass, a feedback control scheme is employed and the lift coefficient is adjusted according to a two-stage gamma guidance law. Further improvements are possible via a modified gamma guidance which is more stable with respect to dispersion effects arising from navigation errors, variations of the atmospheric density, and uncertainties in the aerodynamic coefficients than gamma guidance trajectory. A byproduct of the studies on dispersion effects is the following design concept. For coplaner aeroassisted orbital transfer, the lift-range-to-weight ratio appears to play a more important role than the lift-to-drag ratio. This is because the lift-range-to-weight ratio controls mainly the minimum altitude (hence, the peak heating rate) of the guidance trajectory; on the other hand, the lift-to-drag ratio controls mainly the duration of the atmospheric pass of the guidance trajectory.
Topological Phase Effects

Quantum eigenstates undergoing cyclic changes acquire a phase factor of geometric origin. This phase, known as the Berry phase, or the geometric phase, has found applications in a wide range of disciplines throughout physics, including atomic and molecular physics, condensed matter physics, optics, and classical dynamics. In this article, the basic theory of the geometric phase is presented along with a number of representative applications. The article begins with an account of the geometric phase for cyclic adiabatic evolutions. An elementary derivation is given along with a worked example for two-state systems. The implications of time-reversal are explained, as is the fundamental connection between the geometric phase and energy level degeneracies. We also discuss methods of experimental observation. A brief account is given of geometric magnetism; this is a Lorenz-like force of geometric origin which appears in the dynamics of slow systems coupled to fast ones. A number of theoretical developments of the geometric phase are presented. These include an informal discussion of fibre bundles, and generalizations of the geometric phase to degenerate eigenstates (the nonabelian case) and to nonadiabatic evolution. There follows an account of applications. Manifestations in classical physics include the Hannay angle and kinematic geometric phases. Applications in optics concern polarization dynamics, including the theory and observation of Pancharatnam's phase. Applications in molecular physics include the molecular Aharonov-Bohm effect and nuclear magnetic resonance studies. In condensed matter physics, we discuss the role of the geometric phase in the theory of the quantum Hall effect.
Running into new territory in SUSY parameter space

The LEP-II bound on the light Higgs mass rules out the vast majority of parameter space left to the Minimal Supersymmetric Standard Model (MSSM) with weak-scale soft-masses. This suggests the importance of exploring extensions of the MSSM with non-minimal Higgs physics. In this article, we explore a theory with an additional singlet superfield and an extended gauge sector. The theory has a number of novel features compared to both the MSSM and Next-to-MSSM, including easily realizing a light CP-even Higgs mass consistent with LEP-II limits, tan β1, and a lightest Higgs which is charged. These features are achieved while remaining consistent with perturbative unification and without large stop-masses. Discovery modes at the Tevatron and LHC are discussed.
Substitute valuations: Generation and structure

Substitute valuations (in some contexts called gross substitute valuations) are prominent in combinatorial auction theory. An algorithm is given in this paper for generating a substitute valuation using a random number generator. In addition, the geometry of the set of all substitute valuations for a fixed number of goods K is investigated. The set consists of a union of polyhedrons, and the maximal polyhedrons are identified for K=4. It is shown that the maximum dimension of the polyhedrons increases with K nearly as fast as two to the power K. Consequently, under broad conditions, if a combinatorial algorithm can present an arbitrary substitute valuation given a list of input numbers, the list must grow nearly as fast as two to the power K.
Estimating a graphical intra-class correlation coefficient (GICC) using multivariate probit-linear mixed models

Data reproducibility is a critical issue in all scientific experiments. In this manuscript, the problem of quantifying the reproducibility of graphical measurements is considered. The image intra-class correlation coefficient (I2C2) is generalized and the graphical intra-class correlation coefficient (GICC) is proposed for such purpose. The concept for GICC is based on multivariate probit-linear mixed effect models. A Markov Chain Monte Carlo EM (mcmcEM) algorithm is used for estimating the GICC. Simulation results with varied settings are demonstrated and our method is applied to the KIRBY21 test-retest dataset.
CRYOGENIC COMPRESSIVE PROPERTIES OF BASIC EPOXY RESIN SYSTEMS

The compressive properties of short cylindrical samples of many different epoxy resin systems have been measured at ambient temperature and at 77 degrees Kelvin. These are pure resin systems of known chemistry, without the inorganic fillers or fibrous reinforcements needed in final cryogenic systems. Of course, chemically incorporated modifiers, such as flexibilizing resins, have been included. These data should make possible inferences about cryogenic properties from molecular structures and provide specific data useful to formulators and end users.
DETECTION RATES FOR CLOSE BINARIES VIA MICROLENSING

Microlensing is one of the most promising methods of reconstructing the stellar mass function down to masses even below the hydrogen-burning limit. The fundamental limit to this technique is the presence of unresolved binaries, which can, in principle, significantly alter the inferred mass function. Here we quantify the fraction of binaries that can be detected using microlensing, considering specifically the mass ratio and separation of the binary. We find that almost all binary systems with separations greater than b ~ 0.4 of their combined Einstein ring radius are detectable assuming a detection threshold of 3%. For two M dwarfs, this corresponds to a limiting separation of 1 AU. Since very few observed M dwarfs have companions at separations 1 AU, we conclude that close binaries will probably not corrupt the measurements of the mass function. We find that the detectability depends only weakly on the mass ratio. For those events for which individual masses can be determined, we find that binaries can be detected down to b ~ 0.2.
Heparin and heparan sulfate: structure and function

Covering: up to August 2001This review covers the structure and function of heparin and heparan sulfate glycosaminoglycans. Their chemical structures are discussed, including recently developed methods for sequencing picomole to nanomole quantities of heparin- and heparan sulfate-derived oligosaccharides. The biosynthesis of heparin and heparan sulfate is reviewed as it relates to their diverse and varied structures, and their biological activities and functions are discussed. The literature up to August 2001 is reviewed, and 208 references are cited.
Left Behind By Design: Proficiency Counts and Test-Based Accountability

Abstract We show that within the Chicago Public Schools, both the introduction of NCLB in 2002 and the introduction of similar district-level reforms in 1996 generated noteworthy increases in reading and math scores among students in the middle of the achievement distribution but not among the least academically advantaged students. The stringency of proficiency requirements varied among the programs implemented for different grades in different years, and our results suggest that changes in proficiency requirements induce teachers to shift more attention to students who are near the current proficiency standard.
Synthesis of 5-methyl-6h-pyrido[4,3-b]carbazole-11-methanol

Abstract The structures of some of the intermediates in Saulnier-Gribble synthesis of ellipticine have been determined. One of the intermediates 8 has been converted to 5-methyl-6H-pyrido[4,3-b]carbazole-11-methanol, an alkaloid isolated from Strychnos dinklagei .
Hydrocortisone stability in human feces

Hydrocortisone stability in human feces was studied under various conditions to determine whether stability accounts for the variable effects of hydrocortisone enemas. Recovery from feces and assay specificity were assured using dual isotopes, TLC separation, and liquid scintillation counting. Hydrocortisone degraded slightly from 7 to 26% in 24 hr when incubated in fresh human feces at 37°. Less than 7% degradation occurred in feces stored at 10°, and negligible degradation occurred with hydrocortisone in water at 37°. Fecal bacteria may account for the observed degradation. Hydrocortisone stability in feces may contribute to local persistence and may account partly for its efficacy in ulcerative colitis treatment.
Objective molecular dynamics

We introduce a generalization of periodic molecular dynamics that we term objective molecular dynamics. It is a method of doing molecular dynamics for a restricted set of atoms, nonperiodically mapping the time-dependent displacements of this small set of atoms onto the full, typically infinite structure, such that the full structure satisfies exactly the full, unconstrained set of equations of molecular dynamics subject to certain group-invariant initial conditions. The method is applicable to a wide variety of interesting molecular structures including the tails, capsids and other parts of many viruses, carbon nanotubes, many of the common proteins, C60 and many other nanostructures now being synthesized, especially via the process of self-assembly. The method is illustrated by simulations of carbon nanotubes. r 2007 Elsevier Ltd. All rights reserved.
Diogenites as asteroidal cumulates; insights from spinel chemistry

The chemical composition of spinel was determined for a suite of 19 diogenites (orthopyroxenites) thought to be from asteroid 4 Vesta. Previous studies (Fowler et al. 1994, 1995) of orthopyroxene demonstrated that these diogenites are linked genetically, perhaps through fractional crystallization, in one or more crustal intrusions. The present study focuses on spinel to see if it also retains some chemical signatures of an igneous history. The chemical compositions across spinel grains reveal flat concentration profiles, indicating major subsolidus exchange with orthopyroxene. Nevertheless, significant chemical differences exist among the average spinel compositions from individual diogenites in the suite. A chemical continuum exists from high-Cr, low-Al spinel in diogenite LAP 91900 (Cr 203 60.7 wt%; Al203 6.1 wt%) to low-Cr, high-Al spinel in diogenite ALHA 77256 (Cr 203 44.7 wt%; Al203 21.8 wt%), which may represent one or more fractionation series. In these trends, Al and Ti behave as incompatible elements whose abundances increase with crystallization. These systematics differ from those in spinel in terrestrial or lunar basaltic systems because of the extremely Al-depleted nature of the diogenite parental melts. In terrestrial and lunar basalts, the increase in Al concentration in spinel is interrupted when plagioclase crystallizes. In diogenite parental melts, plagioclase does not come onto the liquidus until the very end of spinel crystallization.
Microcantilever-Based Force Tracking With Applications to High-Resolution Imaging and Nanomanipulation

This paper presents the development and implementation of a robust nonlinear control framework for piezoresistive nanomechanical-cantilever (NMC)-based force tracking with applications to high-resolution imaging and nanomanipulation. Among many nanoscale force sensing platforms, NMC is an attractive approach to measure and apply forces at this scale when compared with other previously reported configurations utilizing complicated MEMS devices or inconvenient-to-handle nanowires and nanotubes. More specifically, a piezoresistive layer is utilized here to measure nanoscale forces at the NMC's tip instead of bulky laser-based feedback that is commonly used in atomic force microscopy. Excluding the laser from the sensing loop offers a compact, inexpensive, and portable yet precise nanoscale force sensing platform. In order to track a predefined force trajectory at the NMC's tip, there is a need to model the piezoresistive NMC and design appropriate controller to move its base to provide the desired force. In previous publications of the authors, a new distributed-parameter modeling framework has been proposed to precisely predict the force acting on the microcantilever's tip. In contrast to this approach and in an effort to ease the follow-up controller development, the NMC-based force sensor is modeled here as a lumped-parameter system. However, replacing the NMC with a linear mass-spring-damper trio creates a variety of uncertainties and unmodeled dynamics that need to be addressed for a precise force sensor's readout. Moreover, the very slow response of NMC's piezoresistive layer to force variations at the NMC's tip makes the tracking problem even more challenging. For this, a modified robust controller, built around sliding mode control strategy and augmented with a perturbation estimation module, is proposed to overcome these roadblocks. Extensive numerical simulations and experimental results are presented to demonstrate the stability and performance characteristics of the designed controller. It is shown that utilizing the proposed controller instead of the commonly used proportional-integral-derivative controller can significantly enhance the controller's stability and performance characteristics and, ultimately, the imaging resolution and manipulation accuracy needed at this scale.
TURBULENCE DRIVEN BY OUTFLOW-BLOWN CAVITIES IN THE MOLECULAR CLOUD OF NGC 1333

Outflows from young stellar objects (YSOs) have been identified as a possible source of turbulence in molecular clouds. To investigate the relationship between outflows, cloud dynamics, and turbulence, we compare the kinematics of the molecular gas associated with NGC 1333, traced in 13CO (1-0), with the distribution of YSOs within. We find a velocity dispersion of ~1-1.6 km s-1 in 13CO that does not significantly vary across the cloud and is uncorrelated with the number of nearby young stellar outflows identified from optical and submillimeter observations. However, from velocity channel maps we identify about 20 depressions in the 13CO intensity of scales 0.1-0.2 pc and velocity widths 1-3 km s-1. The depressions exhibit limb-brightened rims in both individual velocity channel maps and position-velocity diagrams, suggesting that they are slowly expanding cavities. We interpret these depressions to be remnants of past YSO outflow activity: if these cavities are presently empty, they would fill in on timescales of ~106 yr. This can exceed the lifetime of a YSO outflow phase or the transit time of the central star through the cavity, explaining the absence of any clear correlation between the cavities and YSO outflows. We find that the momentum and energy deposition associated with the expansion of the cavities is sufficient to power the turbulence in the cloud. In this way we conclude that the cavities are an important intermediate step between the conversion of YSO outflow energy and momentum into cloud turbulent motions.
What is the Homogeneity of our Universe Telling Us

The universe we observe is homogeneous on super-horizon scales, leading to the "cosmic homogeneity problem". Inflation alleviates this problem but cannot solve it within the realm of conservative extrapolations of classical physics. A probabilistic solution of the problem is possible but is subject to interpretational difficulties. A genuine deterministic solution of the homogeneity problem requires radical departures from known physics.
Plant-Level Irreversible Investment and Equilibrium Business Cycles

This paper evaluates the importance of microeconomic irreversibilities for aggregate dynamics using a real-business-cycle (RBC) model characterized by investment irreversibilities at the establishment level. The main finding is that investment irreversibilities do not play a significant role in an otherwise standard realbusiness-cycle model: Even though investment irreversibilities are crucial for establishment-level dynamics, aggregate fluctuations are basically the same under fully flexible or completely irreversible investment. (JEL E22, E32)
Stripe and bubble phases in quantum Hall systems

We present a brief survey of the charge density wave phases of a two-dimensional electron liquid in moderate to weak magnetic fields where several higher Landau levels are occupied. The review follows the chronological development of this new and emerging field: from the ideas that led to the original theoretical prediction of the novel ground states, to their dramatic experimental discovery, to the currently pursued directions and open questions.
Production Efficiency in Ukrainian Agriculture and the Process of Economic Reform

A representative sample of 49 state and collective farms in Ukraine provides data in physical units on livestock and crop production and input use for 1989-92. The changes in production efficiency for beef, pork, dairy, winter wheat, grain, and potato production, investigated using stochastic frontier methods, show declining technical efficiency in livestock production and especially low marginal contribution of labor inputs. The number of workers, size of farm, and distance from nearest city are related to efficiency in agricultural production.
A training-based no-reference image quality assessment algorithm

We present a new image quality assessment algorithm that does not rely on reference images. Our general framework is to emulate human quality assessment by first detecting visual components, then assessing quality against an empirical model. We describe an instance of this framework where visual component detection is realized as a face detection method, and quality modeling is realized using radial basis function (RBF) networks. Experiments with this prototype system yielded promising results.
Cloak or Flaunt? The Fashion Dilemma

There exists a dichotomy in the communication strategies of fashion firms---some firms purposefully cloak information on the tastefulness of their products, whereas others openly flaunt their tasteful or “it” products. This divide in communication strategies cannot be explained by existing wealth signaling models of fashion. In this paper, we offer a model of fashion that explains the above dichotomy. We model fashion as a social device that plays the dual role of allowing people to both fit in with their peers and differentiate themselves by signaling their good taste or access to information. In this context, we show that a fashion firm faces an interesting dilemma---if it restricts information, then only sophisticated consumers buy its products and use them to signal their taste. Cloaking thus preserves the signaling value of its products but reduces the number of social interactions enabled by them. In contrast, flaunting undermines the signaling value of its products but increases the interactions enabled by them. Given these trade-offs, we derive the conditions under which cloaking occurs. We also show that, in equilibrium, the most tasteful product endogenously emerges as the fashion hit or “it” product.
Firm performance, corporate governance, and top executive turnover in Japan

Abstract We examine the role of corporate governance mechanisms during top executive turnover in Japanese corporations. Consistent with evidence from U.S. data, the likelihood of nonroutine turnover is significantly related to industry-adjusted return on assets, excess stock returns, and negative operating income, but is not related to industry performance. The sensitivity of nonroutine turnover to earnings performance is higher for firms with ties to a main bank than for firms without such ties. Outside succession in Japan is more likely for firms with large shareholders and a main bank relationship. We document performance improvements subsequent to nonroutine turnover and outside succession.