cssi/SciSciGPT-SciSciNet huggingface dataset:
Maneuver Reconstruction Techniques for Open-Loop Spin-Stabilized Spacecraft

The Pioneer missions were supported by spin-stabilized spacecraft designs using open-loop control and blow-down propulsion subsystems. Reliable estimates of the ever-changing performance inherent to these subsystems were needed to effectively design and reconstruct trajectory correction maneuver (TCM) strategies. These performance updates were obtained by adjusting model parameters to match independent telemetric and radiometric observations to define the simultaneous changes in attitude, velocity, and spin rate during a maneuver sequence.
Application of a p-version finite element code to analysis of cracks

A commercially available finite element analysis computer package, i.e., the MECHANICA®-APPLIED STRUCTURE code of the RASNA Corporation, has been used to generate stress intensity solutions for structural damage tolerance analysis applications. A building block approach has been implemented in developing a data reduction technique for using the finite element code. Through two sets of numerical examples, it is demonstrated that stress intensity solutions for the center crack panels (two-dimensional), and the almond shaped crack (three-dimensional), matched very well with known solutions available in the literature
Petaflop/s, seriously

Sustained floating-point rates on real applications, as tracked by the Gordon Bell Prize, have increased by over five orders of magnitude from 1988, when 1 Gigaflop/s was reported on a structural simulation, to 2006, when 200 Teraflop/s were reported on a molecular dynamics simulation. Various versions of Moore's Law over the same interval provide only two to three orders of magnitude of improvement for an individual processor; the remaining factor comes from concurrency, which is of order 100,000 for the BlueGene/L computer, the platform of choice for the majority of recent Bell Prize finalists. As the semiconductor industry begins to slip relative to its own roadmap for silicon-based logic and memory, concurrency will play an increasing role in attaining the next order of magnitude, to arrive at the long-awaited milepost of 1 Petaflop/s sustained on a practical application, which should occur around 2009. Simulations based on Eulerian formulations of partial differential equations can be among the first applications to take advantage of petascale capabilities, but not the way most are presently being pursued. Only weak scaling can get around the fundamental limitation expressed in Amdahl's Law and only optimal implicit formulations can get around another limitation on scaling that is an immediate consequence of Courant-Friedrichs-Lewy stability theory under weak scaling of a PDE. Many PDE-based applications and other lattice-based applications with petascale roadmaps, such as quantum chromodynamics, will likely be forced to adopt optimal implicit solvers. However, even this narrow path to petascale simulation is made treacherous by the imperative of dynamic adaptivity, which drives us to consider algorithms and queuing policies that are less synchronous than those in common use today. Drawing on the SCaLeS report (2003-2004), the latest ITRS roadmap, some back-of-the-envelope estimates, and numerical experiences with PDE-based codes on recently available platforms, we will attempt to project the pathway to Petaflop/s for representative applications.
Soft related lending: A tale of two Korean banks

Abstract In this paper, we present indirect evidence that the IMFs insistence on foreign control of two large nationwide Korean banks in exchange for short-term support during the 1997 financial crisis helped restrain soft related lending practices. News signaling the likely sale of a bank to a foreign financial institution yields an average daily decrease of about 2% in the stock price of related borrowers. News indicating difficulty in finding an interested foreign investor generates an increase in the stock price of related borrowers of about the same magnitude. These signals have larger impacts on less-profitable, less-liquid, and more bank-dependent firms.
Random choice methods with applications to reacting gas flow

Abstract The random choice method is analyzed, appropriate boundary conditions are described, and applications to time-dependent reacting gas flow in one dimension are carried out. These applications illustrate the advantages of the method when one is solving problems where the diffusion constant vanishes or is very small, and where artificial or numerically induced diffusion cannot be tolerated.
Permanent Magnets in Audio Devices

The permanent magnet is considered as a component for changing the form of energy, and a brief review of the basic physics of the permanent magnet is included with emphasis on the nature of the magnetization process and how the permanent magnet functions in establishing external magnetic field energy. Presently availabIe characteristics of permanent magnets and future possibilities for improving the efficiency of the permanent magnet are discussed as well as the relationships between audio device performance and the unit properties of permanent magnets. In using the permanent magnet, the choice of unit properties, volume, geometry, and magnetic circuit arrangement greatly influence the end performance and efficiency of audio devices. As an aid in exploiting the optimum combination of these variables an electrical analog system using lumped constants is introduced. Data on leakage permeance are presented for the more widely used permanent magnet arrangements in audio work. The analog technique is of general interest from the viewpoint of understanding the energy relationships involved in the efficient application of the permanent magnet and as an aid in predicting permanent magnet performance on a firm engineering basis.
Asymmetric binary covering codes

An asymmetric binary covering code of length n and radius R is a subset C of the n-cube Qn such that every vector x ∈ Qn can be obtained from some vector c ∈ c by changing at most R 1's of c to 0's, where R is as small as possible. K+ (n, R) is defined as the smallest size of such a code. We show K+(n, R) ∈ Θ (2n/nR) for constant R, using an asymmetric sphere-covering bound and probabilistic methods. We show K+(n,n -R) = R+ 1 for constant coradius R iff n ≥ R(R + 1)/2. These two results are extendetd to near-constant R and R, respectively. Various bounds on K+ are given in terms of the total number of 0's or 1's in a minimal code. The dimension of a minimal asymmetric linear binary code ([n, R]+-code) is determined to be min{0, n - R}. We conclude by discussing open problems and techniques to compute explicit values for K+, giving a table of best-known bounds.
Catalytic enantioselective diboration, disilation and silaboration: new opportunities for asymmetric synthesis

This article summarizes recent developments in the area of catalytic enantioselective reactions of unsaturated organic substrates with diboron, silylboron, and disilane reagents. These reactions provide new routes to the functionalization of prochiral substrates and therefore offer new strategies in asymmetric organic synthesis.
In-reactor precipitation and ferritic transformation in neutron-irradiated stainless steels

Abstract Ferritic transformation (γ → α) was observed in type 304L, 20% cold-worked AISI 316, and solution-annealed AISI 316 stainless steels when subjected to fast neutron irradiation. Each material demonstrated an increasing propensity for transformation with increasing irradiation temperature between 400 and 550° C. Irradiation-induced segregation of Ni solute to precipitates was found not to be a controlling factor in the transformation kinetics in 304L. Similar compositiondata from 316 materials demonstrates a much greater temperature dependence of matrix Ni depletion by precipitation reactions during neutron irradiation. The 316 data establishes a strong link between such depletion and the observed γ → α transformation. Moreover, the lack of correlation between precipitate-related Ni depletion and the γ → α transformation in 304L can be related to the fact that irradiation-induced voids nucleate very quickly in 304L steel during irradiation. These voids present competing sites for Ni segregation through a defect drag mechanism, and hence Ni segregates to voids rather than to precipitates, as evidenced by observed stable γ shells around voids in areas of complete transformation.
Multiple Bonding Involving Phosphorus; Some Recent Developments

Abstract The first boraphosphene, (tmp)B=P(Ar) (tmp = 2,2,6,6-tetramethylpiperidino; Ar = 2,4,6-t-Bu3C6H2) has been prepared by thermolysis of the corresponding dimer, [(tmp)BP(Ar)]2 at 250°C. Mass spectral data are reported for (tmp)B=P(Ar) and ab initio MO calculations have been performed on the parent boraphosphene, HB=PH. The nature of the phosphorus-phosphorus bond in ArP=PAr has been investigated by solid state 31P NMR. The reactivity of the phosphavinylidene, [Mo(CO)2(n1−P=C(SiMe3)2(n-C5H5)] has been explored. The reaction of ArPCl2 with Na2[(n-C5H5)-V(CO)3] affords [V2(CO)4(n-C5H5)2{μ-PAr}], the first example of a group 5 phosphinidene complex.
Nathanson heights in finite vector spaces

Abstract Let p be a prime, and let Z p denote the field of integers modulo p. The Nathanson height of a point v ∈ Z p n is the sum of the least nonnegative integer representatives of its coordinates. The Nathanson height of a subspace V ⊆ Z p n is the least Nathanson height of any of its nonzero points. In this paper, we resolve a quantitative conjecture of Nathanson [M.B. Nathanson, Heights on the finite projective line, Int. J. Number Theory, in press], showing that on subspaces of Z p n of codimension one, the Nathanson height function can only take values about p , p / 2 , p / 3 , … . We show this by proving a similar result for the coheight on subsets of Z p , where the coheight of A ⊆ Z p is the minimum number of times A must be added to itself so that the sum contains 0. We conjecture that the Nathanson height function has a similar constraint on its range regardless of the codimension, and produce some evidence that supports this conjecture.
The geodesic X-ray transform with fold caustics

We give a detailed microlocal study of X-ray transforms over geodesics-like families of curves with conjugate points of fold type. We show that the normal operator is the sum of a pseudodifferential operator and a Fourier integral operator. We compute the principal symbol of both operators and the canonical relation associated to the Fourier integral operator. In two dimensions, for the geodesic transform, we show that there is always a cancellation of singularities to some order, and we give an example where that order is infinite; therefore the normal operator is not microlocally invertible in that case. In the case of three dimensions or higher if the canonical relation is a local canonical graph we show microlocal invertibility of the normal operator. Several examples are also studied.
Structure, Function and Folding of Phosphoglycerate Kinase are Strongly Perturbed by Macromolecular Crowding

We combine experiment and computer simulation to show how macromolecular crowding dramatically affects the structure, function and folding landscape of phosphoglycerate kinase (PGK). Fluorescence labeling shows that compact states of yeast PGK are populated as the amount of crowding agents (Ficoll 70) increases. Coarse-grained molecular simulations reveal three compact ensembles: C (crystal structure), CC (collapsed crystal) and Sph (spherical compact). With an adjustment for viscosity, crowded wild type PGK and fluorescent PGK are about 15 times or more active in 200 mg/ml Ficoll than in aqueous solution. Our results suggest a new solution to the classic problem of how the ADP and diphosphoglycerate binding sites of PGK come together to make ATP: rather than undergoing a hinge motion, the ADP and substrate sites are already located in proximity under crowded conditions that mimic the in vivo conditions under which the enzyme actually operates. We also examine T-jump unfolding of PGK as a function of crowding experimentally. We uncover a non-monotonic folding relaxation time vs. Ficoll concentration. Theory and modeling explain why an optimum concentration exists for fastest folding. Below the optimum, folding slows down because the unfolded state is stabilized relative to the transition state. Above the optimum, folding slows down because of increased viscosity.
Porphyrin building blocks for modular construction of bioorganic model systems

Abstract We outline a modular building block strategy for the covalent assembly of porphyrin-containing model systems. Molecular design issues for the synthesis of porphyrin dimers, dye-porphyrin dyads, and multi-porphyrin arrays have been used to guide the development of this approach. The major design constraints are to achieve directed coupling of free base and/or metalloporphyrin building blocks in dilute solution under non-acidic non-metalating conditions. A set of 24 porphyrin building blocks has been synthesized. The porphyrins are prepared by reaction of substituted benzaldehydes with pyrrole using the two-step one-flask room temperature porphyrin synthesis. Routes to 7 substituted aldehydes are described. Each porphyrin bears one or four functional groups, and many also are facially-encumbered in order to achieve increased solubility. 12 functional groups that meet the design criteria include those that can be reacted directly in coupling reactions such as active esters, α-chloroacetamido, benzoyl, and iodo groups, and others that require deprotection prior to coupling, such as phthalimidomethyl, FMOC-prolyl, trimethylsilylethynyl, dithiolane, methoxycarbonyl, and trimethylsilylethoxycarbonyl groups. The synthesis of 13 porphyrin dimers and dye-porphyrin dyads has been explored as a testbed for refining strategies for the synthesis of molecular devices containing multiple porphyrins and other components. The coupling strategies investigated have yielded dimers or dyads with subunits linked by amide, butadiyne, ethyne, or thiourea groups. This building block approach should enable rapid assembly of architecturally-defined porphyrin-based model systems.
Application of nonlinear adaptive control techniques to an electrohydraulic velocity servomechanism

Adaptive and nonadaptive versions of the feedback linearization control technique are used here for the control of a nonlinear electrohydraulic velocity Servomechanism, the nonlinear behavior arising from load friction as well as the valve flow-pressure drop relationship. An adaptive fuzzy controller is used here for the same application as well. The three controllers are compared based on simulation and experimental results of tracking performance as well as their ability to adjust to disturbances caused by variation in the system parameters.
CYCLIC COSET ORBIFOLDS

We apply the new orbifold duality transformations to discuss the special case of cyclic coset orbifolds in further detail. We focus in particular on the case of the interacting cyclic coset orbifolds, whose untwisted sectors are ℤλ(permutation)-invariant g/h coset constructions which are not λ copies of coset constructions. Because λ copies are not involved, the action of ℤλ(permutation) in the interacting cyclic coset orbifolds can be quite intricate. The stress tensors and ground state conformal weights of all the sectors of a large class of these orbifolds are given explicitly and special emphasis is placed on the twisted h subalgebras which are generated by the twisted (0, 0) operators of these orbifolds. We also discuss the systematics of twisted (0, 0) operators in general coset orbifolds.
Laser optoacoustic detection of explosive vapors

The direct detection of nitroglycerine, ethylene glycol dinitrate, and dinitrotoluene by optoacoustic spectroscopy techniques at 6 μm, 9 μm, and 11 μm is reported. The effect of interference by normal atmospheric pollutants is investigated, and it is found that of those wavelengths used in this investigation the 9-μm and 11-μm spectral regions, using a CO2 laser as radiation source, are the most promising for use in explosive detection.
Straightforward protocol for the efficient synthesis of varied N1-acylated (aza)indole 2-/3-alkanoic acids and esters: optimization and scale-up

A library of approximately 40 N1-acylated (aza)indole alkanoic esters and acids was prepared employing a microwave-assisted approach. The optimized synthetic route allows for parallel synthesis, variation of the indole substitution pattern and high overall yield. Additionally, the procedure has been scaled up to yield multi-gram amounts of preferred indole compounds, e.g.: 2′-des-methyl indomethacin 2. The reported compounds were designed as biomedical tools for primary and secondary in vitro and in vivo studies at relevant molecular targets.
EUV coronal pattern of complexes of solar activity

Abstract Studying of the coronal plasma associated with long-lived complexes of the solar activity is important for understanding a relationship between the magnetic activity and the solar corona changing during the solar cycle. In the present paper, two long-lived complexes of the solar activity at the beginning of the current solar cycle 23 are investigated by using the Extreme-Ultraviolet data (EUV) from SOHO/EIT. For this purpose the EIT limb synoptic maps during the CR1916–CR1919 (11 November 1996–1 March 1997) are obtained. The coronal temperature structures derived from the three lines 171A (Fe IX,X), 195A (Fe XII)and 284A (Fe XV) are investigated by applying an algorithm developed by Zhang et al. [Zhang, J., White, S.M., Kundu, M.R. ApJ 527, 977, 1999]. Standard EIT software are used for the temperature estimation from the ratio of two lines of Fe IX,X and Fe XII. The method of the rotational tomography with a correction for an inclination of the Earth’s orbit (B-angle) to the helioequator is applied to obtain the three-dimensional (3-D) coronal structure of the complex of the solar activity. The results reveal difference in temperature structures related to multi-poles magnetic structures of the complex of solar activity and to the typical, the bipolar activity complex.
Buy-Side vs. Sell-Side Analysts’ Earnings Forecasts

The study reported here is a comparison of the earnings-forecasting performance of analysts at a large buy-side firm with the performance of sell-side analysts in the 1997–2004 period. The tests show that the buy-side analysts made more optimistic and less accurate forecasts than their counterparts on the sell side. The performance differences appear to be partially explained by the buy-side firm’s greater retention of poorly performing analysts and by differences in the performance benchmarks used to evaluate buy-side and sell-side analysts.
Alfred Chandler and "capabilities" theories of strategy and management

Alfred D. Chandler's scholarship on the large industrial enterprise has deepened understanding of economic development, and helped establish the field of strategic management research. Chandler's monumental work emphasized the importance of organizational innovation, managerial acumen and business performance. A particular contribution was the support provided for a "capabilities" theory of the business enterprise. This article also looks at recent developments in industrial organization that are less well explained and appreciated in the Chandler framework. Copyright 2010 The Author 2010. Published by Oxford University Press on behalf of Associazione ICC. All rights reserved., Oxford University Press.
Testing and validation of a low-cost cystoscopy teaching model: a randomized controlled trial.

OBJECTIVE:To estimate whether the use of a low-cost cystoscopy model effectively trains residents in cystourethroscopy and to validate the model as a teaching tool.METHODS:A randomized, controlled, and evaluator-blinded study was performed. Twenty-nine obstetrician–gynecologist residents had access
Lewis acid-mediated cyclizations of (2′-amino-N′-tert-butoxycarbonyl-benzylidene)-3-alkenylamines

Abstract Depending on the method of activation, (2′-amino- N ′- tert -butoxycarbonyl-benzylidene)-3-alkenylamines ( 1 ) react with Lewis acids (TiCl 4 or TMSOTf) to afford either a novel Boc-assisted iminium ion formation/trapping sequence (giving hexahydropyrido[1,2-c]quinazolin-6-ones ( 2 ) or tetrahydropyrrolo[1,2-c]quinazolin-5-ones ( 4 )) or a pseudodimerization process (leading to iminodibenzo[b,f]diazocines ( 3 )).
Private provision of a discrete public good: efficient equilibria in the private-information contribution game

We study the voluntary provision of a discrete public good via the contribution game. Players independently and simultaneously make nonrefundable contributions to fund a discrete public good, which is provided if and only if contributions cover the cost of production. We characterize nonconstant continuous symmetric equilibria, giving sufficient conditions for their existence. We show the common normalization by which players’ values are distributed over [0, 1] is not without loss of generality: if the distribution over this interval has continuous density f with f(0) > 0, then no (nonconstant) continuous symmetric equilibrium exists. We study in detail the case in which players’ private values are uniformly distributed, showing that, generically, when one continuous equilibrium exists, a continuum of continuous equilibria exists. For any given cost of the good, multiple continuous equilibria cannot be Pareto ranked. Nevertheless, not all continuous equilibria are interim incentive efficient. The set of interim incentive efficient equilibria is exactly determined.
Preparation and X-ray crystal structure analysis of a stable trimethylsilyloxy epoxide

Abstract Reaction of trimethylsilyl enol ether6 with buffered m -chloroperbenzoic acid at 20°C leads efficiently to7, the first shelf-stable silyloxy epoxide. The structural dimensions of7 have been ascertained by means of X-ray crystallography.
Global/local stress analysis of composite panels

A method for performing a global/local stress analysis is described and its capabilities are demonstrated. The method employs spline interpolation functions which satisfy the linear plate bending equation to determine displacements and rotations from a global model which are used as 'boundary conditions' for the local model. Then, the local model is analyzed independently of the global model of the structure. This approach can be used to determine local, detailed stress states for specific structural regions using independent, refined local models which exploit information from less-refined global models. The method presented is not restricted to having a priori knowledge of the location of the regions requiring local detailed stress analysis. This approach also reduces the computational effort necessary to obtain the detailed stress state. Criteria for applying the method are developed. The effectiveness of the method is demonstrated using a classical stress concentration problem and a graphite-epoxy blade-stiffened panel with a discontinuous stiffener.
Young volcanic deposits in the Valles Marineris, Mars?

The emplacement of a sequence of deposits covering the chasma floors of the central Valles Marineris of Mars, ranging from thin dust to several km in thickness, appears to have been the last major formational event. These deposits fall into the categories of (1) dark patches lying along faults, (2) light-colored deposits locally associated with craters, and (3) mottled, rugged deposits. It is presently suggested that these materials may be of volcanic origin, in view of their low albedo, their association with faults and possible volcanic features, and their embayment relations and lobate margins. If the suggestion is true, then the occasionally explosive volcanism in question was associated with rifting in the Valles Marineris, and may be as young as the late Tharsis volcanism.
Algebras associated to acyclic directed graphs

We construct and study a class of algebras associated to generalized layered graphs, i.e. directed graphs with a ranking function on their vertices and edges. Each finite acyclic directed graph admits countably many structures of a generalized layered graph. We construct linear bases in such algebras and compute their Hilbert series. Our interest to generalized layered graphs and algebras associated to those graphs is motivated by their relations to factorizations of polynomials over noncommutative rings.
Flight dynamics of rotorcraft in steep high-g turns

An analyticl procedure developed to permit a systematic examination of rotorcraft flight dynamics in steep high-g turns is presented. The procedure is used in a numerical investigation of a tilt-rotor aircraft and three single-rotor helicopters that have different types of main rotor systems. The results indicate (1) that strong coupling in longitudinal and lateral-directional motions exists for these rotorcraft in high-g turns; (2) that for single-rotor helicopters, the direction of turn has a significant influence on flight dynamics; and (3) that a stability and control augmentation system that is designed on the basis of standard small-disturbance equations of motion from steady straight and level flight and that otherwise performs satisfactorily in operations near 1 g, becomes significantly degraded in steep turning flight.
Juhl's formulae for GJMS operators and Q-curvatures

Direct proofs are given of Juhl's formulae for GJMS operators and Q-curvatures starting from the original construction of GJMS.
Stability of Functional Rational Expectations Equilibria

Abstract In this paper we examine a representative agent forecasting prices in a first-order self-referential overlapping generations model. We first consider intermediate stage learning, where agents update the forecasting rule every m periods. We show that, in theory and simulations, the learning rule does not converge to the rational expectations equilibrium (REE). We next consider two stage learning, where agents learn the functional mapping between the current forecast function and the previous forecast function. We show that in theory and simulations the two stage learning rule converges to the REE. Journal of Economic Literature Classifications Numbers: C62, C63, D83.
Small volumes in compactified string theory

Abstract We discuss some of the classical and quantum geometry associated to the degeneration of cycles within a Calabi-Yau compactification. In particular, we focus on the definition and properties of quantum volume, especially as it applies to identifying the physics associated to loci in moduli space where non-perturbative effects become manifest. We discuss some unusual features of quantum volume relative to its classical counterpart.
Galaxy density profiles and shapes – II. Selection biases in strong lensing surveys

Many current and future astronomical surveys will rely on samples of strong gravitational lens systems to draw conclusions about galaxy mass distributions. We use a new strong lensing pipeline (presented in Paper I of this series) to explore selection biases that may cause the population of strong lensing systems to differ from the general galaxy population. Our focus is on point-source lensing by early-type galaxies with two mass components (stellar and dark matter) that have a variety of density profiles and shapes motivated by observational and theoretical studies of galaxy properties. We seek not only to quantify but also to understand the physics behind selection biases related to: galaxy mass, orientation and shape; dark matter profile parameters such as inner slope and concentration; and adiabatic contraction. We study how all of these properties affect the lensing Einstein radius, total cross-section, quad/double ratio and image separation distribution, with a flexible treatment of magnification bias to mimic different survey strategies. We present our results for two families of density profiles: cusped and deprojected Sersic models. While we use fixed lens and source redshifts for most of the analysis, we show that the results are applicable to other redshift combinations, and we also explore the physics of how our results change for very different redshifts. We find significant (factors of several) selection biases with mass; orientation, for a given galaxy shape at fixed mass; cusped dark matter profile inner slope and concentration; concentration of the stellar and dark matter deprojected Sersic models. Interestingly, the intrinsic shape of a galaxy does not strongly influence its lensing cross-section when we average over viewing angles. Our results are an important first step towards understanding how strong lens systems relate to the general galaxy population.
Rural Wages and Returns to Education: Differences Between Whites, Blacks, and American Indians

Abstract This paper examines racial and gender wage differences for rural workers. Its contribution is twofold, with a broadening of the existing research regarding rural workers, and its new evidence of the structure of wages faced by American Indians. The results show that with the rural focus, American Indian males and Black females experience the weakest wage returns to education within their respective genders. However, merely examining employment and wage rates, American Indians and Blacks of both genders face an economic disadvantage relative to Whites. Examining wage gaps, gender differences are more striking. Females face smaller actual majority/minority wage gaps, but more of the gap remains unexplained by personal and job characteristics. In other words, male wage gaps are driven more by differences in characteristics, while female wage gaps are driven more by difference in returns. This implies that discrimination is more prevalent in the rural female labor market, although its actual effect on wages is smaller.
Palladium- and copper-catalyzed 1,4-additions of organozinc compounds to conjugated aldehydes.

Conjugated aldehydes undergo smooth Pd(OAc)2·PPh3- or Me2CuCNLi2-catalyzed 1,4-addition of dialkylzinc reagents.
Method for quantitative validation of image-based correction for intraoperative brain shift

Stereotactic neuronavigational systems use pre-operatively acquired 3D images for procedural planning and also are employed in intraoperative navigations to help localize and resect brain lesions. Intraoperatively, multiple factors contribute to anatomic changes that limit the accuracy of navigation based solely on pre-operative images. Loss of CSF, cortical swelling, and the effect of gravity relative to the craniotomy location are some of the factors that contribute to errors in navigation. Neuronavigational systems assume a one to one correlation between intraoperative patient anatomy, and pre-operatively acquired MRI images. Since the brain deforms in a non-linear manner, intraoperative brain shift must be corrected via intraoperative sensing methods that effectively update the pre-operatively acquired image data. Our method to correct for intra-operative brain shift utilizes ultrasound imaging to update the patient specific pre-operative MRI scans, combined with a physics based dynamic model. To quantitatively validate the imaging and modeling process, a phantom was designed that realistically simulates brain shifting patterns that occur during a brain operation. MRI and US datasets were acquired for several permutations of phantom parameters. Deformation algorithms applied to the phantom data demonstrate the efficacy of this approach to effectively update pre-operatively acquired MRI data during an operation, thus improving the accuracy of navigation.
PDFgetX3: a rapid and highly automatable program for processing powder diffraction data into total scattering pair distribution functions

PDFgetX3 is a new software application for converting X-ray powder diffraction data to an atomic pair distribution function (PDF). PDFgetX3 has been designed for ease of use, speed and automated operation. The software can readily process hundreds of X-ray patterns within a few seconds and is thus useful for high-throughput PDF studies that measure numerous data sets as a function of time, temperature or other environmental parameters. In comparison to the preceding programs, PDFgetX3 requires fewer inputs and less user experience and it can be readily adopted by novice users. The live-plotting interactive feature allows the user to assess the effects of calculation parameters and select their optimum values. PDFgetX3 uses an ad hoc data correction method, where the slowly changing structure-independent signal is filtered out to obtain coherent X-ray intensities that contain structure informa­tion. The output from PDFgetX3 has been verified by processing experimental PDFs from inorganic, organic and nanosized samples and comparing them with their counterparts from a previous established software. In spite of the different algorithm, the obtained PDFs were nearly identical and yielded highly similar results when used in structure refinement. PDFgetX3 is written in the Python language and features a well documented reusable code base. The software can be used either as a standalone application or as a library of PDF processing functions that can be called from other Python scripts. The software is free for open academic research but requires paid license for commercial use.
Reduction of the indole ring system: synthesis of 4,5,6,7-tetrahydroindoles

Abstract A general two-step procedure for the reduction of indoles to the corresponding 4,5,6,7-tetrahydroindoles has been developed. A regioselective Birch reduction followed by catalytic hydrogenation is employed to accomplish this transformation. Yields for the sensitive pyrrole products are typically between 40 and 50%. This method provides access to complex chiral pyrroles that cannot be readily prepared by other methods.
A self-checking system for high-speed transmission of magnetic-tape digital data

Several years ago it became evident that high-speed communications facilities were required as part of many future data-processing systems. The need had appeared in the planning phases of several systems and certainly, as the speeds of computer operation increased, it would be desirable to centralize computing systems to take maximum advantage of them. Situations indicating its need are:1) Real time surveillance and control systems of military significance.2) Faster computers which are able to do the total data processing for a large business so the data from the many sources must be brought to the computer site.3) The necessity for prompt sending of data to a central location to permit over-all control, even if the development of small internally programmed computers permits many geographically separated computer installations.4) There is a gross difference between the new and the old data-processing speeds.
Using Dual Beta Distributions to Create "Proper" ROC Curves Based on Rating Category Data.

Background: Receiver operating characteristic (ROC) analysis helps investigators quantify and describe how well a diagnostic system discriminates between 2 mutually exclusive conditions. The conventional binormal (CvB) curve-fitting model usually produces ROCs that are improper in that they do not have the ever-decreasing slope required by signal detection theory. When data sets evaluated under the CvB model have hooks, the resulting ROCs can contain misleading information about the diagnostic performance of the method at low and high false positive rates. Objective: To present and evaluate a dual beta (DB) ROC model that assumes diagnostic data arise from 2 β distributions. The DB model’s parameter constraints assure that the resulting ROC curve has a positive, monotonically decreasing slope. Design/Method: Computer simulation study comparing results from CvB, DB, and weighted power function (WPF) models. Results: The DB model produces results that are as good as or better than those from the WPF model, ...
The Effect of Wire Rope Mechanics on the Mechanical Response of Cord Composite Laminates: An Energy Approach

The behavior of one-ply and two-ply laminated cord-rubber composite plates in uniaxial tension is presented. The plate mechanical properties are presented as functions of cord angle for various cord modulus to matrix modulus ratios. The model developed takes account of the extension-twisting coupling of the cord, as well as the exact location of the cord within the composite plate
Did the 2008 rebate fail? a response to Taylor and Feldstein

Did the 2008 rebate fail to stimulate consumer spending? In their influential American Economic Review articles, John Taylor and Martin Feldstein each claim that Bureau of Economic Analysis (BEA) aggregate time series data show that the 2008 rebate failed. Reexamining the BEA data, we find that the data instead show there is a high probability that the rebate stimulated consumption. Moreover, the hypothesis that a rebate has half the impact of ordinary disposable income cannot be rejected. Thus, we find that analysis of the BEA aggregate time series data is consistent with the conclusion from the microdata studies that the 2008 rebate stimulated consumer spending.
A Micromodeling Approach to Investigate the Advertising-Sales Relationship

The purpose of this paper is to derive a model of advertising effects on the firm's sales. A micromodel is postulated and aggregated across individuals and over time to produce a macromodel of the aggregate sales-advertising relationship for a single product. The micromodel postulated is very simple. It incorporates two factors: reach of the ads and rate of decay of their effectiveness over time. This approach to modeling advertising effects is shown to be fruitful in several respects: 1 the coefficients of the aggregate equation are easily interpretable-in terms of the reach and decay parameters; 2 the model derived is nonlinear yet estimable; 3 a special case of the model is very similar to lag models that have been in use; 4 the model can be used whatever the unit of time is; 5 the carryover effect of advertising as commonly defined is not constant, but depends upon the previous spending levels; and 6 the model helps illustrate that the duration of advertising may be greatly overstated if aggregate lagged dependent variable models are simplistically interpreted.
5-BENZYLOXYRESORCINOL, A MONOPROTECTED PHLOROGLUCINOL

(1997). 5-BENZYLOXYRESORCINOL, A MONOPROTECTED PHLOROGLUCINOL. Organic Preparations and Procedures International: Vol. 29, No. 2, pp. 240-242.
Overview of theory and simulations in the Heavy Ion Fusion Science Virtual National Laboratory

The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) is a collaboration of Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and Princeton Plasma Physics Laboratory. These laboratories, in cooperation with researchers at other institutions, are carrying out a coordinated effort to apply intense ion beams as drivers for studies of the physics of matter at extreme conditions, and ultimately for inertial fusion energy. Progress on this endeavor depends upon coordinated application of experiments, theory, and simulations. This paper describes the state of the art, with an emphasis on the coordination of modeling and experiment; developments in the simulation tools, and in the methods that underly them, are also treated.
E-state modeling of HIV-1 protease inhibitor binding independent of 3D information.

Data for HIV-1 protease inhibitors (in vitro enzyme binding) were used as a training set to develop a QSAR model based on topological descriptors, including two hydrogen E-state indices, along with a molecular connectivity χ and a κ shape index. A statistically satisfactory four-variable model was obtained for the 32 compounds in the training set, r2 = 0.86, s = 0.60, and q2 = 0.79, without the use of information from 3D geometries or detailed interaction energy calculations. The model was validated through the prediction of 15 compounds in the external test set, yielding a mean absolute error, MAE, = 0.82. Structure interpretation is given for each variable to assist in the design of new compounds. Structure features emphasized in the model include hydrogen bond donating ability, nonpolar groups, skeletal branching, and molecular globularity. On the basis of these statistical criteria, this E-state model may be considered useful for prediction of pIC50 values for new HIV-1 protease inhibitors.
Mixed-metal tellurites : Synthesis, structure, and characterization of Na1.4Nb3Te4.9O18 and NaNb3Te4O16

Two new mixed-metal tellurites, Na1.4Nb3Te4.9O18 and NaNb3Te4O16, have been synthesized by standard solid-state techniques using Na2CO3, Nb2O5, and TeO2 as reagents. The structures of Na1.4Nb3Te4.9O18 and NaNb3Te4O16 were determined by single-crystal X-ray diffraction. Both of the materials exhibit three-dimensional structures composed of NbO6 octahedra, TeO4, and TeO3 polyhedra. The Nb5+ and Te4+ cations are in asymmetric coordination environments attributable to second-order Jahn-Teller (SOJT) effects. The Nb5+ cations undergo an intraoctahedral distortion toward a corner (local C4 direction), whereas the Te4+ cations are in distorted environments owing to their nonbonded electron pair. Infrared and Raman spectroscopy, UV-vis diffuse reflectance spectroscopy, thermogravimetric analysis, and dielectric measurements were also performed on the reported materials. Crystal data: Na1.4Nb3Te4.9O18, monoclinic, space group C2/m (No. 12), with a = 32.377(5) A, b = 7.4541(11) A, c = 6.5649(9) A, beta = 95.636(5) degrees, V = 1576.7(4) A3, and Z = 4; NaNb3Te4O16, monoclinic, space group P2(1)/m (No. 11), with a = 6.6126(13) A, b = 7.4738(15) A, c = 14.034(3) A, beta = 102.98(3) degrees, V = 675.9(3) A3, and Z = 2.
Interactions between cytochromes P450 2B4 (CYP2B4) and 1A2 (CYP1A2) lead to alterations in toluene disposition and P450 uncoupling.

The goal of this study was to characterize the effects of CYP1A2·CYP2B4 complex formation on the rates and efficiency of toluene metabolism by comparing the results from simple reconstituted systems containing P450 reductase (CPR) and a single P450 to those using a mixed system containing CPR and both P450s. In the mixed system, the rates of formation of CYP2B4-specific benzyl alcohol and p-cresol were inhibited, whereas that of CYP1A2-specific o-cresol was increased, results consistent with the formation of a CYP1A2·CYP2B4 complex in which the CYP1A2 moiety has a higher affinity for CPR binding. Comparison of the rates of NADPH oxidation and production of hydrogen peroxide and excess water by the simple and mixed systems indicated that excess water formed at a much lower rate in the mixed system. The commensurate increase in the rate of CYP1A2-specific product formation suggested the P450·P450 interaction increased the rate of the putative rate-limiting step of CYP1A2 catalysis, abstraction of a hydrogen...
Market Talk: Competition Policy in America

A dreary debate has occupied the antitrust community over the past 25 to 30 years. The debate is a more elegant, scholarly version of the commercials for Miller Lite beer that ran during much of the same period. In the beer commercials, one group of modestly recognizable celebrities and personalities of the day shouted "Tastes great" while the opposing group shouted "Less filling." This was the extent of the debate. The antitrust equivalent of this debate involves distinguished academics and policymakers arguing whether antitrust law and policy should be "more efficient" or should incorporate "greater fairness." Both schools of thought have enjoyed their periods of supremacy. The more economically oriented efficiency camp, normally dubbed "The Chicago School," has reigned supreme since the mid-1970s as its narrower version of antitrust policy has been adopted by the Supreme Court, has been relied upon by the Reagan and Bush administrations, and has persuaded the majority of commentators. Today, that ascendancy is in jeopardy as the politics of the Clinton administration, new economic theories, and the globalization of the economy have led to actions more in line with the preferred outcomes, if not the reasoning, of the beleaguered fairness advocates.1
Effects of Multiple Reflections on Hole Formation During Short-Pulsed Laser Drilling

Beam guiding effects during laser drilling due to multiple specular reflections inside the hole are analyzed for the case of very short laser pulses (nanosecond range). Specular reflections are valid for materials that retain a smooth surface during laser evaporation (small optical roughness compared to the laser wavelength). The problem is assumed to be two-dimensional axisymmetric (unpolarized laser), with the hole geometry defined by nodal values connected through a cubic spline. The net radiative flux onto a surface node is determined through ray tracing methods. The resulting absorbed laser flux is combined with a simple quasi-one-dimensional conduction model (to assess the minor conduction losses) and an Arrhenius evaporation rate model, to predict hole development as a function of time through iteration. To stabilize this highly nonlinear and thus unstable problem (in numerical analysis as well as in experiments) the laser beam is diffused a small amount from the specular direction (to also account for the limitation that no beam can be focused down to a point), and by periodic slight smoothing of the irradiation levels. Results show that drilling rates are increased dramatically due to beam trapping for highly reflective materials, resulting in a more pointed hole profile.
Stability robustness measures utilizing structural information

This paper presents techniques of using weighted l1 - and ∞ -norms to incorporate the structural information of the return difference and the perturbation matrices in the measure of stability robustness of multivariable control systems. The flexibility offered by these norms along with the use of non-negative matrix theory enables one, in most cases, to reduce the conservatism which has been a typical concern with the use of singular-value based stability robustness tests. New stability robustness criteria are derived on the basis of weighted l1 - and ∞ -norms. Examples are given to demonstrate the merits of these methods over singular-value tests.
The combination of urinary and recombinant HCG improves outcome in patients with decreased oocyte/follicle ratio in previous cycles

This report describes three cases in which the addition of recombinant HCG to urinary HCG to trigger ovulation in IVF improved oocyte recovery in patients with a history of scant oocyte yield in previous cycles.
On the Complexity of Teaching

While most theoretical work in machine learning has focused on the complexity of learning, recently there has been increasing interest in formally studying the complexity of teaching. In this paper we study the complexity of teaching by considering a variant of the on-line learning model in which a helpful teacher selects the instances. We measure the complexity of teaching a concept from a given concept class by a combinatorial measure we call the teaching dimension, Informally, the teaching dimension of a concept class is the minimum number of instances a teacher must reveal to uniquely identify any target concept chosen from the class.
Supramolecular polymer chemistry: design, synthesis, characterization, and kinetics, thermodynamics, and fidelity of formation of self-assembled dendrimers

Abstract Dendrimers 1a–d were synthesized in 10 steps from dendrons 4–7 , bromobenzene and succinic anhydride. Tetraacids 1e and 1f were prepared in an analogous fashion. The aggregation of 1a–f was studied in solution by size exclusion chromatography (SEC), vapor pressure osmometry (VPO), low angle laser light scattering (LLS), small angle neutron scattering (SANS), and by 1H NMR. The data are consistent with a stable, discrete hexameric aggregate for 1b–d in methylene chloride, non-discrete polymeric aggregates for 1a , 1e , and 1f , and monomers for all compounds in tetrahydrofuran and dimethyl sulfoxide. Kinetic and thermodynamic studies and mixing experiments confirmed the highly cooperative nature of the self-assembly process.