cssi/SciSciGPT-SciSciNet huggingface dataset:
Policy, Practice and Intent: Forum Analysis and the Uncertain Status of the Student Press at Public Colleges and Universities

The ruling of the United States Court of Appeals for the Seventh Circuit in Hosty v. Carter, which used forum analysis to determine that subsidized college and university student newspapers could be subject to prior review, raised a number of questions about the First Amendment rights of the student press. In Hosty and Kincaid v. Gibson federal courts of appeal ruled that university-subsidized publications are subject to forum analysis, and it is the policy, practices, and intent of administrators toward the publications that determine that forum status. However, the courts' inconsistency in interpreting those policies and practices has led to a great deal of confusion. This article posits that consistently applying strict scrutiny to non-curricular student publications at public colleges and universities would reduce confusion and better protect the free expression rights of students.
Spray impact resistance of a superhydrophobic nanocomposite coating

The performance of a polyurethane/organoclay superhydrophobic nanocomposite modified with perfluoroalkyl methacrylic copolymer in the presence of a high-pressure air-water spray which mimics an icing cloud impact is investigated in this study. To quantify the average velocites of droplets impacting the superhydrophobic samples, a computational study was performed. Such a study is important to understand the interaction between the jet and surface. Impacting velocities for three different testing conditions were estimated to be 14.5, 4.5, and 3.4 m/s. Liquid saturation did not occur immediately, but over time, the high mass flow rate of water led to antiwetting performance degradation. Upon evaporation, contact angle returned to pretest values, indicating little mechanical erosion. This was consistent with scanning electron microscopy which showed that the nano and microstructure was preserved, and with energy-dispersive X-ray spectroscopy, which showed no surface chemistry change after testing. However, sliding angle showed stronger degradation, especially at higher impact velocities. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3025–3032, 2014
Crystal structural analyses of 1:3 (Lu, In)(OH)3 and 1:3 (Yb, In)(OH)3

Abstract Single crystals of Lu0.25In0.75(OH)3 and Yb0.25In0.75(OH)3 were obtained by hydrothermal methods. Both compounds crystallize in space group Im3 (Th5, No. 204) with lattice constants of 8.043(2) A and 8.038(1) A respectively. The crystal structures have been determined by means of single-crystal X-ray diffraction and full-matrix least-squares refinements yielded respective R values of 0.021 and 0.023, based on 130 and 131 unique reflections. The metal atoms in each system share the same site, with refined occupancies of 0.25 and 0.75. The unit cell of each compound contains eight formula units and each metal atom is octahedrally coordinated to six oxygen atoms. Each oxygen atom is coordinated by two metal atoms forming infinite M-O-M chains. Atomic coordinates, temperature factors and other supporting crystallographic data are reported. The important bond and contact distances for each compound are: M-O = 2.182(4) A and 2.180(5) A and O…O = 2.77(2) A and 2.88(2) A , and 2.79(3) A and 2.86(3) A respectively.
Spectral Equivalence of Bosons and Fermions in One-Dimensional Harmonic Potentials

Recently, Schmidt and Schnack [Physica A 260, 479 (1998)], following earlier references, reiterate that the specific heat of N noninteracting bosons in a one-dimensional harmonic well equals that of N noninteracting fermions in the same potential. We show that this peculiar relationship between heat capacities results from a more dramatic equivalence between Bose and Fermi systems. Namely, we prove that the excitations of such Bose and Fermi systems are spectrally equivalent. Two complementary proofs of this equivalence are provided; one based on a combinatoric argument, the other from analysis of the underlying dynamical symmetry group.
Effect of magnesium on cocaine-induced, catecholamine-mediated platelet and vascular response in term pregnant ewes.

Ten pregnant ewes were alternated in a study of the blocking effect of parenteral magnesium on the catecholamine response to cocaine. Indirect blood pressures were recorded at 1-minute intervals for 12 minutes before and after a bolus of 2 mg/kg of cocaine. Fetal heart rates were continuously recorded from skin electrodes. Platelet counts were performed before and 12 minutes after cocaine. Control ewes received lactated Ringer's solution, and test animals had 5 mg/kg of elemental magnesium in the form of MgS04-7H20 in a rapid infusion. A semicrossover was also performed. Platelet counts fell precipitately in controls and rose after magnesium infusions. Fetal heart rates rose in controls at 5-minute intervals and were unchanged in magnesium-treated mothers. Because of disparity of the baseline mean arterial pressure, direct comparisons were not significant before and after cocaine. Alterations from the baseline were different in magnesium-treated versus control animals, with values in the latter rising by 28 ± 10 mm Hg with lactated Ringer's solution plus cocaine and falling by 3 ± 5 mm Hg with magnesium pretreatment. Values in test animals originally treated with magnesium rose 4 ± 11 mm Hg for an overall significance of p
Some Evidence on the Empirical Significance of Credit Rationing

This paper examines the credit rationing debate using detailed contract information on over one million commercial bank loans from 1977 to 1988. While commercial loan rates are "sticky," consistent with rationing, this stickiness varies with loan contract terms in ways that are not predicted by equilibrium credit rationing theory. In addition, the proportion of new loans issued under commitment does not increase significantly when credit markets are tight, despite the fact that borrowers without commitments can be rationed whereas commitment borrowers are contractually insulated from rationing. Overall, the data suggest that equilibrium rationing is not a significant macroeconomic phenomenon.
Neural-Network-Based Controller for Nonlinear Aeroelastic System

Attenuation of vibratory response is an important design consideration in many aeroelastic systems, and active methods of vibration reduction have been studied extensively in this context. Synthesis of active controllers requires that a good analytical model of the system be available. In those problems in which the aeroelastic system is inherently nonlinear, a robust control scheme is difficult to implement, particularly in the presence of large uncertainties in the model. The use of artificial neural networks, with on-line learning capabilities, is explored as an approach for developing robust control strategies for such problems. In particular, the use of neural networks to mimic the behavior of a linear quadratic Gaussian controller that is applicable to nonlinear systems is presented. The helicopter rotor blade is a classic example of an aeroelastic system in which vibration reduction is an overriding concern, and in which the plant is both nonlinear and contains uncertainties. A simplified two-dimensional representation of this aeroelastic system, consisting of an airfoil with a trailing-edge control flap, is considered as a test case in the present work; both structural and aerodynamic nonlinearities are included in the problem. Nomenclature a = offset of elastic axis from the midchord b = sernichord of airfoil c = distance between midchord and flap hinge cmo = mean pitching-moment coefficient before stall Cms, cPs = static pitching-moment and lift coefficients, respectively Cma, cpa = slopes of linear pitching moment and lift curves, respectively Ia, Is = moments of inertia of airfoil and trailing-edge flap per unit span, respectively Ka, Kh = spring stiffnesses of torsional and translational restraints m = mass of airfoil per unit span Sa, Ss = static moments of airfoil and trailing-edge flap per unit span, respectively 8 = flap angle
The cost benefits of the Spacelab system to scientific investigations and space applications

Cost advantages of the Spacelab system to scientific experiments in space and space operations are presented. The payload integration concepts developed for Spacelab are examined, and it is shown that Spacelab and Shuttle integration, communications and data processing, launch support requirements and flight operations will provide a considerable savings in the costs of space research relative to previous space systems. Spacelab modular design, incorporating features such as standard payload interfaces, optional mission dependent equipment and standard services, such as the Experiment Computer Operating System, is shown to offer the user a wider range of services than previous programs, also at significantly lower costs. It is concluded that the Spacelab system will greatly reduce the costs and broaden the opportunities for scientific investigation in space.
Working with the Grain for Reforming the Public Service : A Live Example from Sierra Leone

Development practitioners still lack a critical mass of empirical evidence which can help identify the set of interventions that are more likely to work, and inform the design and implementation of feasible reforms. This paper contributes to fill this gap by looking at the case of the 'Sierra Leone Pay and Performance Project', a World Bank-supported initiative to reform the civil service. It analyzes the functional problems characterizing the civil service and discusses what factors account for the observed dysfunctions. The central argument is that the current dysfunctions might be difficult to reverse as they define a sub-optimal equilibrium which serves political purposes (dysfunctions by design). However, politics is not all that matters. This equilibrium is further reinforced by systemic dysfunctions that may not be the consequence of any strategic design or the outcome of elite preferences (dysfunctions by default). This is where there is scope for change, even in the short run. The authors conclude that the chances of successful civil service reforms are likely to be maximized if reform initiatives support modest and incremental changes that work with the grain of existing incentives and are consistent with government preferences. The Sierra Leone Pay and Performance Project aims to do so by adopting a limited and targeted focus on pay reform, performance management and recruitment and staffing. In addition, the use of the results-based lending instrument is expected to help mitigate the current dysfunctions by aligning the incentives of the various players and, in this way, create the conditions for greater coordination across government agencies. Although the suggested approach is not without risks, recent dynamics suggest that the chances of success are greater today than in the past.
Risk-sharing within families: Evidence from the Health and Retirement Study

Abstract We report strong empirical support for the presence of self-interest-based risk sharing within extended families in the U.S. A standard model of self-interest-based risk sharing predicts that the share of current family income consumed by a child positively depends on that child׳s permanent income. It follows that parental transfers to children that are expected to earn more over the period of risk-sharing arrangements should exhibit less sensitivity to the recipient׳s income fluctuations. We test this distinguishing prediction of self-interest-based risk sharing by exploiting the variation of transfer receipts among siblings, observed over 17 years of longitudinal data spanned by the Health and Retirement Study.
Locality and Information Transfer in Quantum Operations

We investigate the situation in which no information can be transferred from a quantum system B to a quantum system A, even though both interact with a common system C.
Some stable derivatives of 7,8-dihydropurines

The synthesis of a number of 7,8-dihydropurines is described. The unusual stability of these molecules is due to the presence of an electron whithdrawing substituent in the 6-position
A note on the interaction effects of non-financial measures of performance

Abstract Using principal-agent analyses, the effect of the interactions between two non-financial measures of performance in an agent’s incentive compensation scheme is studied. The agent can allocate effort between “meeting output targets” and “getting output that needs no rework.” The principal trades off (1) a penalty for not meeting output targets, and (2) cost of reworking output that is defective when initially produced. In a compensation mechanism that includes incentives based on measures of output that needs no rework, as well as total output, it is shown that the agent may respond to an increased weight on output that needs no rework by reducing effort allocated towards it. This occurs when the increased weight on the output that needs no rework is accompanied by a sufficiently steep decrease in the weight on total output in the compensation mechanism, leading to a reduction of all effort, and all output. Numerical analyses and implications for the use of multiple measures of performance-based incentives are provided.
High-Temperature Cermets: I, Compatibility

The stability of refractory oxides (Y2O3,-stabilized HfO2 and ZrO2, Tho2, CeO2), carbides (HfC, NbC, TaC, and ZrC), borides (NbB2 and TaB2), and HfN was determined in combination with the Groups VIA and VIIA refractory metals and combinations thereof. Thermodynamic calculations were made to predict stability up to 2500°K between the ceramic oxides and carbides in contact with Mo, Re, and W. Reaction studies were conducted between the ceramics and the Groups VIA and VIIA refractory metals in vacuum and in helium to 2750°C. The Mo-40 wt% Re, Re, and W were stable in contact with the carbides, nitrides, and oxides to 2450°C with two exceptions. These occurred when CeO2 reacted with W at 1700°C and Mo-40 wt% Re reacted with WC. The Mo-40 wt% Re and Re also reacted with the NbB2 and TaBa above 2200°C to form very hard single-phase compounds.
Organocatalytic dimerization of ketoketenes.

A general method for the catalytic dimerization of ketoketenes is described. Tri-n-butylphosphine was found to be the optimal organocatalyst for the racemic reaction. When lithium iodide was used as an additive, the reaction was rendered selective for dimer formation (dimer/trimer ≥16:1). Ring-opening reactions of the ketoketene dimers as well as preliminary studies toward the development of an asymmetric variant are also reported.
Synthesis, Photophysics, Electrochemistry and Electrogenerated Chemiluminescence of a Homologous Set of BODIPY-Appended Bipyridine Derivatives

Two new 2,2′-bipyridine (bpy)-based ligands with ancillary BODIPY chromophores attached at the 4- and 4′-positions were prepared and characterized, which vary in the substitution pattern about the BODIPY periphery by either excluding (BB1) or including (BB2) a β-alkyl substituent. Both absorb strongly throughout the visible region and are strongly emissive. The basic photophysics and electrochemical properties of BB1 and BB2 are comparable to those of the BODIPY monomers on which they are based. The solid-state structures and electronic structure calculations both indicate that there is negligible electronic communication between the BODIPY moieties and the intervening bpy spacers. Electrogenerated chemiluminescence spectra of the two bpy-BODIPY derivatives are similar to their recorded fluorescence profiles and are strongly influenced by substituents on the BODIPY chromophores. These 2,2′-bipyridine derivatives represent a new set of ligands that should find utility in applications, including light-harve...
Why Do Employers Pay For College

Abstract Employers routinely provide financial support for their employees who pursue post-secondary education despite the fact that it represents perhaps the classic example of a “general skill” that costs the employer money and raises the market wages of employees who possess it. The analysis below examines why employers provide such support, and the results suggest that employees do not pay for tuition assistance through below market or training wages, the typical arrangement for funding general skills training. Instead, tuition assistance appears to select better quality employees who stay on the job longer, at least in part to keep making use of that benefit.
Cascade reactions: a driving force in akuammiline alkaloid total synthesis.

The akuammiline alkaloids are a family of intricate natural products which have received considerable attention from scientists worldwide. Despite the fact that many members of this alkaloid class were discovered over 50 years ago, synthetic chemistry has been unable to address their architectures until recently. This minireview provides a brief overview of the rich history of the akuammiline alkaloids, including their isolation, structural features, biological activity, and proposed biosyntheses. Furthermore, several recently completed total syntheses are discussed in detail. These examples not only serve to highlight modern achievements in alkaloid total synthesis, but also demonstrate how the molecular scaffolds of the akuammilines have provided inspiration for the discovery and implementation of innovative cascade reactions for the rapid assembly of complex structures.
A geometric effective Nullstellensatz

The purpose of this paper is to present a geometric theorem which clarifies and extends in several directions work of Brownawell, Kollar and others on the effective Nullstellensatz. Specifically, we work on an arbitrary smooth complex projective variety X, with the previous “classical” results corresponding to the case when X is projective space. In this setting we prove a local effective Nullstellensatz for ideal sheaves, and a corresponding global division theorem for adjoint-type bundles. We also make explicit the connection with the intersection theory of Fulton and MacPherson. Finally, constructions involving products of prime ideals that appear in earlier work are replaced by geometrically more natural conditions involving orders of vanishing along subvarieties. Much of the previous activity in this area has been algebraic in nature, and seems perhaps not well-known in detail among geometers. Therefore we have felt it worthwhile to include here a rather extended Introduction. We start with an overview of the questions and earlier work on them. Then we present the set-up and statement of our main theorem. We conclude with a series of examples (which can be read before the general result) of what it yields in special cases.
Set partition statistics and q-Fibonacci numbers

We consider the set partition statistics ls and rb introduced by Wachs and White and investigate their distribution over set partitions that avoid certain patterns. In particular, we consider those set partitions avoiding the pattern 13/2, @P"n(13/2), and those avoiding both 13/2 and 123, @P"n(13/2,123). We show that the distribution over @P"n(13/2) enumerates certain integer partitions, and the distribution over @P"n(13/2,123) gives q-Fibonacci numbers. These q-Fibonacci numbers are closely related to q-Fibonacci numbers studied by Carlitz and by Cigler. We provide combinatorial proofs that these q-Fibonacci numbers satisfy q-analogues of many Fibonacci identities. Finally, we indicate how p,q-Fibonacci numbers arising from the bistatistic (ls,rb) give rise to p,q-analogues of identities.
Novel Total Synthesis of the Anticancer Natural Product Dysidiolide

The marine natural product dysidiolide has been synthesized in a highly diastereoselective fashion that features the sequential transfer of chirality from a cyclohexenone precursor.
PAMELA: An open-source software package for calculating nonlocal exact exchange effects on electron gases in core-shell nanowires

We present a new pseudospectral approach for incorporating many-body, nonlocal exact exchange interactions to understand the formation of electron gases in core-shell nanowires. Our approach is efficiently implemented in the open-source software package PAMELA (Pseudospectral Analysis Method with Exchange & Local Approximations) that can calculate electronic energies, densities, wavefunctions, and band-bending diagrams within a self-consistent Schrodinger-Poisson formalism. The implementation of both local and nonlocal electronic effects using pseudospectral methods is key to PAMELA's efficiency, resulting in significantly reduced computational effort compared to finite-element methods. In contrast to the new nonlocal exchange formalism implemented in this work, we find that the simple, conventional Schrodinger-Poisson approaches commonly used in the literature (1) considerably overestimate the number of occupied electron levels, (2) overdelocalize electrons in nanowires, and (3) significantly underestimate the relative energy separation between electronic subbands. In addition, we perform several calculations in the high-doping regime that show a critical tunneling depth exists in these nanosystems where tunneling from the core-shell interface to the nanowire edge becomes the dominant mechanism of electron gas formation. Finally, in order to present a general-purpose set of tools that both experimentalists and theorists can easily use to predict electron gas formation in core-shell nanowires, we document and provide our efficient and user-friendly PAMELA source code that is freely available at http://alum.mit.edu/www/usagi.
Parallel higher-radix signed-digit arithmetic using shared content addressable memory

A novel optical computing technique using recoded quaternary signed-digit arithmetic is presented in this paper. An efficient shared content-addressable memory based optical implementation which employs a fixed number of minterms independent of the operand length is developed. This technique requires the minimum number of minterms when compared to the similar previously reported techniques. An alternate algorithm for quaternary signed-digit arithmetic is .also suggested.
Ni, Ga, Ge and Ir in the metal of iron- meteorites-with-silicate-inclusions

Abstract Neutron-activation determined concentrations of Ni, Ga, Ge and Ir in the metal of 19 iron-meteorites-with-silicate-inclusions are in good agreement with the classification of Bunch , Keil and Olsen , which is based mainly on the mineralogy and texture of the inclusions. Odessa-type and Copiapo-type irons-with-silicate-inclusions are found to be very closely related to each other, and to other members of chemical group I of the iron meteorites. Kendall County is probably related to these irons. Elga is a new Weekeroo Station-type iron-with-silicate-inclusion, and Netschaevo is closely related to these objects. Tucson is unique. Odessa-type and Copiapo-type meteorites appear to have formed non-igneously, whereas shock mixing and associated differentiation of silicates appears to have been a late step in the history of the Weekeroo Station-type irons.
Dynamic learning in a two-person experimental game

Abstract We analyze learning in a two-person simultaneous choice repeated game. Agents form beliefs about their rival's strategies, which they revise as the game progresses. We test this model using data from a series of experiments. We obtain data on subjects’ expectations by asking them to predict their rival's choice in each period of the game; subjects are paid for each correct prediction. We analyze the data using the Kalman filtering technique, and find that learning is broadly consistent with Bayesian updating. The predicted equilibrium based on this learning process is indistinguishable from observed behavior for most subjects in later periods.
$Q$-Curvature and Poincaré Metrics

This article presents a new definition of Branson's Q-curvature in even-dimensional conformal geometry. We derive the Q-curvature as a coefficient in the asymptotic expansion of the formal solution of a boundary problem at infinity for the Laplacian in the Poincare metric associated to the conformal structure. This gives an easy proof of the result of Graham-Zworski that the log coefficient in the volume expansion of a Poincare metric is a multiple of the integral of the Q-curvature, and leads to a definition of a non-local version of the Q-curvature in odd dimensions.
A Welfare Analysis of Regulation in Relationship Banking Markets

The increasing dependence of individuals on debt financing raises several welfare considerations that we analyze in this paper. We develop a dynamic, competitive model of relationship banking to determine how regulation influences borrowing and lending behavior, and analyze how it affects welfare in the market. We characterize the lending regimes that arise based on public policy, and evaluate the optimal choice by the government to induce particular lending practices to arise. Finally, we consider the effect that a credit reporting agency has on the market. In the paper, we highlight the new empirical implications that the model generates. Copyright 2009, Oxford University Press.
Searching for composite neutrinos in the cosmic microwave background

We analyze signals in the Cosmic Microwave Background (CMB) in theories where the small Dirac neutrino masses arise as a consequence of the compositeness of right-handed neutrinos. In such theories, the right-handed neutrinos are massless ``baryons'' of a new strong gauge interaction. We find that the results crucially depend on whether or not the new strong sector undergoes chiral symmetry breaking. In the case with chiral symmetry breaking, we find that there are indeed signals in the CMB, but none of them is a direct consequence of neutrino compositeness. In contrast, if the underlying theory does not undergo chiral symmetry breaking, the large scattering cross-section among the composites gives rise to a sizable CMB signal over a wide region of the parameter space, and it can potentially probe whether the neutrino mass spectrum is hierarchical, inverse-hierarchical, or degenerate. We also discuss collider constraints on the compositeness in the context of the CMB signals.
Statistical Estimation of Economic Life for Aircraft Structures

An analytical methodology for the statistical prediciton of the economic life of advanced aircraft structures is presented. The approach allows for the determination of the economic life based on either one of the following criteria: 1) a rapid increase of the number of crack damages exceeding the economic repair crack size, and 2) a rapid increase of the maintenance cost, including the costs of inspection and repair. The formulation is general enough for practical applications. While the inspection and repair maintenance procedure has a significant impact on aircraft structural reliability and safety, its effect on the economic life is shown to be limited. Numerical examples are worked out to demonstrate the application of the methodology.
A Hybrid Robot System Guided by Computer Tomography for Percutaneous Lung Cancer Cryosurgery

Using the common serial robot or parallel robot it is difficult to implement computed tomography (CT) guided surgery in a limited workspace. A novel hybrid robot with 9 d.o.f. is presented, the det...
Electrical Breakdown Strength of Alumina at High Temperatures

The dc electrical strength of sapphire and poly crystalline alumina was studied up to 1400°C. The electrical strength was essentially identical for both materials. It was > 106 V/cm at room temperature and decreased gradually with temperature up to 900°C (2.6×105 V/ cm), then dropped rapidly to 2×104 V/cm at 1400°C for a sample thickness of ∼ 100 μm. The electrical strength decreased with the sample thickness. It was inversely proportional to the thickness for samples thicker than ∼ 600 μm at 1200°C. The breakdown behavior was explained on the basis of a thermal breakdown model.
Quark and gluon orbital angular momentum and spin in hard processes

Abstract We suggest a method of constructing gauge-invariant quark and gluon distributions that describe an abstract QCD observable and apply this method to analyze angular momentum of a hadron. In addition to the known quark and gluon polarized structure functions, we obtain gauge-invariant distributions for quark and gluon orbital angular momenta, and consider some basic properties of these distributions and their moments.
Two-batch liar games on a general bounded channel

We consider an extension of the 2-person Renyi-Ulam liar game in which lies are governed by a channel C, a set of allowable lie strings of maximum length k. Carole selects x@?[n], and Paul makes t-ary queries to uniquely determine x. In each of q rounds, Paul weakly partitions [n]=A"0@?...@?A"t"-"1 and asks for a such that x@?A"a. Carole responds with some b, and if a b, then x accumulates a lie (a,b). Carole's string of lies for x must be in the channel C. Paul wins if he determines x within q rounds. We further restrict Paul to ask his questions in two off-line batches. We show that for a range of sizes of the second batch, the maximum size of the search space [n] for which Paul can guarantee finding the distinguished element is ~t^q^+^k/(E"k(C)(qk)) as q->~, where E"k(C) is the number of lie strings in C of maximum length k. This generalizes previous work of Dumitriu and Spencer, and of Ahlswede, Cicalese, and Deppe. We extend Paul's strategy to solve also the pathological liar variant, in a unified manner which gives the existence of asymptotically perfect two-batch adaptive codes for the channel C.
Multi-component synthesis of 2-amino-6-(alkylthio)pyridine-3,5-dicarbonitriles using Zn(II) and Cd(II) metal–organic frameworks (MOFs) under solvent-free conditions

Multi-component synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines has been developed by using the reaction of aldehydes, malononitrile, and thiophenols in the presence of a Zn(II) or a Cd(II) metal–organic framework (MOF) as the heterogeneous catalyst. This protocol tolerates different functional groups on the substrates and does not require the use of any organic solvent. Moreover, the Zn(II) and Cd(II) MOF catalysts can be recovered and reused for a number of runs without loss of activity.
Chemical Equilibrium Prediction of Potassium, Sodium, and Chlorine Concentrations in the Product Gas from Biomass Gasification

An investigation of the use of chemical equilibrium calculations to predict experimental measurements of the trace species K, Na, and Cl in a gasifier product stream was completed. The method applied two sequential equilibrium calculations. The first calculation used fuel and air data as input and was performed at the gasifier temperature (∼800 °C). A second calculation used the results of the first calculation as input and was performed at the temperature of the hot gas filter (∼700 °C). Equilibrium calculations based only on the fuel composition and air input data predicted potassium, sodium, and chlorine concentrations that were greater than measured experimental values. The equilibrium concentration of potassium, which is the alkali metal of particular interest in this study, was an order of magnitude larger than the experimental results (153 ppmw vs 28 ppmw). Including the mass of bed material used in the experiments as input to the equilibrium calculation reduced the predicted potassium concentratio...
HiLight: Hiding Bits in Pixel Translucency Changes

We present HiLight, a new form of unobtrusive screen-camera communication for off-theshelf smart devices. HiLight hides information underlying any images shown on an LED or OLED screen, and camera-equipped smart devices can fetch the information by turning their cameras to the screen. HiLight achieves this by leveraging the transparency (alpha) channel, a well-known concept in computer graphics, to encode bits into pixel translucency changes without modifying pixel color (RGB) values. We demonstrated HiLight's feasibility using smartphones. By offering an unobtrusive, flexible, and lightweight communication channel between screens and cameras, HiLight allows new HCI and context-aware applications to emerge.
The Relation Between RS CVn and Algol

Late-type secondaries in Algol binaries are rapidly rotating convective stars and thus should be chromospherically active (CA). They are examined with respect to observational manifestations which characterize already known CA stars: Ca II H and K emission cores, photometric variability attributable to starspots, soft x-ray emission, non-thermal radio emission, ultraviolet and infrared excess, and alternating period changes. The conclusion is that they can be regarded as another class of CA stars. In most respects they are literally indistinguishable from other CA stars. Ca II H and K emission cores are observed in the lobe-filling component of six semi-detached binaries: U Cep, RT Lac, RV Lib, AR Mon, S Vel, HR 5110. Alternating period changes are shown to occur only in Algols containing a late-type (convective) star. It is proposed, therefore, that the Matese-Whitmire mechanism explains these changes. Specifically, the interval from one increase (or decrease) to the next can be equated with the star’s magnetic cycle. Cycle lengths for 31 stars, derived in this way, range between 7 years and 109 years, with a median of 50 years.
Integer Programming as a Framework for Optimization and Approximability

Structural approximation theory seeks to provide a framework for expressing optimization problems and isolating structural or syntactic conditions that explain the apparent difference in the approximation properties of different NP-optimization problems. In this paper, we initiate a study of structural approximation using integer programming (an optimization problem in its own right) as a general framework for expressing optimization problems. We isolate three classes of constant-approximable maximization problems, based on restricting appropriately the syntactic form of the integer programs expressing them. The first of these classes subsumes Max?1, which is the syntactic version of the well-studied class MaxNP. Moreover, by allowing variables to take on not just 0/1 values but rather values in a polylogarithmic or polynomial range, we obtain syntactic maximization classes that are polylog-approximable and poly-approximable, respectively. The other two classes contain problems, such as MaxMatching, for which no previous structural explanation of approximability has been found. We also investigate structurally defined classes of integer programs for minimization problems and show a difference between their maximization counterparts.
Constraints on low-dimensional string compactifications

Abstract We study the restrictions imposed by cancellation of the tadpoles for two-, three-, and four-form gauge fields in string theory, M-theory and F-theory compactified to two, three and four dimensions, respectively. For a large class of supersymmetric vacua, turning on a sufficient number of strings, membranes and three-branes, respectively, can cancel the tadpoles, and preserve supersymmetry. However, there are cases where the tadpole cannot be removed in this way, either because the tadpole is fractional, or because of its sign. For M-theory and F-theory compactifications, we also explore the relation of the membranes and three-branes to the non-perturbative space-time superpotential.
Occupant model for human motion

Abstract A two-dimensional model of a human being has been developed for display on a computer graphic terminal. The model was designed for use with the simula program which predicts the positions of an occupant within a vehicle cabin during a crash. However, the model can also be used in the simulation of other human motions, such as walking, etc. Also presented is the design of a simple device to automatically generate movies from a terminal screen. Triggered by the bell on the terminal, one frame is taken of each position of any time-varying event, thus creating a movie depicting simulated motion.
Laboratory instrumentation and techniques for characterizing multi-junction solar cells for space applications

An integrated system is described which consists of a spectral radiometer and dual-source solar simulator, and personal computer-based current-voltage and quantum efficiency equipment. The apparatus was used to measure the dependence of the absolute external quantum efficiency of triple-junction a-Si:H alloy solar cells. The cells were measured under AM0 light bias at various forward-bias voltages including the maximum-power point. The quantum efficiencies of the cells were measured with both spectral-light bias and AM0 light bias.
How America's fragmented approach to public safety wastes money and spectrum

Emergency responders such as firefighters, police, and paramedics depend on reliable and ubiquitous wireless communications. Failures in these communications systems can cost lives. Particularly since 9/11, there has been great concern in the US about the possibility of failures due to lack of interoperability, and failures due to a shortage of public safety spectrum. This paper shows how both of these and other serious problems are a logical consequence of America's fragmented approach to public safety, in which thousands of local agencies make independent decisions without a coherent strategy to unify or guide them. Because of this fragmented approach, public safety agencies build more infrastructure than they should, spend more tax-payer money than they should, and consume more scarce spectrum than they should, all for a system that is unnecessarily prone to interoperability failures. This paper also considers the most widely cited estimates of public safety's spectrum needs, which predict a serious shortage unless considerably more spectrum becomes available to public safety by 2010. This paper shows that estimates for the amount of spectrum needed in 2010 would be vastly lower if the US adopted an effective national strategy that included coordinated planning and modern technology. On the other hand, if the US retains today's fragmented approach, regions where coordination among local public safety agencies is particularly weak may need more spectrum than popular estimates would indicate, leading to an even greater shortage. Thus, the federal government should start playing a large role in setting the direction of public safety communications, rather than leaving this to many independent local governments.
The Clouds of Venus: II. An Investigation of the Influence of Coagulation on the Observed Droplet Size Distribution

An approximate numerical technique is used to investigate the influence of coagulation, sedimentation and turbulent motions on the observed droplet size distribution in the upper layers of the Venus clouds. If the cloud mass mixing ratio is less than 0.000001 at 250 K or the eddy diffusivity throughout the cloud is greater than 1,000,000 sq cm per sec, then coagulation is unimportant. In this case, the observed droplet size distribution is the initial size distribution produced by the condensation of the droplets. It is found that all cloud models with droplet formation near the cloud top (e.g., a photochemical model) must produce the observed droplet size distribution by condensation without subsequent modification by coagulation. However, neither meteoritic or surface dust can supply sufficient nucleating particles to account for the observed droplet number density. If the cloud droplets are formed near the cloud bottom, the observed droplet size distribution can be produced solely by the interaction of coagulation and dynamics; all information about the initial size distribution is lost. If droplet formation occurs near the cloud bottom, the lower atmosphere of Venus is oxidizing rather than reducing.
Synthesis of an Isophorone‐Based Nonlinear Optical Chromophore

Abstract The synthesis of a “CLD‐type” nonlinear optical chromophore incorporating the isophorone unit to rigidize the polyene segment is described. The synthesis required seven steps with an overall yield of 17%.
Highly Active and Selective Catalysts for the Formation of α-Aryl Ketones

Bulky, electron-rich phosphine ligands with a biphenyl backbone, when combined with Pd(OAc)2, give highly active catalysts for the α-arylation of ketones. The ligand 2-methyl-2‘-dicyclohexylphosphinobiphenyl is particularly effective, and with 0.1−1.0 mol % Pd, a large variety of aryl halides and ketones react efficiently and with high selectivity. For two types of substrates, the ligands BINAP and Xantphos are more effective than the biphenyl-based ligands. It is also shown that K3PO4 can be used as the base in these reactions, and that base-sensitive functional groups are better tolerated if this is used instead of NaOtBu or NaHMDS. In some cases, α-aryl ketones can be produced without adding a ligand to the reaction. Although the substrate scope of the ligandless conditions is limited, some combinations react in high yield, and in one case, 100 000 turnovers were obtained. The results of experiments on the Pd-catalyzed arylation of diethyl malonate, cyclic 1,3-diketones, and nitroalkanes are also reported.
Selection of a Fault Model for Fault Diagnosis Based on Unique Responses

In this paper, we describe a preprocessing step to fault diagnosis of an observed response obtained from a faulty chip. In this step, a fault model for diagnosing the observed response is selected. This step allows fault diagnosis to be performed based on a single fault model after identifying the most appropriate one. We describe a specific implementation of this preprocessing step based on what is referred to as the unique output response of a fault model. As an example, we apply it to the diagnosis of multiple stuck-at faults, selecting between single and double stuck-at faults as the fault model for diagnosis. Experimental results demonstrate improvements compared to diagnosis based on single stuck-at faults, and compared to diagnosis based on both single and double stuck-at faults. We also discuss the use of a subset of double stuck-at faults for diagnosis, and the application of the proposed preprocessing step with other fault models.
Effects of gas models on hypersonic base flow calculations

Numerical solutions for the Navier-Stokes equations are obtained for laminar, hypersonic flows around a flatbased projectile using perfect gas, equilibrium air, and nonequilibrium air models. The effects of different gas models are investigated for a freestream condition of Mach 20 at an altitude of 73 km. The species compositions for the equilibrium and nonequilibrium gases are obtained by minimizing the Helmholtz free energy and by solving species continuity equations, respectively. The chemical equations are combined with the gasdynamics equations using a loosely coupled technique. A finite volume method is implemented with the flux vector splitting of Steger and Warming for convective terms and centered differencing for viscous terms. Both explicit and implicit time integration schemes are used.
The Diversity-Multiplexing Tradeoff of the MIMO Half-Duplex Relay Channel

The fundamental diversity-multiplexing tradeoff of the three-node, multi-input, multi-output (MIMO), quasi-static, Rayleigh faded, half-duplex relay channel is characterized for an arbitrary number of antennas at each node and in which opportunistic scheduling (or dynamic operation) of the relay is allowed, i.e., the relay can switch between receive and transmit modes at a channel dependent time. In this most general case, the diversity-multiplexing tradeoff is characterized as a solution to a simple, two-variable optimization problem. This problem is then solved in closed form for special classes of channels defined by certain restrictions on the numbers of antennas at the three nodes. The key mathematical tool developed here that enables the explicit characterization of the diversity-multiplexing tradeoff is the joint eigenvalue distribution of three mutually correlated random Wishart matrices. Besides being relevant here, this distribution result is interesting in its own right. Previously, without actually characterizing the diversity-multiplexing tradeoff, the optimality in this tradeoff metric of the dynamic compress-and-forward protocol based on the classical compress-and-forward scheme of Cover and El Gamal was shown by Yuksel and Erkip. However, this scheme requires global channel state information at the relay. In this paper, the so-called quantize-map and forward (QMF) coding scheme is adopted as the achievability scheme with the added benefit that it achieves optimal tradeoff with only the knowledge of the (channel dependent) switching time at the relay node. Moreover, in special classes of the MIMO half-duplex relay channel, the optimal tradeoff is shown to be attainable even without this knowledge. Such a result was previously known only for the half-duplex relay channel with a single antenna at each node, also via the QMF scheme. More generally, the explicit characterization of the tradeoff curve in this study enables the in-depth comparisons herein of full-duplex versus half-duplex relaying as well as static versus dynamic relaying, both as a function of the numbers of antennas at the three nodes.
Strings in Time-Dependent Orbifolds

We continue and extend our earlier investigation ``Strings in a Time-Dependent Orbifold'' (hep-th/0204168). We formulate conditions for an orbifold to be amenable to perturbative string analysis and classify the low dimensional orbifolds satisfying these conditions. We analyze the tree and torus amplitudes of some of these orbifolds. The tree amplitudes exhibit a new kind of infrared divergences which are a result of some ultraviolet effects. These UV enhanced IR divergences can be interpreted as due to back reaction of the geometry. We argue that for this reason the three dimensional parabolic orbifold is not amenable to perturbation theory. Similarly, the smooth four dimensional null-brane tensored with sufficiently few noncompact dimensions also appears problematic. However, when the number of noncompact dimensions is sufficiently large perturbation theory in these time dependent backgrounds seems consistent.
Do black holes radiate

The prediction that black holes radiate due to quantum effects is often considered one of the most secure in quantum field theory in curved space-time. Yet this prediction rests on two dubious assumptions: that ordinary physics may be applied to vacuum fluctuations at energy scales increasing exponentially without bound; and that quantum-gravitational effects may be neglected. Various suggestions have been put forward to address these issues: that they might be explained away by lessons from sonic black hole models; that the prediction is indeed successfully reproduced by quantum gravity; that the success of the link provided by the prediction between black holes and thermodynamics justifies the prediction. This paper explains the nature of the difficulties, and reviews the proposals that have been put forward to deal with them. None of the proposals put forward can so far be considered to be really successful, and simple dimensional arguments show that quantum-gravitational effects might well alter the evaporation process outlined by Hawking. Thus, a definitive theoretical treatment will require an understanding of quantum gravity in at least some regimes. Until then, no compelling theoretical case for or against radiation by black holes is likely to be made. The possibility that non-radiating `mini' black holes exist should be taken seriously; such holes could be part of the dark matter in the Universe. Attempts to place observational limits on the number of `mini' black holes (independent of the assumption that they radiate) would be most welcome.
Abelian cascade dynamics in bootstrap percolation

Abstract The culling process in bootstrap percolation is Abelian since the final stable configuration does not depend on the details of the updating procedure. An efficient algorithm is devised using this idea for the determination of the bootstrap percolation threshold in two dimension which takes L 2 time compared to the L 3 log L in the conventional method. A generalised bootstrap percolation allowing many particles at a site is studied where continuous phase transitions are observed for all values of the threshold parameter. Similar results are also obtained for the continuum bootstrap percolation model.