cssi/SciSciGPT-SciSciNet huggingface dataset:
Improving steel fiber reinforced concrete pull-out strength with nanoscale iron oxide coating

Abstract Fiber-reinforced concrete (FRC) has been extensively used all over the world for over 40 years. Steel fiber, being the first and most commonly employed reinforcement fiber, is always favored as the uniformly dispersed reinforcement for concrete due to its improvement towards mechanical strength, failure mode and bonding toughness. This article depicts a nanoscale reinforcement of iron oxide coatings on steel fibers prepared by electrodeposition method. The results indicate that pristine Fe 2 O 3 particles, Fe 2 O 3 nanorods and nanosheets were synthesized under different depositing conditions. The nanorod and nanosheet coated steel fibers were embedded in cement mortar for fiber pull-out tests. Corresponding pull-out tests revealed that iron oxide coating showed a strength enhancement up to 82% compared to the conventional fiber reinforced cement mortar samples.
Arab Identity and Ideology in Sudan: The Politics of Language, Ethnicity, and Race

In what is now Sudan there occurred over the centuries a process of ta'rib, or Arabization, entailing the gradual spread of both Arab identity and the Arabic language among northern peoples. After the Anglo-Egyptian conquest of 1898, British colonial policies favoured a narrow elite from within these ‘Arab’ communities. Members of this elite went on to develop a conception of a self-consciously Sudanese Arabic national identity, in the process adapting the term ‘Sudanese’ (sudani), which derived from an Arabic word for blackness and previously had servile connotations. At decolonization in the 1950s, these nationalists turned ta'rib, into an official policy that sought to propagate Arabic quickly throughout a territory where scores of languages were spoken. This article considers the historical diffusion of Sudanese Arabic-language culture and Arab identity, contrasts this with the post-colonial policy of Arabization, and analyses the relevance of the latter for civil conflicts in Southern Sudan, the Nuba Mountains, and, more recently, Darfur. Far from spreading Arabness, Arabization policy sharpened non-Arab and, in some cases, self-consciously ‘African’ (implying culturally pluralist) identities. Arabization policy also accompanied, in some quarters, the growth of an ideology of Arab cultural and racial supremacy that is now most evident in Darfur.
Finding Trajectories of Feature Points in a Monocular Image Sequence

Identifying the same physical point in more than one image, the correspondence problem, is vital in motion analysis. Most research for establishing correspondence uses only two frames of a sequence to solve this problem. By using a sequence of frames, it is possible to exploit the fact that due to inertia the motion of an object cannot change instantaneously. By using smoothness of motion, it is possible to solve the correspondence problem for arbitrary motion of several nonrigid objects in a scene. We formulate the correspondence problem as an optimization problem and propose an iterative algorithm to find trajectories of points in a monocular image sequence. A modified form of this algorithm is useful in case of occlusion also. We demonstrate the efficacy of this approach considering synthetic, laboratory, and real scenes.
Is There No End to the Total Syntheses of Strychnine? Lessons Learned in Strategy and Tactics in Total Synthesis

From the 19th century to the present, the complex indole alkaloid strychnine has engaged the chemical community. In this Review, we examine why strychnine has been and remains today an important target for directed synthesis efforts. A selection of the diverse syntheses of strychnine is discussed with the aim of identifying their influence on the evolution of the strategy and tactics of organic synthesis.
Photoelectric Cross-sections of Gas and Dust in Protoplanetary Disks

We provide simple polynomial fits to the X-ray photoelectric cross-sections (0.03keV 1 μm) can reduce the X-ray opacity of dust appreciably at EX ∼ 1 keV, coincident with the peak of typical T Tauri X-ray spectra. However, the reduction of dust opacity by dust settling, which is known to occur in protoplanetary disks, is probably a more significant effect. The absorption of 1‐10 keV X-rays is dominated by gas opacity once the dust abundance has been reduced to about 1% of its diffuse interstellar value. The gas disk establishes a floor to the opacity at which point X-ray transport becomes insensitive to further dust evolution. Our choice of fitting function follows that of Morrison & McCammon, providing a degree of backward compatibility.
Black Gold & Fool’s Gold: Speculation in the Oil Futures Market

This paper addresses the question of whether the oil price spike of 2003-2008 was a bubble. We document and discuss what is known about the level of speculation in the paper oil market. We then analyze the dynamics of the term structure of futures prices, both during the earlier period of 1985-2002 and during the spike. The dynamics of the term structure changed in important ways during this latter period, and we explain how this may have contributed to generating a bubble. We also explain how this answers the puzzle of the lack of accumulating above-ground inventories. Finally, we discuss the implications for regulatory reform of the paper oil markets.
REAL ASPECTS OF EXCHANGE RATE REGIME CHOICE WITH COLLAPSING FIXED RATES

Abstract Typical evaluations of the choice of exchange rate regime examine the performance of the real economy and assume that the regimes last indefinitely. In contrast, actual regimes are quite transitory. This paper examines how the predictions of two popular models for the determination of some real economic variables must be modified when agents rationally perceive that a fixed rate regime will be transitory. The models studied are simple stochastic versions of the models in Dornbusch (1976) and Flood and Marion (1982) .
Atomic and electronic structure of solids

This text is a modern treatment of the theory of solids. The core of the book deals with the physics of electron and phonon states in crystals and how they determine the structure and properties of the solid. The discussion uses density functional theory as a starting point and covers electronic and optical phenomena, magnetism and superconductivity. There is also an extensive treatment of defects in solids, including point defects, dislocations, surfaces and interfaces. A number of modern topics where the theory of solids applies are also explored, including quasicrystals, amorphous solids, polymers, metal and semiconductor clusters, carbon nanotubes and biological macromolecules. Numerous examples are presented in detail and each chapter is accompanied by problems and suggested further readings. An extensive set of appendices provides all the necessary background for deriving all the results discussed in the main body of the text.
Motivation Deprivation: No Reason to Stay

/ can't motivate my teachers anymore. I pay them more than neighboring districts. I offer them an excellent fringe bene fits package, we have a good retirement system, our schools are bright and clean, and our students are relatively consi derate. Maybe it's me. Maybe what I need is a good course in human relations.
Economic stagnation, fixed factors, and policy thresholds

Analysis of decade-long growth rates in all countries shows a striking regularity: episodes of rapid growth are limited largely to a middle range of initial income; neither very poor nor very rich countries experienced rapid growth. Episodes of negative growth are limited to low and middle-income countries. This paper develops a simple model that sheds light on this experience. The model has two familiar elements from the growth literature: (1) a Stone-Gearly utility function (saving is low at low income), and (2) fixed factors with the marginal product of capital bounded away from zero. The second property is derived by assuming an elasticity of substitution greater than one between an exogenous labor input and a broad concept of capital. The paper extends the model to consider multiple capital goods and public capital. It finds that stagnation is consistent with an array of statistical evidence because of fixed factors. Economic policies - not initial conditions - determine whether countries stagnate. Results confirm that initial income and policy variables have a different effect on whether a country stagnates than they do on the rate of growth once it starts growing, as expected from the distinction between steady-state and transitional effects. These results suggest that cross-section growth regressions may be misspecified because of the nonlinearity inherent in the possibility of steady-state stagnation.
Electron Mobility in Inversion and Accumulation Layers on Thermally Oxidized Silicon Surfaces

Accurate modeling of MOS devices requires quantitative knowledge of carrier mobilities in surface inversion and accumulation layers. Optimization of device structures and accurate circuit simulation, particularly as technologies push toward fundamental limits, necessitate an understanding of how impurity doping levels, oxide charge densities, process techniques, and applied electric fields affect carrier surface nobilities. It is the purpose of this paper to present an extensive set of experimental results on the behavior of electron surface mobility in thermally oxidized silicon structures. EmpiricaI equations are developed which allow the calculation of electron mobility under a wide variety of substrate, process, and electrical conditions. The experimental results are interpreted in terms of the dominant physical mechanisms responsible for mobility degradation at the Si/SiO/sub 2/ interface. From the observed effects of process parameters on mobility roll-off under high vertical fields, conclusions are drawn about optimum process conditions for maximizing mobility. The implications of this work for performance limits of several types of MOS devices are described.
Formation of Quantum-Degenerate Sodium Molecules

Ultracold sodium molecules were produced from an atomic Bose-Einstein condensate by ramping an applied magnetic field across a Feshbach resonance. More than ${10}^{5}$ molecules were generated with a conversion efficiency of $\ensuremath{\sim}4%$. Using laser light resonant with an atomic transition, the remaining atoms could be selectively removed, preventing fast collisional relaxation of the molecules. Time-of-flight analysis of the pure molecular sample yielded an instantaneous phase-space density greater than 20.
Community College Growth Opportunities: Untapped Potential in America's Heartland?

Over 1,100 two-year public institutions have been established in the U.S. which enroll almost two-fifths of all students in postsecondary education. However, some parts of the country may not be adequately served by these educational institutions despite demand and supply indicators that indicate future growth potential in the sub-baccalaureate educational market. This paper examines the geographical, demographic, and economic characteristics of counties that host community colleges. It finds that community college access is uneven. A multiple regression analysis reveals several correlates with community college location and identifies counties where opportunities may exist to “seed” additional community colleges.
The Zinc-62/copper-62 generator: A convenient source of copper-62 for radiopharmaceuticals

Abstract 62 Cu is a short-lived (9.8 min) positron emitter results from the decay of 62 Zn (9.2 h). 62 Zn is easily produced in good yield (2.3 mCi/μAh) by bombardment of a 0.4 mm thick target of natural copper with 22 MeV protons. A simple separation of zinc and copper as chloride complexes using anion exchange chromatography is described. The performance of 62 Zn/ 62 Cu generator system based upon a similar anion exchange separation is evaluated. Using a 0.7 cm i.d. × 8.0 cm high column of “Dowex 1-X10” resin of 200–400 mesh, eluted with 0.1 N HCl containing 100 mg/ml NaCl and 1 μg/ml CuCl 2 , over 85% of the available 62 Cu is recovered in a 3.5 ml volume. The 62 Zn is less than 0.001% at the time of elution. A variety of potentially useful radiopharmaceutics using this generator system have been developed and are being evaluated in clinical trials.
Negative Externalities and Evolutionary Implementation

In this paper, we model externality abatement as an implementation problem. Our model incorporates techniques from evolutionary game theory, assuming that agents dynamically adjust their choices in response to the incentives they currently face. We offer a simple condition on aggregate payoffs under which a planner with limited information about preferences can nevertheless ensure that efficient behaviour is globally stable. Finally, we present a series of applications that show that our sufficient condition holds in a variety of models involving negative externalities.
The Nucleosynthetic Signature of Population III

Growing evidence suggests that the first generation of stars may have been quite massive (~100-300 M?). Could these stars have left a distinct nucleosynthetic signature? We explore the nucleosynthesis of helium cores in the mass range MHe = 64-133 M?, corresponding to main-sequence star masses of approximately 140-260 M?. Above MHe = 133 M?, without rotation and using current reaction rates, a black hole is formed, and no nucleosynthesis is ejected. For lighter helium core masses, ~40-63 M?, violent pulsations occur, induced by the pair instability and accompanied by supernova-like mass ejection, but the star eventually produces a large iron core in hydrostatic equilibrium. It is likely that this core, too, collapses to a black hole, thus cleanly separating the heavy-element nucleosynthesis of pair instability supernovae from those of other masses, both above and below. Indeed, black hole formation is a likely outcome for all Population III stars with main-sequence masses between about 25 and 140 M? (MHe = 9-63 M?) as well as those above 260 M?. Nucleosynthesis in pair instability supernovae varies greatly with the mass of the helium core. This core determines the maximum temperature reached during the bounce. At the upper range of exploding core masses, a maximum of 57 M? of 56Ni is produced, making these the most energetic and the brightest thermonuclear explosions in the universe. Integrating over a distribution of masses, we find that pair instability supernovae produce a roughly solar distribution of nuclei having even nuclear charge (Si, S, Ar, etc.) but are remarkably deficient in producing elements with odd nuclear charge?Na, Al, P, V, Mn, etc. This is because there is no stage of stable post-helium burning to set the neutron excess. Also, essentially no elements heavier than zinc are produced owing to a lack of s- and r-processes. The Fe/Si ratio is quite sensitive to whether the upper bound on the initial mass function is over 260 M? or somewhere between 140 and 260 M?. When the yields of pair instability supernovae are combined with reasonable estimates of the nucleosynthesis of Population III stars from 12 to 40 M?, this distinctive pattern of deficient production of odd-Z elements persists. Some possible strategies for testing our predictions are discussed.
SCALING OF ENTANGLEMENT IN FINITE ARRAYS OF EXCHANGE-COUPLED QUANTUM DOTS

We present a nite-size scaling analysis of the entanglement in a two-dimensional arrays of quantum dots modeled by the Hubbard Hamiltonian on a triangular lattice. Using multistage block renormalization group approach, we have found that there is an abrupt jump of the entanglement when a rst-order quantum phase transition occurs. At the critical point, the entanglement is constant, independent of the block size.
Assignment-based partitioning in a condition monitoring system

A condition monitoring system tracks real-world variables and alerts users when a predefined condition becomes true, e.g., when enemy planes take off, or when suspicious terrorist activities and communication are detected. However, a monitoring server can easily get overwhelmed by rapid incoming data. To prevent this, we partition the condition being monitored and distribute the workload onto several independent servers. In this paper, we study the problem of how to make a partitioned system behave “equivalently” to a one-server system. We identify and formally define three desirable properties of a partitioned system, namely, orderedness, consistency, and completeness. We propose assignment-based partitioning as a solution that can handle opaque conditions and simplifies load balancing. We also look at a few typical partitioned systems, and discuss their merits using several metrics that we define. Finally, an algorithm is presented to reduce complex system configurations to simpler ones.
Parameterized Modal Satisfiability

We investigate the parameterized computational complexity of the satisfiability problem for modal logic and attempt to pinpoint relevant structural parameters which cause the problem’s combinatorial explosion, beyond the number of propositional variables v. To this end we study the modality depth, a natural measure which has appeared in the literature, and show that, even though modal satisfiability parameterized by v and the modality depth is FPT, the running time’s dependence on the parameters is a tower of exponentials (unless P = NP). To overcome this limitation we propose possible alternative parameters, namely diamond dimension and modal width. We show fixed-parameter tractability results using these measures where the exponential dependence on the parameters is much milder (doubly and singly exponential respectively) than in the case of modality depth thus leading to FPT algorithms for modal satisfiability with much more reasonable running times. We also give lower bound arguments which prove that our algorithms cannot be improved significantly unless the Exponential Time Hypothesis fails.
Life Cycle Considerations in Propulsion Alternatives for Fast Vessels

Fast vessels are being built and operated for a large range of passenger-carrying applications. Fast cargo-carrying vessels are being considered in a variety of sizes as well. A major decision in design and construction of these vessels is the propulsion system; this decision has major impacts on the operation economics as well as the operational capabilities of the vessels. Factors involved in consideration of propulsion alternatives for fast vessels are examined, with emphasis upon the total life cycle operating implications of these factors. A methodology for considering the factors is suggested, and an example is presented with results of the consideration tradeoffs.
Partial Gaussian Graphical Model Estimation

This paper studies the partial estimation of Gaussian graphical models from high-dimensional empirical observations. We derive a convex formulation for this problem using l1-regularized maximum-likelihood estimation, which can be solved via a smoothing approximation algorithm. Statistical estimation performance can be established for our method. The proposed approach has competitive empirical performance compared with existing methods, as demonstrated by various experiments on synthetic and real data sets.
A growth model of inflation, tax evasion, and financial repression☆

Abstract This paper studies the relation between policies of financial repression, inflation rates, and long-term growth. We set up a model which shows that governments might want to express the financial sector because this sector is an ‘easy’ source of resources for the public budget (the inflation tax). To the extent that the financial sector increases the efficiency of the allocation of savings to productive investment, the choice of the degree of financial development will have real effects on the growth rate of the economy. In countries where tax evasion is large the government will optimally choose to repress the financial sector in order to increase seigniorage taxation. This policy will then reduce the efficiency of the financial sector, increase the costs of intermediation, reduce the amount of investment, and reduce the growth rate of the economy. Financial repression will therefore be associated with high tax evasion, low growth, and high inflation.
Nucleus reticularis lateralis involvement in the pressor component of the cerebral ischemic response

Lesions of the ventromedial portion of the nucleus reticularis lateralis (NRL) of the medulla oblongata in the rabbit significantly and markedly reduced the pressor component of the cerebral ischemic response (CIR) without altering vasomotor tone. Use of horseradish peroxidase as an anterograde and retrograde tracer indicated that the ventromedial NRL projects to the intermediolateral cell column (IML) of the upper thoracic spinal cord. Injections of glutamate into ventromedial NRL elevated blood pressure (BP), indicating that neuronal cell bodies in this area are capable of eliciting BP elevations when stimulated. These findings suggest that cell bodies in the ventromedial NRL are capable of eliciting pressor responses during the CIR via direct projections to sympathetic preganglionic cell bodies.
Creating a design science of human-computer interaction

Abstract An increasingly important task of computer science is to support the analysis and design of computers as things to learn from, as tools to use in one's work, as media for interacting with other people. Human-computer interaction (HCI) is the speciality area that addresses this task. Through the past two decades, HCI has pursued a broad and ambitious scientific agenda, progressively integrating its research concerns with the contexts of system development and use. This has created an unprecedented opportunity to manage the emergence of new technology so as to support socially responsive objectives.
Manipulation of data structures in a numerical analysis problem solving system: NAPSS

During the past several years considerable effort has been expended designing and implementing systems which are intended to provide extended capabilities for persons with mathematical problems to solve. Some of them in addition to NAPSS are CULLER FRIED, KLERER MAY, MAP, RECKONER, AMTRAN, and POSE. These systems can be classified as problem solving systems for applied mathematics.
Effects of biomechanical stress on bones in animals

The signals that allow bone to adapt to its mechanical environment most likely involve strain-mediated fluid flow through the canalicular channels. Fluid can only be moved through bone by cyclic loading, and the shear stresses generated on bone cells are proportional to the rate of loading. The proportional relation between fluid shear stresses on cells and loading rate predicts that the magnitude of bone's adaptive response to loading should be proportional to strain rate. For lower loading frequencies within the physiologic range, experimental evidence shows this is true. It is also true that the mechanical sensitivity of bone cells saturates quickly, and that a period of recovery either between loading cycles or between periods of exercise can optimize adaptive response. Together, these concepts suggest that short periods of exercise, with a 4-8 h rest period between them, are a more effective osteogenic stimulus than a single sustained session of exercise. The data also suggest that activities involving higher loading rates are more effective for increasing bone formation, even if the duration of the activity is short.
Addition of Carbon-Based Nucleophiles to Fmoc-Protected Acyl Iminium Ions

Weakly basic carbon nucleophiles add efficiently to a Fmoc-protected N,O-acetal compound. The new reactions highlight the compatibility of the Fmoc protecting group with moderately basic reaction conditions and should serve as a model for the development of more efficient syntheses of Fmoc-protected amino acids.
Fishing in Poisson streams: Focusing on the whales, ignoring the minnows

This paper describes a low-complexity approach for reconstructing average packet arrival rates and instantaneous packet counts at a router in a communication network, where the arrivals of packets in each flow follow a Poisson process. Assuming that the rate vector of this Poisson process is sparse or approximately sparse, the goal is to maintain a compressed summary of the process sample paths using a small number of counters, such that at any time it is possible to reconstruct both the total number of packets in each flow and the underlying rate vector. We show that these tasks can be accomplished efficiently and accurately using compressed sensing with expander graphs. In particular, the compressive counts are a linear transformation of the underlying counting process by the adjacency matrix of an unbalanced expander. Such a matrix is binary and sparse, which allows for efficient incrementing when new packets arrive. We describe, analyze, and compare two methods that can be used to estimate both the current vector of total packet counts and the underlying vector of arrival rates.
General properties of holographic entanglement entropy

The Ryu-Takayanagi formula implies many general properties of entanglement entropies in holographic theories. We review the known properties, such as continuity, strong subadditivity, and monogamy of mutual information, and fill in gaps in some of the previously-published proofs. We also add a few new properties, including: properties of the map from boundary regions to bulk regions implied by the RT formula, such as monotonicity; conditions under which subadditivity-type inequalities are saturated; and an inequality concerning reflection-symmetric states. We attempt to draw lessons from these properties about the structure of the reduced density matrix in holographic theories.
Surface Recombination Measurements in HgCdTe by Optical Modulation Frequency Response

The frequency response in the modulation of the excess electron concentration, produced by a modulated photogenerating pump beam, is used to determine bulk life-time and the surface or interface recombination velocity. The depth-wise integrated excess electron concentration is contactlessly monitored by the proportional absorption/ transmission modulation of a second probe beam. Using this approach over the 20 kHz to 3 MHz frequency range recombination velocities up to 104 cm/sec have been measured in n-type epitaxial HgCdTe films.
Stereoselective formation of 1,4-dialkoxy-1,3-dienes from propargyl ethers and molybdenum carbene complexes

Abstract Under mild conditions, 1-4-dialkoxy-1,3-butadienes can be smoothly prepared with a high level of stereoselectivity by thermolysis of molybdenum carbene complexes in the presence of propargyl ethers.
A General Method to Estimate Earthquake Moment and Magnitude Using Regional Phase Amplitudes

Abstract This article presents a general method of estimating earthquake magnitude using regional phase amplitudes, called regional M 0 or regional M w . Conceptually, this method uses an earthquake source model along with an attenuation model and geometrical spreading that accounts for the propagation to utilize regional phase amplitudes of any phase and frequency. Amplitudes are corrected to yield a source term from which one can estimate the seismic moment. Moment magnitudes can then be reliably determined with sets of observed phase amplitudes rather than predetermined ones and afterward averaged to robustly determine this parameter. We first examine in detail two events to demonstrate the methodology. We then look at various ensembles of phases and frequencies and compare results to existing regional methods. We find regional M 0 to be a stable estimator of earthquake size that has several advantages over other methods. Because of its versatility, it is applicable to many more events, particularly smaller events. We make moment estimates for earthquakes ranging from magnitude 2 to as large as 7. Even with diverse input amplitude sources, we find magnitude estimates with this method to be more robust than typical magnitudes and existing regional methods, and the magnitude estimates might be tuned further to improve upon them. The method yields a more meaningful quantity of seismic moment, which can be recast as M w . Lastly, it is applied here to the Middle East region using an existing calibration model, but it would be easy to transport to any region with suitable attenuation calibration.
Evaluation of metal and radionuclide data from neutron activation and acid-digestion-based spectrometry analyses of background soils: Significance in environmental restoration

A faster, more cost-effective, and higher-quality data acquisition for natural background-level metals and radionuclides in soils is needed for remedial investigations of contaminated sites. The advantages and disadvantages of neutron activation analysis (NAA) compared with those of acid-digestion-based spectrometry (ADS) methods were evaluated using Al, Sb, As, Cr, Co, Fe, Mg, Mn, Hg, K, Ag,232Th,235U,238U, V, and Zn data. The ADS methods used for this project were inductively coupled plasma (ICP), ICP-mass spectrometry (ICP-MS), and alpha spectrometry. Scatter plots showed that the NAA results for As, Co, Fe, Mn,232Th, and238U are reasonably correlated with the results from the other analytical methods. Compared to NAA, however, the ADS methods underestimated Al, Cr, Mg, K, V, and Zn. Because of the high detection limits of ADS methods, the scatter plots of Sb, Hg, and Ag did not show a definite relationship. The NAA results were highly correlated with the alpha spectrometry results for232Th and238U but poorly correlated for235U. The NAA, including the delayed neutron counting, was a far superior technique for quantifying background levels of radionuclides (232Th,235U, and238U) and metals (Al, Cr, Mg, K, V, and Zn) in soils.
The Economic Consequences of Regulatory Taking Risk on Land Value and Development Activity

Abstract In this paper the real options approach to land valuation is extended by: (i) showing how land value may be adversely effected when localities threaten a regulatory taking with less than full compensation, (ii) quantifying the resulting probability of development, which may increase in an attempt to thwart the taking of development rights; and (iii) measuring the value of lost income on an ex ante basis when an interim taking occurs. We find that the economic impact of such regulation can be substantial, which has implications for measuring just compensation claims as well as for general land use regulatory policy and related legal theory.
Analysis of defect-assisted tunneling based on low frequency noise measurements of resonant tunnel diodes

Abstract An experimental apparatus and procedure using noise measurement techniques have been developed in order to identify conduction mechanisms in RTDs due to defect assisted tunneling. The theory of noise measurements is discussed as the basis for the appropriate modelling of RTD noise data. The activation energies and capture cross-sections have been determined in a typical RTD for each of three distinct trap levels. A conjecture is made as to the physical location of the traps. This interpretation yields qualitative behavior consistent with the known bias and temperature dependence of the experimental results.
Compensation for image retention in an amorphous silicon detector

Because of traps in the photodiodes, amorphous silicon detectors retain charge and release it slowly after exposure. One effect of this property is that after an exposure, a ghost image may appear in subsequent images. This is a particular problem when fluoroscopic imaging follows radiographic exposure. In this paper we propose a method for predicting the magnitude of the ghost image so that it can be eliminated. The method uses linear systems theory to model the time behavior of the signal. Then the model is used to predict the offset as a function of time so that offset correction can be performed.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Normal binary graph models

We show that the marginal semigroup of a binary graph model is normal if and only if the graph is free of K4 minors. The technique, based on the interplay of normality and the geometry of the marginal cone, has potential applications to other normality questions in algebraic statistics.
Improved Physics for Simulating Submicron Bipolar Devices

The conventional device physics in most numerical simulations of bipolar transistors may not predict the measured electrical performance of shallow heavily doped emitters and bases. This paper summarizes improved device physics for numerical simulations of solid-state devices with dopant densities up to about 3 x 10 /sup 20/ cm /sup -3/ and with junction depths as small as 0.1 μm. This improved device physics pertains to bandgap narrowing, effective intrinsic carrier concentrations, carrier mobilities, and lifetimes. When this improved physics is incorporated into device analysis codes such as SEDAN and then used to compute the electrical performance of n-p-n transistors, the predicted values agree very well with the measured values of the current-voltage characteristics and dc common emitter gains for devices with emitter-base junction depths between 10-0.16 μm.
Damage tolerant design using collapse techniques

A new approach to the design of structures for improved global damage tolerance is presented. In its undamaged condition the structure is designed subject to strength, displacement and buckling constraints. In the damaged condition the only constraint is that the structure will not collapse. The collapse load calculation is formulated as a maximization problem and solved by an interior extended penalty function. The design for minimum weight subject to constraints on the undamaged structure and a specified level of the collapse load is a minimization problem which is also solved by a penalty function formulation. Thus the overall problem is of a nested or multilevel optimization. Examples are presented to demonstrate the difference between the present and more traditional approaches.
Development of high current and high brightness negative hydrogen ion sources

Negative hydrogen ions have found important applications in particle accelerators and in fusion research. These ions can be generated from two different types of ion sources---the surface conversion source and the volume production source. Recent experiments demonstrate that H/sup /minus// current exceeding 1 A can be obtained from both types of ion sources. Because of the lower H/sup /minus// ion temperature and the fact that they can be operated without cesium, volume H/sup /minus// sources are highly desired. However, further technology must be developed on the control of electrons and the reduction of gas flow before this type of sources become practical units of a multiampere neutral beam injection system.
9-Allenyl-9-BBN: A new reagent for the efficient allenylboration of carbonyl compounds producing the homopropargylic alcohols in high purity and yield

Abstract A new reagent, 9-allenyl-9-BBN (1), has been developed for the convenient and efficient synthesis of a variety of homopropargylic alcohols via the
Evaluation of Suspected Urinary Tract Infection in Ambulatory Women: A Cost-Utility Analysis of Office-Based Strategies

BACKGROUND The purpose of this study was to determine the most cost-effective strategy for managing suspected urinary tract infections in otherwise healthy adult women presenting to their primary care physician with dysuria and no symptoms or signs of pyelonephritis. Several office-based management strategies are considered: empiric therapy, use of dipstick analysis, use of complete urinalysis, and several strategies using office or laboratory cultures. METHODS We constructed a decision tree using model probabilities obtained from the literature. Where published probabilities were unavailable, we used extensive sensitivity analyses. Utilities were obtained from the Index of Well-Being. We obtained costs by surveying hospitals, physicians, and pharmacies. RESULTS The most cost-effective strategy is to treat empirically ($71.52 per quality-adjusted life month, QALM). When the cost of antibiotics exceeds $74.50 or if the prior probability of having a UTI is under 0.30, then treatment guided by the results of a complete urinalysis is preferred. While it was the preferred strategy, other strategies (complete urinalysis, culture and treat, and dipstick testing only) were associated with greater utility. The marginal cost-effectiveness of these strategies compared with empiric therapy ranged from $2964 to $48,460 per additional QALM. CONCLUSIONS The preferred strategy of empiric therapy is robust over a wide range of sensitivity analyses. While empiric therapy is associated with the best cost-utility ratio, doing a culture yields the greatest utility at greater incremental cost per QALM. Many primary care physicians already treat UTIs empirically with antibiotics. This study confirms that empiric therapy, while frowned upon by some, is a cost-effective strategy. Other strategies may be considered, but at greater marginal cost. Ultimately these findings need to be confirmed in clinical trials.
A Low-Power, Compact, Adaptive Logarithmic Transimpedance Amplifier Operating Over Seven Decades of Current

This paper presents a detailed insight into the design space of wide-range transimpedance amplifiers enabling the design of micro-power, adaptive circuits for integrated current sensing applications. The analysis proves that the power dissipation of the nonadaptive structures varies linearly with dynamic range and quadratically with bandwidth. We present two adaptation techniques, modifying the bias current or output resistance, both of which alleviate this strong dependence on dynamic range. It is shown that adapting the bias current is most suitable for our application which requires a modest bandwidth but very wide dynamic range. Measurements demonstrate operation with currents ranging seven orders of magnitude from 200 fA to 2 muA with an average error of 0.8% and maximum error of 3.4%. The power consumption averaged over this entire range of currents is 3.45 muW . Either signal-to-noise ratio (SNR) or bandwidth can be made to tradeoff with the input current magnitude depending on the application. If the bandwidth is limited to 5 kHz, it achieves an average SNR of 65 dB.
A study of compaction of composite particles by multi-particle finite element method

We study the compaction of composite mixture of soft and hard micro-/nano-size particles using multi-particle finite element method. In this method, each particle is fully discretized into finite element mesh. Local non-uniform contact deformation and non-uniformity stress chains transmitted through the composite are well illustrated. In this work, we focus on the effect of inter-particle friction and volume fraction of hard particles on compaction pressure. Results of closed die compaction of 400 two-dimensional monosize spherical particles of zero and 40% volume fraction hard particles are presented. The results show that compaction pressure increases with inter-particle friction and volume fraction of hard particles. The predicted compaction pressure curves are in good agreement with experimental data and other models.
Characterization of the Dip Pen Nanolithography Process for Nanomanufacturing

Dip pen nanolithography (DPN) is a flexible nanofabrication process for creating 2-D nanoscale features on a surface using an “inked” tip. Although a variety of ink-surface combinations can be used for creating 2-D nanofeatures using DPN, the process has not yet been characterized for high throughput and high quality manufacturing. Therefore, at present it is not possible to (i) predict whether fabricating a part is feasible within the constraints of the desired rate and quality and (ii) select/design equipment appropriate for the desired manufacturing goals. Herein, we have quantified the processing rate, tool life, and feature quality for DPN line writing by linking these manufacturing metrics to the process/system parameters. Based on this characterization, we found that (i) due to theoretical and practical constraints of current technology, the processing rate cannot be increased beyond about 20 times the typical rate of ∼1 μm2 /min, (ii) tool life for accurate line writing is limited to 1–5 min, and (iii) sensitivity of line width to process parameters decreases with an increase in the writing speed. Thus, we conclude that for a high throughput and high quality system, we need (i) parallelization or process modification to improve throughput and (ii) accurate fixtures for rapid tool change. We also conclude that process control at high speed writing is less stringent than at low speed writing, thereby suggesting that DPN has a niche in high speed writing of narrow lines.
A Computational Procedure for Diffuser-Combustor Flow Interaction Analysis

This paper describes a diffuser-combustor flow interaction analysis procedure for gas turbine combustion systems. The method is based on the solution of the Navier-Stokes equations in a generalized non-orthogonal coordinate system. The turbulence effects are modeled via the standard two-equation (k-e) model. The method has been applied to a practical gas turbine combustor-diffuser system that includes support struts and fuel nozzles. Results have been presented for a three-dimensional simulation, as well as for a simplified axisymmetric simulation. The flow exhibits significant three-dimensional behavior. The axisymmetric simulation is shown to predict the static pressure recovery and the total pressure losses reasonably well.Copyright © 1990 by ASME
LP Decoding Corrects a Constant Fraction of Errors

We show that for low-density parity-check (LDPC) codes whose Tanner graphs have sufficient expansion, the linear programming (LP) decoder of Feldman, Karger, and Wainwright can correct a constant fraction of errors. A random graph will have sufficient expansion with high probability, and recent work shows that such graphs can be constructed efficiently. A key element of our method is the use of a dual witness: a zero-valued dual solution to the decoding linear program whose existence proves decoding success. We show that as long as no more than a certain constant fraction of the bits are flipped by the channel, we can find a dual witness. This new method can be used for proving bounds on the performance of any LP decoder, even in a probabilistic setting. Our result implies that the word error rate of the LP decoder decreases exponentially in the code length under the binary-symmetric channel (BSC). This is the first such error bound for LDPC codes using an analysis based on "pseudocodewords." Recent work by Koetter and Vontobel shows that LP decoding and min-sum decoding of LDPC codes are closely related by the "graph cover" structure of their pseudocodewords; in their terminology, our result implies that that there exist families of LDPC codes where the minimum BSC pseudoweight grows linearly in the block length
Benign Breast Disease Heterogeneity: Association with histopathology, age, and ethnicity

Background Benign breast biopsies with concurrent multiple benign lesions with different histopathologic diagnoses were termed heterogeneous benign breast disease (HBBD). Multiplicity of benign breast disease (BBD) lesions in a biopsy is a risk factor for progression to breast cancer (BC). Elucidation of the biological characteristics and clinical implications of HBBD may also be relevant to the refinement of risks for BC in women with a BBD diagnosis. Design In this study, we investigated the association of HBBD with histopathology, age, and ethnicity. A cohort of 4,341 women, 1,208 African Americans and 3,133 Caucasians, diagnosed with BBD, was identified after examination of an excisional breast biopsy. BBD biopsies were categorized as nonproliferative (NP, low risk or risk 1 lesions), proliferative without atypia (P, intermediate risk or risk 2 lesions), and proliferative with atypia (AH, high risk or risk 3 lesions). A BBD biopsy with only a single BBD lesion was termed simple BBD (SBBD). BBD biopsies with multiple lesions were further classified as single level HBBD (SL-HBBD) if the concurrent lesions were within the same risk level, or as multiple level HBBD (ML-HBBD) if lesions fell into more than one risk group. Results In this cohort, 69% of women with a BBD diagnosis fit the HBBD criteria. Among women with HBBD, ML-HBBD was almost three times more prevalent than SL-HBBD and was significantly more likely to be composed of risk 2 and risk 3 lesions. The likelihood of HBBD was 57% higher in Caucasian American women than in African American women with BBD (OR 1.57; 95% CI: 1.37, 1.81). The average lesion number in HBBD was directly proportional to increasing lesion risk (P 55 years had a 3.12 (95% CI: 2.59, 3.75) and a 2.28 (95% CI: 1.94, 2.68) fold higher likelihood of HBBD compared to those ≤45 years. Significant interaction was found between concurrent lesion levels and age (P 55 years, respectively. Conclusion HBBD is more prevalent in Caucasian American women than in African American women. Women with higher risk BBD lesions are more likely to have HBBD. Lesion number and higher risk BBD lesions are significantly correlated with ML-HBBD. Additionally, the associations of HBBD and lesion risk level are modified by age.
Monetary politics and unemployment persistence

Abstract This paper develops a positive model of monetary policy that allows for persistent unemployment and electoral uncertainty. The common credibility problem associated with low-inflation monetary policy results in both a more severe inflation bias and a stabilization bias. However, a simple state contingent performance contract eliminates both biases. Monetary policy is also subject to two different strategic political considerations: It is used to influence future policy decisions as well as to increase the incumbent party's probability of re-election. This results in a political business cycle which, however, is fundamentally different for left-wing and right-wing governments.
Noncommutative solitons on Kahler manifolds

We construct a new class of scalar noncommutative multi-solitons on an arbitrary Kahler manifold by using Berezin's geometric approach to quantization and its generalization to deformation quantization. We analyze the stability condition which arises from the leading 1/ correction to the soliton energy and for homogeneous Kahler manifolds obtain that the stable solitons are given in terms of generalized coherent states. We apply this general formalism to a number of examples, which include the sphere, hyperbolic plane, torus and general symmetric bounded domains. As a general feature we notice that on homogeneous manifolds of positive curvature, solitons tend to attract each other, while if the curvature is negative they will repel each other. Applications of these results are discussed.
Automata-driven efficient subterm unification

Syntactic unification has widespread use in computing. There are several operations used in deductive computing such as critical pair generation, paramodulation and narrowing that require unifying a term s with every subterm of another term p. This subterm unification problem can be solved naively by repeatedly unifying s with each subterm of p in isolation. The drawback of doing unification in isolation is that commonality among subterms of p is ignored. We present an algorithm for efficient subterm unification by exploiting this commonality. The central idea used in our algorithm is to reduce the common part computation in unification into a string-matching problem and solve it efficiently using a string-matching automaton. The automaton succinctly captures the commonality between subterms of p. The string-matching approach, in conjunction with two new techniques called bidirectional-reduce and marking enables efficient unification of s with every subterm of p.