cssi/SciSciGPT-SciSciNet huggingface dataset:
Enhancing 5th graders' science content knowledge and self-efficacy through game-based learning

Many argue that games can positively impact learning by providing an intrinsically motivating and engaging learning environment for students in ways that traditional school cannot. Recent research demonstrates that games have the potential to impact student learning in STEM content areas and that collaborative gameplay may be of particular importance for learning gains. This study investigated the effects of collaborative and single game player conditions on science content learning and science self-efficacy. Results indicated that there were no differences between the two playing conditions; however, when conditions were collapsed, science content learning and self-efficacy significantly increased. Future research should focus on the composition of collaboration interaction among game players to assess what types of collaborative tasks may yield positive learning gains.
On models for multi-user Gaussian channels with fading

An analytically tractable model for Gaussian multiuser channels with fading is studied, and the capacity region of this model is found to be a good approximation of the capacity region of the original Gaussian network. This work extends the existing body of work on deterministic models for Gaussian multiuser channels to include the physical phenomenon of fading. In particular, it generalizes these results to a unicast, multiple node network setting with fading.
Worms: Identifying Impacts on Education and Health in the Presence of Treatment Externalities

This brief summarizes worms: identifying impacts on education and health in the presence of treatment externalities in Kenya for the period 1998-99. Intestinal helminthes includes hookworm, roundworm, whipworm, and schistoso-miasis-infect more than one-quarter of the world's population. Studies in which medical treatment is randomized at the individual level potentially doubly underestimate the benefits of treatment, missing externality benefits to the comparison group from reduced disease transmission, and therefore also underestimating benefits for the treatment group. The author evaluate a Kenyan project in which school-based mass treatment with deworming drugs was randomly phased into schools, rather than to individuals, allowing estimation of overall program effects. The program reduced school absenteeism in treatment schools by one-quarter, and was far cheaper than alternative ways of boosting school participation. Deworming substantially improved health and school participation among untreated children in both treatment schools and neighboring schools and these externalities are large enough to justify fully subsidizing treatment.
Biosynthesis and Chemical Synthesis of Presilphiperfolanol Natural Products

Presilphiperfolanols constitute a family of biosynthetically important sesquiterpenes which can rearrange to diverse sesquiterpenoid skeletons. While the origin of these natural products can be traced to simple linear terpene precursors, the details of the enzymatic cyclization mechanism that forms the stereochemically dense tricyclic skeleton has required extensive biochemical, computational, and synthetic investigation. Parallel efforts to prepare the unique and intriguing structures of these compounds by total synthesis have also inspired novel strategies, thus resulting in four synthetic approaches and two completed syntheses. While the biosynthesis and chemical synthesis studies performed to date have provided much insight into the role and properties of these molecules, emerging questions regarding the biosynthesis of newer members of the family and subtle details of rearrangement mechanisms have yet to be explored.
An Impossibility Theorem on Beliefs in Games

A paradox of self-reference in beliefs in games is identified, which yields a game-theoretic impossibility theorem akin to Russell’s Paradox. An informal version of the paradox is that the following configuration of beliefs is impossible:
Estimation of illuminant direction, albedo, and shape from shading

A robust approach to recovery of shape from shading information is presented. Assuming uniform albedo and Lambertian surface for the imaging model, methods are presented for the estimation of illuminant direction and surface albedo. The illuminant azimuth is estimated by averaging local estimates. The illuminant elevation and surface albedo are estimated from image statistics. Using the estimated reflectance map parameters, the surface shape is computed using a procedure that implements the smoothness constraint by enforcing the gradients of reconstructed intensity to be close to the gradients of the input image. Typical results on real images are given to illustrate the usefulness of this approach. >
The Future Is Now: The Formation of Single Low-Mass White Dwarfs in the Solar Neighborhood

Low-mass helium-core white dwarfs (M < 0:45 M� ) can be produced from interacting binary systems, and traditionally all of them have been attributed to this channel. However, a low-mass white dwarf could also result from a single star that experiences severe mass loss on the first ascent giant branch. A large population of low-mass He-core white dwarfs has been discovered in the old metal-rich cluster NGC 6791. There is therefore a mechanism in clusters to produce low-mass white dwarfs without requiring binary star interactions, and we search for evidence of a similar population in field white dwarfs. We argue that there is a significant field population (of order half of the detected systems)thatarisesfrom oldmetal-richstarswhichtruncatetheirevolutionpriortotheheliumflashfromseveremass loss. There is a consistent absence of evidence for nearby companions in a large fraction of low-mass white dwarfs. The number of old metal-rich field dwarfs is also comparable with the apparently single low-mass white dwarf population, and our revised estimate for the space density of low-mass white dwarfs produced from binary interactions is also compatible with theoretical expectations. This indicates that this channel of stellar evolution, hitherto thought hypothetical only, has been in operation in our own Galaxy for many billions of years. One strong implication of our model is that single low-mass white dwarfs should be good targets for planet searches because they are likely to arise from metal-rich progenitors. We also discuss other observational tests and implications, including the potential impact on SNIa rates and the frequency of planetary nebulae.
Inorganic nanostructures for photoelectrochemical and photocatalytic water splitting

The increasing human need for clean and renewable energy has stimulated research in artificial photosynthesis, and in particular water photoelectrolysis as a pathway to hydrogen fuel. Nanostructured devices are widely regarded as an opportunity to improve efficiency and lower costs, but as a detailed analysis shows, they also have considerably disadvantages. This article reviews the current state of research on nanoscale-enhanced photoelectrodes and photocatalysts for the water splitting reaction. The focus is on transition metal oxides with special emphasis of Fe2O3, but nitrides and chalcogenides, and main group element compounds, including carbon nitride and silicon, are also covered. The effects of nanostructuring on carrier generation and collection, multiple exciton generation, and quantum confinement are also discussed, as well as implications of particle size on surface recombination, on the size of space charge layers and on the possibility of controlling nanostructure energetics via potential determining ions. After a summary of electrocatalytic and plasmonic nanostructures, the review concludes with an outlook on the challenges in solar fuel generation with nanoscale inorganic materials.
De-monetisation, inflation and coffee: the demand for money in Uganda

This paper investigates the recent macroeconomic history of Uganda using time series models for the demand for the three main monetary aggregates. A collapse of income and high inflation led to de-monetisation. The flight from currency and demand deposits was limited by their use for transactions, but demand for time and savings deposits was largely a function of inflation. The role of the exchange rate and the price of coffee in determining an asset demand for money was mixed. Re-monetisation since the late 1980s has been slower than de-monetisation. Copyright 1999 by Oxford University Press.
Stochastic Model for Power Grid Dynamics

We introduce a stochastic model that describes the quasi-static dynamics of an electric transmission network under perturbations introduced by random load fluctuations, random removing of system components from service, random repair times for the failed components, and random response times to implement optimal system corrections for removing line overloads in a damaged or stressed transmission network. We use a linear approximation to the network flow equations and apply linear programming techniques that optimize the dispatching of generators and loads in order to eliminate the network overloads associated with a damaged system. We also provide a simple model for the operator's response to various contingency events that is not always optimal due to either failure of the state estimation system or due to the incorrect subjective assessment of the severity associated with these events. This further allows us to use a game theoretic framework for casting the optimization of the operator's response into the choice of the optimal strategy which minimizes the operating cost. We use a simple strategy space which is the degree of tolerance to line overloads and which is an automatic control (optimization) parameter that can be adjusted to trade off automatic load shed without propagating cascades versus reduced load shed and an increased risk of propagating cascades. The tolerance parameter is chosen to describes a smooth transition from a risk averse to a risk taken strategy. We present numerical results comparing the responses of two power grid systems to optimization approaches with different factors of risk and select the best blackout controlling parameter
Impulse control with random reaction periods: A central bank intervention problem

a b s t r a c t We model an impulse control problem when the controller's action affects the state as well as the dynamics of the state process for a random amount of time. We apply our model to solve a central bank intervention problem in the foreign exchange market when the market observes and reacts to the bank's interventions.
Robust Stabilization of Non-Minimum Phase Nonlinear Systems Using Extended High-Gain Observers

A robust, stabilizing output feedback controller for systems in the normal form, which could potentially include unstable zero dynamics, is presented. The control scheme adopted herein incorporates continuously-implemented sliding mode control-chosen for its robustness properties as well as its ability to prescribe or constrain the motion of trajectories in the sliding phase-and an extended high gain observer to estimate the derivatives of the output and one of the unknown functions. Stabilization in the case of an unknown control coefficient and uncertain constant parameters is shown.
COMPRESSIVE SENSING WITH LOCAL GEOMETRIC FEATURES

We propose a framework for compressive sensing of images with local distinguishable objects, such as stars, and apply it to solve a problem in celestial navigation. Specifically, let x ∈ ℝN be an N pixel image, consisting of a small number of local distinguishable objects plus noise. Our goal is to design an m × Nmeasurement matrix A with m ≪ N, such that we can recover an approximation to x from the measurements Ax. We construct a matrix A and recovery algorithm with the following properties: (i) if there are k objects, the number of measurements m is O((k log N)/(log k)), undercutting the best known bound of O(k log (N/k)) (ii) the matrix A is very sparse, which is important for hardware implementations of compressive sensing algorithms, and (iii) the recovery algorithm is empirically fast and runs in time polynomial in k and log(N). We also present a comprehensive study of the application of our algorithm to attitude determination, or finding one's orientation in space. Spacecraft typically use cameras...
Comparison of 1,4-distyrylfluorene and 1,4-distyrylbenzene analogues: synthesis, structure, electrochemistry and photophysics.

A series of nine 1,4-distyrylfluorene derivatives (2) functionalized with substituents of variable electron-donating or -accepting capabilities was synthesised. The photophysical properties of the molecules were investigated, including UV/vis absorption, photoluminescence emission, and fluorescence quantum yields. Photophysical properties of chromophores 2 were found to exhibit significant solvatochromic effects, especially in the Stokes shift and photoluminescence maxima. The electrochemical properties of series 2 were also assessed by cyclic voltammetry and differential pulse voltammetry. Results of photophysical and electrochemical analyses were further supported by DFT calculations (B3LYP/6-31G*) and single crystal X-ray diffraction on select molecules. The contributions of intermolecular π-stacking and hydrogen bonding to crystal packing are discussed. A series of nine 1,4-distyrylphenylene derivatives (3) were also synthesised and similarly characterized for comparison to photophysical and solvatochromic effects observed in series 2. Properties of similarly-substituted molecules in series 2 and 3 were compared to one another in order to assess the influence of the 1,4-fluorenylene unit.
First synthesis of antimalarial Machaeriols A and B

Abstract A short and efficient synthesis of the naturally occurring antimalarial compounds, Machaeriols A and B, from commercially available citronellal via hetero-Diels–Alder cycloaddition and Suzuki coupling in 33% overall yield is described.
Fine ZnO patterning with controlled sidewall-etch front slope

This paper describes a wet-etching technique that solves the major difficulty of fine patterning a c-axis oriented polycrystalline ZnO film. The technique uses aqueous NH/sub 4/Cl with electrolytically added copper ions and convection flow, and for the first time, allows the ZnO film to be etched 1) with controlled etch rate ratio between the vertical and horizontal etch rates and 2) with controlled etch-front slope. The ratio between the vertical and horizontal etch rates is as high as 20 to 1, while the angle between the sidewall etch-front surface and the substrate surface can be electrically controlled between 73/spl deg/ and 106/spl deg/. Also, ZnO films can now be patterned to fine features (even sub-/spl mu/m level) with a wet etchant. The electroless galvanic etching technique described in this paper produces uniform etching over a large area (larger than 3" in diameter).
A version of Simpson's rule for multiple integrals

Abstract Let M(f) denote the midpoint rule and T(f) the trapezoidal rule for estimating ∫ a b f(x) d x . Then Simpson's rule =λM(f)+(1−λ)T(f), where λ= 2 3 . We generalize Simpson's rule to multiple integrals as follows. Let Dn be some polygonal region in R n , let P0,…,Pm denote the vertices of Dn, and let Pm+1 equal the center of mass of Dn. Define the linear functionals M(f)=Vol(Dn)f(Pn+1), which generalizes the midpoint rule, and T(f)=Vol(Dn)([1/(m+1)]∑j=0mf(Pj)), which generalizes the trapezoidal rule. Finally, our generalization of Simpson's rule is given by the cubature rule (CR) Lλ=λM(f)+(1−λ)T(f), for fixed λ, 0⩽λ⩽1 . We choose λ, depending on Dn, so that Lλ is exact for polynomials of as large a degree as possible. In particular, we derive CRs for the n simplex and unit n cube. We also use points Qj∈∂(Dn), other than the vertices Pj, to generate T(f). This sometimes leads to better CRs for certain regions — in particular, for quadrilaterals in the plane. We use Grobner bases to solve the system of equations which yield the coordinates of the Qj's.
The Moral Imperative and Social Rationality of Government-Guaranteed Employment and Reskilling

Abstract Unemployment exacts a high cost to its victims, not only in lost income, but also in terms of quality of life (insecurity, depression, abandoned families, divorce, suicide and poorer health). It also exacts a high cost to society in terms of lost output, foregone tax revenue, depreciating human capital, and increased costs of welfare, crime and health care. Yet modern wealthy societies have, principally for the sake of price stability and to avoid the budget costs of a full remedy, chosen to tolerate a substantial level of permanent unemployment. This article explores the moral conditions of this social choice and its rationality in terms of social welfare. It makes and develops support for two claims: society's tolerance of involuntary unemployment is morally wrong, and it is socially and economically irrational. It concludes that government should guarantee employment by serving as employer of last resort and where appropriate provide for retraining.
Robust Estimation of Timing Yield with Partial Statistical Information on Process Variations

This paper illustrates the application of distributional robustness theory to compute the worst-case timing yield of a circuit. Our assumption is that the probability distribution of process variables are unknown and only the intervals of the process variables and their class of distributions are available. We consider two practical classes to group potential distributions. We then derive conditions that allow applying the results of the distributional robustness theory to efficiently and accurately estimate the worst-case timing yield for each class. Compared to other recent works, our approach can model correlations among process variables and does not require knowledge of exact function form of the joint distribution function of process variables. While our emphasis is on robust timing yield estimation, our approach is also applicable to other types of parametric yield.
Using Caenorhabditis elegans to probe toxicity of 1-alkyl-3-methylimidazolium chloride based ionic liquids

Ionic liquids are gaining attention as new solvents within the green chemistry community; however this attention has quickly outstripped current environmental and toxicological data available. In the present communication, we establish the use of Caenorhabditis elegans as a model organism for inexpensively and quickly exploring toxicological effects of 1-alkyl-3-methylimidazolium chloride ionic liquids.
Phase Equilibria in the System Barium Titanate—Strontium Titanate

Phase equilibria in the system BaTiO3–SrTiO3 (with 0 to 7 mol% SrTiO3) were studied at temperatures above 1600°C in air. Quenching experiments were performed using high-purity starting materials, and run products were examined by X-ray diffraction and differential scanning calorimetry to determine phase composition and Sr concentration. Melting involves a binary loop intersected by the invariant reaction hexagonal (Ba, Sr)TiO3(ss) ⇌ cubic (Ba, Sr)TiO3(ss) + liquid. In contrast with earlier work, these results indicate that there is no depression of the melting point with Sr addition and no congruent melting point in this compositional range.
A Tool and Methodology for AC-Stability Analysis of Continuous-Time Closed-Loop Systems

Presented are a methodology and a DFII-based tool for AC-stability analysis of a wide variety of closed-loop continuous-time systems (operational amplifiers and other linear circuits). The methodology used allows for easy identification and diagnostics of AC-stability problems including not only main-loop effects, but also local-instability loops in current mirrors, bias circuits and emitter or source followers without breaking the loop. The results of the analysis are easy to interpret. Estimated phase margin is readily available. Instability nodes and loops along with their respective oscillation frequencies are immediately identified and mapped to the existing circuit nodes, thus offering significant advantages compared to traditional "black-box" methods of stability analysis (transient overshoot, bode and phase margin plots, etc.). The tool for AC-stability analysis is written in SKILL/spl trade/ and is fully integrated in the DFII/spl trade/ environment. Its "pushbutton" graphical user interface (GUI) is easy to use and understand. The tool can be invoked directly from a Composer/spl trade/ schematic and does not require an active Analog Artist/spl trade/ session. The tool is not dependent on the use of a specific fabrication technology or process design kit customization. It requires OCEAN/spl trade/, Spectre/spl trade/ and waveform calculator capabilities to run.
Heavy sneutrinos as dark matter

Abstract We calculate the relic density of very heavy, stable scalar neutrinos in the minimal supersymmetric standard model. We include all two-body final states, as well as the effects of co-annihilation with scalar electrons. We find that the sneutrino relic density is in the cosmologically interesting region 0.1 ⪅ Ω ν h 2 ⪅ 1.0 for 550 GeV ⪅ m ν ⪅ 2300 GeV . For nominal values of the parameters of our galactic halo, recent results from the Heidelberg-Moscow direct detection experiment set an upper limit on Ω ν which is lower by a factor ranging from two to ten, depending on m ν .
Dynamics and Control of High Precision Magnetically Levitated Vibration Isolation Systems

In this paper, key issues associated with the dynamics and control of vibration isolation systems are addressed. We first focus on the selection of proper actuator and sensor locations leading to a controllable and observable system. The modal analysis method is used to develop a lumped-parameter model and to investigate the system's controllability and observability including the coupling effects introduced by the magnetic bearing. This analysis results in necessary and sufficient conditions for proper selection of actuator and sensor locations. Furthermore, the instability effects caused by magnetic bearing dynamics are investigated. A favorable pole-zero plot of the open loop transfer functions is presented along with necessary and sufficient condition for reducing the controller complexity.
Target fabrication for inertial confinement fusion and fast ignition

Summary form only given, as follows. Direct-drive inertial confinement fusion (ICF) offers the potential for high gain and is a leading candidate for an inertial fusion-energy power plant. Laser and target nonuniformities can seed hydrodynamic instabilities during the implosion that, in turn, can compromise target performance. This is the primary target physics issue for direct-drive ICF. Several methods have been devised to control these seeds and their subsequent growth, including laser beam smoothing, advanced pulse shaping, target design, etc. LLE's baseline direct-drive ignition design for the National Ignition Facility (presently under construction at the Lawrence Livermore National Laboratory) is composed of a thin (3-/spl mu/m) plastic shell enclosing a thick (350-/spl mu/m) deuterium-tritium (DT)-ice layer. It provides a gain of 45 in spherically symmetric calculations (30 m two-dimensional simulations which include the effects of laser and target nonuniformities). Recent improvements to the ignition target design include the addition of a picket to the beginning of the laser pulse shape that reduces both the seeds and growth rate of the hydrodynamic instabilities Experiments performed on the 60-beam, 30-kJ UV OMEGA laser on warm and cryogenic targets are diagnosed using X-rays and nuclear particles. Significant improvements in warm capsule implosion target performance have been observed with improvements in beam smoothing on OMEGA.
Characterization of the atmosphere of the hot Jupiter HAT-P-32Ab and the M-Dwarf companion HAT-P-32B

We report secondary eclipse photometry of the hot Jupiter HAT-P-32Ab, taken with Hale/Wide-field Infra-Red Camera (WIRC) in H and K_S bands and with Spitzer/IRAC at 3.6 and 4.5 μm. We carried out adaptive optics imaging of the planet host star HAT-P-32A and its companion HAT-P-32B in the near-IR and the visible. We clearly resolve the two stars from each other and find a separation of 2."923 ± 0."004 and a position angle 110.o64 ± 0.o12. We measure the flux ratios of the binary in g'r'i'z' and H and K_S bands, and determine T_(eff)= 3565 ± 82 K for the companion star, corresponding to an M1.5 dwarf. We use PHOENIX stellar atmosphere models to correct the dilution of the secondary eclipse depths of the hot Jupiter due to the presence of the M1.5 companion. We also improve the secondary eclipse photometry by accounting for the non-classical, flux-dependent nonlinearity of the WIRC IR detector in the H band. We measure planet-to-star flux ratios of 0.090% ± 0.033%, 0.178% ± 0.057%, 0.364% ± 0.016%, and 0.438% ± 0.020% in the H, K_S , 3.6 and 4.5 μm bands, respectively. We compare these with planetary atmospheric models, and find they prefer an atmosphere with a temperature inversion and inefficient heat redistribution. However, we also find that the data are equally well described by a blackbody model for the planet with T_p = 2042 ± 50 K. Finally, we measure a secondary eclipse timing offset of 0.3 ± 1.3 minutes from the predicted mid-eclipse time, which constrains e = 0.0072^(+0.0700)_(-0.0064) when combined with radial velocity data and is more consistent with a circular orbit.
Misclassification of the dependent variable in binary choice models: evidence from five Latin American countries

Misclassification of the dependent variable in binary choice models can result in inconsistency of the parameter estimates. I estimate probit models that treat misclassification probabilities as estimable parameters for three labour market outcomes: formal sector employment, pension contribution and job change. I use Living Standards Measurement Study (LSMS) data from Nicaragua, Peru, Brazil, Guatemala and Panama. I find that there is a significant misclassification in 11 of the 16 cases that I investigate. If misclassification is present but is ignored, estimates of the probit parameters and their SEs are biased toward zero. In most cases, predicted probabilities of the outcomes are significantly affected by misclassification of the dependent variable. Even a moderate degree of misclassification can have substantial effects on the estimated parameters and on many of the predictions.
Interconnection delay in very high-speed VLSI

Interconnection delay of VLSI in high-speed digital systems is addressed. A formal analysis of the signal propagation delay in VLSI circuits is presented. It is shown that, depending on the circuit parameters, there are basically two delay domains: the RC delay domain and the transmission-line-delay domain. The results derived from the more traditional lumped-RC model mainly capture the properties of the RC delay domain. However, in the transmission-line-delay domain the wire inductance becomes an important factor, and hence RC modeling is no longer adequate to estimate the delay. Two delay formulas are derived in this paper for the RC delay domain and the transmission-line-delay domain. The effect of feature size scaling on VLSI circuit performance is evaluated, and the inherent limitation on scaling due to interconnection delay is discussed. Finally, the relationship between delay and technology parameters such as wire resistance, capacitance, inductance, wire width and length, and load capacitance is investigated to provide design guidelines. >
Application of quality function deployment to the design of a lithium battery

Quality Function Deployment (QFD) is the tool we have selected to aid in the design, development and subsequent commercial manufacture of a lithium/thionyl chloride "D" cell for use in weapons applications. QFD is a structured methodology used to help assure that customer needs and expectations will be satisfied throughout the product life cycle. In this paper, we describe our application of QFD, some of the lessons learned, and what we expect to be the final product of this QFD exercise. >
Innovative quantum technologies for microgravity fundamental physics and biological research

The many advanced technology requirements dictated by the demanding low-Earth orbit research environment can only be satisfied through the adaptation of innovative methods and technologies. The fundamental physics research program currently supports research in four areas: gravitational and relativistic physics, laser cooling and atomic physics, low temperature and condensed matter physics, and biological physics. The microgravity fundamental physics is one of the science disciplines within the new NASA Office of Biological and Physical Sciences Research, where quantum technology plays a major role. Quantum technology, based on controlled manipulation of fundamentally quantum processes of atoms, molecules, or soft matter, enables novel and significantly extended capabilities. This paper presents a new technology program, within the fundamental physics, focusing on four quantum technology areas: quantum atomics, quantum optics, space superconductivity and quantum sensor technology, and quantum fluid based sensor and modeling technology.
A comparison of voltage-mode soft-switching methods for PWM converters

A comparison study was conducted to characterize the loss mechanisms, component stresses, and overall efficiencies of a group of voltage-mode soft-switching pulse width modulation (PWM) methods, including two methods developed by the authors. All soft-switching methods in the selected group allow zero voltage turn-on and turn-off of the main switch and utilize a single auxiliary switch with some resonant components. Advantages and disadvantages are identified for each method. Experimental verification for each soft-switching method is provided. It was found that only those methods that softly switch the auxiliary switch, minimize redirection current, and recover the auxiliary circuit energy improve efficiency over most of the load range.
Electoral Campaign Financing: The Role of Public Contributions and Party Ideology

This article analyzes the effects of public financing of electoral campaigns on policies announced by ideologically oriented parties, subject to pre-electoral lobbying. Parties’ ideologies make politicians announce divergent platforms, even though it means losing some votes. Divergent platforms, in turn, make lobbies actually contribute to parties’ electoral campaigns. The announced platforms are biased in favor of the parties’ ideology and interest groups’ preferred policies. Finally, increasing public financing of electoral campaigns may generate unequal electoral competition and may significantly raise the chances of one party becoming hegemonic, wiping out party competition in the long run.
THE COTTON HARVESTER IN RETROSPECT: LABOR DISPLACEMENT OR REPLACEMENT?

The prevailing view of new mechanical technology is that it has, in large part, pushed labor out of agriculture. An alternative hypothesis is that labor has been pulled out of agriculture by higher wages in nonfarm occupations. The mechanical cotton harvester is used to test the two hypotheses. Estimation of a simultaneous-equation model of the labor market for cotton pickers reveals 79 percent of reduction in hand picking of cotton was due to increased nonfarm wages—the pull effect; the remaining 21 percent is attributed to the decreased cost of machine harvesting—the push effect.
Boson-fermion correspondence of type B and twisted vertex algebras

The boson-fermion correspondence of type A is an isomorphism between two super vertex algebras (and so has singularities in the operator product expansions only at z = w). The boson-fermion correspondence of type B plays similarly important role in many areas, including representation theory, integrable systems, random matrix theory and random processes. But the vertex operators describing it have singularities in their operator product expansions at both z = w and \(z = -w\), and thus need a more general notion than that of a super vertex algebra. In this paper we present such a notion: the concept of a twisted vertex algebra, which generalizes the concept of super vertex algebra. The two sides of the correspondence of type B constitute two examples of twisted vertex algebras. The boson-fermion correspondence of type B is thus an isomorphism between two twisted vertex algebras.
Alternative Approaches to the Management of Priapism

Herein we describe the use of intracavernous methylene blue (MB), a guanylate cyclase inhibitor, or internal pudendal artery embolization for the treatment of priapism. Eleven patients with priapism were treated from 1993-1996. Etiologies of priapism included PGE1/papaverine (3), trazodone (2), and sickle cell disease (1), in the other five cases the causes the cause was unknown. The average duration of priapism was 27 h for all patients (6-72 h). Five patients who failed intracavernous MB or an alpha-adrenergic agonist, underwent unilateral or bilateral pudendal artery embolization. The average duration of priapism for patients undergoing embolization was 43 h. Sixty-seven percent of the patients treated with MB responded with immediate detumescence. One-hundred percent of patients with priapism secondary to intracavernous injection therapy or trazodone responded. Of the five patients who underwent embolization, 40% achieved immediate pain relief and subsequent detumescence. The three non-responders exhibited a partial detumescence over 47-72 h. After follow-up of one year embolization available for only two patients revealed that one regained potency while the other remained impotent. These results confirmed that MB is effective for pharmacologically-induced priapism. Embolization is a less invasive option for refractory priapism, although results are less than satisfactory in men with priapism of several days duration.
AN ANALYSIS OF WOMEN'S RETURN‐TO‐WORK DECISIONS FOLLOWING FIRST BIRTH

Women's labor force participation has increased sharply over the last two decades, particularly for married women with young children. This suggests women are spending less time out of the labor force for child bearing and rearing. Using the detailed information available in the NLSY, I explore women s decisions to return to work within one year of their first child's birth, focusing on the effect of child care costs. Consistent with economic theory, women facing lower child care costs are more likely to return to work as are women with higher potential wages and lower family income from other sources. (JEL J0)
Statistical estimation and moment evaluation of a stochastic growth model with asset market restrictions

Abstract This paper estimates the parameters of a stochastic growth model with asset market and contrasts the model’s moments with moments of the actual data. We solve the model through log-linearization along the line of Campbell (1994) [Journal of Monetary Economics 33(3), 463] and estimate the model without and with asset pricing restrictions. As asset pricing restrictions we employ the riskfree interest rate and the Sharpe-ratio. To estimate the parameters we employ, as in Semmler and Gong (1996a) [Journal of Economics Behavior and Organization 30, 301], a ML estimation. The estimation is conducted through the simulated annealing. We introduce a diagnostic procedure which is closely related to Watson (1993) [Journal of Political Economy 101(6), 1011] and Diebold et al. (1995) [Technical Working Paper No. 174, National Burea of Economic Research] to test whether the second moments of the actual macroeconomic time series data are matched by the model’s time series. Several models are explored. The overall results are that sensible parameter estimates may be obtained when the actual and computed riskfree rate is included in the moments to be matched. The attempt, however, to include the Sharpe-ratio as restriction in the estimation does not produce sensible estimates. The paper thus shows, by employing statistical estimation techniques, that the baseline real business cycle (RBC) model is not likely to give correct predictions on asset market pricing when parameters are estimated from actual time series data.
Growth in Agricultural Loan Market Share for Arkansas Commercial Banks

Changes in commercial bank market shares of farm debt are decomposed into portfolio decisions, loanable funds availability and loan market size for 64 counties in Arkansas from 1986 through 1990. A seemingly unrelated regression model is hypothesized to identify county characteristics that are related to changes in commercial bank market shares, Regression results indicate that county differences in economic activity, the relative risk associated with agriculture, farm structure and regional location contributed to changes in commercial bank market shares. The results imply a market niche for rural commercial banks emphasizing agricultural loans in the presence of unlimited branch banking.
Role of Endonucleases XPF and XPG in Nucleotide Excision Repair of Platinated DNA and Cisplatin/Oxaliplatin Cytotoxicity

Resistance of tumor cells to platinum anticancer agents poses a major problem in cancer chemotherapy. One of the mechanisms associated with platinum-based drug resistance is the enhanced capacity of the cell to carry out nucleotide excision repair (NER) on platinum-damaged DNA. Endonucleases XPF and XPG are critical components of NER, responsible for excising the damaged DNA strand to remove the DNA lesion. Here, we investigated possible consequences of down-regulation of XPF and XPG gene expression in osteosarcoma cancer cells (U2OS) and the impact on cellular transcription and DNA repair. We further evaluated the sensitivity of such cells toward the platinum anticancer drugs cisplatin and oxaliplatin.
Serum inflammatory markers and risk of colorectal cancer in patients with inflammatory bowel diseases.

Background & Aims Patients with inflammatory bowel diseases (IBDs) (Crohn's disease, ulcerative colitis) are at increased risk of colorectal cancer (CRC). Persistent inflammation is hypothesized to increase risk of CRC in patients with IBD; however, the few studies in this area have been restricted to cross-sectional assessments of histologic severity. No prior studies have examined association between C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) elevation and risk of CRC in an IBD cohort. Methods From a multi-institutional validated IBD cohort, we identified all patients with at least one measured CRP or ESR value. Patients were stratified into quartiles of severity of inflammation on the basis of their median CRP or ESR value, and subsequent diagnosis of CRC was ascertained. Logistic regression adjusting for potential confounders was used to identify the independent association between CRP or ESR elevation and risk of CRC. Results Our study included 3145 patients with at least 1 CRP value (CRP cohort) and 4008 with at least 1 ESR value (ESR cohort). Thirty-three patients in the CRP cohort and 102 patients in the ESR cohort developed CRC during a median follow-up of 5 years at a median age of 55 years. On multivariate analysis, there was a significant increase in risk of CRC across quartiles of CRP elevation (P trend = .017; odds ratio for quartile 4 vs quartile 1, 2.72; 95% confidence interval, 0.95–7.76). Similarly higher median ESR was also independently associated with risk of CRC across the quartiles (odds ratio, 2.06; 95% confidence interval, 1.14–3.74) (P trend = .007). Conclusions An elevated CRP or ESR is associated with increased risk of CRC in patients with IBD.
Tilt detection and stable approach methods for near field recording

We present advanced methods to improve the performance of near field system. Using the RF signal, a near field system detects tilt error and finds the best tilt condition. The 2-step approach process shortens the pull-in time and decreases the possibility of collision.
Quaternion‐based visual servo control in the presence of camera calibration error

Visual servo control systems use information from images along with knowledge of the optic parameters (i.e. camera calibration) to position the camera relative to some viewed object. If there are inaccuracies in the camera calibration, then performance degradation and potentially unpredictable response from the visual servo control system may occur. Motivated by the desire to incorporate robustness to the camera calibration, different control methods have been developed. Previous adaptive/robust controllers (especially for six degree-of-freedom camera motion) rely heavily on properties of the rotation parameterization to formulate state estimates and a measurable closed-loop error system. All of these results are based on the singular axis–angle parameterization. Motivated by the desire to express the rotation by a non-singular parameterization, efforts in this paper address the question: Can state estimates and a measurable closed-loop error system be crafted in terms of the quaternion parameterization when the camera calibration parameters are unknown? To answer this question, a contribution of this paper is the development of a robust controller and closed-loop error system based on a new quaternion-based estimate of the rotation error. A Lyapunov-based analysis is provided which indicates that the controller yields asymptotic regulation of the rotation and translation error signals given a sufficient approximate of the camera calibration parameters. Simulation results are provided that illustrate the performance of the controller for a range of calibration uncertainty. Copyright © 2009 John Wiley & Sons, Ltd.
The functions of the family in the great society

Criticisms by Hodgson and others that Hayek and other Austrians cannot offer a theory of the family are responded to with a discussion of the functions of the family in a market society. The family can be understood as a bridge between what Hayek terms 'organisations', or face-to-face social institutions and 'orders', or the anonymous social institutions of the Great Society. The family's necessary role is then linked to familiar Hayekian themes of knowledge and incentives. Families help us to learn the explicit and tacit social rules necessary for functioning in the wider world, and families are uniquely positioned to do so, because it is those closest to us who have the knowledge and incentives necessary to provide that learning. Copyright 2005, Oxford University Press.
Carbon sequestration and carbon management policy effects on production agriculture in the Texas High Plains

This study evaluated carbon emissions and carbon sequestration in the Texas High Plains (THP) in order to comprehend the effect that alternative carbon management policies would have on agricultural production. The objective was to examine the impacts of payments for sequestration and taxes on carbon emissions on cropping choices, profitability, and water consumption in the Texas High Plains. Results showed that reduction of total carbon emissions and tax on carbon emissions reduced the amount of water while p ayment for sequestration did not affect reduction of carbon emissions, water consumption nor product mix. However, payments for sequestration slightly increased net revenue for this region.
Solvent-Dependent Chemoselectivities in Additions of β-Carbonyl Imines to Allyltrimethylsilane with CTAN

The oxidative coupling of beta-carbonyl imines and allyltrimethylsilane with CTAN were investigated in CH(3)CN and CH(2)Cl(2). In CH(3)CN allylation products were obtained predominantly, while in CH(2)Cl(2), dihydropyrrole products were obtained exclusively. Solvent-assisted nucleophilic cleavage of the intermediate beta-silyl cation is proposed to play a role in the solvent-dependent chemoselectivity.
Converting a tetrahedral mesh to a prism-tetrahedral hybrid mesh for FEM accuracy and efficiency

This paper presents a computational method for converting a tetrahedral mesh to a prism–tetrahedral hybrid mesh for improved solution accuracy and computational efficiency of finite element analysis. The proposed method performs this conversion by inserting layers of prism elements and deleting tetrahedral elements in sweepable sub-domains, in which cross-sections remain topologically identical and geometrically similar along a certain sweeping path. The total number of finite elements is reduced because roughly three tetrahedral elements are converted to one prism element. The solution accuracy of the finite element analysis improves since a prism element yields a more accurate solution than a tetrahedral element due to the presence of higher-order terms in the shape function. Only previously known method for creating such a prism–tetrahedral hybrid mesh was to manually decompose a target volume into sweepable and non-sweepable sub-volumes and mesh each of the sub-volumes separately. Unlike the previous method, the proposed method starts from a cross-section of a tetrahedral mesh and replaces the tetrahedral elements with layers of prism elements until prescribed quality criteria can no longer be satisfied. A series of computational fluid dynamics simulations and structural analyses have been conducted, and the results verified a better performance of prism–tetrahedral hybrid mesh. Copyright © 2009 John Wiley & Sons, Ltd.
Replacing 99mTc with 111In Improves MORF/cMORF Pretargeting by Reducing Intestinal Accumulation

Purpose To reduce accumulation in the abdomen by MORF/cMORF pretargeting, 111In was compared to 99mTc as the radiolabel.
Compact nanoplasmonic Mach-Zehnder interferometers

We present a novel design of two nano-scale plasmonic devices: a 2×2 directional coupler switch and a Mach-Zehnder interferometer. The overall efficiency was 37% for the former one and 70% for the latter one.
Exposure to violent video games and desensitization to violence in children and adolescents

Entertainment computing is central to the leisure activities of many Americans, with a remarkable array of choices now available to the average person. Video and computer games, in particular violent games, are especially popular, even with relatively young children. With this popularity, concern has been raised about possible unintended consequences of participation in interactive violence. Desensitization to violence has been cited as one possible undesirable outcome of video game violence, but there is little evidence for this relationship. This paper presents a conceptual model and supporting data to begin the examination of possible relationships between exposure to violent video games and desensitization. Examining correlates of desensitization including empathy and attitudes towards violence, surveys of children and adolescents have identified a relationship between greater exposure to violent video games, lower empathy, and stronger proviolence attitudes. Additional research is needed to substantiate and to understand the causal implications of these results.
Probing High-Redshift Radiation Fields with Gamma-Ray Absorption

The next generation of gamma-ray telescopes may be able to observe gamma-ray blazars at high redshift, possibly out to the epoch of reionization. The spectrum of such sources should exhibit an absorption edge due to pair production against UV photons along the line of sight. One expects a sharp drop in the number density of UV photons at the Lyman edge L. This implies that the universe becomes transparent after gamma-ray photons redshift below E ~ (mec2)2/L ~ 18 GeV. Thus, there is only a limited redshift interval over which GeV photons can pair produce. This implies that any observed absorption will probe radiation fields in the very early universe, regardless of the subsequent star formation history of the universe. Furthermore, measurements of differential absorption between blazars at different redshifts can cleanly isolate the opacity due to UV emissivity at high redshift. An observable absorption edge should be present for most reasonable radiation fields with sufficient energy to reionize the universe. Ly? photons may provide an important component of the pair production opacity. Observations of a number of blazars at different redshifts will thus allow us to probe the rise in comoving UV emissivity with time.
Calabi-Yau duals for CHL strings

Abstract We find M-theory (Tyoe IIA) duals for compactifications of the 9d CHL string to 5d (4d) on K3 (K3 × S1). The IIA duals are Calabi-Yau orbifolds with non-trivial RR U(1) backgrounds turned on.