cssi/SciSciGPT-SciSciNet huggingface dataset:
Apparent scintillation of subpixel targets imaged by focal plane arrays

For small unresolved or partially resolved objects, the prediction of the performance of an infrared (IR) sensor system depends not only on the optics and the atmosphere, but also on the geometry of the sensing elements within the detector. The apparent scintillation caused by subpixel displacements of the detector from the optimum position is investigated. The effect is linked to the system point spread function (PSF) as well as the shape and size of the object. The effect of the shape and size of the sensing element, the optics, and the viewed object are simulated. The simulation also evaluates the effect that vibrations or pointing accuracy have on the performance of the sensor system for different types of targets. Results are presented that show that the variation in contrast of objects due to the shape and size of the active portion of a detector and the position of the target projection on the detector can be significant, and should be taken into account when estimating system performance. Although these effects are most significant in wide field of view surveillance systems, narrow field of view systems are also described and evaluated.
Anomalous scaling behavior in Takens-Bogdanov bifurcations

Abstract A general algorithm is presented for estimating the nonlinear instability threshold, σ c , for subcritical transitions in systems where the linearized dynamics is significantly non-normal (i.e. subcritical bifurcations of Takens-Bogdanov type). The N -dimensional degenerate node is presented as an example. The predictions are then compared to numerical studies with excellent agreement.
Openness, income-tax progressivity, and inflation

Abstract This paper considers a model of an open economy in which the degree of income-tax progressivity influences the interaction among openness, central bank independence, and the inflation rate. Our model suggests that an increase in the progressivity of the tax system induces a smaller response in real output to a change in the price level. This implies that increased income-tax progressivity reduces the equilibrium inflation rate and that the effect of increased income-tax progressivity on inflation is smaller when the central bank places a higher weight on inflation or when there is greater openness. Examination of cross-country inflation data provides empirical support for these key predictions.
Gold-Catalyzed Oxidative Coupling Reactions with Aryltrimethylsilanes

During continuing studies with a novel oxidative gold oxyarylation reaction, arylsilanes were found to be competent coupling partners, providing further evidence for an intramolecular electrophilic aromatic substitution mechanism. While providing yields complementary to those of the previously described boronic acid methods, the use of trimethylsilanes reduces the observation of homocoupling byproducts and allows for facile intramolecular coupling reactions.
Evaluation of High-Frequency Mean Streamwater Transit-Time Estimates Using Groundwater Age and Dissolved Silica Concentrations in a Small Forested Watershed

Many previous investigations of mean streamwater transit times (MTT) have been limited by an inability to quantify the MTT dynamics. Here, we draw on (1) a linear relation (r2 = 0.97) between groundwater 3H/3He ages and dissolved silica (Si) concentrations, combined with (2) predicted streamwater Si concentrations from a multiple-regression relation (R2 = 0.87) to estimate MTT at 5-min intervals for a 23-year time series of streamflow [water year (WY) 1986 through 2008] at the Panola Mountain Research Watershed, Georgia. The time-based average MTT derived from the 5-min data was ~8.4 ± 2.9 years and the volume-weighted (VW) MTT was ~4.7 years for the study period, reflecting the importance of younger runoff water during high flow. The 5-min MTTs are normally distributed and ranged from 0 to 15 years. Monthly VW MTTs averaged 7.0 ± 3.3 years and ranged from 4 to 6 years during winter and 8–10 years during summer. The annual VW MTTs averaged 5.6 ± 2.0 years and ranged from ~5 years during wet years (2003 and 2005) to >10 years during dry years (2002 and 2008). Stormflows are composed of much younger water than baseflows, and although stormflow only occurs ~17 % of the time, this runoff fraction contributed 39 % of the runoff during the 23-year study period. Combining the 23-year VW MTT (including stormflow) with the annual average baseflow for the period (~212 mm) indicates that active groundwater storage is ~1,000 mm. However, the groundwater storage ranged from 1,040 to 1,950 mm using WY baseflow and WY VW MTT. The approach described herein may be applicable to other watersheds underlain by granitoid bedrock, where weathering is the dominant control on Si concentrations in soils, groundwater, and streamwater.
Life tests and failure mechanisms of GaN/AlGaN/InGaN light-emitting diodes

Our studies of device lifetime and the main degradation mechanisms in Nichia blue LEDs date back to Spring 1994. Following the initial studies ofrapid failures under high current electrical pulses, where metal migration was identified as the cause of degradation, we have placed a number ofNichia NLPB-500 LEDs on a series oflife tests. The first test ran for 1000 hours under normal operating conditions (20 mA at 23 °C). As no noticeable degradation was observed, the second room temperature test was performed with the same devices but with a range of currents between 20 and 70 mA. After 1600 hours, some degradation in output intensity was observed in devices driven at 60 and 70 mA, but it was still less than 20%. The subsequent tests included stepping up the temperature by 10 °C in 500 h intervals up to a fmal temperature of 95 °C using the same currents applied in the second test. This work reviews the failure analysis that was performed on the degraded devices and the degradation mechanisms that were identified.
An asymmetric convex body with maximal sections of constant volume

We show that in all dimensions d>2, there exists an asymmetric convex body of revolution all of whose maximal hyperplane sections have the same volume. This gives the negative answer to the question posed by V. Klee in 1969.
Scatterer mediated modal coupling in active optical microcavities

Scattering induced mode splitting is demonstrated in active microcavities which are optically pumped below and above the lasing threshold. We show that optical gain can enhance light-matter interactions and improve the sensitivity of nanoparticle detection.
Energy Shifts and Relative Intensities of K X Rays Produced by Swift Heavy Ions

The energy shifts of Fe, Co, Zr, and Sn $K$ x rays produced by 5-MeV/amu He, C, O, Ne and 10 MeV/amu C ions depend nearly linearly on the stopping power for the bombarding ion. The shifts and the $\frac{K\ensuremath{\beta}}{K\ensuremath{\alpha}}$ ratios show a projectile energy dependence similar to that predicted for the $L$-ionization cross section. This suggests that these phenomena can be explained by existing Coulomb excitation theories.
The binomial ideal of the intersection axiom for conditional probabilities

The binomial ideal associated with the intersection axiom of conditional probability is shown to be radical and is expressed as an intersection of toric prime ideals. This solves a problem in algebraic statistics posed by Cartwright and Engstrom.
Schottky-barrier formation on a covalent semiconductor without Fermi-level pinning: The metal-MoS2(0001) interface.

Chemical interaction and Schottky-barrier formation at the metal-${\mathrm{MoS}}_{2}$ interface were studied by evaporating metals (Ag, Al, Au, Co, Fe, In, Mn, Pd, Rh, Ti, and V) onto the (0001) basal-plane surface of cleaved molybdenite, and then analyzing the interface with x-ray photoelectron spectroscopy (XPS). Except for Mn, negligible changes were revealed in the Mo (3${d}_{5/2}$) and S (2${p}_{3/2}$) peak shapes, or widths, after deposition. The shifts in the binding energies did not correlate with the electron configuration of the metal but rather with the metal electronegativity, and are interpreted in terms of band bending at the metal-semiconductor interface, rather than chemical reaction. Plots of both Mo and S binding energies versus metal electronegativity yield approximately linear curves with nonzero (positive) slopes, which provide an average ``index of interface behavior'' of S'=1.28\ifmmode\pm\else\textpm\fi{}0.22. This value is considerably higher than for other covalent semiconductors, which exhibit S'0.3 due to Fermi-level pinning. The anomalous behavior of ${\mathrm{MoS}}_{2}$ results from the extreme inertness of the basal-plane surface and the stability of the layered crystal lattice of ${\mathrm{MoS}}_{2}$. The absence of chemical interaction at the interface causes the formation of a Schottky barrier exhibiting behavior that may approach the Schottky limit. This behavior for ${\mathrm{MoS}}_{2}$(0001) is compared with that of other semiconductors, and is discussed in terms of their ionicity, reactivity, and dielectric response. Metals (Ag, Au, Co, Cu, Fe, Pd, Ti, and V) were also deposited onto ${\mathrm{MoS}}_{2}$(0001) surfaces that were bombarded with 10-keV ${\mathrm{Ar}}^{+}$ ions. The Fermi level was not strongly pinned, even though defect densities as high as \ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ were produced in the surface region.
Teaching software project management: a response-interaction approach

Abstract Southern Polytechnic State University has recently implemented a new Master of Science in Software Engineering degree, which includes a course in Software Project Management in its core requirements. This paper addresses an innovative approach to teaching this course through what is described as response–interaction. Also included are the results of the first offering of this course.
Wavelet Analysis of Space-Varying Intermittent Wall Pressure Field of Transitional Boundary Layer

Measurements of the space-time fluctuating wall pressure field across the transition region of a flat plate zero pressure gradient boundary layer have been performed in an anechoic wind tunnel with a 64-element linear array of sub-miniature hearing-aid microphones (d+ = 15). Wavelet transforms are being used to quantify the structure and nonhomogeneous wavenumber-frequency spectral content of the field. The results illustrate that the fluctuations within the turbulent spots scale with those which exists in a fully developed turbulent boundary layer consistent with previous findings. The spectral contributions due to a second much larger length/time scale associated with the mean spacing between spots (e.g., turbulent spot wavepacket pulse trains) is under investigation. Based on an analysis of sinusoidal pulse train signals and consideration of the well established bursting frequency in turbulent boundary layers, it is conjectured here that the turbulent spot wavepacket pulse trains should produce a statistical distribution of energy about the mean fundamental pulse train frequency.Copyright © 2003 by ASME
Matrix perturbation theory for M-theory on a PP-wave

In this paper, we study the matrix model proposed by Berenstein, Maldacena, and Nastase to describe M-theory on the maximally supersymmetric pp-wave. We show that the model may be derived directly as a discretized theory of supermembranes in the pp-wave background, or alternatively, from the dynamics of D0-branes in type-IIA string theory. We consider expanding the model about each of its classical supersymmetric vacua and note that for large values of the mass parameter μ, interaction terms are suppressed by powers of μ−1, so that the model may be studied in perturbation theory. We compute the exact spectrum about each of the vacua in the large-μ limit and find the complete (infinite) set of BPS states, which includes states preserving 2, 4, 6, 8, or 16 supercharges. Through explicit perturbative calculations, we then determine the effective coupling that controls the perturbation expansion for large μ and estimate the range of parameters and energies for which perturbation theory is valid.
Experimental characterization of the hysteretic and rate-dependent electromechanical behavior of dielectric electro-active polymer actuators

Dielectric electro-active polymers (DEAPs) can achieve substantial deformation (>300% strain) while sustaining, compared to their ionic counterparts, large forces. This makes them attractive for various actuation and sensing applications such as in light weight and energy efficient valve and pumping systems. Many applications operate DEAP actuators at higher frequencies where rate-dependent effects influence their performance. This motivates the seeking of dynamic characterization of these actuators beyond the quasi-static regime. This paper provides a systematic experimental investigation of the quasi-static and dynamic electromechanical properties of a DEAP actuator. In order to completely characterize the fully coupled behavior, force versus displacement measurements at various constant voltages and force versus voltage measurements at various fixed displacements are conducted. The experiments are conducted with a particular focus on the hysteretic and rate-dependent material behavior. These experiments provide insight into the electrical dynamics and viscoelastic relaxation inherent in DEAP actuators. This study is intended to provide information, including high frequency performance analysis, useful to anyone designing dynamic actuator systems using DEAPs.
On spacing policies for highway vehicle automation

This paper develops a framework for the design and evaluation of spacing policies for adaptive cruise control. Spacing policies are evaluated from the point of view of string stability, traffic flow stability and traffic flow capacity. The standard constant time-gap spacing policy can guarantee string stability but is shown to suffer from poor traffic capacity and traffic flow instability. An "ideal" spacing policy is proposed that evolves naturally from the evaluation framework. The proposed spacing policy is a nonlinear function of speed. It provides string stability and traffic flow stability as well as a higher traffic flow capacity compared to the standard time-gap controller. An associated result proved in the paper is that traffic flow stability implies string stability for flow volumes up to a described maximum value.
Norm enforcement: anger, indignation or reciprocity?

Theenforcementofsocialnormsoftenrequiresthatunaffectedthirdpartiessanctionoffenders.Given the renewed interest of economists in norms, the literature on third-party punishment is surprisingly thin. In this paper, we report the results of an experiment designed to replicate the anger-based punishment of directly affected second parties and evaluate two distinct explanations for third-party punishment: indignation and group reciprocity. We find evidence in favor of both, with the caveat that the incidence of indignation-driven sanctions is perhaps smaller than earlier studies have hinted. Furthermore, our results suggest that second parties use sanctions to promote conformism while third parties intervene primarily to promote efficiency. (JEL: C79, C91, C92, D64, H41)
Control of inconsistency and redundancy in PROLOG-type knowledge bases

Abstract Because of the incremental and piecemeal nature of its construction, logical inconsistency and redundancy can be built inadvertently into a knowledge base. This paper discusses a methodology for analyzing the contents of a PROLOG-type knowledge base and for eliminating inconsistent and redundant logical elements. It introduces a graphical representation, the goal-fact network, of the logic required to infer a goal and describes the identification of inconsistency in that network. Three increasingly general alternatives, Boolean algebra, the Karnaugh map, and the Quine-McCluskey algorithm, are presented as tools to identify and to eliminate redundancy.
Belting of the cyclooctatetraene ring across the transannular 1- and 5-positions

Abstract Four cyclooctatetraenes bridged in a previously unknown 1,5-manner have been prepared by a general route that also allows introduction of a C-3 methyl group to break the axial symmetry.
Possible Origins of Macroscopic Left-Right Asymmetry in Organisms

I consider the microscopic mechanisms by which a particular left-right (L/R) asymmetry is generated at the organism level from the microscopic handedness of cytoskeletal molecules. In light of a fundamental symmetry principle, the typical pattern-formation mechanisms of diffusion plus regulation cannot implement the “right-hand rule”; at the microscopic level, the cell’s cytoskeleton of chiral filaments seems always to be involved, usually in collective states driven by polymerization forces or molecular motors. It seems particularly easy for handedness to emerge in a shear or rotation in the background of an effectively two-dimensional system, such as the cell membrane or a layer of cells, as this requires no pre-existing axis apart from the layer normal. I detail a scenario involving actin/myosin layers in snails and in C. elegans, and also one about the microtubule layer in plant cells. I also survey the other examples that I am aware of, such as the emergence of handedness in neurons, in eukaryote cell motility, and in non-flagellated bacteria.
Structural Dynamics of Stiffened Plates with Piezoceramic Sensors and Actuators

A dynamic model of a stiffened plate, developed for the purpose of analyzing the coupling between piezoceramic transducers and the plate dynamics, is presented. The model is based on Hamilton's principle and discretized with a polynomial expansion of the transverse plate vibration. The effects of eccentric stiffeners, piezoceramic transducers, and point masses located on the plate are accounted for in the model. To validate the model, the results of numerical simulations are compared with experiments on a rectangular aluminum plate with one eccentric stiffener and simply supported boundary conditions. The model accurately predicts the first seven natural frequencies and mode shapes of the plate as well as the coupling between piezoceramic transducers and the plate vibration. A study of the plate natural frequencies and transducer coupling over a range of stiffener heights reveals that for geometries with slight asymmetries and near repeated eigenvalues the corresponding mode shapes are very sensitive to small changes in stiffener height. For the structure studied in this work, the sensitivity of the mode shapes caused the piezoceramic transducer modal strain energy fraction for the fourth mode to increase by 140% with only an 8% increase in stiffener height. Over the same range of stiffener heights, the piezoceramic transducer modal strain energy fraction for the symmetric structure's fourth mode only changed by 5%.
Inelastic neutron scattering from single crystal Zn under high pressure.

Inelastic neutron-scattering experiments have been performed for single crystals of Zn under pressures up to 8.8 GPa at 300 K. The phonon modes q/${\mathit{q}}_{\mathrm{max}}$=\ensuremath{\xi}=0.075 and \ensuremath{\xi}=0.10 were measured in the transverse acoustic branch ${\mathrm{\ensuremath{\Sigma}}}_{3}$, where q=0 corresponds with the elastic constant ${\mathit{C}}_{44}$. The phonon energy showed a substantial hardening with increasing pressure. The experimental data below 6.8 GPa for \ensuremath{\xi}=0.075 yield a constant Gr\"uneisen mode ${\ensuremath{\gamma}}_{\mathit{i}}$=-ln${\mathrm{\ensuremath{\omega}}}_{\mathit{i}}$/lnV of 2.25 in good agreement with a previous calculation [H. Ledbetter, Phys. Status Solidi B 181, 81 (1994)]. Above 6.8 GPa, there is a very rapid increase of ${\ensuremath{\gamma}}_{\mathit{i}}$ which is indicative of the presence of a giant Kohn anomaly. This rapid divergence at high pressure indicates that a phonon softening may occur at pressures higher than 8.8 GPa caused by the collapse of the giant Kohn anomaly via an electronic topological transition (ETT). In an earlier M\"ossbauer Zn study at 4 K [W. Potzel et al., Phys. Rev. Lett. 74, 1139 (1994)], a drastic drop of the Lamb-M\"ossbauer factor was observed at 6.6 GPa, which was interpreted as being due to phonon softening, indicating this ETT had occurred. This paper also compares the compressibility data for single crystal Zn and Zn powder using neutron scattering. The results were found to be similar to an earlier x-ray Zn powder experiment [O. Schulte et al., High Pressure Res. 6, 169 (1991)]. \textcopyright{} 1996 The American Physical Society.
Wait-free clock synchronization

Multiprocessor computer systems are becoming increasingly important as vehicles for solving computationally expensive problems. Synchronization among the processors is achieved with a variety of clock configurations. A new notion of fault-tolerance for clock synchronization algorithms is defined, tailored to the requirements and failure patterns of shared memory multiprocessors. Algorithms in this class can tolerate any number of napping processors, where a napping processor can fail by repeatedly ceasing operation for an arbitrary time interval and then resume operation without necessarily recognizing that a fault has occurred. These algorithms guarantee that, for some fixed k, once a processor P has been working correctly for at least k time, then as long as P continues to work correctly, (1) P does not adjust its clock, and (2) P's clock agrees with the clock of every other processor that has also been working correctly for at least k time. Because a working processor must synchronize in a fixed amount of time regardless of the actions of the other processors, these algorithms are called wait-free. Another useful type of fault-tolerance is called self-stabilization: starting with an arbitrary state of the system, a self-stabilizing algorithm eventually reaches a point after which it correctly performs its task. Two wait-free clock synchronization algorithms are presented for a model with global clock pulses. The first one is self-stabilizing; the second one is not but it converges more quickly than the first one. The self-stabilizing algorithm requires each processor's communication register contents to be a part of the processor's state. This last requirement is proven necessary. A wait-free clock synchronization algorithm is also presented for a model with local clock pulses. This algorithm is not self-stabilizing.
On the Bounded Sum-of-Digits Discrete Logarithm Problem in Finite Fields

In this paper, we study the bounded sum-of-digits discrete logarithm problem in finite fields. Our results are concerned primarily with fields Fqn, where n|q - 1. The fields are called Kummer extensions of Fq. It is known that we can efficiently construct an element g with order exponential in n. Let $S_q(\bullet)$ be the function from integers to the sum of digits in their q-ary expansions. We first present an algorithm that, given ge (0 $\leq$ e < qn), finds e in random polynomial time, provided that Sq (e) < n. We then show that the problem is solvable in random polynomial time for most of the exponent e with Sq (e) < 1.32 n by exploring an interesting connection between the discrete logarithm problem and the problem of list decoding of Reed--Solomon codes and applying the Guruswami--Sudan algorithm. As far as we are aware, our algorithm is the first one which can solve discrete logarithms of $2^{\log^{1-\epsilon}{q^n}}$ many instances in polynomial time for infinite many constant characteristic fields Fqn. Furthermore, since every finite field has an extension of reasonable degree, which is a Kummer extension, our result reveals an unexpected property of the discrete logarithm problem, namely, the bounded sum-of-digits discrete logarithm problem in any given finite field becomes polynomial-time solvable in certain low degree extensions. As a side result, we obtain a sharper lower bound on the number of congruent polynomials generated by linear factors than the one based on the Stothers--Mason ABC-theorem. We also prove that, in the field Fqq-1, the bounded sum-of-digits discrete logarithm with respect to g can be computed in random time O(f(w)log4 (qq-1)), where f is a subexponential function and w is the bound on the q-ary sum-of-digits of the exponent; hence the problem is fixed parameter tractable. These results are shown to be generalized to Artin--Schreier extension Fpp, where p is a prime.
Interlaminar Stress Analysis of Shell Structures with Piezoelectric Patch Including Thermal Loading

Interlaminar stress distribution in smart composite shells using a coupled thermal-piezoelectric-mechanical model is investigated. To maintain local accuracy of stress distributions, the trial displacement field is assumed layerwise higher order and C 0 continuous through the entire laminate thickness, accommodating zigzag in-plane warping and interlaminar shear stress continuity. The temperature and electrical fields are modeled using higher-order descriptions that can satisfy surface flux boundary conditions at structural surfaces and equipotential conditions at electrode surfaces. These assumptions ensure computational efficiency. A variational principle, addressing the interaction between thermal, piezoelectric, and mechanical fields, is used to derive the governing equations of equilibrium. The proposed theory is used to investigate the cylindrical bending problem of simply supported composite host structures with attached piezoelectric actuators, subject to a combination of mechanical, piezo-electric, and thermal loading. The interlaminar stress distributions under comprehensive loading are presented for different geometries and stacking sequences. The effects of two-way piezoelectric and thermal coupling on the stress distributions are investigated. The significance of the thermal mismatch effect on interlaminar stress distribution is also discussed. The results from present theory are validated with available exact elasticity solutions.
Off-shell closed string amplitudes: Towards a computation of the tachyon potential

Abstract We derive an explicit formula for the evaluation of the classical closed string action for any off-shell string field, and for the calculation of arbitrary off-shell amplitudes. The formulae require a parametrization, in terms of some moduli space coordinates, of the family of local coordinates needed to insert the off-shell states on Riemann surfaces. We discuss in detail the evaluation of the tachyon potential as a power series in the tachyon field. The expansion coefficients in this series are shown to be geometrical invariants of Strebel quadratic differentials whose variational properties imply that closed string polyhedra, among all possible choices of string vertices, yield a tachyon potential which is as small as possible order by order in the string coupling constant. Our discussion emphasizes the geometrical meaning of off-shell amplitudes.
Cobalt oxide hollow nanoparticles derived by bio-templating

We present here the first fabrication of hollow cobalt oxide nanoparticles produced by a protein-regulated site-specific reconstitution process in aqueous solution and describe the metal growth mechanism in the ferritin interior.
Infrared land surface remote sensing using high spectral resolution observations

This study presents a new technique for the separation of land surface infrared emissivity and surface skin temperature using high spectral resolution infrared observations. High spectral resolution observations of upwelling radiance at 20 km altitude were obtained by the Scanning High-resolution Interferometer Sounder (S-HIS) aboard the NASA ER-2 aircraft during the TX-2001 experiment. These aircraft observations are used in conjunction with complementary ground-based observations of downwelling radiance at the surface to estimate the surface skin temperature and absolute emissivity for a region in north central Oklahoma, USA. Coincident MODIS Airborne Simulator (MAS) observations are used to quantify the land surface variability within the S-HIS scene in the vicinity of the DOE ARM Southern Great Plain central facility. Ground truth data is presented from a ground based Scanning Atmospheric Emitted Radiance Interferometer. This remote sensing technique has application to satellite based observations from the NASA AIRS, the NPOESS CrIS, the EUMETSAT IASI, and the NASA GIFTS instruments.
A class of DC-free subcodes of convolutional codes

We describe a class of DC-free subcodes of convolutional codes that satisfy certain runlength constraints and that also possess error-correcting capability. The running disparity and the maximum runlength of these codes are bounded by quantities that are independent of the free distance. They can be decoded using a Viterbi decoder for the underlying convolutional code.
Adverse Selection, Political Parties, and Policy Delegation in the American Federal System

We extend research on the nexus of federalism, policy delegation, and American politics by asserting that partisan politics at both the national and subnational levels of government matter when explaining variations in U.S. federal intergovernmental policymaking. Specifically, we maintain that national level institutions not only respond to the partisan composition of state level institutions in a direct manner, but also use this information as a means to mitigate adverse selection problems that they confront when making policy in a federal system. Using a novel data set of 459 U.S. public laws spanning the 1947--98 period, we uncover support for the importance of vertical partisan institutional relationships on policy delegation in American federalism. The conclusions drawn from this study highlight the importance attached to vertical institutional relationships for understanding policy delegation by showing how state governments influence the balance of policymaking authority in the United States, even when formal decision-making authority resides at the national level. Copyright 2005, Oxford University Press.
A general mechanism for perceptual decision-making in the human brain

Findings from single-cell recording studies suggest that a comparison of the outputs of different pools of selectively tuned lower-level sensory neurons may be a general mechanism by which higher-level brain regions compute perceptual decisions. For example, when monkeys must decide whether a noisy field of dots is moving upward or downward, a decision can be formed by computing the difference in responses between lower-level neurons sensitive to upward motion and those sensitive to downward motion1,2,3,4. Here we use functional magnetic resonance imaging and a categorization task in which subjects decide whether an image presented is a face or a house to test whether a similar mechanism is also at work for more complex decisions in the human brain and, if so, where in the brain this computation might be performed. Activity within the left dorsolateral prefrontal cortex is greater during easy decisions than during difficult decisions, covaries with the difference signal between face- and house-selective regions in the ventral temporal cortex, and predicts behavioural performance in the categorization task. These findings show that even for complex object categories, the comparison of the outputs of different pools of selectively tuned neurons could be a general mechanism by which the human brain computes perceptual decisions.
Analysis of drill failure modes by multi-sensors on a robotic end effector

The characteristics of nine common drill failure modes have been analyzed. To facilitate detecting and diagnosing these failure modes, a multi-sensor approach is developed. Based on the dynamic characteristics ofthree different measurements including thrust, torque, and lateral vibration, necessary signatures are extracted for the nine failure modes. Experimental tests were conducted to confirm the characteristics of these nine drill failure modes.
Intracluster stars and the chemical enrichment of the intracluster medium

We explore the contribution of intracluster stars (ICS) to the chemical enrichment history of the intracluster medium (ICM). In contrast to scenarios in which all the metals originate in cluster galaxies and are then transported into the ICM, ICS enrich the ICM in situ, thereby contributing 100% of their supernovae ejecta directly into the ICM. Modeling the ICS as an ancient single-burst stellar population with a normal initial mass function, we generate ICM iron abundances in the range of the observed values of several tenths solar. Large observational and theoretical uncertainties preclude us from concluding that the ICS are the primary contributor of metals to the ICM in general. However, for the two clusters in our sample and one from the literature, for which all of the required observational constraints exist, we are able to reproduce between half and all of the ICM iron with this simple model. Because of the ubiquity of ICS in clusters and their direct connection with the ICM, we conclude that all models of the chemical enrichment history and energy budget of the ICM should account for the impact of the ICS.
Transient Flow Thrust Prediction for an Ejector Propulsion Concept

A method for predicting transient thrust augmenting ejector characteristics is introduced. The analysis blends classic self-similar turbulent jet descriptions with a mixing region control volume analysis to predict transient effects in a new way. Details of the theoretical foundation, the solution algorithm, and sample calculations are given.
Fabrication and Yield of Large Area Quantum Well Modulators

InP-based multiple quantum well modulators were fabricated and the yield of the modulators was explored. Bad pixels were removed from operation which reduced the modulation area but limits the power consumption. Leakage around the 15 volts reverse bias were also investigated.
On minimal log discrepancies

An explanation to the boundness of minimal log discrepancies conjectured by V.V. Shokurov would be that the minimal log discrepancies of a variety in its closed points define a lower semi-continuous function. We check this lower semi-continuity behaviour for varieties of dimension at most 3 and for toric varieties of arbitrary dimension.
The contact invariant in sutured Floer homology

We describe an invariant of a contact 3-manifold with convex boundary as an element of Juhasz’s sutured Floer homology. Our invariant generalizes the contact invariant in Heegaard Floer homology in the closed case, due to Ozsvath and Szabo.
Should Trade Agreements Include Environmental Policy

AbstractThis article examines the extent to which environmental and trade policies should be treated equally, or symmetrically, in international negotiations. It reviews the recent economics litera...
CP Results from Belle

Abstract The Belle detector at KEKB has collected 6.2 fb −1 of data at the ϒ(4S) resonance. Presented here are preliminary measurements, from this data sample, of sin 2φ 1 and other quantities relating to CP.
Operant behavioural demonstration of qualitative differences between the d- and l-isomers of amphetamine

Publisher Summary This chapter elaborates the operant behavioral demonstration of qualitative differences between the d- and l-isomers of amphetamine. One of the major problems associated with studying the behavioral and/or neurochemical consequences of pharmacological agents is that no one unitary hypothesis can describe the mechanism by which drugs act. It is found that when a dose of 1 mg d-amphetamine sulfate/kg is administered to rats trained to bar-press for food pellets on a fixed ratio 30 schedule, the behavior is altered so that the subjects are responding at about 40% of control rates. A dose of 4 mg 1-amphetamine sulfate/kg likewise brought FR-30 responding down to about 40% of control. It is observed that when tolerance to the disruptive effect of either isomer developed, a challenge by the other isomer resulted in a demonstration of no cross-tolerance, suggesting differential mechanisms. It is found that if a more sensitive measure of operant behavior is used, one see a differential effect of d and l-amphetamine on components of fixed-interval responding.
RECENT PROGRESS IN HEAVY QUARK PHYSICS

Some of the recent progress in heavy quark physics is reviewed. Special attention is paid to inclusive methods for determining Vub and factorization in nonleptonic decays. Theoretical predictions for production near threshold are also discussed.
From Metaphors To Equations: How Can We Find The Good Ones?

Among the metaphors used in the target article are “musical instruments,” “water waves,” and other types of mechanical oscillators. The corresponding equations have inertial properties and lead to standing waves that depend on boundary conditions. Other, physiologically relevant quantities like refractory times are not contained in the mechanical oscillator model but occur naturally, for instance, in biological forest fire metaphors.
High quality factor photonic crystal nanobeam cavities

We investigate the design, fabrication, and experimental characterization of high quality factor photonic crystal nanobeam cavities in silicon. Using a five-hole tapered one-dimensional photonic crystal mirror and precise control of the cavity length, we designed cavities with theoretical quality factors as high as 1.4×107. By detecting the cross-polarized resonantly scattered light from a normally incident laser beam, we measure a quality factor of nearly 7.5×105. The effect of cavity size on mode frequency and quality factor was simulated and then verified experimentally.
On the Notion of Complete Intersection Outside the Setting of Skew Polynomial Rings

In recent work of T. Cassidy and the author, a notion of complete intersection was defined for (noncommutative) regular skew polynomial rings, defining it using both algebraic and geometric tools, where the commutative definition is a special case. In this article, we extend the definition to a larger class of algebras that contains regular graded skew Clifford algebras, the coordinate ring of quantum matrices, and homogenizations of universal enveloping algebras. Regular algebras are often considered to be noncommutative analogues of polynomial rings, so the results herein support that viewpoint.
Performance sampling and bimodal duration dependence

Performance sampling models of duration dependence in employee turnover and firm exit predict that hazard rates will initially be low, gradually rise to a maximum, and then fall. Some empirical duration distributions have bimodal hazard rates, however. In this paper, we present a generalization of the performance sampling model that can account for such deviations from unimodality. While the standard model of performance sampling assumes that the mean and the standard deviation of performance are constant over time, we allow them to change in time, to reflect the fact that tasks may change over time. We derive the hazard rate implied by this more general model and show that it can be bimodal. Using data on turnover in law firms, we show that the hazard rate predicted by these models fit data better than existing models.
High-density QCD: the effects of strangeness

Abstract I discuss the zero temperature phase diagram of QCD, as a function of baryon density and strange quark mass. The noteworthy points are that at sufficiently high density chiral symmetry is always restored, and at low strange quark mass there need be no phase transition between nuclear matter and quark matter. I comment on the possibility that introducing a strange quark may make it easier to see finite-density physics on the lattice.
Multicomponent reaction design: a one-pot route to substituted di-O-acylglyceric acid amides from α-diazoketones

A four-component assembly of substituted di-O-acylglyceric acid amides has been developed from α-diazoketones. The process involves copper-catalyzed reaction of the α-diazoketone with a carboxylic acid, and subsequent Passerini condensation of the in situ formed α-acyloxyketone.
Coupled Torsion-Lateral Stability of a Shaft-Disk System Driven Through a Universal Joint

Understanding the instability phenomena of rotor-shaft and driveline systems incorporating universal joints is becoming increasingly important because of the trend towards light-weight, high-speed supercritical designs. In this paper, a nondimensional, periodic, linear time-varying model with torsional and lateral degrees-of-freedom is developed for a rotor shaft-disk assembly supported on a flexible bearing and driven through a U-joint. The stability of this system is investigated utilizing Floquet theory. It is shown that the interaction between torsional and lateral dynamics results in new regions of parametric instability that have not been addressed in previous investigations. The presence of load inertia and misalignment causes dynamic coupling of the torsion and lateral modes, which can result in torsion-lateral instability for shaft speeds near the sum-type combinations of the torsion and lateral natural frequencies. The effect of angular misalignment, static load-torque, load-inertia, lateral frequency split, and auxiliary damping on the stability of the system is studied over a range of shaft operating speeds. Other than avoiding the unstable operating frequencies, the effectiveness of using auxiliary lateral viscous damping as a means of stabilizing the system is investigated. Finally, a closed-form technique based on perturbation expansions is derived to determine the auxiliary damping necessary to stabilize the system for the least stable case (worst case). ©2002 ASME
THE NGC 300 TRANSIENT: AN ALTERNATIVE METHOD FOR MEASURING PROGENITOR MASSES

We present an alternative technique for measuring the precursor masses of transient events in stars undergoing late stage stellar evolution. We use the well-established techniques of stellar population modeling to age-date the stars surrounding the site of the recent transient event in NGC 300 (NGC 300 OT2008-1). The surrounding stars must share a common turnoff mass with the transient, since almost all stars form in stellar clusters that remain physically associated for periods longer than the lifetime of the most massive stars. We find that the precursor of NGC 300 OT2008-1 is surrounded by stars that formed in a single burst between 8 and 13 Myr ago, with 70% confidence. The transient was therefore likely to be due to a progenitor whose mass falls between the main sequence turnoff mass (12-17 M{sub sun}) and the maximum stellar mass (16-25 M{sub sun}) found for isochrones bounding this age range. We characterize the general applicability of this technique in identifying precursor masses of historic and future transients and supernovae (SNe), noting that it requires neither precursor imaging nor sub-arcsecond accuracy in the position of the transient. It is also based on the well-understood physics of the main sequence, and thus may bemore » a more reliable source of precursor masses than fitting evolutionary tracks to precursor magnitudes. We speculate that if the progenitor mass is {approx}>17 M {sub sun}, there may be a connection between optical transients such as NGC 300 OT2008-1 and the missing type II-P SNe, known as the 'red supergiant problem'.« less
Highly enantioselective carbonyl-ene reactions catalyzed by a hindered silyl-salen-cobalt complex.

We report here the enantioselective carbonyl-ene reactions of various 1,1-disubstituted and trisubstituted alkenes with ethyl glyoxylate. The reactions are catalyzed by a new Co−salen complex, in which bulky triisobutylsilyl (TIBS) substituents occupy the positions ortho to the phenolic oxygens. This complex catalyzes the reactions under nearly ideal conditionsat room temperature and using catalyst loadings as low as 0.1 mol %and provides the chiral, homoallylic alcohol products in excellent yields, enantioselectivities, and diastereoselectivities.
Saving our children from children. Conquering teen pregnancy challenges for our youngest mothers.

Many reasons have been forwarded to explain the high adolescent pregnancy rate found in the US. Studies have shown that 75% of girls who have engaged in sexual intercourse at or before age 14 were sexually abused or raped that two-thirds of the fathers of babies born to adolescent mothers are at least 4 years older than the girls and that the age gap is widest for the youngest girls. When a young minor becomes pregnant nurses have a responsibility to report the statutory rape that occurred. The age of consent is 14 in 2 states 15 in 2 states and 16-18 in the others. Rape conviction criteria usually include finding that the couple has an age difference of 2-3 years. Policy-makers have recently strengthened statutory rape laws in response to increased awareness of the impact of older men on teenage pregnancy rates. A study commissioned by a popular teenage girls magazine showed that most girls engage in sexual intercourse under pressure from boys. More than 80% of the girls and 60% of the boys who had experienced sexual intercourse regretted not waiting until they were older. Nurses must educate their communities about sexual victimization and statutory rape and must report these crimes to the proper authorities.
Seismic structure in southern Peru: evidence for a smooth contortion between flat and normal subduction of the Nazca Plate

Rapid changes in slab geometry are typically associated with fragmentation of the subducted plate; however, continuous curvature of the slab is also possible. The transition from flat to normal subduction in southern Peru is one such geometrical change. The morphology of the subducted Nazca Plate along this transition is explored using intraslab earthquakes recorded by temporary regional seismic arrays. Observations of a gradual increase in slab dip coupled with a lack of any gaps or vertical offsets in the intraslab seismicity suggest warping of the slab. Concentrations of focal mechanisms at orientations which are indicative of slab bending are also observed along the change in slab geometry. The presence of a thin ultra-slow velocity layer (USL) atop the horizontal Nazca slab is identified and located. The lateral extent of this USL is coincident with the margin of the projected linear continuation of the subducting Nazca Ridge, implying a causal relationship wherein increased hydration of the ridge results in the formation of the USL downdip. Waveform modelling of the 2-D structure in southern Peru using a finite-difference algorithm provides constraints on the velocity and geometry of the slab's seismic structure and confirms the absence of any tears in the slab. The seismicity and structural evidence suggests smooth contortion of the Nazca Plate along the transition from flat to normal subduction. The slab is estimated to have experienced 10 per cent strain in the along-strike direction across this transition.
An extension of the Tiebout hypothesis of voting with one’s feet: the Medicaid magnet hypothesis

This study empirically extends the Tiebout hypothesis of ‘voting with one’s feet’ in two ways. First, it provides updated estimates using net migration data for the period 2000–2008. Second, in addition to investigating variables reflecting public education outlays, property taxation and income taxation, it investigates whether migrants are attracted to states with higher Medicaid benefits per recipient. The latter hypothesis is referred to as the ‘Medicaid magnet hypothesis’. The analysis includes three economic variables, three quality of life variables and three Tiebout-type factors in addition to Medicaid benefits. Results indicate that consumer voters were attracted to states with higher per pupil public school spending, lower property and income tax rates, and that certain consumer-voters may be attracted to states that offer higher levels of Medicaid benefits.
Some explicit badly approximable pairs

Abstract I consider the Diophantine approximation problem of sup-norm simultaneous rational approximation with common denominator of a pair of irrational numbers, and compute explicitly some pairs with large approximation constant. One of these pairs is the most badly approximable pair yet computed.