cssi/SciSciGPT-SciSciNet huggingface dataset:
Initiation propagation and termination of elastodynamic ruptures associated with segmentation of faults and shaking hazard

[1] Using a model of a complex fault system, we examine the initiation, propagation, and termination of ruptures and their relationship to fault geometry and shaking hazard. We find concentrations of epicenters near fault step overs and ends; concentrations of terminations near fault ends; and persistent propagation directivity effects. Taking advantage of long sequences of dynamic events, we directly measure shaking hazards, such as peak ground acceleration exceedance probabilities, without need for additional assumptions. This provides a new tool for exploring shaking hazard from a physics-based perspective, its dependence on various physical parameters, and its correlation with other geological and seismological observables. Using this capability, we find some significant aspects of the shaking hazard can be anticipated by measures of the epicenters. In particular, asymmetries in the relative peak ground motion hazard along the faults appear well correlated with asymmetries in epicentral locations.
Fast-phase space computation of multiple arrivals

We present a fast, general computational technique for computing the phase-space solution of static Hamilton–Jacobi equations. Starting with the Liouville formulation of the characteristic equations, we derive “Escape Equations” which are static, time-independent Eulerian PDEs. They represent all arrivals to the given boundary from all possible starting configurations. The solution is numerically constructed through a “one-pass” formulation, building on ideas from semi-Lagrangian methods, Dijkstra-like methods for the Eikonal equation, and Ordered Upwind Methods. To compute all possible trajectories corresponding to all possible boundary conditions, the technique is of computational order O(N log N), where N is the total number of points in the computational phase-space domain; any particular set of boundary conditions then is extracted through rapid post-processing. Suggestions are made for speeding up the algorithm in the case when the particular distribution of sources is provided in advance. As an application, we apply the technique to the problem of computing first, multiple, and most energetic arrivals to the Eikonal equation.
Dynamic Power Control in a Wireless Static Channel Subject to a Quality-of-Service Constraint

A controller dynamically chooses a state-dependent transmission rate on a static, point-to-point wireless link by varying transmission power over time. The transmitter is modeled as a finite-buffer Markovian queue with adjustable service rates. That is, data packets arrive to the system according to a Poisson process, and packet size is exponentially distributed. The controller chooses a transmission rate from a fixed set A of available values, depending on the backlog in the system. The objective is to minimize long-run average energy consumption subject to a quality-of-service constraint, which is expressed as an upper bound on the packet drop rate. An explicit formula is developed for the optimal transmission rate as a function of the packet queue length.
An efficient diamine.copper complex-catalyzed coupling of arylboronic acids with imidazoles

[formula: see text] A novel diamine.copper complex-catalyzed intermolecular coupling of arylboronic acids (1) with imidazoles (3) is described. In the presence of a catalytic amount of [Cu(OH).TMEDA]2Cl2 (2), arylboronic acids (1) react smoothly with imidazoles (3) in dichloromethane at room temperature to give a variety of N-arylimidazoles (4) in good to excellent yields.
Organic reactions at high pressure. Wittig reaction of hindered ketones with nonstabilized ylides.

Abstract The Wittig reaction between n-butylidenetriphenylphosphorane and a series of cyclohexanones of increasing steric hindrance around the carbonyl group has been studied at 7 kbar and 15 kbar pressure (0.75–1.5 GPa) and at 40 °C. In all cases, except 2,2,6,6-tetramethylcyclohexanone and fenchone, 45-60% yields of olefins were obtained, in contrast to poor to no yields which were obtained under ambient conditions.
Effective field theory for fluids: Hall viscosity from a Wess-Zumino-Witten term

We propose an effective action that describes a relativistic fluid with Hall viscosity. The construction involves a Wess-Zumino-Witten term that exists only in (2+1) spacetime dimensions. We note that this formalism can accommodate only a Hall viscosity which is a homogeneous function of the entropy and particle number densities of degree one.
Bridge and pants complexities of knots

We modify an approach of Johnson to define the distance of a bridge splitting of a knot in a 3-manifold using the dual curve complex and pants complex of the bridge surface. This distance can be used to determine a complexity, which becomes constant after a sufficient number of stabilizations and perturbations, yielding an invariant of the manifold-knot pair. We also give evidence toward the relationship between the pants distance of a bridge splitting and the hyperbolic volume of the exterior of a knot.
TeV-PeV Neutrinos from Giant Flares of Magnetars and the Case of SGR 1806-20

We estimate the high-energy neutrino flux from the giant flare of SGR 1806-20 on 2004 December 27, which irradiated Earth with a gamma-ray flux ~104 times larger than the most luminous gamma-ray bursts (GRBs) ever detected. The Antarctic Cerenkov neutrino detector AMANDA was online during the flare and may either have detected high-energy neutrinos for the first time from a cosmic point source or put constraints on the flare mechanism of magnetars. If TeV neutrinos are detected, one would also expect detectable EeV cosmic rays and possibly TeV gamma-ray emission in coincidence.
Radial Profiles of Star Formation in the Far Outer Regions of Galaxy Disks

Star formation in galaxies is triggered by a combination of processes, including gravitational instabilities, spiral wave shocks, stellar compression, and turbulence compression. Some of these persist in the far outer regions, where the column density is far below the threshold for instabilities, making the outer disk cutoff somewhat gradual. We show that in a galaxy with a single exponential gas profile the star formation rate can have a double exponential, with a shallow one in the inner part and a steep one in the outer part. Such double exponentials have been observed recently in the broadband intensity profiles of spiral and dwarf irregular galaxies. The break radius in our model occurs slightly outside the threshold for instabilities, provided the Mach number for compressive motions remains of order unity to large radii. The ratio of the break radius to the inner exponential scale length increases for higher surface brightness disks because the unstable part extends farther out. This is also in agreement with observations. Galaxies with extended outer gas disks that fall more slowly than a single exponential, such as 1/R, can have their star formation rate scale approximately as a single exponential with radius, even out to 10 disk scale lengths. Hα profiles should drop much faster than the star formation rate as a result of the rapidly decreasing ambient density.
Geometric Variational Crimes: Hilbert Complexes, Finite Element Exterior Calculus, and Problems on Hypersurfaces

A recent paper of Arnold, Falk, and Winther (Bull. Am. Math. Soc. 47:281–354, 2010) showed that a large class of mixed finite element methods can be formulated naturally on Hilbert complexes, where using a Galerkin-like approach, one solves a variational problem on a finite-dimensional subcomplex. In a seemingly unrelated research direction, Dziuk (Lecture Notes in Math., vol. 1357, pp. 142–155, 1988) analyzed a class of nodal finite elements for the Laplace–Beltrami equation on smooth 2-surfaces approximated by a piecewise-linear triangulation; Demlow later extended this analysis (SIAM J. Numer. Anal. 47:805–827, 2009) to 3-surfaces, as well as to higher-order surface approximation. In this article, we bring these lines of research together, first developing a framework for the analysis of variational crimes in abstract Hilbert complexes, and then applying this abstract framework to the setting of finite element exterior calculus on hypersurfaces. Our framework extends the work of Arnold, Falk, and Winther to problems that violate their subcomplex assumption, allowing for the extension of finite element exterior calculus to approximate domains, most notably the Hodge–de Rham complex on approximate manifolds. As an application of the latter, we recover Dziuk’s and Demlow’s a priori estimates for 2- and 3-surfaces, demonstrating that surface finite element methods can be analyzed completely within this abstract framework. Moreover, our results generalize these earlier estimates dramatically, extending them from nodal finite elements for Laplace–Beltrami to mixed finite elements for the Hodge Laplacian, and from 2- and 3-dimensional hypersurfaces to those of arbitrary dimension. By developing this analytical framework using a combination of general tools from differential geometry and functional analysis, we are led to a more geometric analysis of surface finite element methods, whereby the main results become more transparent.
Dynamic Resource Allocation Problem for Transportation Network Evacuation

Allocating movable response resources dynamically enables evacuation management agencies to improve evacuation system performance in both the spatial and temporal dimensions. This study proposes a mixed integer linear program (MILP) model to address the dynamic resource allocation problem for transportation evacuation planning and operations. To enable realism in practice, the proposed model includes spatiotemporal constraints related to the time required to reallocate resources to another location, the minimum time allocated resources should be at a location, and the minimum time gap between successive allocations of resources to a location. The proposed model is transformed into a two-stage optimization program for which a greedy-type heuristic algorithm is developed to solve the MILP approximately but efficiently. Results from computational experiments demonstrate the effectiveness of the proposed model and the efficiency of the heuristic solution algorithm.
Prevalence of non-Lipschitz Anosov foliations

We give sharp regularity results for the invariant subbundles of hyperbolic dynamical systems in terms of contraction and expansion rates and prove optimality in a strong sense: we construct open dense sets of codimension one systems where this regularity is not exceeded. Furthermore, we exhibit open dense sets of symplectic, geodesic, and codimension one systems where the analogous regularity results of [PSW] are optimal. As our main result we produce open sets of symplectic Anosov diffeomorphisms and flows with low transverse Holder regularity of the invariant foliations almost everywhere. Prevalence of low regularity of conjugacies is a corollary. We also establish a new connection between the transverse regularity of foliations and their tangent subbundles.
Parametric instability of a liquid sheet

When a liquid sheet is subject to vertical vibration, parametric instabilities may occur and give rise to standing waves. The present work develops the linear theory of this phenomenon for inviscid, Newtonian and viscoelastic liquids. Floquet theory is applied to the governing equations to obtain recursion relations for the temporal modes of the deformations of the free surfaces. In contrast to the case where there is no vibration, we find that the symmetric and antisymmetric deformations of the liquid sheet are coupled to each other. For the inviscid case, the recursion relations are shown to be equivalent to a pair of coupled Mathieu equations. For the Newtonian and viscoelastic cases, the recursion relations are converted into an eigenvalue problem which is solved numerically to obtain the critical vibration amplitude needed to excite the instability, along with the corresponding critical wavenumber. The results display behaviour which is similar in several ways to that of the classic Faraday instability. The parametric instabilities studied here may be an important mechanism in the initial stages of foam destruction by ultrasound, as well as in several other practical applications.
Health and Death Risk and Income Decisions: Evidence from Microfinance

Abstract This paper examines the relationship between health and death risk and income decisions in rural Pakistan. Using data from a microfinance institution, we analyse how insurance against hospitalisation and accidental death influences the purpose of microcredit loans. After correcting for the endogeneity of insurance uptake, we find that individuals are more likely to maintain the same loan purpose as their previous loan if they are insured. The result suggests that households that are insured against hospitalisation and accidental death pursue less diversified income portfolios. This movement away from diversification may increase expected profits.
Hypersonic Boundary-Layer Transition with Ablation and Blowing ⁄

Hypersonic boundary-layer transition is afiected by many factors, including Mach number, Reynolds number, geometry, roughness, and tunnel noise. The efiect of ablation or surface blowing is reviewed by summarizing the experimental data. Blowing generally moves transition upstream, with larger mass∞ow rates or lighter gases causing a larger efiect. Blowing that occurs farther upstream on the model generally also has a larger efiect. It may be feasible to estimate the efiect of blowing using semi-empirical stability-based methods such as e N : Experimental data suitable for comparisons to these methods are summarized, for blunt bodies and for slender bodies at zero and nonzero angles of attack.
THE RETURN OF THE SACRED: THE ARGUMENT ABOUT THE FUTURE OF RELIGION

This is the 70th anniversary of the establishment of the first chairs in sociology at the London School of Economics. In Ig07, Leonard Trelawney Hobhouse gave his inaugural address on assuming the first of the two Martin White Professorships in Sociology. (The other was E. A. Westermarck.) This is also the 43rd Hobhouse Memorial Lecture, the first being given in I930 by J. A. Hobson on the topic are there no constants in sociological thought? or is it that there is no progress?'Towards Social Equality'. Over the years, the lecturers, as I review the list, understandably have had fewer and fewer associations with Professor Hobhouse, and even fewer intellectual ties. This is always sad, particularly since I do believe strongly, as will be evident in this talk, in the value of tradition. In a curious way, I would like to claim two affinities, one of them attenuated, but one of them I would like to think elective, with the lineage and the style of thought of Leonard Hobhouse. To do so, I have to begin, first,
A Spitzer Census of the IC 348 Nebula

Spitzer mid-infrared surveys enable an accurate census of young stellar objects by sampling large spatial scales, revealing very embedded protostars, and detecting low-luminosity objects. Taking advantage of these capabilities, we present a Spitzer-based census of the IC 348 nebula and embedded star cluster, covering a 2.5 pc region and comparable in extent to the Orion Nebula. Our Spitzer census supplemented with ground-based spectra has added 42 Class II T Tauri sources to the cluster membership and identified ~20 Class 0/I protostars. The population of IC 348 likely exceeds 400 sources after accounting statistically for unidentified diskless members. Our Spitzer census of IC 348 reveals a population of Class I protostars that is anticorrelated spatially with the Class II/III T Tauri members, which comprise the centrally condensed cluster around a B star. The protostars are instead found mostly at the cluster periphery about ~1 pc from the B star and spread out along a filamentary ridge. We further find that the star formation rate in this protostellar ridge is consistent with that rate which built the older exposed cluster, while the presence of 15 cold, starless, millimeter cores intermingled with this protostellar population indicates that the IC 348 nebula has yet to finish forming stars. Moreover, we show that the IC 348 cluster is of order 3-5 crossing times old, and, as evidenced by its smooth radial profile and confirmed mass segregation, is likely relaxed. While it seems apparent that the current cluster configuration is the result of dynamical evolution and its primordial structure has been erased, our finding of a filamentary ridge of Class I protostars supports a model in which embedded clusters are built up from numerous smaller subclusters. Finally, the results of our Spitzer census indicate that the supposition that star formation must progress rapidly in a dark cloud should not preclude these observations that show it can be relatively long lived.
Understanding wind ramp events through analysis of historical data

As renewable resources start providing an increasingly larger percentage of our energy needs, we need to improve our understanding of these intermittent resources so we can manage them better. In the case of wind resources, large unscheduled changes in the energy output, called ramp events, make it challenging to keep the load and the generation balanced. In this paper, we show that simple statistical analysis of the wind energy generation can provide quantitative insights into these ramp events. In particular, this analysis can help answer questions such as the time period during the day when these events are likely to occur, the relative severity of positive and negative ramps, and the frequency of their occurrence.
Aliased register allocation for straight-line programs is NP-complete

Register allocation is NP-complete in general but can be solved in linear time for straight-line programs where each variable has at most one definition point if the bank of registers is homogeneous. In this paper we study registers which may alias: an aliased register can be used both independently or in combination with an adjacent register. Such registers are found in commonly-used architectures such as x86, the HP PA-RISC, the Sun SPARC processor, and MIPS floating point. In 2004, Smith, Ramsey, and Holloway presented the best algorithm for aliased register allocation so far; their algorithm is based on a heuristic for coloring of general graphs. Most architectures with register aliasing allow only aligned registers to be combined: for example, the low-address register must have an even number. Open until now has been the question of whether working with restricted classes of programs can improve the complexity of aliased register allocation with alignment restrictions. In this paper we show that aliased register allocation with alignment restrictions for straight-line programs is NP-complete. We also present a proof of a related result by Stockmeyer: the shipbuilding problem is NP-complete.
Transitions to self-employment at older ages: The role of wealth, health, health insurance and other factors

Abstract Relatively little research has been devoted to studying self-employment among older workers although they make up a disproportionate share of the self-employed workforce. This study uses 5 waves of panel data from the Health and Retirement Study to investigate the determinants of labor force transitions to self-employment at older ages. We estimate a multinomial logit model of transitions from wage and salary employment to self-employment, retirement or not working. Results are compared with those found in previous studies. New findings on the impact of health on transitions to self-employment are highlighted.
Variations on a Theme by Schalkwijk and Kailath

Schalkwijk and Kailath (1966) developed a class of block codes for Gaussian channels with ideal feedback for which the probability of decoding error decreases as a second-order exponent in block length for rates below capacity. This well-known but surprising result is explained and simply derived here in terms of a result by Elias (1956) concerning the minimum mean-square distortion achievable in transmitting a single Gaussian random variable over multiple uses of the same Gaussian channel. A simple modification of the Schalkwijk-Kailath scheme is then shown to have an error probability that decreases with an exponential order which is linearly increasing with block length. In the infinite bandwidth limit, this scheme produces zero error probability using bounded expected energy at all rates below capacity. A lower bound on error probability for the finite bandwidth case is then derived in which the error probability decreases with an exponential order which is linearly increasing in block length at the same rate as the upper bound.
Neuronal activities in epileptogenic foci of immature cortex.

Summary Extracellular and intracellular recordings were obtained from neurons of penicillin-induced epileptogenic foci of kittens aged 3–16 days in order to examine the electrophysiological properties of neurons which might account for the decreased seizure susceptibility in immature cortex. Surface interictal discharges were associated with depolarizations in neurons; however, synaptic depolarizations and surface interictal discharges were longer in duration and more variable in amplitude in the kitten focus than in the focus of mature cortex. During depolarizations most neurons generated bursts of 1–5 spikes at a frequency of 100/sec or less. This behavior was in marked contrast to that seen in mature neurons of a penicillin focus where stereotyped long bursts of high frequency spike discharge accompany each depolarization shift. Spike potentials were long in duration, perhaps accounting for the relatively low frequency output of most neurons during interictal discharges. Prolonged IPSPs were generated in the cells of the focus, even at times when no epileptiform discharge was noted. IPSP generation did not account for the rapid attenuation of triggered epileptiform discharges and depolarizations which occurred at stimulus intervals of 2.5 sec or longer. Asynchrony of activities in the epileptic neuronal aggregate was evidenced by the occurrence of isolated depolarization shifts in some cells and a marked variability both in the size of cellular depolarizations and in their relationships to the surface discharges. The data suggest that asynchrony of activities in the population reduced capacity for high frequency spike generation, and failure of excitatory electrogenesis at relatively low frequencies all contribute to the decreased seizure susceptibility of immature cortex.
A Grammatical Approach for Customization of Laminated Composite Materials

The wide range of properties covered by the manufacturable fiber—matrix combinations of composite materials, along with their directional property characteristics, provides designers with material ...
Predicting polarization enhancement in multicomponent ferroelectric superlattices

Ab initio calculations are utilized as an input to develop a simple model of polarization in epitaxial short-period $\mathrm{Ca}\mathrm{Ti}{\mathrm{O}}_{3}∕\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}∕\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_{3}$ superlattices grown on a $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$ substrate. The model is then combined with a genetic algorithm technique to optimize the arrangement of individual $\mathrm{Ca}\mathrm{Ti}{\mathrm{O}}_{3}$, $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$, and $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_{3}$ layers in a superlattice, predicting structures with the highest possible polarization and a low in-plane lattice constant mismatch with the substrate. This modeling procedure can be applied to a wide range of layered perovskite-oxide nanostructures providing guidance for experimental development of nanoelectromechanical devices with substantially improved polar properties.
Prophylaxis against Early Adrenal Insufficiency to Prevent Chronic Lung Disease in Premature Infants

Prophylaxis against Early Adrenal Insufficiency to Prevent Chronic Lung Disease in Premature Infants
Synthetic approaches to hexahydropyrrolo[1,2-b]isoquinolones

Synthetic routes to 1,2,3,5,10,10a-hexahydropyrrolo[1,2,-b]isoquinolin-5-ones functionalized at C-10 were investigated. Attempts to prepare the ketone 2, and subsequently introduce the desired C-10 hydroxymethylene group were unsuccessful due to the failure of 6 to cyclize and the unreactivity of 9 to relevant nucleophiles. Compound 1 was prepared by the condensation of 1-pyrroline with 7-methoxyisobenzopyran-1,3,-(4H)-dione to give 12 in quantitative yield. Acyl halide formation and subsequent reduction gave the desired compound 1.
Diagnosis and management of out-of-phase endometrial biopsies among patients receiving clomiphene citrate for ovulation induction

Eighty-seven patients who underwent a late secretory phase endometrial biopsy while taking clomiphene citrate (CC) for ovulation induction were studied. Of the endometrial biopsies, 21 (24%) showed an endometrium > 2 days out of phase (OOP) with respect to the subsequent menstrual cycle. All 87 patients were categorized by age, weight, CC dosage, and underlying disease entity. The patients then were evaluated by these categories in relation to the incidence of an OOP biopsy while taking CC. Patients with a diagnosis of hypothalamic amenorrhea were statistically more likely to have an OOP endometrium. No other subgroup showed an increased or decreased incidence of OOP biopsies. Conception and spontaneous abortion rates were similar among patients with in-phase biopsies and those with out-of-phase biopsies, which subsequently were corrected with further medical therapy. An aggressive approach to the diagnosis and treatment of luteal phase insufficiency in patients who receive CC for ovulation induction is recommended.
Difficulties with the QPOs resonance model

Abstract High frequency quasi-periodic oscillations (HFQPOs) have been detected in microquasars and neutron star systems. The resonance model suggested by Kluźniak and Abramowicz (2000, 2001) explains twin QPOs as two weakly coupled nonlinear resonant epicyclic modes in the accretion disk. Although this model successfully explains many features of the observed QPOs, it still faces difficulties and shortcomings. Here we summarize the aspects of the theory that remain a puzzle and we briefly discuss likely developments.
The rise in returns to education and the decline in household savings

Abstract Over the past 25 years, returns to higher education have increased while the household savings rate has fallen to almost zero. In this paper, we present a representative agent model where a decline in savings emerges as an outcome of an exogenously driven increase in the return to education. In particular, we find that a rise in the return to education raises the education spending ratio by less than what it reduces the aggregate savings rate, and for some parameter values, it actually reduces both ratios. The paper highlights the fact that a part of the decline in savings may reflect a relative reallocation towards human capital investments away from physical capital.
Treatment of decompensated chronic obstructive pulmonary disease in the emergency department — correlation between clinical features and prognosis

Study objective: Patients with decompensated chronic obstructive pulmonary disease (COPD) are at high risk of relapse after treatment in an emergency department. The purpose of this study was to determine if the risk of relapse correlates with the clinical features of the disease. Patients: Three hundred fifty-two patients with documented COPD who were treated for dyspnea in the ED of the Albuquerque Veterans Administration Medical Center over a three-year period. Methods: We reviewed the clinical features and pulmonary function tests of the patients, who were considered to have COPD if the baseline prebronchodilator one-second forced expiratory volume (FEV 1 ) was less than 80% predicted, and less than 80% of the forced vital capacity and inhaled bronchodilators failed to increase the FEV 1 to levels of more than 80% predicted. Visits for pneumonia, pneumothorax, pleural effusion, or pulmonary emboli were excluded. A relapse was defined as an unscheduled revisit to the ED within 14 days of initial treatment. Data were entered into a microcomputer data base and analyzed by a commercial statistical package. Results: Of 877 visits in which the patient was treated and released from the ED, 281 (32.0%) resulted in relapse and were considered unsuccessful. Compared with successful visits, unsuccessful visits were characterized by a shorter duration of dyspnea ( P = .002), a lower entry FEV 1 ( P = .027), a lower discharge FEV 1 ( P = .040), a greater number of treatments with nebulized bronchodilators ( P = .009), more frequent use of parenteral adrenergic drugs ( P = .006), and less frequent use of oral prednisone on discharge ( P = .016). Patients with one or more relapse visits during the study period (relapsers) differed from nonrelapsers in several respects. Relapsers had a greater bronchodilator response on baseline FEV 1 than nonrelapsers ( P = .047). Nevertheless, relapsers required more bronchodilator treatments in the ED ( P P P P 1 ( P Conclusion: Bronchodilator response on baseline pulmonary function testing appears to identify patients with COPD who have a poor prognosis after emergency treatment. Their poor response to intensive bronchodilator treatment suggests that loss of bronchodilator response may be involved in the pathogenesis of respiratory decompensation.
A comparison of three algorithms for tracing nonlinear equilibrium paths of structural systems

The relative efficiencies of the Riks/Wempner, Crisfield, and normal flow solution algorithms for tracking nonlinear equilibrium paths of structural systems are compared. It is argued that the normal flow algorithm may be both more computationally efficient and more robust compared to the other two algorithms when tracing the path through severe nonlinearities such as those associated with structural collapse. This is demonstrated qualitatively by comparing the relative behaviors of each algorithm in the vicinity of a severe nonlinearity. Quantitative results are presented for the collapse a blade stiffened panel.
Single Pilot IFR Autopilot Complexity/Benefit Tradeoff Study

Five levels of autopilot complexity were flown in a single engine IFR simulation for several different IFR terminal operations. A comparison was made of the five levels of complexity ranging from no-autopilot to a fully coupled lateral and vertical guidance mode to determine the relative benefits vs. complexity/cost of state-of-the-art autopilot capability in the IFR terminal area. For the levels of progression tested, the heading select mode made the largest difference in decreasing workload and simplifying the approach task. It was also found that the largest number of blunders was detected with the most fully automated mode. The data also showed that, regardless of the autopilot mode, performance during an IFR approach was highly dependent on the type of approach being flown. These results indicate that some level of automation is desirable when making IFR approaches in a high workload environment, but also that some disturbing trends are associated with the higher levels of automation.
Carbon Nanotube/Polyelectrolyte Composites as Novel Actuator Materials

Mechanical actuators that simultaneously provide high power densities and large force generation capacities are of great scientific and technological interest. Recently single wall carbon nanotube (SWNT) papers (“bucky” papers) were shown to possess significant promise as electrochemical actuators. Embedding polyelectrolytes, like Nafion™, within the nanotube matrix has the potential to address the limitations of SWNT bundling and tube slippage thus increasing force generation. In this paper two types of Nafion/SWNT composite actuators have been investigated depending on the method of fabrication. In the first case, infiltration of Nafion within SWNT paper matrix was followed by annealing at 150°C to invert Nafion’s micellar structure and render it insoluble. This has resulted in a substantially exfoliated layer morphology that causes a reduction in both conductivity and actuation strain (c.a. 0.03%). In the second case, slow casting of a methanolic suspension of Nafion and SWNT soot, followed by annealing at 150°C, resulted in a more homogeneous structure. This composite, upon electrochemical cycling between -1 and +1 V in aqueous electrolytes, exhibited actuation strains (as high as 0.43%). However, these higher strains are accompanied by an order of magnitude reduction in modulus largely due to Nafion swelling.
Bearing currents and their relationship to PWM drives

This paper examines AC motor shaft voltages and the resulting bearing currents when operated under pulse width modulation (PWM) voltage source inverters. The paper reviews the mechanical and electrical characteristics of the bearings and motor in relation to shaft voltages and bearing currents. A brief review of previous work is addressed, including the system model and experimental results. The theory of electric discharge machining (EDM) is presented, including component calculations of the system elements. The effect of system elements on shaft voltages and bearing currents are evaluated experimentally and the results compared to theory. A design calculation is proposed that provides the relative potential for EDM. Finally, the paper presents quantitative results on one solution to the shaft voltage and bearing current problem.
Quantum lower bound for the collision problem

(MATH) The collision problem is to decide whether a function X: { 1,…,n} → { 1, …,n} is one-to-one or two-to-one, given that one of these is the case. We show a lower bound of Ω(n1/5) on the number of queries needed by a quantum computer to solve this problem with bounded error probability. The best known upper bound is O(n1/3), but obtaining any lower bound better than Ω(1) was an open problem since 1997. Our proof uses the polynomial method augmented by some new ideas. We also give a lower bound of Ω(n1/7) for the problem of deciding whether two sets are equal or disjoint on a constant fraction of elements. Finally we give implications of these results for quantum complexity theory.
A new clustering methodology for the analysis of sorted or categorized stimuli

This paper introduces a new stochastic clustering methodology devised for the analysis of categorized or sorted data. The methodology reveals consumers' common category knowledge as well as individual differences in using this knowledge for classifying brands in a designated product class. A small study involving the categorization of 28 brands of U.S. automobiles is presented where the results of the proposed methodology are compared with those obtained from KMEANS clustering. Finally, directions for future research are discussed.
Nitric oxide in the lower thermosphere

Abstract Satellite measurements of nitric oxide in the lower thermosphere (100–120 km) show the density to be highly variable. The variation at low latitudes is correlated with solar activity and the variation at polar latitudes is connected with geomagnetic activity. A study of a one-dimensional, photochemical model shows that calculations of nitric oxide density in the lower thermosphere are sensitive to uncertainties in the branching ratios for the production of excited and ground state nitrogen by two reactions: the dissociative recombination of ionized nitric oxide and the electron impact dissociation of molecular nitrogen. To a lesser extent, the calculations are also sensitive to uncertainties in the following four reactions: the reaction of excited nitrogen atoms with molecular oxygen, the photodissociation of nitric oxide, the ion-molecule reaction between ionized molecular nitrogen and atomic oxygen, and the deactivation of excited atomic nitrogen by atomic oxygen. The large variability in polar nitric oxide is produced by the variation in the auroral electron flux. A calculation using the model demonstrates that the relationship between the electron flux and the nitric oxide density is non-linear. The Joule heating associated with auroral activity also produces variations in the nitric oxide density. The variability in low latitude nitric oxide is produced by variations in the solar soft x-ray flux. A model calculation shows the relationship between the x-ray flux and the nitric oxide density to be nearly linear.
Was the Mangala Valles system incised by volcanic flows

[1] The Mangala Valles system of channels heads at one of the graben that comprise Memnonia Fossae, extends northward nearly 1000 km across Noachian and Hesperian highlands, and terminates at basins contiguous with Amazonis Planitia. The Mangala Valles system has previously been interpreted to have formed through one or more catastrophic aqueous floods on the basis of similarities between the characteristics of its channel landforms and those of terrestrial systems, including the Channeled Scabland of Washington. Although aqueous mechanisms for formation of Mangala Valles are broadly congruous with known characteristics of the channel system, an alternative volcanic hypothesis for formation of the system appears to be worthy of consideration on the basis of (1) its consistency with the volcanotectonic nature of the system and (2) commonalities between the basic nature of the system and that of large volcanic channels of the inner solar system. Estimates based on thermal considerations suggest that formation of Mangala Valles could conceivably have taken place through eruption of a lava volume of ∼2 × 105 km3, or roughly the total volume of the terrestrial Columbia River Basalt Group. The volcanic hypothesis for formation of Mangala Valles, and a hybrid hypothesis involving formation of Mangala Valles through aqueous processes followed by or in concert with substantial modification of the system by volcanic erosion and deposition, appears viable and worthy of future consideration.
Actuation and ion transportation of polyelectrolyte gels

Consisting of charged network swollen with ionic solution, polyelectrolyte gels are known for their salient characters including ion exchange and stimuli responsiveness. The active properties of polyelectrolyte gels are mostly due to the migration of solvent molecules and solute ions, and their interactions with the fixed charges on the network. In this paper, we extend the recently developed nonlinear field theory of polyelectrolyte gels by assuming that the kinetic process is limited by the rate of the transportation of mobile species. To study the coupled mechanical deformation, ion migration, and electric field, we further specialize the model to the case of a laterally constrained gel sheet. By solving the field equations in two limiting cases: the equilibrium state and the steady state, we calculate the mechanical responses of the gel to the applied electric field, and study the dependency on various parameters. The results recover the behavior observed in experiments in which polyelectrolyte gels are used as actuators, such as the ionic polymer metal composite. In addition, the model reveals the mechanism of the selectivity in ion transportation. Although by assuming specific material laws, the reduced system resembles those in most existing models in the literature, the theory can be easily generalized by using more realistic free-energy functions and kinetic laws. The adaptability of the theory makes it suitable for studying many similar material systems and phenomena.
On the lack of thermal emission from the quiescent black hole XTE J1118+480: Evidence for the event horizon

A soft component of thermal emission is very commonly observed from the surfaces of quiescent, accreting neutron stars. We searched with Chandra for such a surface component of emission from the dynamical black hole candidate XTE J1118+480 (=J1118), which has a primary mass M1 ≈ 8 M☉. None was found, as one would expect if the compact X-ray source is a bona fide black hole that possesses an event horizon. The spectrum of J1118 is well fitted by a simple power-law model that implies an unabsorbed luminosity of LX ≈ 3.5 × 1030 ergs s-1 (0.3-7 keV). In our search for a thermal component, we fitted our Chandra data to a power-law model (with slope and NH fixed) plus a series of nine hydrogen atmosphere models with radii ranging from 9/8 to 2.8 Schwarzschild radii. For the more compact models, we included the important effect of self-irradiation of the atmosphere. Because of the remarkably low column density to J1118, NH ≈ 1.2 × 1020 cm-2, we obtained very strong limits on a hypothetical thermal source: kT∞ < 0.011 keV and L∞,th < 9.4 × 1030 ergs s-1 (99% confidence level). In analogy with neutron stars, there are two possible sources of thermal radiation from a hypothetical surface of J1118: deep crustal heating and accretion. The former mechanism predicts a thermal luminosity that exceeds the above luminosity limit by a factor of 25, which implies that either one must resort to contrived models or, as we favor, J1118 is a true black hole with an event horizon. In addition to neutron stars, we also consider emission from several exotic models of compact stars that have been proposed as alternatives to black holes. As we have shown previously, accreting black holes in quiescent X-ray binaries are very much fainter than neutron stars. One potential explanation for this difference is the larger and hence cooler surface of an 8 M☉ compact object that might be masked by the interstellar medium. However, our upper limit on the total luminosity of J1118 of 1.3 × 1031 ergs s-1 is far below the luminosities observed for neutron stars. This result strengthens our long-held position that black holes are faint relative to neutron stars because they possess an event horizon.
A Matrix Addressable 1024 Element Blue Light Emitting InGaN QW Diode Array

We have fabricated a 32 × 32 two-dimensional proof-of-concept array of individually matrix addressable blue InGaN MQW LEDs. Each 30 μm diameter element is equipped with its own integrated microlens, making these types programmable arrays potentially useful as sources for proximity microscopy with high parallel throughput such as in spatially resolved fluorescence spectroscopic imaging applications.
Economic Laws and Economic History

Preface 1. Engels' law 2. The iron law of wages 3. Gresham's law 4. The law of one price Discussion Comments.
Plausibility of Signals by a Heterogeneous Committee

Krishna and Morgan propose “amendments” to two of Gilligan and Krehbiel’s theoretical studies of legislative signaling. The new results for homogeneous committees do not significantly change the empirical expectations of prior works, but the results for heterogeneous committees contradict earlier claims. This note gives primary attention to heterogeneous committees and compares and contrasts the new and old equilibria and their empirical implications. The notion of signaling is somewhat nebulous in all such games but seems distinctly less plausible in the key Krishna-Morgan proposition than in previous legislative signaling games. Furthermore, the empirical literature on choice of rules—specifically, the finding of a positive relationship between committee heterogeneity and restrictive rules—is inconsistent with the Krishna-Morgan analysis but consistent with Gilligan-Krehbiel analyses, even though the former is informationally efficient and the latter are not.
Unemployment Insurance Taxes and the Cyclical and Seasonal Properties of Unemployment

Abstract We combine Current Population Survey micro data for 1979–1987 with a newly assembled database of tax rates for the U.S. unemployment insurance system to measure the effects of imperfect experience-rating on the incidence of unemployment. We find a strong negative association between the degree of experience-rating and the rate of temporary layoff unemployment, with the largest effect in recessionary years and the smallest effect in expansionary years. Increases in the degree of experience-rating are also associated with dampened seasonal fluctuations in temporary layoffs, particularly in construction and durable manufacturing.
An Empirical Examination of the Stated Purposes of Issuer Tender Offers to Purchase Common Stock

This paper documents the purposes of issuer tender offers to repurchase stock, as stated in Securities and Exchange Commission (SEC) disclosures, over the period 1994-2006. We explore whether stated purposes relate to announcement period returns and find returns are significantly lower when repurchases replace dividends, distribute cash from unspecified sources, or occur subsequent to third-party tender offers. Announcement period returns are significantly higher when repurchases are viewed by management as the best investment opportunity available or when they occur subsequent to previous repurchase programs. Finally, we find evidence in support of signaling theory and Jensen's (1986) agency cost of free cash flow theory.
Diels-Alder and ene reactions of nitrosyl hydride and nitrosoformaldehyde

Abstract Nitrosyl hydride and nitrosoformaldehyde have been prepared by the thermolysis of their 9,10-dimethylanthracene adducts. Both HNO and HCONO are found to be reactive as enophiles and dienophiles.
Circular array STAP

Traditionally, space-time adaptive processing (STAP) for airborne early warning (AEW) radar has been applied to uniform linear arrays (ULAs). However, when considering the overall radar system, electronically scanned circular arrays have advantages: a better combination of even and continual angular and temporal coverage, and mechanical simplicity because it does not need to rotate. This paper answers the question "How well does STAP perform when applied to a circular array?" This paper shows that for the AEW mission, circular arrays are indeed STAP compatible. However, when conventional STAP algorithms are used there may be a small loss in performance when compared with a ULA. With some care in the choice and implementation of the STAP algorithm, the majority of the degradation is at close ranges, where the target returns are relatively strong. At long ranges performance is barely affected. A STAP algorithm which compensates for the circular array environment and provides better performance than existing algorithms is presented.
Topological Strings and (Almost) Modular Forms

The B-model topological string theory on a Calabi-Yau threefold X has a symmetry group Γ, generated by monodromies of the periods of X. This acts on the topological string wave function in a natural way, governed by the quantum mechanics of the phase space H3(X). We show that, depending on the choice of polarization, the genus g topological string amplitude is either a holomorphic quasi-modular form or an almost holomorphic modular form of weight 0 under Γ. Moreover, at each genus, certain combinations of genus g amplitudes are both modular and holomorphic. We illustrate this for the local Calabi-Yau manifolds giving rise to Seiberg-Witten gauge theories in four dimensions and local IP2 and IP1 × IP1. As a byproduct, we also obtain a simple way of relating the topological string amplitudes near different points in the moduli space, which we use to give predictions for Gromov-Witten invariants of the orbifold \({{\mathbb {C}^3} / {\mathbb {Z}_3}}\).