cssi/SciSciGPT-SciSciNet huggingface dataset:
The Effect of Cluster Environment on Galaxy Evolution in the Pegasus I Cluster

We present neutral hydrogen observations of 54 galaxies in the Pegasus Cluster. The observations include single-dish H I measurements, obtained with the Arecibo telescope for all 54 galaxies in the sample, as well as H I images obtained with the Very Large Array (VLA) for 10 of these. The Arecibo profiles reveal an overall H I deficiency in the cluster, with ~40% of the galaxies in the core of the cluster showing modest deficiencies of typically a factor of 2-3. The H I morphology of some galaxies shows that the H I disk is smaller than the optical disk and slightly offset from the stars. We find a correlation between H I deficiency and the ratio of the H I disk size to optical disk size. More H I-deficient galaxies have relatively smaller H I disks, a configuration that is usually attributed to an interaction between the interstellar medium (ISM) of the galaxy and the hot intracluster medium (ICM). Such a result is surprising, since the Pegasus Cluster has a low level of X-ray emission and a low velocity dispersion. The low velocity dispersion, coupled with the lack of a dense hot ICM, indicate that ram pressure stripping should not play a significant role in this environment. In addition, two of the galaxies, NGC 7604 and NGC 7648, are morphologically peculiar. Their peculiarities indicate contradictory scenarios of what is triggering their unusual star formation. Hα imaging, along with long-slit spectroscopy of NGC 7648, reveal morphological features that point to a recent tidal interaction. On the other hand, Hα imaging of NGC 7604 reveals a strong episode of star formation concentrated into an asymmetric arc, preferentially located on one side of the galaxy. VLA H I mapping shows that H I is also highly concentrated into that region, suggestive of a ram pressure event. Our data indicate that ISM-ICM interactions may play a role in a wider variety of environments than suggested by simple ram pressure arguments.
A lexicographic shellability characterization of geometric lattices

Geometric lattices are characterized in this paper as those finite, atomic lattices such that every atom ordering induces a lexicographic shelling given by an edge labeling known as a minimal labeling. Equivalently, geometric lattices are shown to be exactly those finite lattices such that every ordering on the join-irreducibles induces a lexicographic shelling. This new characterization fits into a similar paradigm as [email protected]?s characterization of supersolvable lattices as those lattices admitting a different type of lexicographic shelling, namely one in which each maximal chain is labeled with a permutation of {1,...,n}.
Experimental modeling of central axis and jet-ring turbine disk cooling

The test facility, experimental methods, and summary results are presented from a study modeling turbine disk cooling with multiple impinging jets, such as employed on the Space Shuttle Main Engine oxygen turbopump. The study was designed to provide a comparison of detailed local convection heat transfer information obtained with a single center-supply of disk coolant, as opposed to the present flight configuration where disk coolant is supplied through an array of 19 radially outboard jets. Specially constructed turbine disk models were used in a program to evaluate possible benefits and tradeoffs of employing an alternate disk cooling scheme. The study involved the design, construction, and testing of two full-scale rotating model disks, one plane and smooth for baseline testing and the second contoured to the present flight configuration, together with the corresponding plane and contoured stators. Local heat transfer rates are determined from the color display of encapsulated liquid crystals coated on the disk in conjunction with use of a computer vision system. The test program was composed of a wide variety of disk speeds, flow rates, and geometrical configurations, including testing for the effects of bolt heads and hot gas entrainment into the disk cavity.
Commitment under uncertainty: Two-stage stochastic matching problems

We define and study two versions of the bipartite matching problem in the framework of two-stage stochastic optimization with recourse. In one version, the uncertainty is in the second stage costs of the edges, and in the other version, the uncertainty is in the set of vertices that needs to be matched. We prove lower bounds, and analyze efficient strategies for both cases. These problems model real-life stochastic integral planning problems, such as commodity trading, reservation systems and scheduling under uncertainty.
Statistical mechanics of negative temperature states

The dynamics of two-dimensional interacting line vortices is identical to that of the two-dimensional electrostatic guiding center plasma. Both are Hamiltonian systems and are therefore susceptible to statistical mechanical treatments. The predictions of the microcanonical ensemble are explored for this system. Interest focuses primarily on the regime of total positive interaction energy, which should be above the Onsager negative temperature threshold. Calculations of the probability distribution for a component by means of the central limit theorem are carried out in the manner of Khinchin. The probability distribution of a component reduced to the usual Gibbs distribution in the regime of positive temperatures, and is still explicitly calculable for negative temperatures. The negative temperature states are neither quiescent nor spatially uniform. Expressions for the temperature are explicitly provided in terms of the total particle energy and particle number. A BBGKY hierarchy can be derived for both temperature regimes. Numerical simulations involving solutions of the equations of motion of 4008 particles are presented.
Chain-elongation and degradation of carboxylic acids by barton-ester based radical chemistry

The reaction of α-trifluoroacetoxy acrylates and acrylonitriles with carbon radicals formed from carboxylic acids gives adducts that can be transformed into vic-diols, esters, amides, and homoaldehydes in good to high yield. Aldoses can be smoothly degraded to the corresponding nor- or bis-nor compounds using radical chemistry.
Simulations and measurements of the background encountered by a high-altitude balloon-borne experiment for hard X-ray astronomy

Abstract We have modelled the hard X-ray background expected for a high-altitude balloon flight of the Energetic X-ray Imaging Telescope Experiment (EXITE2), an imaging phoswich detector/telescope for the 20–600 keV energy range. Photon- and neutron-induced contributions to the background are considered. We describe the code and the results of a series of simulations with different shielding configurations. The simulated hard X-ray background for the actual flight configuration agrees reasonably well (within a factor of ∼2) with the results measured on the first flight of EXITE2 from Palestine, Texas. The measured background flux at 100 keV is ∼4 × 10 −4 counts cm −2 s −1 keV −1 .
Vane Clocking in a Three-Stage Compressor: Frequency Domain Data Analysis

Blade row interactions affect compressor performance and durability. As design systems expand to account for these interactions, a better understanding of the underlying physics is necessary. In this paper, results from a vane clocking experiment in a three-stage compressor are discussed. Efforts are focused on the second stage, specifically the change in stator 2 wake profiles with respect to the placement of the stator 1 wake. The two clocking conditions presented position the wake from stator 1 at the leading edge of stator 2 and in the middle of the stator 2 passage. The time-accurate data are Fourier decomposed to determine the relative magnitudes of the frequencies in the spectrum. With data acquired at 50 circumferential locations spanning one vane passage for each clocking configuration, an enormous amount of data is collected, and a useful method for synthesizing this information is presented. Results show that, by placing the stator 1 wake at the leading edge of stator 2, the stator 2 boundary-layer response to the large incidence variations associated with the rotor 2 wakes is dampened, resulting in a thinner and more shallow stator 2 wake.
Weyl Curvature, Einstein Metrics, and Seiberg-Witten Theory

We show that solutions of the Seiberg-Witten equations lead to non-trivial lower bounds for the L2-norm of the Weyl curvature of a compact Riemannian 4-manifold. These estimates are then used to derive new obstructions to the existence of Einstein metrics. These results considerably refine those previously obtained using scalar-curvature estimates alone.
Surge Voltages in Residential and Industrial Power Circuits

Special instrumentation was developed for monitoring the magnitude and frequency of occurrence of surge voltages in residential and industrial circuits. Over a period of 2 years, more than 400 locations in 20 cities were surveyed. Monitoring was accomplished by automatic recording cathode-ray oscilloscopes and simple surge counters. In residential circuits, two significant sources of surge voltages were identified: load switching within the house, and external surges, most likely associated with lightning, coming through the service drop. In industrial circuits, the levels of surges are lower than in residential circuits. However, switching surges on the load side of the switch can be severe. Internally generated surges as high as 2500 volts were recorded during this test program, and surges due to lightning reaching 5600 volts have been recorded on a 120-volt overhead distribution line.
Cosmetic Upper Blepharoplasty

The anatomy of the upper eyelid is complex; however, those structures that make it complex are not involved in routine cosmetic blepharoplasty. The most common reason for patients seeking cosmetic surgery of the upper eyelids is excess skin and its associated heaviness. Appropriate removal of skin, preseptal orbicularis oculi muscle, submuscular fat, and orbital fat will achieve consistently good results.
The wage labor market and inequality in Viet Nam in the 1990s

Has the expansion of wage employment in Vietnam exacerbated social inequalities, despite its contribution to income growth? Gallup uses the two rounds of the Vietnamese Living Standards Survey (VLSS) to evaluate the contribution of wage employment to inequality and income growth over the period of rapid economic growth in the 1990s following market reforms. If Vietnam sustains its economic development in the future, wage employment will become an ever more important source of household income as family farms and self-employed household enterprises become less prevalent. Observing the recent evolution of wage employment compared with farm and non-farm self-employment provides clues as to how economic development will change Vietnamese society, in particular its impact on income inequality within and between communities. The author shows that standard methods for calculating income inequality can be severely biased due to measurement error when decomposing the contribution of different sectors, regions, or groups to overall inequality. A new method for consistent decomposition of inequality by income source shows that despite the rapid growth of wages in the 1990s, wage inequality fell modestly. Contrary to the results of uncorrected methods, wage employment contributes a roughly similar amount to overall income inequality as other nonagricultural employment (household enterprise and remittances, mainly). Agricultural income actually reduces overall income inequality because inequality between agricultural households is much lower than inequality between nonagricultural households, and agricultural income has a lower correlation with other income sources. Wage employment has not been the locus of growing disparity between the haves and the have-nots in Vietnam. A declining share of agriculture as the economy grows in Vietnam means that income inequality will rise, assuming that within-sector inequality does not change. This rising inequality, due to the shrinking share of agriculture, will be difficult to avoid without giving up economic growth and rapid poverty reduction in Vietnam. Historically, the process of economic development has always brought about a transition out of small farms and household enterprises into wage employment as worker productivity increases and non-household enterprises dominate the economy.
Variations in planetary convection via the effect of climate on damage

Abstract A new model for the generation of plate tectonics suggests an important interaction between a planet's climate and its lithospheric damage behavior; and thus provides a simple explanation for the tectonic difference between Earth and Venus. We propose that high surface temperatures will lead to higher healing rates (e.g. grain growth) in the lithosphere that will act to suppress localization, plate boundary formation, and subduction. This leads to episodic or stagnant lid convection on Venus because of its hotter climate. In contrast, Earth's cooler climate promotes damage and plate boundary formation. The damage rheology presented in this paper attempts to describe the evolution of grain size by allowing for grain reduction via deformational work input and grain growth via surface tension-driven coarsening. We explore the interaction of damage and healing in two-dimensional numerical convection simulations. We also develop a simple “drip-instability” model to test the hypothesis that the competition between damage and healing controls convective and plate tectonic style by modulating episodicity at subduction zones. At small values of damage, f A , (or large values of healing, k A ) the lithosphere remains strong enough to resist subduction on time scales of billions of years. At intermediate values of f A and k A the lithosphere may become mobilized and allow for short bursts of tectonic behavior followed by periods of quiescence. At large (small) values of f A ( k A ) the fineness is increased so that the viscosity of the plate boundary is reduced to allow for continuous, unimpeded subduction of lithosphere and plate-like deformation. The results suggest the feasibility of our proposed hypothesis that the interplay of climate and damage control the mode of tectonics on a planet.
Hierarchical N-body methods

Abstract The hierarchical tree method offers the possibility of computing the interaction between N self-gravitating particles in a time ≈ 0 (N log N), without using a grid. The potential advantages of this technique for collisionless systems and for particle hydrodynamic schemes are discussed.
Scaling of space and timelike response of confined relativistic particles

Abstract The response of a relativistic particle bound in a linear confining well is calculated as a function of the momentum and energy transfer, q , ν. At large values of | q | the response exhibits scaling in the variable y =ν−| q | , which is proportional to the Nachtmann variable, ξ. The approach to scaling is studied at smaller values of | q | . Scaling occurs at ν∼| q | at relatively small | q | , and its validity extends over the entire ξ range as | q | increases; this behavior is observed in electron–proton scattering. About 10% of the response at large | q | is in the timelike region where ν>| q | , and it is necessary to include it to fulfill the particle number sum rule. The Gross–Llewellyn Smith and Gottfried sum rules are discussed in the context of these results.
Superconducting properties of Tl-Ba-Ca-Cu-O films on silver substrates

Films of Ba-Ca-Cu-O have been RF-magnetron-sputtered onto Consil 995 substrates. A postdeposition anneal in an overpressure of Tl produces the superconducting 1212 and 2212 phases. Varying the annealing procedures changes the electrical properties of the final films dramatically. Dynamic impedance, a novel approach to the electrical characterization of these films on a conductive substrate, is discussed and compared with SEM (scanning electron microscope), XRD (X-ray diffraction) and RBS (Rutherford backscattering) measurements as a function of differing annealing protocols. The improvement in the superconducting responses as a function of annealing procedures correlates well with the improved morphology observed in the SEM photographs. Also, the XRD data show increased c-axis material with the C annealing protocol.
Fluorous Chemistry in Pittsburgh: 1996–2008

The article summarizes a lecture presented at the American Chemical Society Symposium for the 2008 Award for Creative Work in Fluorine Chemistry on April 7, 2008. A high level, historical overview of work in the fluorous field at the University of Pittsburgh is presented.
On Generalizations of the Pentagram Map: Discretizations of AGD Flows

In this paper we investigate discretizations of AGD flows whose projective realizations are defined by intersecting different types of subspace in $\mathbb{RP}^{m}$ . These maps are natural candidates to generalize the pentagram map, itself defined as the intersection of consecutive shortest diagonals of a convex polygon, and a completely integrable discretization of the Boussinesq equation. We conjecture that the r-AGD flow in m dimensions can be discretized using one (r−1)-dimensional subspace and r−1 different (m−1)-dimensional subspaces of $\mathbb{RP}^{m}$ .
Synthesis on N-Alkylated Maleimides

Abstract A two step synthesis of N-alkylated maleimides is presented. This method allows for the use of widely available starting materials and produces maleimides in high purity and yields. The maleimide precursors are of interest for potential thermo- and photo-setting polymerization processes.
NATURAL GOLD DENDRITES FROM HYDROTHERMAL Au-Ag DEPOSITS: CHARACTERISTICS AND COMPUTER SIMULATIONS

Epithermal vein gold deposits in the western United States locally contain bonanza zones with extraordinary concentrations of gold in banded ores consisting of alternating gold-rich and barren silica bands. Gold-rich bands commonly consist of coalescing or isolated gold dendrites, which occur in a matrix of variably preserved colloidal silica. Most dendrites appear to have grown outward from near-vertical vein walls and have a rough radial symmetry. SEM images of dendrite surfaces suggest that they formed by the aggregation of spherical particles in the 10–100 nm range. Fractal dimension (Df) of true two-dimensional slices through the dendrites typically are in the 1.6–1.7 range, which compares favorably with the theoretical Df value of ~1.7 for 2-dimensional diffusion-limited colloid aggregation (DLA). Monte Carlo computer simulations best reproduce natural dendrite morphologies when particle randomness is large, sticking efficiency=1, and when particles are required to contact 3 adjacent particles on the dendrite as a prerequisite for aggregation. Thus, the physical transport and aggregation of gold colloids offers an attractive explanation for the origin of these enigmatic super high-grade gold ores.
Who Counts? Dilemmas of Justice in a Postwestphalian World

: Who counts as a subject of justice? Not so long ago, it was widely assumed that those “who counted” were simply the citizens of a bounded territorial state. Today, however, as activists target injustices that cut across borders, that “Westphalian” view is contested and the “who” of justice is an object of hot dispute. This new situation calls for a new kind of justice theorizing, whose contours I sketch in this essay. Arguing, first, for a reflexive mode of theorizing, I introduce the concept of “misframing”, which can subject the Westphalian “who” to critical scrutiny. Arguing, second, for the necessity of a substantive normative principle to evaluate competing “who’s”, I introduce the “all-subjected principle” as superior to three better known alternatives: namely, membership, humanism, and the all-affected principle.
Lip shave or vermilionectomy: indications and technique.

Summary Excision of the exposed mucosa or vermilion of the lips can be readily and safely performed under local an˦sthesia and is particularly indicated in situations requiring resurfacing of the lip, notably extensive precancerous leukoplakia or chronic solar cheilitis—the chronic sunburn of the weather-beaten "farmer's or sailor's skin" or "tropical skin" of the inhabitants of sunny climates. The "lip shave" can also be employed for reduction of lip size in hyperttrophy and should be combined with a V-resection whenever frank epithelioma is associated with leukoplakia of the remainder of the lip in order to prevent the occurrence of a new lesion elsewhere on the lip. The "lip shave" is thus a non-deforming plastic operation of great value in the prophylaxis and treatment of lip cancer and in the cosmetic correction of certain congenital, neoplastic, and traumatic lip deformities.
Barrier certificates for nonlinear model validation

Methods for model validation of continuous-time nonlinear systems with uncertain parameters are presented in this paper. The methods employ functions of state-parameter-time, termed barrier certificates, whose existence proves that a model and a feasible parameter set are inconsistent with some time-domain experimental data. A very large class of models can be treated within this framework; this includes differential-algebraic models, models with memoryless/dynamic uncertainties, and hybrid models. Construction of barrier certificates can be performed by convex optimization, utilizing recent results on the sum of squares decomposition of multivariate polynomials.
An MPI Implementation of a Self-Submitting Parallel Job Queue

We present a simple and easy to apply methodology for using high-level self-submitting parallel job queues in an MPI environment. Using C++, we implemented a library of functions, MPQueue, both for testing our concepts and for use in real applications. In particular, we have applied our ideas toward solving computational combinatorics problems and for finding bifurcation diagrams of solutions of partial differential equations (PDE). Our method is general and can be applied in many situations without a lot of programming effort. The key idea is that workers themselves can easily submit new jobs to the currently running job queue. Our applications involve complicated data structures, so we employ serialization to allow data to be effortlessly passed between nodes. Using our library, one can solve large problems in parallel without being an expert in MPI. We demonstrate our methodology and the features of the library with several example programs, and give some results from our current PDE research. We show that our techniques are efficient and effective via overhead and scaling experiments.
Looking at scenes while searching for numbers: Dividing attention multiplies space

Observers tend to remember seeing a greater expanse of a scene than was shown (boundary extension [BE]). Is undivided visual attention necessary for BE? In Experiment 1, 108 observers viewed photographs with superimposed numerals (2s and 5s). Each appeared for 750 msec, followed by a masked interval and a test picture (same, closer up, or wider angled). Test pictures were rated as the same, closer, or wider angled on a 5-point scale. Visual attention was manipulated with a search task: The observers reported the number of 5s (zero, one, or two). The observers performed search only, picture rating only, or both (giving search priority). Search accuracy was unaffected by condition. BE occurred in both conditions but was greater with divided attention. The results were replicated using incidental BE tests (Experiments 2 and 3). We propose that anticipatory representation of layout occurs automatically during scene perception, with focal attention serving to constrain the boundary error.
The Wasteland of Random Supergravities

We show that in a general $ \mathcal{N} = {1} $ supergravity with N ≫ 1 scalar fields, an exponentially small fraction of the de Sitter critical points are metastable vacua. Taking the superpotential and Kahler potential to be random functions, we construct a random matrix model for the Hessian matrix, which is well-approximated by the sum of a Wigner matrix and two Wishart matrices. We compute the eigenvalue spectrum analytically from the free convolution of the constituent spectra and find that in typical configurations, a significant fraction of the eigenvalues are negative. Building on the Tracy-Widom law governing fluctuations of extreme eigenvalues, we determine the probability P of a large fluctuation in which all the eigenvalues become positive. Strong eigenvalue repulsion makes this extremely unlikely: we find P ∝ exp(−c N p ), with c, p being constants. For generic critical points we find p ≈ 1.5, while for approximately-supersymmetric critical points, p ≈ 1.3. Our results have significant implications for the counting of de Sitter vacua in string theory, but the number of vacua remains vast.
Weighted Aumann-Shapley pricing

Cost allocation problems arise in many contexts in economics and management science. In a typical problem that we have in mind, a decision maker must decide how to allocate the joint cost of production among several commodities using prices. Furthermore, these prices must satisfy certain reasonable postulates among which is the requirement that total revenue associated with these prices must cover total cost. In this paper, we investigate a generalization of Aumann-Shapley pricing, called Weighted Aumann-Shapley pricing, that allows for asymmetric pricing of commodities even when those commodities affect costs in a symmetric fashion. Weighted AS pricing is a natural extension of (symmetric) Aumann-Shapley pricing, and may be considered a non-atomic analogue of Owen's modified diagonal formula (with respect to the multilinear extension) for the weighted TU Shapley Value.
Next generation sequence analysis of the transcriptional response to neonatal hyperoxia

Results 248 genes were identified as differentially expressed between hyperoxia and control samples by both SAM (median FDR = 0) and CuffDiff2 (p<0.05) and had a foldchange ≤ 2. We successfully validated 17 of 24 genes by qPCR. Canonical pathways significantly dysregulated in hyperoxia lungs included Nrf2-mediated oxidative stress signaling, p53 signaling, hepatic fibrosis and sildenafil pathways. Interestingly most genes significantly affected following hyperoxia exposure (~70%) showed a pattern of expression consistent with an arrest in lung development. A subset of the genes dysregulated in hyperoxic neonatal mouse lungs, were also differentially expressed in human BPD lung tissue. Conclusions We have identified genes dysregulated in mouse of BPD-like pathology. Further analysis of these data will enhance our current knowledge of BPD, and may be useful for developing novel therapeutic strategies.
Code Reverse Engineering Problem for Identification Codes

At ITW'10, Bringer suggested to strengthen their previous identification protocol where the security depends on computational assumptions (related to the Polynomial Reconstruction problem) by extending the Code Reverse Engineering (CRE) problem to identification codes. We formalize this new problem and we extend security results by Tillich on this very problem. This enables us to prove the security of this protocol using information theoretical arguments.
Measuring planetary hydrogen by remote gamma-ray sensing

Abstract A γ-ray spectrometer (GRS) orbiting about an airless or nearly airless planetary body may be used to detect and measure hydrogen concentration and the neutron leakage flux. The H concentration affects both the magnitude and energy spectrum of the neutron flux, while the neutron flux, in turn, determines the intensity of the observed H γ-ray line for a given concentration. Because of this interconnection, the dual measurement of both H and neutron flux enhances the accuracy of each, and assists in the measurement of other elements. Hydrogen is detected by means of its 2.223 MeV γ ray which arises from the capture of thermal neutrons producing deuterium. The 2.223 MeV H signal is observed in the γ-ray spectrum against an interference spectrum consisting of cosmic γ rays, planetary background emission, and a variety of γ rays arising from cosmic-ray particle interactions with the γ-ray spectrometer and spacecraft (SC). In addition, line interferences are generated by the interactions of neutrons with hydrogenous materials in the GRS and SC. In this paper the expected signal levels and the sources of continuum and line interference in the detection and measurement of H are assessed in terms of two possible missions, a lunar orbiter and a comet nucleus rendezvous. In lunar orbit, a 100 h observation at an altitude of 100 km should enable the detection of H at a level of 0.06% with an uncertainty of ∼ 0.02%. At a distance equal to the radius of a comet's nucleus, in 100 h a GRS can detect H at a level of 0.07% and can measure H at expected cometary levels (∼ 6%) with an uncertainty of 0.06%.
Approximability of Minimum AND-Circuits

Given a set of monomials, the Minimum AND-Circuit problem asks for a circuit that computes these monomials using AND-gates of fan-in two and being of minimum size. We prove that the problem is not polynomial-time approximable within a factor of less than 1.0051 unless $\mathsf{P}=\mathsf{NP}$, even if the monomials are restricted to be of degree at most three. For the latter case, we devise several efficient approximation algorithms, yielding an approximation ratio of 1.278. For the general problem, we achieve an approximation ratio of d−3/2, where d is the degree of the largest monomial. In addition, we prove that the problem is fixed parameter tractable with the number of monomials as parameter. Finally, we discuss generalizations of the Minimum AND-Circuit problem and relations to addition chains and grammar-based compression.
Flutter of an Infinitely Long Panel in a Duct

The aeroelastic stability is examined of an infinitely long panel of finite width enclosed in a duct such that both the upper and lower surfaces of the panel are exposed to an inviscid, and compressible flow. The panel behavior is accounted for by small deflection plate theory, whereas the aerodynamic forces acting on the panel are described by the classical linearized small disturbance potential theory. As such, a self-consistent theoretical model is constructed for the asymptotic behavior of the panel. Two panel boundary conditions are considered; the panel is assumed to be either simply supported, or clamped along the side edges. For the simply supported case, rather extensive numerical results have been obtained. The effects of Mach number, air/panel mass ratio, and duct dimension on the flutter velocity are determined. a a* b c CQ c* D E h h* hp L / /* M m P t U U* U*T W x y z y Nomenclature speed of sound a/c0 panel width wave speed reference wave speed, 2n(D/pmhb2)1/2 C/CQ plate stiffness modulus of elasticity height of duct nondimensional height of duct, h/b panel thickness panel length wavelength nondimensional wavelength, l/b Mach number, U*/a* number of modes pressure time flow velocity U/CQ critical flutter velocity panel deflection streamwise coordinate spanwise coordinate coordinate perpendicular to plane of panel separation constant nondimensional dynamic pressure, /x£/*2
Production and Abatement Distortions under Noisy Green Taxes

A pollution regulator seeking to maximize social surplus can be viewed as facing two efficiency problems. One is that, given abatement technology investment decisions, it should attempt to ensure that firms which should produce do produce and firms which should not produce do not produce. This ex-post efficiency problem is not trivial when there is noise concerning the extent of environmental damage a firm does. We use a Bayesian information framework to show that the regulator may find it efficient to tax a firm that reads as a high (low) damage polluter at less (more) than the damage reading. Unfortunately when an abatement decision has to be made, this ex-post efficient tax system also dampens the incentive to abate. In the absence of wrong-firm concerns, a regulator can solve the abatement problem by an ex ante declaration that taxes will not be adjusted for signal noise. However, the regulator has a commitment problem as such taxes may not be ex-post efficient. The most appropriate policy may involve a combination of instruments.
Ultrafast Dynamics of Defect-Assisted Electron–Hole Recombination in Monolayer MoS2

In this Letter, we present nondegenerate ultrafast optical pump–probe studies of the carrier recombination dynamics in MoS2 monolayers. By tuning the probe to wavelengths much longer than the exciton line, we make the probe transmission sensitive to the total population of photoexcited electrons and holes. Our measurement reveals two distinct time scales over which the photoexcited electrons and holes recombine; a fast time scale that lasts ∼2 ps and a slow time scale that lasts longer than ∼100 ps. The temperature and the pump fluence dependence of the observed carrier dynamics are consistent with defect-assisted recombination as being the dominant mechanism for electron–hole recombination in which the electrons and holes are captured by defects via Auger processes. Strong Coulomb interactions in two-dimensional atomic materials, together with strong electron and hole correlations in two-dimensional metal dichalcogenides, make Auger processes particularly effective for carrier capture by defects. We pres...
An inexpensive carbohydrate derivative used as a chiral auxiliary in the synthesis of α-hydroxy carboxylic acids

Abstract Protected α-hydroxy carboxylic acids were synthesized in moderate yield and high diastereoselectivity by alkylation of glycolate (α-hydroxy acetate) enolates using a d -fructose-derived chiral auxiliary. The new chiral center was assigned the R configuration based on comparisons of optical rotations and on one crystal structure analysis. This alkylation methodology is compatible with several hydroxyl protecting groups. The free hydroxy acids were obtained upon removal of the protecting group from the hydroxyl functionality followed by saponification.
Perceptual completion of occluded surfaces

Researchers in computer vision have primarily studied the problem of visual reconstruction of environmental structure that is plainly visible. In this paper, the conventional goals of visual reconstruction are generalized to include both visible and occluded forward facing surfaces. This larger fraction of the environment is termed theanterior surfaces. Because multiple anterior surface neighborhoods project onto a single image neighborhood wherever surfaces overlap, surface neighborhoods and image neighborhoods are not guaranteed to be in one-to-one correspondence, as conventional “shape-from” methods assume. The result is that the topology of three-dimensional scene structure can no longer be taken for granted, but must be inferred from evidence provided by image contours. In this paper, we show that the boundaries of the anterior surfaces can be represented in viewer-centered coordinates as alabeled knot-diagram. Where boundaries are not occluded and where surface reflectance is distinct from that of the background, boundaries will be marked by image contours. However, where boundaries are occluded, or where surface reflectance matches background reflectance, there will be no detectable luminance change in the image. Deducing the complete image trace of the boundaries of the anterior surfaces under these circumstances is called thefigural completionproblem. The second half of this paper describes a computational theory of figural completion. In more concrete terms, the problem of computing a labeled knot-diagram representing an anterior scene from a set of contour fragments representing image luminance boundaries is investigated. A working model is demonstrated on a variety of illusory contour displays. The experimental system employs a two-stage process of completion hypothesis and combinatorial optimization. The labeling scheme is enforced by a system of integer linear inequalities so that the final organization is the optimal feasible solution of an integer linear program.
Stability Theorems for Chiral Bag Boundary Conditions

We study asymptotic expansions of the smeared L 2-traces Fe−t P^2 and FPe−tP^2, where P is an operator of Dirac type and F is an auxiliary smooth endomorphism. We impose chiral bag boundary conditions depending on an angle θ. Studying the θ-dependence of the above trace invariants, θ-independent pieces are identified. The associated stability theorems allow one to show the regularity of the eta function for the problem and to determine the most important heat kernel coefficient on a four dimensional manifold.
Finite generation of symmetric ideals

Let be a commutative Noetherian ring, and let be the polynomial ring in an infinite collection of indeterminates over . Let be the group of permutations of . The group acts on in a natural way, and this in turn gives the structure of a left module over the group ring . We prove that all ideals of invariant under the action of are finitely generated as -modules. The proof involves introducing a certain well-quasi-ordering on monomials and developing a theory of Grobner bases and reduction in this setting. We also consider the concept of an invariant chain of ideals for finite-dimensional polynomial rings and relate it to the finite generation result mentioned above. Finally, a motivating question from chemistry is presented, with the above framework providing a suitable context in which to study it.
Psychiatrists' concept of adolescent self-image

The objectives of the study were as follows: (1) to determine the accuracy of psychiatrists' concepts of the self-image of healthy and disturbed adolescents, and (2) to examine the effects of psychiatrists' gender, experience, and specialization on the accuracy of these concepts. Toward this end, eighty-four psychiatrists completed a modified Offer Self-image Questionnaire as they believed a mentally healthy 15-year-old of their gender would respond. These responses were compared to those of 140 nonpatient 15-year-olds. Sixty-one psychiatrists completed the questionnaire as they believed a disturbed 15-year-old of their gender would respond. These responses were compared to the responses of 70 psychiatric inpatient 15-year-olds of the same diagnosis. The results were that psychiatrists had a more accurate concept of normal adolescents' self-image than was found in 1981. However, their view of the self-image of disturbed adolescents was more psychopathological than the disturbed adolescents viewed themselves. Psychiatrists' gender, number of years postresidency, and type of training had no effect on the accuracy of the psychiatrists' concepts. The results demonstrate that while psychiatrists work with disturbed adolescents, they have a more accurate perception of the self-image of normal adolescents. This can effect the diagnosis and treatment of adolescent patients.
Feedback control logic for spacecraft eigenaxis rotations under slew rate and control constraints

The problem of reorienting a rigid spacecraft as fast as possible within the physical limits of actuators and sensors is investigated. In particular, a nonlinear feedback control logic which accommodates the actuator and sensor saturation limits is introduced. The nearminimum-time eigenaxis reorientation problem of the Xray Timing Explorer spacecraft under slew rate and control torque constraints is used as an example to demonstrate the effectiveness and simplicity of the proposed nonlinear feedback control logic.
Design and evaluation of an automated highway system with optimized lane assignment

Highway automation entails the application of control, sensing and communication technologies to road vehicles, with the objective of improving highway performance. It has been envisioned that automation could increase highway capacity by a factor of three. The purpose of this paper is to develop a methodology for predicting highway capacity and comparing alternative automation concepts. It extends earlier research on optimal lane assignment on an automated highway to dynamic networks. A path-based linear program is formulated and solved through a column generation method. The algorithm has been applied to networks with as many as 20 on and off ramps, 80 segments, 4 lanes and 12 time periods.
Rethinking Real Time Electricity Pricing

Abstract Most US consumers are charged a near-constant retail price for electricity, despite substantial hourly variation in the wholesale market price. This paper evaluates the first program to expose residential consumers to hourly real-time pricing (RTP). I find that enrolled households are statistically significantly price elastic and that consumers responded by conserving energy during peak hours, but remarkably did not increase average consumption during off-peak times. The program increased consumer surplus by $10 per household per year. While this is only one to two percent of electricity costs, it illustrates a potential additional benefit from investment in retail Smart Grid applications, including the advanced electricity meters required to observe a household’s hourly consumption.
Connections between real polynomial solutions of hypergeometric-type differential equations with Rodrigues formula

Starting from the Rodrigues representation of polynomial solutions of the general hypergeometric-type differential equation complementary polynomials are constructed using a natural method. Among the key results is a generating function in closed form leading to short and transparent derivations of recursion relations and addition theorem. The complementary polynomials satisfy a hypergeometric-type differential equation themselves, have a three-term recursion among others and obey Rodrigues formulas. Applications to the classical polynomials are given.
PDE-constrained optimization with error estimation and control

The paper describes an algorithm for PDE-constrained optimization that controls numerical errors using error estimates and grid adaptation during the optimization process. A key aspect of the algorithm is the use of adjoint variables to estimate errors in the first-order optimality conditions. Multilevel optimization is used to drive the optimality conditions and their estimated errors below a specified tolerance. The error estimate requires two additional adjoint solutions, but only at the beginning and end of each optimization cycle. Moreover, the adjoint systems can be formed and solved with limited additional infrastructure beyond that found in typical PDE-constrained optimization algorithms. The approach is general and can accommodate both reduced-space and full-space formulations of the optimization problem. The algorithm is illustrated using the inverse design of a nozzle constrained by the quasi-one-dimensional Euler equations.
An illustrative statistical analysis of cutoff-based randomized clinical trials.

Abstract Cutoff-based randomized clinical trials (RCTs) are designed to balance ethical and scientific concerns. Patients scoring below a cutoff score on a baseline measure (i.e. the least severely ill) are assigned to the control-treated group, those scoring above a second cutoff score (i.e. the most severely ill) are assigned to the test-treated group, and those scoring within the interval (i.e. the moderately ill) are randomly assigned. This paper provides a formal illustration on the statistical analysis of cutoff based RCTs using data from the Xanax Cross-National Collaborative Study. To overcome problems specific to cutoff-based designs, we generally recommend a backward elimination approach that tests interactions before main effects.
Does foreign investor demand for information affect forecast accuracy? Evidence from the Chinese stock markets

Abstract Prior international accounting studies have examined mainly the supply side of analyst research. Specific trading rights and financial reporting systems in China provide a unique opportunity to test both demand and supply factors of analyst information. For shares traded only by less-informed foreign investors, the increased information demand may create incentives for analysts to exert greater efforts than for shares traded by local investors. This study provides evidence that analyst effort (proxied by analyst coverage) and expertise (proxied by consensus cross-analyst forecast variability) affect forecast accuracy more significantly for shares traded by foreign investors than for shares traded by local investors. Additionally, I find that the relation between analyst characteristics and relative forecast accuracy is stronger for shares traded by the foreign investors. The findings are consistent with analysts responding to demands for information by less-informed investors.
The Ricci iteration and its applications

Abstract In this Note we introduce and study dynamical systems related to the Ricci operator on the space of Kahler metrics as discretizations of certain geometric flows. We pose a conjecture on their convergence towards canonical Kahler metrics and study the case where the first Chern class is negative, zero or positive. This construction has several applications in Kahler geometry, among them an answer to a question of Nadel and a construction of multiplier ideal sheaves. To cite this article: Y.A. Rubinstein, C. R. Acad. Sci. Paris, Ser. I 345 (2007).
Does jury bias matter

Froeb and Kobayashi (1996) find that endogenous expenditure decisions at trial tend to eliminate an exogenously given jury bias. For interior solutions, they find the initial bias to be totally eliminated. We find, however, that once the participation constraint of the plaintiff and defendant are taken into account, strong priors by the jury tend to deteriorate the quality of the cases which are filed by the plaintiff and defended by the defendant. We also explore an alternative form for jury bias, and find that it is generally non-neutral with respect to the trial outcome. Further, we find that the use of the English rule may exacerbate the effects of a strong jury bias.
LDPC Codes for Compressed Sensing

We present a mathematical connection between channel coding and compressed sensing. In particular, we link, on the one hand, channel coding linear programming decoding (CC-LPD), which is a well-known relaxation of maximum-likelihood channel decoding for binary linear codes, and, on the other hand, compressed sensing linear programming decoding (CS-LPD), also known as basis pursuit, which is a widely used linear programming relaxation for the problem of finding the sparsest solution of an underdetermined system of linear equations. More specifically, we establish a tight connection between CS-LPD based on a zero-one measurement matrix over the reals and CC-LPD of the binary linear channel code that is obtained by viewing this measurement matrix as a binary parity-check matrix. This connection allows the translation of performance guarantees from one setup to the other. The main message of this paper is that parity-check matrices of “good” channel codes can be used as provably “good” measurement matrices under basis pursuit. In particular, we provide the first deterministic construction of compressed sensing measurement matrices with an order-optimal number of rows using high-girth low-density parity-check codes constructed by Gallager.
Zirconium-mediated SN2' substitution of allylic ethers: regio- and stereospecific formation of protected allylic amines.

A new zirconium-mediated, regio- and stereospecific SN2‘ substitution of allylic ethers with a nitrogen nucleophile has been developed. Cbz-protected amine products were isolated in high yield from reactions with a wide range of Z allylic ethers. A mechanism of the allylic substitution consistent with the results of the kinetics and kinetic isotope effect studies was proposed.
The Mixing Time of the Thorp Shuffle

The Thorp shuffle is defined as follows. Cut a deck of cards into two equal piles. Drop the first card from the left pile or the right pile according to the outcome of a fair coin flip, then drop from the other pile. Continue this way until both piles are empty. We show that the mixing time for the Thorp shuffle with $2^d$ cards is polynomial in $d$.