cssi/SciSciGPT-SciSciNet huggingface dataset:
Proper orthogonal decomposition for reduced-order thermal solution in hypersonic aerothermoelastic simulations

The ability to perform full-order aerothermoelastic simulations of hypersonic vehicles is hindered by the strong coupling exhibited between the aerodynamics, heat transfer, and structural dynamic response in the hypersonic ight regime. As a result of these interactions, alternative techniques are necessary to obtain computationally tractable systems of governing equations and their solutions. This work addresses the use of proper orthogonal decomposition for reduced-order solution of the heat transfer problem within a hypersonic modeling framework. The specic challenge of handling time-dependent boundary conditions due to transient aerodynamic heating is discussed. An overview of the proper orthogonal decomposition is given and two methods for solution of the reduced system of ordinary dierential equations are outlined. The methodology is applied to a representative hypersonic vehicle control surface model for two cases in which the time-history of the thermal load vector is known a priori: one in which the boundary conditions are time-independent and another in which they are time-varying. Results demonstrate the ability of the reduced-order solution to approximate the full-order solution with reasonable accuracy. Finally, a time-marching hypersonic aerothermoelastic framework is described in which proper orthogonal decomposition is used for the transient thermal solution.
COMPLEX ORGANIC MOLECULES AT HIGH SPATIAL RESOLUTION TOWARD ORION-KL. II. KINEMATICS

It has recently been suggested that chemical processing can shape the spatial distributions of complex molecules in the Orion-KL region and leads to the nitrogen-oxygen 'chemical differentiation' seen in previous observations of this source. Orion-KL is a very dynamic region, and it is therefore also possible that physical conditions can shape the molecular distributions in this source. Only high spatial resolution observations can provide the information needed to disentangle these effects. Here, we present millimeter imaging studies of Orion-KL at various beam sizes using the Combined Array for Research in Millimeter-wave Astronomy. We compare molecular images with high spatial resolution images that trace the temperature, density, and kinematics of the source in order to investigate the effects of physical conditions on molecular distributions. These observations were conducted at {lambda} = 3 mm and included transitions of ethyl cyanide [C{sub 2}H{sub 5}CN], methyl formate [HCOOCH{sub 3}], formic acid [HCOOH], acetone [(CH{sub 3}){sub 2}CO], SiO, and methanol [CH{sub 3}OH]. We find differences in the molecular distributions as a function of each of the aforementioned physical factors. These results indicate that acetone may be produced by chemical processing and is robust to large changes in physical conditions, while formic acid is readily destroyedmore » by gas-phase processing in warm and dense regions. We also find that while the spatial distributions of ethyl cyanide and methyl formate are not distinct as is suggested by the concept of 'chemical differentiation', local physical conditions shape the small-scale emission structure for these species.« less
Phosphatidylserines Transduce Cell-Penetrating Peptides

Certain short polycations, such as TAT and polyarginine, rapidly pass through cell membranes and pervade all intracellular compartments by an unknown mechanism called transduction. These cell-penetrating peptides (CPPs) when fused to biologically active peptides promise to be medically useful. I offer a simple model in which phosphatidylserine (and possibly other anions) transduce CPPs. The model also involves surface tension and the electrostatic field across the membrane of the cell. The model is consistent with the empirical upper limit on the cargo peptide of about 35 amino acids. More importantly, it also fits experimental data on how the transduction of a polyarginine-fluorophore into mouse C2C12 myoblasts depends on the number of arginines in the CPP and on the CPP concentration.
Harmonicity of Gibbs measures

We show that any continuous measure ν in the class of a generalized Gibbs stream on the boundary of a CAT(−κ) group G arises as a harmonic measure for a random walk on G. Under an additional mild hypothesis on G and for ν, Holder equivalent to a Gibbs measure, we show that (∂G,ν) arises as a Poisson boundary for a random walk on G. We also prove a new approximation theorem for general metric measure spaces giving quite flexible conditions for a set of functions to be a positive basis for the cone of positive continuous functions
Kazhdan–Lusztig polynomials for maximally-clustered hexagon-avoiding permutations

Abstract We provide a nonrecursive description for the bounded admissible sets of masks used by Deodhar's algorithm to calculate the Kazhdan–Lusztig polynomials P x , w ( q ) of type A , in the case when w is hexagon avoiding and maximally clustered. This yields a combinatorial description of the Kazhdan–Lusztig basis elements of the Hecke algebra associated to such permutations w . The maximally-clustered hexagon-avoiding elements are characterized by avoiding the seven classical permutation patterns { 3421 , 4312 , 4321 , 46718235 , 46781235 , 56718234 , 56781234 } . We also briefly discuss the application of heaps to permutation pattern characterization.
Effects of continental‐scale snow albedo anomalies on the wintertime Arctic oscillation

The NCAR CAM3 GCM with prescribed, satellite-based snow albedo (SA) is used to investigate the remote effects of snow cover on Northern Hemisphere (NH) winter climate. A pair of 100 ensemble member experiments are integrated through the autumn-winter season, with prescribed high and low SA over Eurasia (EA). Similar to other non-CAM GCM studies using prescribed snow mass, anomalous EA snow albedo produces a wave activity pulse that propagates into the stratosphere, culminating in a negative phase Arctic Oscillation– (AO-) like surface response. This occurs for idealized but representative SA anomalies, as well as for more realistic SA anomalies. Similar experiments over North America (NA) and the entire NH are also performed. Unlike prior studies, anomalous NA snow yields a significant AO signal. Here, the local NA surface cooling elicits a transient eddy response, which propagates downstream to Eurasia, resulting in significant but short-lived cooling and upward propagating wave activity over Siberia. A negative AO-like response develops, primarily confined to the stratosphere/upper troposphere, which eventually gives way to a tropospheric AO-like response of the opposite phase, due to equatorward wave refraction and wave divergence. Reanalysis data support this NA snow-positive AO response. Snow forcing experiments for the whole NH, however, yield a weakened AO signal. This is due to a muted wavenumber-1 and -2 response caused by destructive interference between the background stationary wave and the corresponding Rossby wave response, which results in negligible wave activity reaching the stratosphere.
Gamuts and globes: the cartography of color

A device gamut can be visualized as a 3D object in a given color space. The globe is approximately a 3D ellipsoid and has been the motivation for centuries of research in the area of geometric projections. Neither the globe nor a typical device gamut is flat but there are often times when it is useful to examine the globe and device gamuts in 2D. Cartography provides a multitude of geometric projections and terminology that can be used for gamut visualization and mapping. This paper provides examples of how the concepts and principles of cartography can be used for gamut visualization and gamut mapping. The Mercator, Cassini, Bonne, Mollweide, and Sinusoidal projections are used to visualize the sRGB gamut. Finally, a simple example using spherical coordinates is used to demonstrate how gamut projection can be used to implement a specific type of gamut mapping.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Independent central banks, regime type, and fiscal performance: the case of post-communist countries

This article analyzes the effect of central bank independence on fiscal deficits. Previous literature finds a negative relationship between bank independence and deficits in OECD countries. No such relationship is found for developing countries. We argue that independent and conservative central bankers prefer budget discipline due to the long run connection between deficits and inflation and can enforce their preference through interest rate hikes and refusal to lend to the government. The claim, however, is that the legislated independent status of the central bank is cheap talk in the absence of democratic institutions. We test empirically the conditional effect of central bank independence on a sample of 23 democratic and undemocratic post-communist countries from 1990 to 2002. Results show that independent central banks restrain budget deficits only in democracies. Also, democracies that have not granted independence to their central banks have the worst fiscal discipline.
A general topology, Godunov method

Abstract A numerical technique that utilizes a general topology mesh is described. The method employs the arbitrary Lagrangian-Eulerian procedure and explicit, finite-volume, Godunov numerics. Material interfaces are resolved to eliminate fictitious mixing and nonphysical shear impedance. Cell-centered variables, including velocity, are used to provide consistent control volumes for the advection of mass, momentum, and energy, and to allow arbitrary slip between material regions. The computational mesh is composed of arbitrary polygonal cells. The constraint of a fixed logical connectivity for the mesh is removed. Consequently, geometrical mesh limitations, which are responsible for inaccuracies and code failure during the evolution of region boundaries, are absent. Arbitrary boundaries can be resolved, and the mesh is capable of changing smoothly and rapidly from regions of high to low resolution. Lack of a coherent mesh orientation minimizes numerical anisotropy. A mesh rezoning approach, based on a dual triangulation and coupled with a global remapping algorithm, allows the mesh to evolve dynamically.
Cosmic neutrinos from the sources of galactic and extragalactic cosmic rays

Although kilometer-scale neutrino detectors such as IceCube are discovery instruments, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 1020 eV and 1013 eV, respectively. The puzzle of where and how Nature accelerates the highest energy cosmic particles is unresolved almost a century after their discovery. From energetics considerations we anticipate on the order of 10–100 neutrino events per kilometer squared per year pointing back at the source(s) of both galactic and extragalactic cosmic rays. In this context, we discuss the results of the AMANDA and IceCube neutrino telescopes which will deliver a kilometer-square-year of data over the next 3 years.
Alignment and Initial Operation of an Advanced Solar Simulator

A solar simulator utilizing nine 30-kW xenon arc lamps was built to provide radiant power for testing a solar dynamic space power system in a thermal vacuum environment. The advanced solar simulator achieved the following values specific to the solar dynamic system: (1) a subtense angle of 1 deg; (2) the ability to vary solar simulator intensity up to 1.7 kW/sq m; (3) a beam diameter of 4.8 m; and (4) uniformity of illumination on the order of +/-10%. The flexibility of the solar simulator design allows for other potential uses of the facility.
Unusual Reaction of β-Hydroxy α-Diazo Carbonyl Compounds with Cl3CCN/NaH and Rh(II)-Catalyzed Reaction of β-Trichloroacetylamino α-Diazo Carbonyl Compounds

The hydroxyl group was directly converted into the trichloroacetylamino group by reacting β-hydroxy α-diazo carbonyl compounds with Cl3CCN and NaH. Rh(II)-catalyzed reactions of the β-amino α-diazo carbonyl compounds were discussed.
Spatial aggregation and regional economic forecasting

This research examines the effect of spatial aggregation on the accuracy of regional economic forecasts. Literature in econometrics, business forecasting, regional economic forecasting, spatial econometrics, and spatial time series analysis suggests that the issue is far from settled at either the theoretical or empirical levels. Univariate time series analysis is used to generate both state-level and sub-state regional forecasts of monthly total employment in the State of Idaho and its economic sub-regions. All spatial aggregation methods provide accurate forecasts, but direct state-level forecasts, and disaggregation of state-level forecasts to the sub-state level are slightly more accurate than more directly disaggregated approaches. As state-level data are often subject to less measurement error, and are also more complete and timely, this result should be encouraging to regional forecasting practitioners.
Ortho-hydroxyl assisted deoxygenation of phenones. Regiochemical control in the synthesis of monoprotected resorcinols and related polyphenolic hydroxyl systems

A method for the selective protection of polyphenolic hydroxyls is described. This approach relies on the deoxygenation of a benzylic ketone ortho to at least one of the phenolic hydroxyl groups.
Dependence of the lunar wake on solar wind plasma characteristics

Solar wind plasma effects on lunar wake umbral and penumbral interplanetary magnetic field anomalies, evaluating roles of electrons and ions
OPTIMAL DYNAMIC ROUTING IN COMMUNICATION NETWORKS WITH CONTINUOUS TRAFFIC

New characterizations of optimal state-dependent routing strategies are obtained for the continuous traffic network model proposed by Segall for linear cost with unity weighting at each node and for constant inputs. The concept of flow relaxation is introduced and is used to transform the optimal routing problem into an initial flow optimization problem with convex cost and linear constraints. Three algorithms are given for open-loop computation of the optimal initial flow. The first is a simple iterative algorithm based on gradient descent with bending and it is well suited for decentralized computation. The second algorithm reduces the problem to a series of max-flow problems and it computes the exact optimal flow in O (mod N to the fourth) computations, where mod N is the number of nodes in the network. The third algorithm is based on a search for successive bottlenecks in the network. (Author/TRRL)
Information Sharing and Cooperative Search in Fisheries

We present a dynamic game of search and learning about the productivity of competing fishing locations. Perfect Bayesian Nash equilibrium search patterns for non-cooperating fishermen and members of an information sharing cooperative are compared with first-best outcomes. Independent fishermen do not internalize the full value of information, and do not replicate first-best search. A fishing cooperative faces a free-riding problem, as each coop member prefers that other members undertake costly search for information. Pooling contracts among coop members may mitigate, but are not likely to eliminate free-riding. Our results explain the paucity of information sharing in fisheries and suggest regulators use caution in advocating cooperatives as a solution to common pool inefficiencies in fisheries.
A Problem in Particle Physics and Its Bayesian Analysis

There is a class of statistical problems that arises in several contexts, the Lattice QCD problem of particle physics being one that has attracted the most attention. In essence, the problem boils down to the estimation of an infinite number of parameters from a finite number of equations, each equation being an infinite sum of exponential functions. By introducing a latent parameter into the QCD system, we are able to identify a pattern which tantamounts to reducing the system to a telescopic series. A statistical model is then endowed on the series, and inference about the unknown parameters done via a Bayesian approach. A computationally intensive Markov Chain Monte Carlo (MCMC) algorithm is invoked to implement the approach. The algorithm shares some parallels with that used in the particle Kalman filter. The approach is validated against simulated as well as data generated by a physics code pertaining to the quark masses of protons. The value of our approach is that we are now able to answer questions that could not be readily answered using some standard approaches in particle physics. The structure of the Lattice QCD equations is not unique to physics. Such architectures also appear in mathematical biology, nuclear magnetic imaging, network analysis, ultracentrifuge, and a host of other relaxation and time decay phenomena. Thus, the methodology of this paper should have an appeal that transcends the Lattice QCD scenario which motivated us. The purpose of this paper is twofold. One is to draw attention to a class of problems in statistical estimation that has a broad appeal in science and engineering. The second is to outline some essentials of particle physics that give birth to the kind of problems considered here. It is because of the latter that the first few sections of this paper are devoted to an overview of particle physics, with the hope that more statisticians will be inspired to work in one of the most fundamental areas of scientific inquiry.
Morita equivalence of dual operator algebras

We consider notions of Morita equivalence appropriate to weak* closed algebras of Hilbert space operators. We obtain new variants, appropriate to the dual algebra setting, of the basic theory of strong Morita equivalence, and new nonselfadjoint analogues of aspects of Rieffel�s W*-algebraic Morita equivalence.
Asking Children to Think About Music

The traditionally held operant definitions of creative and critical thinking betray a dichotomy particularly when applied to music education. However, boundaries between creative and critical thinking have blurred as the result of recent developments in music cognition research. Research directions and policy issues need to be approached from a much more global understanding of musical thinking as a function of both cognitive and affective components.
REGULARITY OF LIMITS OF NONCOLLAPSING SEQUENCES OF MANIFOLDS

We prove that iterated spaces of directions of a limit of a noncollapsing sequence of manifolds with lower curvature bound are topologically spheres. As an application we show that for any finite dimensional Alexandrov space X n with $ n \ge 5 $ there exists an Alexandrov space Y homeomorphic to X which cannot be obtained as such a limit.
Two-Dimensional Unsteady Euler-Equation Solver for Arbitrarily Shaped Flow Regions

A new technique is described for solving supersonic fluid dynamics problems containing multiple regions of continuous flow, each bounded by a permeable or impermeable surface. Region boundaries are, in general, arbitrarily shaped and time dependent. Discretization of such a region for solution by conventional finite difference procedures is accomplished using an elliptic solver which alleviates the dependence on a particular base coordinate system. Multiple regions are coupled together through the boundary conditions. The technique has been applied to a variety of problems including a shock diffraction problem and supersonic flow over a pointed ogive.
Constructing Stable Preferences: A Look Into Dimensions of Experience and Their Impact on Preference Stability

There are 2 polar schools of thought regarding the existence of preferences. The economics tradition is based on the assumption of existing preferences. The emerging constructive processing approach assumes preferences are constructed based on the task and context factors present during choice or preference elicitation. Most researchers believe in a middle ground in which consumers construct their preferences when they are new to a category and eventually develop more stable preferences with experience in a domain. This research was designed to bridge the gap between these 2 schools of thought by understanding the process by which preferences are learned and developed over time. Specifically, we investigated the impact of several dimensions of experience (effort, choice, and experience) on preference stability. Results revealed that the type of experience and its corresponding effort had a large impact on the process of preference development. Study 1 demonstrated that by exposing participants to the trade-offs in their environment, their preferences developed and stabilized most rapidly. In addition, the act of making a choice (Study 2) and repeated choices (Study 3) both led to increased preference stability as indicated by measures of objective and subjective preference stability.
Wyner-Ziv video coding with multi-resolution motion refinement: theoretical analysis and practical significance

The accuracy of motion estimation (ME) plays an important role in improving the coding efficiency of Wyner-Ziv video coding (WZVC). Most existing WZVC schemes perform ME at the decoder. The unavailability of the current frame on the decoder side usually impairs the accuracy of ME, which also causes the degradation of coding efficiency of WZVC. To improve the accuracy of ME, some works in the literature assume the current frame can be progressively decoded, and the decoder iteratively refines the motion field based on each partially decoded image. In this paper, we present an analytical model to estimate the potential gain by employing multi-resolution motion refinement (MMR), assuming the current frame is progressively decoded in the frequency domain. The theoretical results show that at high rates, WZVC with MMR falls about 1.5 dB behind the conventional inter-frame coding, but outperforms WZVC with motion extrapolation by 0.9 to 5 dB. Significant gain has also been observed in the simulations using real video data.
Intermolecular atom transfer radical addition to olefins mediated by oxidative quenching of photoredox catalysts.

Atom transfer radical addition of haloalkanes and α-halocarbonyls to olefins is efficiently performed with the photocatalyst Ir[(dF(CF3)ppy)2(dtbbpy)]PF6. This protocol is characterized by excellent yields, mild conditions, low catalyst loading, and broad scope. In addition, the atom transfer protocol can be used to quickly and efficiently introduce vinyl trifluoromethyl groups to olefins and access 1,1-cyclopropane diesters.
Mapping Social Behavior-Induced Brain Activation at Cellular Resolution in the Mouse

Understanding how brain activation mediates behaviors is a central goal of systems neuroscience. Here, we apply an automated method for mapping brain activation in the mouse in order to probe how sex-specific social behaviors are represented in the male brain. Our method uses the immediate-early-gene c-fos, a marker of neuronal activation, visualized by serial two-photon tomography: the c-fos-GFP+ neurons are computationally detected, their distribution is registered to a reference brain and a brain atlas, and their numbers are analyzed by statistical tests. Our results reveal distinct and shared female and male interaction-evoked patterns of male brain activation representing sex discrimination and social recognition. We also identify brain regions whose degree of activity correlates to specific features of social behaviors and estimate the total numbers and the densities of activated neurons per brain areas. Our study opens the door to automated screening of behavior-evoked brain activation in the mouse.
He bubble coarsening by migration and coalescence in annealed Pu―Ga alloys

Abstract The α -decay of plutonium in Pu–Ga alloys continually generates inert He atoms within the lattice of the Pu–Ga matrix. In naturally aged Pu specimens, those He atoms form into bubbles, He-filled vacancy clusters, with a characteristic size distribution centered near 1.4 nm. Upon annealing, the He bubbles are subject to temperature induced changes in the thermodynamic parameters governing their size, which results in a coarsening of the bubble distribution yielding a lower bubble density but larger average bubble sizes. Herein, we investigate, by means of transmission electron microscopy, the coarsening of He bubbles with several annealing treatments. Micrographs subsequent to the annealing treatments as well as in situ observations implicate migration and coalescence as the mechanism for He bubble coarsening with annealing.
A Measurement of the Cosmological Constant Using Elliptical Galaxies as Strong Gravitational Lenses

We have identified seven (field) elliptical galaxies acting as strong gravitational lenses and have used them to measure cosmological parameters. To find the most likely value for Ωm (=Ωmatter) and Λ, we have used the combined probabilities of these lens systems having the observed critical radii (or image deflection) for the measured or estimated values of lens redshifts, source redshifts, and lens magnitudes. Our measurement gives Λ=0.64+ 0.15−0.26 if Ωm + Λ = 1, and the Ωm = 1 model is excluded at the 97% confidence level. We also find, at the 68% (Ω = 0)-82% (Ω = 0.3) confidence level, that an open universe is less likely than a flat universe with nonzero Λ. Except for the possibility of strong perturbations due to cluster potentials and the systematic overestimate of the lens magnitudes, other possible systematic errors do not seem to influence our results strongly: correction of possible systematic errors seems to increase the significance of the result in favor of a nonzero Λ model.
A Simultaneous RXTE and XMM-Newton Observation of the Broad-Line Radio Galaxy 3C 111

We present the results of simultaneous XMM-Newton and RXTE observations of the broad-line radio galaxy 3C 111. We find that the Compton reflection bump is extremely weak; however, broad residuals are clearly present in the spectrum near the Fe Kα emission line region. When fitted with a Gaussian emission line, the feature has an equivalent width of 40-100 eV and FWHM of greater than 20,000 km s-1; however, the exact properties of this weak line are highly dependent on the chosen continuum model. The width of the line suggests an origin in the inner accretion disk, which is, however, inconsistent with the lack of Compton reflection. We find that much of the broad residual emission can be attributed to continuum curvature. The data are consistent with a model in which the primary power-law continuum is reprocessed by an accretion disk that is truncated at small radii. Alternatively, the primary source could be partially covered by a dense absorber. The latter model is less attractive than the former because of the small inclination angle of the jet of 3C 111 to the line of sight. We consider it likely that the curved continuum of the partial covering model is fortuitously similar to the continuum shape of the reprocessing model. In both models, the fit is greatly improved by the addition of an unresolved Fe Kα emission line, which could arise in either a Compton-thin obscuring torus or dense clouds lying along the line of sight. We also find that there are unacceptable residuals at low energies in the MOS data in particular, which were modeled as a Gaussian with an energy of ~1.5 keV; we attribute these residuals to calibration uncertainties of the MOS detectors.
Fluorous synthesis of heterocyclic systems.

1.1. Background Reaction and separation are the two important aspects of organic synthesis. Traditional solution-phase synthesis emphasizes reaction, while resin-based solid-phase combinatorial synthesis and polymer-assisted solution-phase parallel synthesis emphasize separation. Fluorous synthesis, which successfully integrates solution-phase reaction conditions with the phase-tag separation, has been recently introduced as a “beadless” high-speed synthetic technology.1,2 Perfluoroalkyl chains instead of resins are used as the phase tags to facilitate the separation process. Compared to traditional solution-phase and solid-phase synthesis, fluorous synthesis has the following features: Fluorous reactions have homogeneous solution-phase reaction kinetics; Fluorous molecules can be separated by the fluorous separations as well as conventional methods such as chromatography, distillation, and recrystallization; Fluorous reactions can be monitored by conventional analytical methods such as TLC, HPLC, IR and NMR; Fluorous tags are chemically stable and have minor effect on the reactivity of the attached molecules; The solubility of fluorous compounds in organic solvents can be fine-tuned by the fluorine content as well as temperature; Fluorous synthesis does not need large excess of fluorous reagents to complete the reaction; More than one fluorous reagent can be used in a single reaction; Fluorous methods are less problematic in adaptation of literature reaction conditions than that of solid-phase synthesis; Fluorous synthesis can be combined with other methods such as microwave reactions, supercritical CO2 reactions, and solid-phase synthesis; Fluorous materials can be recovered after fluorous separation. The development of fluorous technologies started in the early 1990’s. Among the pioneers, Vogt and Zhu explored the synthesis utility of temperature-dependent miscibility of fluorous solvents with organic solvents.3–4 Horvath and Rabai invented the fluorous biphasic catalysis for the recovery of catalysts.5 The Curran group and Fluorous Technologies, Inc. (FTI) developed the “light fluorous” synthesis to eliminate the use of fluorous solvents.6,7 Other major advances in fluorous technologies include mixture synthesis for making individually pure compound libraries,8 triphasic reactions which integrates the fluorous reaction and separation processes,9 and thermomorphic catalysts for fluorous solvent-free biphasic catalysis.10 Since Horvath’s seminal paper on fluorous in 1994,5 many review articles have covered different aspects of fluorous technologies at different development stages.11–27 A comprehensive and up-to-date monograph entitled “The Handbook on Fluorous Chemistry” will soon be published.28 Described in this Review are synthesis of heterocyclic systems using fluorous reagents, catalysts, scavengers, protecting groups, and tags. Application of fluorous technologies in multicomponent reactions, microwave reactions, solid-phase reactions, triphasic reactions, and mixture synthesis are also described.
Experimental Results of Pitching Moment Tests on Parabolic-Trough Solar-Collector Array Configurations

Two wind-tunnel tests were conducted to investigate specifically the pitching moment characteristics of parabolic-trough solar-collector modules deployed within a collector array. The collector modules were located within various rows of a simulated array configuration to investigate shielding effects from upstream collector rows and/or windscreen fences. Selected fence configurations and fence spacing upstream from the initial array row were studied. The test results demonstrate that pitching moment is significantly reduced by shielding provided by upstream fencing or collector rows.
Using clustering to learn distance functions for supervised similarity assessment

Assessing the similarity between objects is a prerequisite for many data mining techniques. This paper introduces a novel approach to learn distance functions that maximizes the clustering of objects belonging to the same class. Objects belonging to a data set are clustered with respect to a given distance function and the local class density information of each cluster is then used by a weight adjustment heuristic to modify the distance function so that the class density is increased in the attribute space. This process of interleaving clustering with distance function modification is repeated until a ''good'' distance function has been found. We implemented our approach using the k-means clustering algorithm. We evaluated our approach using seven UCI data sets for a traditional 1-nearest-neighbor (1-NN) classifier and a compressed 1-NN classifier, called NCC, that uses the learnt distance function and cluster centroids instead of all the points of a training set. The experimental results show that attribute weighting leads to statistically significant improvements in prediction accuracy over a traditional 1-NN classifier for two of the seven data sets tested, whereas using NCC significantly improves the accuracy of the 1-NN classifier for four of the seven data sets.
A new route to N-substituted heterocycles

Abstract N-(Benzotriazol-1-ylmethyl)-indole, - pyrrole, -carbazole, and -benzimidazole, and analogs substituted in the methylene group are converted by lithium aluminum hydride, or by Grignard reagents, or in two cases by organozinc reagents, into the N-substituted heterocycles in good yields.
Nonsingular dilaton cosmology in the string frame

We consider the theory obtained by adding to the usual string frame dilaton gravity action specially constructed higher derivative terms motivated by the limited curvature construction of [1] and determine the spatially homogeneous and isotropic solutions to the resulting equations of motion. All solutions of the resulting theory of gravity with these symmetries are nonsingular and all curvature invariants are bounded. For initial conditions inspired by the pre-big-bang scenario solutions exist which correspond to a spatially flat Universe starting in a dilaton-dominated superinflationary phase with > 0 and having a smooth transition to an expanding Friedmann Universe with < 0. Hence, the graceful exit problem of pre-big-bang cosmology is solved in a natural way.
PRESSURE SUPPORT IN GALAXY DISKS: IMPACT ON ROTATION CURVES AND DARK MATTER DENSITY PROFILES

Rotation curves constrain a galaxy's underlying mass density profile, under the assumption that the observed rotation produces a centripetal force that exactly balances the inward force of gravity. However, most rotation curves are measured using emission lines from gas, which can experience additional forces due to pressure. In realistic galaxy disks, the gas pressure declines with radius, providing additional radial support to the disk. The measured tangential rotation speed will therefore tend to lag the true circular velocity of a test particle. The gas pressure is dominated by turbulence, and we evaluate its likely amplitude from recent estimates of the gas velocity dispersion and surface density. We show that where the amplitude of the rotation curve is comparable to the characteristic velocities of the interstellar turbulence, pressure support may lead to underestimates of the mass density of the underlying dark matter halo and the inner slope of its density profile. These effects may be significant for galaxies with rotation speeds 75 km s-1 but are unlikely to be significant in higher-mass galaxies. We find that pressure support can be sustained over long timescales, because any reduction in support due to the conversion of gas into stars is compensated for by an inward flow of gas. However, we point to many uncertainties in assessing the importance of pressure support in real or simulated galaxies. Thus, while pressure support may help to alleviate possible tensions between rotation curve observations and ΛCDM on kiloparsec scales, it should not be viewed as a definitive solution at this time.
Advancing circadian rhythms before eastward flight: a strategy to prevent or reduce jet lag.

Study Objectives—To develop a practical pre-eastward flight treatment to advance circadian rhythms as much as possible but not misalign them with sleep. Design—One group had their sleep schedule advanced by 1 hour per day and another by 2 hours per day. Setting—Baseline at home, treatment in lab. Participants—Young healthy adults (11 men, 15 women) between the ages of 22 and 36 years. Interventions—Three days of a gradually advancing sleep schedule (1 or 2 hours per day) plus intermittent morning bright light (one-half hour ~5000 lux, one-half hour of < 60 lux) for 3.5 hours. Measurements and Results—The dim light melatonin onset was assessed before and after the 3-day treatment. Subjects completed daily sleep logs and symptom questionnaires and wore wrist activity monitors. The dim light melatonin onset advanced more in the 2-hours-per-day group than in the 1-hour-perday group (median phase advances of 1.9 and 1.4 hours), but the difference between the means (1.8 and 1.5 hours) was not statistically significant. By the third treatment day, circadian rhythms were misaligned relative to the sleep schedule, and subjects had difficulty falling asleep in the 2-hoursper-day group, but this was not the case in the 1-hour-per-day group. Nevertheless, the 2-hours-perday group did slightly better on the symptom questionnaires. In general, sleep disturbance and other side effects were small. Conclusions—A gradually advancing sleep schedule with intermittent morning bright light can be used to advance circadian rhythms before eastward flight and, thus, theoretically, prevent or reduce subsequent jet lag. Given the morning light treatment used here, advancing the sleep schedule 2 hours per day is not better than advancing it 1 hour per day because it was too fast for the advance in circadian rhythms. A diagram is provided to help the traveler plan a preflight schedule.
The advantage of experienced start-up founders in venture capital acquisition: evidence from serial entrepreneurs

Entrepreneurs with prior firm-founding experience are expected to have more skills and social connections than novice entrepreneurs. Such skills and social connections could give experienced founders some advantage in the process of raising venture capital. This paper uses a large database of venture-backed companies and their founders to examine the advantage associated with prior founding experience. Compared with novice entrepreneurs, entrepreneurs with venture-backed founding experience tend to raise more venture capital at an early round of financing and tend to complete the early round much more quickly. In contrast, experienced founders whose earlier firms were not venture-backed do not show a similar advantage over novice entrepreneurs, suggesting the importance of connections with venture capitalists in the early stage of venture capital financing. However, when the analysis also takes into account later rounds of financing, all entrepreneurs with prior founding experience appear to raise more venture capital. This implies that skills acquired from any previous founding experience can make an entrepreneur perform better and in turn attract more venture capital.
Streamed Graph Drawing and the File Maintenance Problem

In streamed graph drawing, a planar graph, G, is given incrementally as a data stream and a straight-line drawing of G must be updated after each new edge is released. To preserve the mental map, changes to the drawing should be minimized after each update, and Binucci et al. show that exponential area is necessary for a number of streamed graph drawings for trees if edges are not allowed to move at all. We show that a number of streamed graph drawings can, in fact, be done with polynomial area, including planar streamed graph drawings of trees, tree-maps, and outerplanar graphs, if we allow for a small number of coordinate movements after each update. Our algorithms involve an interesting connection to a classic algorithmic problem--the file maintenance problem--and we also give new algorithms for this problem in a framework where bulk memory moves are allowed.
Symmetries of the triple degenerate DNLS equations for weakly nonlinear dispersive MHD waves

Lie symmetries, conservation laws, and Lagrangian and Hamiltonian formulations of the triple degenerate, derivative nonlinear Schrodinger (TDNLS) equations for weakly nonlinear dispersive, magnetohydrodynamic (MHD) waves are derived. The equations describe how Alfven waves propagating parallel to the background magnetic field B interact with the magneto-acoustic modes near the triple umbilic point where the fast, slow and Alfven mode phase speeds coincide. The Lie point symmetries are used to derive classical similarity solutions of the equations. In particular, the similarity solutions corresponding to time translation, space translation and rotational invariance symmetries are reduced to quadrature. The dispersionless TDNLS system is of hydrodynamic type, and has three families of characteristics analogous to the slow, intermediate and fast modes of MHD. The Riemann invariants corresponding to each of these families are obtained in closed analytic form. Examples of solitary wave and periodic travelling wave solutions are investigated by plotting the contours of the Hamiltonian H(v, w) in the (v, w) phase plane, where the canonical variables v and w correspond to the normalized transverse magnetic field perturbations. An analysis of the prolongation Lie algebra is carried out in order to investigate the integrability of the equations.
Reactivity and mechanisms of metalloporphyrin‐ catalyzed oxidations

Effective systems for the catalytic oxygenation of hydrocarbons have been developed based on metalloporphyrins containing iron, manganese and ruthenium. These metalloporphyrin catalysts were inspired by studies of the mechanism of the heme oxygenase cytochrome P450 and related enzymes. Oxometalloporphyrins, which have now been spectroscopically characterized, have very high reactivity as oxygen transfer agents. A combination of experimental and computational methods has begun to provide an understanding of the structure and reactivity of these oxometalloporphyrin complexes and the mechanisms of oxygen transfer reactions they catalyze.
A Reexamination of Firm Size, Book-to-Market, and Earnings Price in the Cross-Section of Expected Stock Returns

This paper reexamines the explanatory power of beta, firm size, book-to-market equity, and the earnings-price ratio for average stock returns, correcting two currently controversial biases: selection bias in COMPUSTAT and the errors-in-variables (EIV) bias. After filling in the missing data on COMPUSTAT with the Moody's sample, I do not find any significantly different results for book-to-market equity from using the COMPUSTAT sample only. After correcting for the EIV bias, I find stronger support for the beta pricing theory than previous studies. Regardless of the presence of firm size, book-to-market equity, and earnings-price ratios, betas have significant explanatory power for average stock returns. In particular, firm size is barely significant using monthly returns, but no longer significant using quarterly returns. However, book-to-market equity still has significant explanatory power for average stock returns, even though the EIV bias is corrected. I. Introduction The primary implication ofthe capital asset pricing model by Sharpe (1964), Lintner (1965), and Black (1972) is the mean-variance efficiency of the market portfolio. Put differently, there exists a positive linear relation between ex ante expected returns and market betas, and variables other than beta should not have power in explaining the cross-section of expected returns. Contrary to the predictions of the CAPM model, previous empirical studies have found that idiosyncratic factors have significant explanatory power for average stock returns, while beta has little power. The most prominent idiosyncratic factors are firm size, book-to-market equity (B/V), and earnings-price (E/P) ratio. Banz (1981), Reinganum (1981), and Keim (1983) find that small (large) firms have greater (smaller) returns than those predicted by the CAPM model.1 Jegadeesh
Kinetics of convective crystal dissolution and melting, with applications to methane hydrate dissolution and dissociation in seawater §

Abstract Large quantities of methane hydrate are present in marine sediment. When methane hydrate is exposed or released to seawater, it dissolves in seawater or dissociates into methane gas and water. There was some confusion in the literature about the kinetics of these processes. It is critical to realize that dissolution and dissociation are two different processes. Dissolution is due to instability in the presence of seawater (similar to dissolution of NaCl in water) and is controlled by mass transfer. Dissociation is due to inherent instability (similar to melting of ice) with or without water (although presence of warm water may increase the dissociation rate). Dissociation of methane hydrate into gas and water is similar to ice melting and is controlled by heat transfer. Hence dissolution is relatively slow and dissociation is rapid. In this work, we extend previous theory on convective crystal dissolution and melting to greater Reynolds numbers. We carry out laboratory experiments on the dissolution and descent of NaCl, KCl, NaBr and KBr in water to verify the applicability of our theory. We then apply our models as well as previous ones to estimate methane hydrate dissolution and dissociation rates for several cases, including dissolution of exposed methane hydrate floor, dissolution and dissociation of hydrate as it rises through seawater. The results show: (i) convective dissolution rate of exposed hydrate floor is of the order 0.07 m/yr; (ii) convective dissolution rate of a rising hydrate crystal is 0.2–0.3 μm/s and a crystal of 5 mm radius is able to survive the rise through an 1800 m seawater column; and (iii) convective dissociation rate is high and depends on the difference between the ambient water temperature and the equilibrium dissociation temperature of hydrate. Starting from a depth when hydrate just reaches dissociation instability, a hydrate sphere of 5 mm radius would survive only a 47 m water column. Because hydrate is unstable in the surface ocean and would undergo rapid dissociation, only very large hydrate chunks (greater than about 0.09 m radius) would be able to survive a 530 m surface water column.
The CYK approach to serial and parallel parsing

Traditional parsing methods for general context-free grammars have been re-investigated in order to see whether they can be adapted to a parallel processing view. In this paper we discuss sequential and parallel versions of the Cocke-Younger-Kasami (CYK) parsing algorithm. The algorithms that are considered turn out to be suitable for implementations ranging from environments with a small number of asynchronous processors to environments consisting of a large array of highly synchronized processors.
A display oriented programmer's assistant

This paper continues and extends previous work by the author in developing systems which provide the user with various forms of explicit and implicit assistance, and in general co-operate with the user in the development of his programs. The system described in this paper makes extensive use of a bit map display and pointing device (a mouse) to significantly enrich the user's interactions with the system, and to provide capabilities not possible with terminals that essentially emulate hard copy devices. For example, any text that is displayed on the screen can be pointed at and treated as input, exactly as though it were typed, i.e. the user can say use this expression or that value, and then simply point. The user views his programming environment through a collection of display windows, each of which corresponds to a different task or context. The user can manipulate the windows, or the contents of a particular window, by a combination of keyboard inputs or pointing operations. The technique of using different windows for different tasks makes it easy for the user to manage several simultaneous tasks and contexts, e.g. defining programs, testing programs, editing, asking the system for assistance, sending and receiving messages, etc. and to switch back and forth between these tasks at his convenience.