cssi/SciSciGPT-SciSciNet huggingface dataset:
Effects of Symmetry and Number of Compositional Elements on Interface and Design Aesthetics

This article describes two experiments investigating the effects of manipulating two compositional elements—symmetry and the number of compositional building blocks—on subjective appraisals of interface aesthetics. The experiments use stimuli with identical composition but varying subject matter. The first experiment uses abstract black-and-white geometric images, whereas the second uses realistic-looking Web pages as stimuli. Both experiments have three levels for each of the two independent variables, with the dependent measure being subjective ratings of aesthetic appeal. Results from both experiments show that the number of compositional elements influences aesthetic appeal ratings. For the abstract imagery, symmetry also plays a role such that participants find the more symmetric images appealing. Implications of these findings on interface design are discussed.
The effect of ambient pressure on laser-induced plasmas in air

A detailed investigation of the effect of ambient pressure in the range of 0.1 to 1.0 atm on the size, temperature, electron number density, and fraction of laser energy absorbed in a laser-induced plasma in air has been conducted. As pressure is reduced the size of the plasma, its electron number density, its peak emission intensity, and the fraction of incident laser energy that is absorbed are all found to decrease significantly. The temporal temperature profile in the plasma and the fraction of the absorbed laser energy that is converted to thermal energy in the plasma remain constant, at least down to 0.2 atm.
Partial estimation of covariance matrices

A classical approach to accurately estimating the covariance matrix Σ of a p-variate normal distribution is to draw a sample of size n > p and form a sample covariance matrix. However, many modern applications operate with much smaller sample sizes, thus calling for estimation guarantees in the regime \({n \ll p}\). We show that a sample of size n = O(m log6p) is sufficient to accurately estimate in operator norm an arbitrary symmetric part of Σ consisting of m ≤ n nonzero entries per row. This follows from a general result on estimating Hadamard products M · Σ, where M is an arbitrary symmetric matrix.
Degree 1 elements of the Selberg class

Abstract We provide a short and simple proof of a beautiful result of Kaczorowski and Perelli classifying the elements of degree one in the Selberg class.
Tests of low scale gravity via gauge boson pair production in gamma gamma collisions

Arkani-Hamed, Dimopoulos, and Dvali have recently proposed that gravity may become strong at energies near 1 TeV thus removing the hierarchy problem. This scenario can be tested in several ways at present and future colliders. In this paper we examine the exchange of towers of Kaluza-Klein gravitons and their influence on the production of pairs of massive gauge bosons in \ensuremath{\gamma}\ensuremath{\gamma} collisions. These tower exchanges are shown to lead to a new dimension-eight operator that can significantly alter the standard model expectations for these processes. The role of polarization for both the initial state photons and the final-state gauge bosons in improving sensitivity to graviton exchange is emphasized. We find the discovery reach for graviton tower exchange in the $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}{W}^{+}{W}^{\ensuremath{-}}$ channel to be significantly greater than for any other process so far examined.
Life Cycle Analysis of Distributed Recycling of Post-consumer High Density Polyethylene for 3-D Printing Filament

The growth of desktop 3-D printers is driving an interest in recycled 3-D printer filament to reduce costs of distributed production. Life cycle analysis studies were performed on the recycling of high density polyethylene into filament suitable for additive layer manufacturing with 3-D printers. The conventional centralized recycling system for high population density and low population density rural locations was compared to the proposed in home, distributed recycling system. This system would involve shredding and then producing filament with an open-source plastic extruder from post-consumer plastics and then printing the extruded filament into usable, value-added parts and products with 3-D printers such as the open-source self replicating rapid prototyper, or RepRap. The embodied energy and carbon dioxide emissions were calculated for high density polyethylene recycling using SimaPro 7.2 and the database EcoInvent v2.0. The results showed that distributed recycling uses less embodied energy than the best-case scenario used for centralized recycling. For centralized recycling in a low-density population case study involving substantial embodied energy use for transportation and collection these savings for distributed recycling were found to extend to over 80%. If the distributed process is applied to the U.S. high density polyethylene currently recycled, more than 100 million MJ of energy could be conserved per annum along with the concomitant significant reductions in greenhouse gas emissions. It is concluded that with the open-source 3-D printing network expanding rapidly the potential for widespread adoption of in-home recycling of post-consumer plastic represents a novel path to a future of distributed manufacturing appropriate for both the developed and developing world with lower environmental impacts than the current system.
The Schwarzian derivative and polynomial iteration

We consider the Schwarzian derivative $S_f$ of a complex polynomial $f$ and its iterates. We show that the sequence $S_{f^n}/d^{2n}$ converges to $-2(\partial G_f)^2$, for $G_f$ the escape-rate function of $f$. As a quadratic differential, the Schwarzian derivative $S_{f^n}$ determines a conformal metric on the plane. We study the ultralimit of these metric spaces.
A numerical study of nonlinear effects on boundary-layer stability

Abstract : A spectral scheme is used to solve for the unsteady, two-dimensional flow over a flat plate in the Reynolds number range of transition. Solutions to the full Navier-Stokes equations agree with solutions to the parabolized vorticity equations for the problems considered. The propagation of large amplitude (nonlinear) Tollmien-Schlichting waves in a boundary layer is studied; in some cases, these large amplitude waves are more unstable than linear waves. Analysis of the solutions shows that the relative phase of the first and second harmonics is related to the nonlinear stability of the waves. (Author)
Stinging insect allergy

Stinging insect allergy is a relatively common medical problem, responsible for an estimated 40 fatalities per year in the USA and considerable anxiety and lifestyle modification. There are no criteria to identify people at risk of initial venom anaphylaxis. Reactions may occur at any age and are unrelated to the time interval of prior venom exposure. There is an approximate 60% re-sting reaction rate in people who have had sting anaphylaxis and have positive venom skin tests. Re-sting reactions are more likely to occur in adults than in children and in people who have had more severe anaphylactic symptoms. Positive venom intradermal skin tests confirm the diagnosis of potential stinging insect allergy in people who have had sting reactions. Venom immunotherapy provides almost 100% protection from further sting reactions. It is recommended for all people who have had venom anaphylaxis and have positive skin tests, except for children who have dermal reactions only. Details of venom dosing are well established. The adequate duration of venom immunotherapy is still an unresolved issue. Conversion to a negative skin test appears to be an absolute criterion to discontinue treatment. In the presence of a persistent positive skin test, 3–5 years of immunotherapy is generally sufficient. People who have had severe reactions, such as loss of consciousenss, may require indefinite therapy.
The internet worm

In November 1988 a worm program invaded several thousand UNIX-operated Sun workstations and VAX computers attached to the Research Internet, seriously disrupting service for several days but damaging no files. An analysis of the work's decompiled code revealed a battery of attacks by a knowledgeable insider, and demonstrated a number of security weaknesses. The attack occurred in an open network, and little can be inferred about the vulnerabilities of closed networks used for critical operations. The attack showed that passwork protection procedures need review and strengthening. It showed that sets of mutually trusting computers need to be carefully controlled. Sharp public reaction crystalized into a demand for user awareness and accountability in a networked world.
Exact criterion of hydromagnetic stability of inviscid vortex flow with finite conductivity.

An analysis considering the stabilization of an inviscid, potential vortex with finite conductivity by means of an axially applied magnetic field is presented. If it is assumed that the marginal state of stability is due to an axisymmetrical stationary secondary flow, and the conductivity of the medium is not negligible, then an exact criterion for magnetic stabilization may be deduced. The marginal magnitude of the applied magnetic field for stabilization is related to the ratio of the radii of the cylindrical walls containing the vortex, the density of the fluid, and the outer peripheral speed. Under the stated assumptions, the stability criterion is equivalent to the result obtained for a medium with infinite conductivity.
QUARK CONDENSATES IN NON-SUPERSYMMETRIC MQCD

Abstract A set of non-supersymmetric minimal area embeddings of an M-theory 5-brane are considered. The field theories on the surface of the 5-brane have the field content of N = 2 SQCD with fundamental representation matter fields. By suitable choice of curve parameters the N = 2 and N = 1 superpartners may be decoupled leaving a semi-classical approximation to QCD with massive quarks. As supersymmetry breaking is introduced a quark condensate grows breaking the low energy ZF flavour symmetry. At θ = (odd) π spontaneous CP violation is observed consistent with that of the QCD chiral lagrangian.
An empirical investigation of decision-making satisfaction in web-based decision support systems

Web-based information systems are increasingly being used for decision support applications. However, few empirical studies have been conducted on web-based decision support systems (DSS). This experimental research endeavors to understand factors that impact decision-making satisfaction in web-based decision support systems. Using structural equation modeling (SEM) approach, the analysis reveals that information quality and system quality influence decision-making satisfaction, while information presentation does not have an effect on decision-making satisfaction.
B and T cells in the brains of autoimmune mice.

Abstract Systemic lupus erythematosus (SLE) is an autoimmune disorder that can involve the central nervous system (CNS). Recently, we reported the presence of autoantibodies bound to the brain tissue of murine models of lupus; MRL/lpr and BXSB. We postulated that the source of these autoantibodies was in part due to in situ production, caused by the entry of B and T cells. Frozen brain sections of MRL/lpr and BXSB at 1 and 4 months of age were stained for CD3 (T cells) and CD19 (B cells) markers using an immunofluorescent antibody binding assay. Confocal fluorescence microscopy showed both CD3 + and CD19 + cells at 4 months of age only in MRL/lpr mice. There were no lymphocytes seen in the other autoimmune model, BXSB. Results suggest a difference in the mechanisms by which autoantibodies access the brain in these two autoimmune models of lupus.
TIDAL DISSIPATION AND OBLIQUITY EVOLUTION IN HOT JUPITER SYSTEMS

Two formation scenarios have been proposed to explain the tight orbits of hot Jupiters. They could be formed in orbits with a small inclination (with respect to the stellar spin) via disk migration, or in more highly inclined orbits via high-eccentricity migration, where gravitational interactions with a companion and tidal dissipation are at play. Here we target hot Jupiter systems where the misalignment λ has been inferred observationally and we investigate whether their properties are consistent with high-eccentricity migration. Specifically, we study whether stellar tides can be responsible for the observed distribution of λ and orbital separations. Improving on previous studies, we use detailed models for each star, thus accounting for how convection (and tidal dissipation) depends on stellar properties. In line with observations suggesting that hotter stars have higher λ, we find that λ increases as the amount of stellar surface convection decreases. This trend supports the hypothesis that tides are the mechanism shaping the observed distribution of λ. Furthermore, we study the past orbital evolution of five representative systems, chosen to cover a variety of temperatures and misalignments. We consider various initial orbital configurations and integrate the equations describing the coupled evolution of the orbital separation, stellar spin,more » and misalignment. We account for stellar tides and wind mass loss, stellar evolution, and magnetic braking. We show that the current properties of these five representative systems can be explained naturally, given our current understanding of tidal dissipation and with physically motivated assumptions for the effects driving the orbital evolution.« less
Evaporation, ignition and combustion of nondilute clusters of drops

A theory of evaporation, ignition, and burning of moderately dense spherical drop clusters has been developed. The theory takes into account burning of premixed air and fuel internal to the cluster at ignition and subsequent burning of fuel emitted from the cluster by a flame sheet surrounding it. The model considers interdrop interaction, momentum exchange between drops and gas, and turbulent exchange processes between the cluster and its surroundings. Calculations are performed for varying initial air-to-fuel-mass ratios, initial cluster radii, ambient gas temperatures and initial drop temperatures. Results are presented for ratios of fuel mass burned to fuel mass lost from the cluster between drop ignition and drop disappearance, fuel burned fractions at ignition and at the moment of drop disappearance, and jump conditions at ignition.
Theory of equity in pricing for resource conservation

Abstract This paper seeks to construct some theoretical tools that can be used to examine formally the equity issues raised in the use of pricing as a means to conserve scarce resources, in particular, the criteria that can be used to judge the equity of such a price change and the special problem raised by differences in elasticity of demand of different customer groups are considered. Toward this end the concept of a “superfair” distribution (a distribution under which each and every participant obtains a share of the total which is equal to or greater than that individuars pro-rata share, in his own estimation) is introduced and discussed.
Comet P/Holmes, 1892III: A case of duplicity?

An analysis of observations of comet P/Holmes 1892III's two 8-10 mag bursts indicates that these phenomena are consistent with the grazing encounter of a small satellite with the nucleus on November 4.6, 1892, and the final encounter on January 16.3, 1893. While after the first burst the total magnitude fell less than 2 mag from November 7 to 30, the fading was much more rapid after the second burst. It is suggested that the grazing encounter distributed a volume of large chunks in the neighborhood of the nucleus, maintaining activity for weeks.
The Economics of Insider Trading: A Free Market Perspective

We deny that asymmetrical information is a market failure. In order to make this case, we subject to critical scrutiny the strongest case for this thesis: the view that laws prohibiting insider trading are viable, necessary, or compatible with the rule of law.
Synthesis of Phosphorylated, Conjugation-Ready Di-, Tri- and Tetrasaccharide Fragments of the O-Specific Polysaccharide of V. cholerae O139

The fragments described contain a galactose residue with cyclic 4,6-phosphate and are equipped with an amino-functionalized spacer, allowing further derivatization or directconjugation to suitable carriers. The core Gal-(13)-GlcNAc disaccharide was obtained by condensation of 8-azido-3,6-dioxaoctyl 2-acetamido-4,6-O-benzylidene-2-deoxy-β-D-glucopyranoside with 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide under Helferich conditions. Reductive opening of the benzylidene acetal, followed by deacetylation and selective benzylation gave 8-azido-3,6-dioxaoctyl 2-acetamido-6-O-benzyl-3-O-(3-O-benzyl-β-D-galactopyranosyl)-2-deoxy-β-D-glucopyranoside, which was regioselectively phosphorylated to give two isomeric 4,6-cyclic 2,2,2-trichloroethyl phosphates. The (R)-phosphate was subjected to catalytic hydrogenation/hydrogenolysis to give the fully deprotected title disaccharide fragment. Glycosylation of the (S)-phosphate diol with 2,4-di-O-benzyl-3,6-dideoxy-α-L-xylo-hexopyranosyl bromide under halide-assisted conditions yielded a mixture of the tetrasaccharide and a trisaccharide, which were readily separable by chromatography. Their hydrogenation/hydrogenolysis effected global deprotection as well as reduction of the azide, to furnish the deprotected title tri- and tetrasaccharide.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Asymptotic dimension of discrete groups

We extend Gromov's notion of asymptotic dimension of finitely generated groups to all discrete groups. In particular, we extend the Hurewicz type theorem proven in (B-D2) to general groups. Then we use this extension to prove a formula for the asymptotic dimension of finitely generated solvable groups in terms of their Hirsch length.
Chemoenzymatic synthesis of (2S,3R)-3-hydroxyproline from cyclopentadiene

Abstract Amido-alcohol 4 , derived from cyclopentadiene and resolved using Candida antarctica lipase B-mediated transacetylation, was transformed to (2 R , 3 R )-3-hydroxy-2-hydroxymethyl-pyrrolidine ( 2 ) and (2 S , 3 R )-3-hydroxyproline ( 1 ).
Inverse Design of Adaptive Airfoils with Aircraft Performance Considerations

Recent advances in the development of inverse airfoil design methods now allow for the incorporation of aircraft performance considerations in the design of a non-flapped airfoil. While these improvements make airfoil-aircraft matching considerably easier, there is a need for a similar capability for adaptive airfoils. This paper presents a design formulation that incorporates aircraft performance considerations in the inverse design of low-speed laminar-flow adaptive airfoils. The benefit of using adaptive airfoils is that the size of the low-drag region of the drag polar can be effectively increased without increasing the thickness of the airfoil. Two aircraft performance parameters are considered: level-flight maximum speed and maximum range. It is shown that the lift coefficient for the lower and upper corners of the airfoil low-drag range can be appropriately adjusted to tailor the airfoil for these two aircraft performance parameters. The design problem is posed as a part of a multidimensional Newton iteration in an existing conformal-mapping based inverse design code, PROFOIL. This formulation automatically adjusts the lift coefficients for the corners of the low-drag range for a given flap deflection as required for the airfoil-aircraft matching. Examples are presented to illustrate the benefits of the process for a general aviation aircraft and the results are validated by comparison with results from post-design aircraft performance computations.
Shape Optimization of a Membrane Wing for Micro Air Vehicles

§† Micro air vehicles with a maximal dimension of 15cm require original design concept due to their low Reynolds number flight regime. It has been empirically observed that a flexible membrane wing can improve the aerodynamic performance of the vehicles. To help advance our knowledge in this area, we investigate shape optimization of a membrane wing. A direct membrane wing optimization employing a coupled Navier-Stokes and flexible structure analysis is computationally expensive. Therefore, we use a rigid wing as a surrogate model. We employ a moving grid technique to facilitate automatic grid generation. Our objective is to maximize the lift-to-drag ratio under aerodynamic and geometry constraints. The optimized design exhibits reduced camber from root to tip. Overall, the aerodynamic improvement is primarily derived from the inner 70% of the wing. The optimized platform is checked for performance of the membrane wings and found to improve the performance by about the same margin. Furthermore, both optimized membrane and rigid wings improve the liftto-drag ratios mainly by reducing the form drag. However, the membrane wing demonstrates less variation in lift-to-drag ratio as the angles of attack vary.
Cities and Ethics: An Essay for Jane Jacobs

This tribute to Jane Jacobs connects her seminal work on cities with her newer focus on ethical systems. I present a model and evidence suggesting that cross-community mobility in cities makes it d...
A New Framing? Constitutional Representation at Philadelphia's National Constitution Center

The National Constitution Center (NCC) in Philadelphia orients its representation of the Constitution around the role of"We the People" in the conduct of constitutional politics. The self-presentation of the NCC explicitly connects its participatory interpreta tion of the Constitution to the interactivity of the museum experience itself, and announces its aspiration that visitors "get involved!" In so doing the NCC draws upon an emerging edge in museum theory that emphasizes the capacity of museums to support political citizenship. Although the museum's aspiration to enact participatory citizenship is laudable, its exhibits-because of their technol ogies, use of space, and content-subvert, rather than sustain, the participatory ideal.
The Galaxy-weighted Small-Scale Velocity Dispersion of the Las Campanas Redshift Survey

The pair-weighted relative velocity dispersion of galaxies provides a measure of the thermal energy of fluctuations of the observed galaxy distribution, but the measure is difficult to interpret and is very sensitive to the existence of rare rich clusters of galaxies. Several alternative statistical procedures have recently been suggested to relieve these problems. We apply a variant of the object-weighted statistical method of Davis, Miller, & White to the Las Campanas Redshift Survey (LCRS), which is the largest and deepest existing redshift survey that is nearly fully sampled. The derived one-dimensional dispersion on scales of ~1 h-1 Mpc is quite low: σ1 = 126 ± 10 km s-1, with a modest decrease at larger scales. The statistic is very stable; the six independent slices of the LCRS all yield consistent results. We apply the same statistical procedure to halos in numerical simulations of an open cosmological model and flat models with and without a cosmological constant. In contrast to the LCRS, all the models show a dispersion that increases for scales >1 h-1 Mpc; it is uncertain whether this is a numerical artifact or a real physical effect. The standard cluster-normalized cold dark matter model with Ωm = 1, as well as a tilted variant with n = 0.8, yield dispersions substantially hotter than the LCRS value, while models with low matter density (Ωm = 0.3) are broadly consistent with the LCRS data. Using a filtered cosmic energy equation, we measure Ωm ≈ 0.2, with small-scale bias factors b = 1.0-1.5 for high-density models and b = 0.7-1.1 for low-density models.
Initializing Sensor Networks of Non-uniform Density in the Weak Sensor Model

Assumptions about node density in the sensor networks literature are frequently too strong. Neither adversarially chosen nor uniform random deployment seem realistic in many intended applications of sensor nodes. We define smooth distributions of sensor nodes to be those where the minimum density is guaranteed to achieve connectivity in random deployments, but higher densities may appear in certain areas. We study basic problems for smooth distribution of nodes. Most notably, we present a Weak Sensor Model-compliant distributed protocol for hop-optimal network initialization (NI), a fundamental problem in sensor networks. In order to prove lower bounds, we observe that all nodes must communicate with some other node in order to join the network, and we call the problem of achieving such a communication the group therapy (GT) problem. We show a tight lower bound for the GT problem in radio networks for any class of protocols, and a stronger lower bound for the important class of randomized uniform-oblivious protocols. Given that any NI protocol also solves GT, these lower bounds apply to NI. We also show that the same lower bound holds for a related problem that we call independent set , when nodes are distributed uniformly, even in expectation.
Photodegradation in Ballistic Laminates: Spectroscopy and Lifetime Extension*

Polycarbonate (PC), a critical component in ballistic laminates (BLs), is known to degrade upon exposure to ultraviolet (UV) light. For the purpose of reducing the photodegradation, a UV blocking chemical has been added to the adhesives used to join the layers of the BL. This report describes the development of a spectroscopic method for monitoring surface photodegradation of PC and the method's use in demonstrating the effectiveness of the UV blocker. Reports in the literature demonstrate that photodegradation in thin PC films may be detected by transmission infrared (IR) spectroscopy. The present work extends this approach to thick films, where small surface changes are detected by reflectance IR spectroscopy. We show that UV photodegradation of the PC surface produces a characteristic shift in the carbonyl absorption band at about 1775 cm -1. This shift is consistently observed in PC samples that have been subjected to direct artificial exposure and in PC samples that have been subjected through the outboard layers of the BL to both natural and artificial exposure. When a UV blocker is incorporated into the adhesive layers of the laminate, no peak shift is observed in the carbonyl band after the equivalent of 10 years of exposure.
High Rate Capacity through Redox Electrolytes Confined in Macroporous Electrodes

The capacitive characteristics of a model macroporous electrode, comprised of vertically aligned carbon nanotubes, with a relatively large volume /unit mass (of ∼40 cm3/g) are discussed. The faradaic characteristics of the capacity were evidenced through a voltage plateau in the galvanostatic discharge experiments. It is shown that the confinement of electrolyte within the spacing between the nanostructures with respect to an appropriate choice of the voltage scan rate yields a regime where both high capacity and rate capability may be realized. Additionally, the absence of diffusional processes allows for large capacitance retention even at discharge
Variations on a spherically symmetrical accretion flow

Spherically symmetrical accretion onto a compact gravitating object is considered from a purely hydrodynamical viewpoint while disregarding heating and cooling processes. The study derives the radial perturbation equation, expresses it in a Eulerian form which is simpler than the Lagrangian form considered, for example, by Balazs (1972), and discusses the relation between the two formulations. This perturbation equation is used for the stability analysis of standing waves as well as for the study of short wavelength traveling waves which are a generalization of Parker's (1966) traveling wave solutions in the sense that they are not restricted to isothermal flows. These traveling waves can cause fluctuations in the mass accretion rate to grow large, but will not drive the unperturbed solution away from its assumed stationary profile. The waves conserve the total energy contained in the perturbation.
Data base education for students of management

One major field of study in the Graduate School of Management at UCLA is in Computers and Information Systems (CIS). This major has evolved from a single course on Electronic Computers in Business introduced in 1957 to one with more than a dozen courses devoted to some aspect of education about computers and information systems. The Announcement of the School describes the program as "designed to provide students with the basic conceptual framework and tools of analysis necessary for the design, implementation and control of information systems. These studies have the goals of training students to develop and implement management information systems---especially those using computers---for a variety of organizations both public and private. ... In particular, the computer and the many technical advancements that have accompanied its development have had a major impact upon information systems design. Therefore, students are expected to acquire a basic understanding of computer technology and terminology and a competence in computer programming. Beyond this, students may pursue studies in computer systems analysis, management of EDP activities, design of computer-based management information systems, modeling and computer simulation, and generalized data base management systems."
Classical solutions in lattice gauge theories

Abstract The solutions of the classical equations of motion on a periodic lattice are found which correspond to abelian single and double Dirac sheets. These solutions exist also in non-abelian theories. Possible applications of these solutions to the calculation of gauge dependent and gauge invariant observables are discussed.
Syzygies of multiplier ideals on singular varieties

Multiplier ideals can be defined on any Q-Gorenstein variety X, or more generally for any pair (X,∆) consisting of an effective Weil Q-divisor ∆ on a normal variety X such that KX +∆ is Q-Cartier. It is natural to wonder whether multiplier ideals in this context satisfy the same sort of algebraic properties as in the smooth case. We will see (Example 3.1) that the result from [10] just quoted does not extend without change. On the other hand, we show that at least for first syzygies, one gets a statement by replacing the maximal ideal m by any parameter ideal.
Effects of Added Vegetation on Sand Bar Stability and Stream Hydrodynamics

Vegetation was added to a fully developed sandy point bar in the meander of a constructed stream. Significant changes in the flow structure and bed topography were observed. As expected, the addition of vegetative resistance decreased the depth-averaged streamwise velocity over the bar and increased it in the open region. In addition, the secondary circulation increased in strength but became confined to the deepest section of the channel. Over the point bar, the secondary flow was entirely outward, i.e., toward the outer bank. The changes in flow led to changes in bar shape. Although the region of the bar closest to the inner bank accumulated sediment, erosion of the bar and the removal of plants by scouring were observed at the interface between the planted bar and the open channel.
Magnetic Energy and Helicity Budgets in the Active Region Solar Corona. I. Linear Force-Free Approximation

Expanding on an earlier work that relied on linear force-free (LFF) magnetic fields, we self-consistently derive the instantaneous free magnetic energy and relative magnetic helicity budgets of an unknown three-dimensional nonlinear force-free (NLFF) magnetic structure extending above a single known lower-boundary magnetic field vector. The proposed method does not rely on the detailed knowledge of the three-dimensional field configuration but is general enough to employ only a magnetic connectivity matrix on the lower boundary. The calculation yields a minimum free magnetic energy and a relative magnetic helicity consistent with this free magnetic energy. The method is directly applicable to photospheric or chromospheric vector magnetograms of solar active regions. Upon validation, it basically reproduces magnetic energies and helicities obtained by well known, but computationally more intensive and non-unique, methods relying on the extrapolated three-dimensional magnetic field vector. We apply the method to three active regions, calculating the photospheric connectivity matrices by means of simulated annealing, rather than a model-dependent NLFF extrapolation. For two of these regions we correct for the inherent LFF overestimation in free energy and relative helicity that is larger for larger, more eruptive, active regions. In the third region studied, our calculation can lead to a physical interpretation of observed eruptive manifestations. We conclude that the proposed method, including the proposed inference of the magnetic connectivity matrix, is practical enough to contribute to a physical interpretation of the dynamical evolution of solar active regions.
Performance characterization in computer vision

Computer vision algorithms are composed of different sub-algorithms often applied in sequence. Determination of the performance of a total computer vision algorithm is possible if the performance of each of the sub-algorithm constituents is given. The problem, however, is that for most published algorithms, there is no performance characterization which has been established in the research literature. This is an awful state of affairs for the engineers whose job it is to design and build image analysis or machine vision systems.
Broadcasting in sensor networks: the role of local information

Flooding based querying and broadcasting schemes have low hop-delays of Theta(1/R(n)) to reach any node that is a unit distance away, where R(n) is the transmission range of any sensor node. However, in sensor networks with large radio ranges, flooding based broadcasting schemes cause many redundant transmissions leading to a broadcast storm problem. In this paper, we study the role of geographic information and state information (i.e., memory of previous messages or transmissions) in reducing the redundant transmissions in the network. We consider three broadcasting schemes with varying levels of local information where nodes have: (i) no geographic or state information, (ii) coarse geographic information about the origin of the broadcast, and (Hi) no geographic information, but remember previously received messages. For each of these network models, we demonstrate localized forwarding algorithms for broadcast (based on geography or state information) that achieve significant reductions in the transmission overheads while maintaining hop-delays comparable to flooding based schemes. We also consider the related problem of broadcasting to a set of "spatially uniform" points in the network (lattice points) in the regime where all nodes have only a local sense of direction and demonstrate an efficient "sparse broadcast" scheme based on a branching random walk that has a low number of packet transmissions. Thus, our results show that even with very little local information, it is possible to make broadcast schemes significantly more efficient.
Semi-analytic approximations for production of atmospheric muons and neutrinos

Abstract Simple approximations for fluxes of atmospheric muons and muon neutrinos are developed which display explicitly how the fluxes depend on primary cosmic-ray energy and on features of pion production. For energies of approximately 10 GeV and above the results are sufficiently accurate to calculate response functions and to use for estimates of systematic uncertainties.
Robust scheme for oblivious detection of watermarks/data hiding in still images

We propose a novel, robust scheme for data hiding/oblivious detection of watermarks in still images. While the low- frequency image coefficients are robust, they cannot be used effectively for oblivious detection methods, when correlative processing is employed for detection. However, in the proposed non-linear detection method, the robust low- frequency bands can be used effectively. Thus the proposed method turns out to be more robust than methods employing linear addition and correlative extraction of the signature. We report the results obtained for 7 test images in terms of probability of error in detection of the watermark/hidden bits.
Facile dearomatizing radical arylation of furan and thiophene.

In the presence of catalytic diphenyl diselenide, reduced in situ to benzeneselenol, tributyltin hydride and V-70 promote the addition of aryl iodides to furan and thiophene. The adduct radicals are trapped by the selenol to give the 2-aryl-2,3-dihydro and 2-aryl-2,5-dihydro heterocyclic products. When the iodide is an o-iodophenol, a cyclization follows the radical addition and provides bridged bicyclic acetals.
Convexity Properties of the Cone of Nonnegative Polynomials

We study metric properties of the cone of homogeneous nonnegative multivariate polynomials and the cone of sums of powers of linear forms, and the relationship between the two cones. We compute the maximum volume ellipsoid of the natural base of the cone of nonnegative polynomials and the minimum volume ellipsoid of the natural base of the cone of powers of linear forms and compute the coefficients of symmetry of the bases. The multiplication by (x12 + ··· + xn2)m induces an isometric embedding of the space of polynomials of degree 2k into the space of polynomials of degree 2(k+m), which allows us to compare the cone of nonnegative polynomials of degree 2k and the cone of sums of 2(k+m)-powers of linear forms. We estimate the volume ratio of the bases of the two cones and the rate at which it approaches 1 as m grows.
Nonlinear evolution of perturbations in marginally stable plasmas

Abstract We derive a general, self-consistent, reduced equation that describes the nonlinear evolution of electrostatic perturbations in marginally stable plasma equilibria. The equation is universal in the sense that it is independent of the equilibrium, and it contains as special cases the beam-plasma, the bump-on-tail, and the two-stream instability problems, among others. In particular, the present work offers a systematic justification of the O'Neil-Winfrey-Malmberg single-wave beam-plasma model. But more importantly, the analysis shows that the single-wave model has a wider range of applicability: it can be applied to localized perturbation in any marginally stable equilibrium. We discuss the linear theory, and construct families of exact nonlinear solutions.
Some Aspects of Measurement Error in Linear Regression of Astronomical Data

I describe a Bayesian method to account for measurement errors in linear regression of astronomical data. The method allows for heteroscedastic and possibly correlated measurement errors and intrinsic scatter in the regression relationship. The method is based on deriving a likelihood function for the measured data, and I focus on the case when the intrinsic distribution of the independent variables can be approximated using a mixture of Gaussian functions. I generalize the method to incorporate multiple independent variables, nondetections, and selection effects (e.g., Malmquist bias). A Gibbs sampler is described for simulating random draws from the probability distribution of the parameters, given the observed data. I use simulation to compare the method with other common estimators. The simulations illustrate that the Gaussian mixture model outperforms other common estimators and can effectively give constraints on the regression parameters, even when the measurement errors dominate the observed scatter, source detection fraction is low, or the intrinsic distribution of the independent variables is not a mixture of Gaussian functions. I conclude by using this method to fit the X-ray spectral slope as a function of Eddington ratio using a sample of 39 z 0.8 radio-quiet quasars. I confirm the correlation seen by other authors between the radio-quiet quasar X-ray spectral slope and the Eddington ratio, where the X-ray spectral slope softens as the Eddington ratio increases. IDL routines are made available for performing the regression.
The effects of cruise ship tourism in coastal heritage cities: A case study of Charleston, South Carolina

Purpose – The purpose of this paper is to explore the introduction of cruise ship tourism into historic urban centers, and the mitigation policies that can be implemented to encourage sustainable development of this relationship.Design/methodology/approach – The paper focuses on the unique aspects of cruise tourism that differentiate it from other forms of mass tourism. Using the specific example of Charleston, South Carolina, it explores the difficulties that cruise tourism present to local residents and policymakers. It looks at different mitigation policies that have previously been implemented in cruise destinations around the world, and analyzes which have been the most effective.Findings – Cruise ship tourism is the fastest growing segment of the tourism industry, and it is an issue that many coastal heritage destinations will soon face. Uncontrolled tourism from cruise ships is unsustainable, and strong government intervention is needed to maintain heritage cities.Originality/value – This paper pro...
Modeling the ortho-to-para abundance ratio of cyclic C3H2 in cold dense cores

Aims. We report a detailed attempt to model the ortho-to-para abundance ratio of c-C 3 H 2 so as to reproduce observed values in the cores of the well-known source TMC-1. According to observations, the ortho-to-para ratios vary, within large uncertainties, from a low of near unity to a high of approximately three depending on the core. Methods. We used the osu.2003 network of gas-phase chemical reactions augmented by reactions that specifically consider the formation, depletion, and interconversion of the ortho and para forms of c-C 3 H 2 and its precursor ion c-C 3 H + 3 . We investigated the sensitivity of the calculated ortho-to-para ratio for c-C 3 H 2 to a large number of factors. Results. For the less evolved cores C, CP, and D, we had no difficulty reproducing the observed ortho-to-para ratios of 1-2. In order to reproduce observed ortho-to-para ratios of near three, observed for the evolved cores A and B, it was necessary to include rapid ion-catalyzed interconversion processes.
Simulation and parameterization of the turbulent transport in the hurricane boundary layer by large eddies

[1] Hurricane boundary layer (HBL) processes, especially the structure of the coherent large eddy circulations (LECs) and their induced vertical transport, are not well understood. This paper introduces a large eddy simulation (LES) framework in a weather hindcasting mode developed from a multiple scale nested Weather Research and Forecasting (WRF) model. Using the WRF–LES, this study investigated the structure of the HBL LECs and the associated vertical transport during the landfall of Hurricane Ivan (2004). The simulation shows that the HBL LECs exist in a mean stable environment and consist of well-defined updraft and downdraft. Statistically, the HBL LECs are only slightly skewed with the updrafts and downdrafts relatively evenly distributed spatially. The inversion base basically envelopes the upper boundary of LECs. The trough in between two adjacent LECs is where most entrainment takes place, whereas the crest of the LECs is where boundary layer air detrains out of the HBL. In such a way, LECs directly connect the surface, the HBL, and the main body of a hurricane vortex and enhance the exchange of energy, moisture, and momentum between them. It is found that the current boundary layer schemes significantly underestimate the resolved turbulent fluxes due to the fact that the effects of LECs have not been included in the parameterizations. On the basis of the statistical structure of LECs simulated by the WRF–LES, this paper proposes a conceptual updraft–downdraft model that can potentially be implemented in weather forecasting models to parameterize the fluxes induced by the HBL LEC transport.
Non-heme iron(II) complexes are efficient olefin aziridination catalysts

Iron(II) complexes of polydentate nitrogen donor ligands catalyze the rapid aziridination of olefins by PhINTs.
Bid‐Ask Spread Estimation For A Correlated Value Innovation Process

Previous studies of bid-ask spread estimators based on serial covariance in returns document high proportions of positive serial covariances and therefore negative spread estimates. These findings may be due to the effects of time-variation in expected returns. Although purging the effects of time-varying expected returns yields more reasonable results, the bid-ask spread estimates from daily and weekly returns are still materially different. We present a method that avoids the need for removing the effects of time-varying expected returns by using a spread estimator developed directly for a correlated value innovation process. The new spread estimator not only yields more reasonable estimates of the bid-ask spread than the Roll (1984) model, but the spread estimates from daily and weekly returns are almost equal.
Free inverse semigroups

This note announces a characterization of the free inverse semigroup I on a non-empty set X.
Abundance of 17 trace elements in carbonaceous chondrites.

Seventeen trace elements (Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Rb, Re, Sb, Se, Te, Tl, U, and Zn) were measured by neutron activation analysis in eight C1 samples (1 Alais, 3 Ivuna, 4 Orgueil and in three C2 samples (one each of Mighei, Murchison, Murray). The results show far less scatter than earlier literature data. The standard deviation of a single measurement from the mean of eight C1 samples lies between 2 and 14%, except for the following four elements: Au, Ag, Rb, and Br. The first two probably reflect contamination and sample heterogeneity, the last two, analytical error. Apparently C1 chondrites have a far more uniform composition than some authors have claimed.
Exclusion zone of convex brushes in the strong-stretching limit.

We investigate asymptotic properties of long polymers grafted to convex cylindrical and spherical surfaces, and, in particular, distribution of chain free ends. The parabolic potential profile, predicted for flat and concave brushes, fails in convex brushes, and chain free ends span only a finite fraction of the brush thickness. In this paper, we extend the self-consistent model developed by Ball, Marko, Milner, and Witten [Macromolecules 24, 693 (1991)] to determine the size of the exclusion zone, i.e., size of the region of the brush free from chain ends. We show that in the limit of strong stretching, the brush can be described by an alternative system of integral equations. This system can be solved exactly in the limit of weakly curved brushes, and numerically for the intermediate to strong curvatures. We find that going from melt state to θ solvent and then to marginal solvent decreases relative size of the exclusion zone. These relative differences grow exponentially as the curvature decreases to zero.