bluuebunny/crossref_metadata_2025 huggingface dataset:
A Gluon Condensate Term in a Heavy Quark Mass
Authors: Kiselev V. V.
Published: August 2003

We investigate a connection between a renormalon ambiguity of heavy quark mass and the gluon condensate contribution into the quark dispersion law related to a virtuality defining a displacement of the heavy quark from the perturbative mass-shell, which happens inside a hadron.
Indication for Large Rescatterings in Charmless Rare B Decays
Authors: Chua Chun-Khiang , Hou Wei-Shu , Yang Kwei-Chou
Published: August 2003

The current wealth of charmless B decay data may suggest the presence of final state rescattering. In a factorized amplitude approach, better fits are found by incorporating two SU(3) rescattering phase differences, giving δ ~ 65° and σ ~ 90°–100°. Fitting with unitarity phase ϕ3 as a fit parameter gives ϕ3 ~ 96°, the CP asymmetries Aπ π, Sπ π agree better with BaBar, and the σ phase is slightly lower. Keeping ϕ3=60° fixed in fit gives Sπ π ~ -0.9, which agrees better with Belle. With the sizable δ, σ rescattering phases as fitted, many direct CP asymmetries flip sign, and B0→π0π0, K-K+ rates are of order 10-6, which can be tested soon.
Hyper-Hamiltonian Dynamics and Quaternionic Regularity
Authors: Morando Paola , Tarallo Massimo
Published: August 2003

The classical Hamilton equations are reinterpreted by means of complex analysis, in a nonstandard way. This suggests a natural extension of the Hamilton equations to the quaternionic case, extension which coincides with the one introduced in Ref. 1 by a completely different approach.
Can the Majorana Neutrino CP-Violating Phases be Restricted?
Authors: Matsuda Koichi , Fukuyama Takeshi , Nishiura Hiroyuki
Published: August 2003

We reanalyze the constraints in neutrino masses and MNS lepton mixing parameters using the new data from the terrestrial (KamLAND) and astrophysical (WMAP) observations together with the Heidelberg–Moscow double beta decay experiment. It leads us to the almost degenerate or inverse hierarchy neutrino mass scenario. We discuss the possibility of getting the bound for the Majorana CP-violating phase.
Bounds for the Mass of the Heaviest Right-Handed Neutrino in SO(10) Theories
Authors: Buccella F. , Falcone D.
Published: August 2003

By relating the Dirac neutrino mass matrix to the mass of the charged fermions and assuming that the product of the masses of the two lightest left-handed neutrinos is of the order of [Formula: see text], we derive, within a leptogenesis scenario, a range of values for the mass of the heaviest right-handed neutrino, centered around the scale of B–L symmetry breaking in the SO(10) theory with Pati–Salam intermediate symmetry.
Workshop '97
Authors: Tolstoy A. , Chapman N. R. , Brooke G.
Published: August 2003

This paper discusses the motivation, preparation of data, and analysis of presented results for the Geoacoustic Inversion Workshop held in Vancouver, BC, on June 24–26, 1997.
Geoacoustic Inversion for the Workshop '97 Benchmark Test Cases Using Simulated Annealing
Authors: Fallat Mark R. , Dosso Stan E.
Published: August 2003

This paper applies simulated annealing matched-field inversion to the Workshop '97 geoacoustic inversion benchmark test cases. The unknown parameters in these test cases include various combinations of sediment and basement geoacoustic properties (layer thickness, compressional and shear speeds, attenuations, and densities) and geometric parameters (water depth, and source range and depth). The sensitivity of the acoustic field data to the different parameters varies substantially. The simulated annealing inversion developed here minimizes a measure of mismatch based on the average Bartlett processor for acoustic data at a number of ranges. The replica pressure fields are computed by summing the modal components provided by an elastic normal mode model, which allows replica fields at multiple ranges to be calculated efficiently. A total of 15 different geoacoustic inversions are considered (three realizations each for five test cases). Excellent results are obtained in a reasonable amount of computation time for all cases. In particular, the final mismatch values are exceedingly small and relatively sensitive parameters (geometric parameters and sediment properties) are generally estimated to high precision. Relatively insensitive parameters (shear speeds and, in some cases, basement properties) are somewhat less well determined, but generally good estimates are obtained.
Genetic Algorithm Inversion of the 1997 Geoacoustic Inversion Workshop Test Case Data
Authors: Heard Garry J. , Hannay David , Carr Scott
Published: August 2003

An analysis of the 1997 Geoacoustic Inversion Workshop test case data was carried out to benchmark the performance of a Genetic Algorithm (GA) inversion code called SAGA_INV.1 The inversion program made use of Westwood's ORCA propagation model,2 FORTRAN subroutines, and Interactive Data Language (Research Systems Inc. IDL). SAGA_INV is capable of performing inversions with either Simulated Annealing (SA) or GA optimization schemes; however, only the GA portion of the code has been benchmarked with the workshop test cases at the present time. Not all of the workshop test cases were processed: this study was concerned only with the CAL, SD, SO, AT, and WA data sets. The CAL data was processed using three different cost functions: (i) standard Bartlett processor, (ii) a broadband coherent processor, and (iii) a transmission loss mismatch function. These processors were applied to three frequency bands: (i) 76 frequencies between 25 Hz and 100 Hz, (ii) nine frequencies between 28 Hz and 36 Hz, and (iii) 13 frequencies between 44 Hz and 56 Hz. The latter two frequency regimes were intended to simulate 1/3-octave bands centered at 32 Hz and 50 Hz, respectively. Four different receiving arrays were simulated: (i) a 1550 m aperture horizontal, bottom mounted array at approximately 1-km range, (ii) a similar array at approximately 4.2-km range, (iii) a 55-m aperture 12-element vertical array located at 1-km range, and (iv) a similar vertical array at 5-km range. In addition to processing the CAL data set, all three subcases of the SD, SO, AT, and WA data sets were also processed; however, only the transmission loss cost function and the two simulated 1/3-octave bands were considered for these test cases.
Can Maximum Likelihood Estimators Improve Genetic Algorithm Search in Geoacoustic Inversion?
Authors: Jesus Sérgio M.
Published: August 2003

The principles for estimating sea floor parameters via matched-field processing (MFP)-based techniques are now well known. In pure MFP, source localization is often seen as a range-depth estimation problem while the use of MFP on geoacoustic estimation generally involves a computationally intensive optimization procedure. In the last few years, much effort has been devoted to developing new or improving upon existing search procedures to solve the optimization problem Little, or no, attention has been given to the ensemble MFP-optimization treating it as a single technique. The question addressed in this paper is centered on the relation between the MFP parameter estimator technique, defining the objective function and the search procedure used to optimize it. In particular, we are interested in questions like: Can a faster search or more accurate estimate be achieved with a "peaky" surface instead of a flat and ambiguous surface? Is the inversion process affected by cross-frequency estimators and model mismatch? Does the search procedure need to be modified, and if yes how to account for this "peaky" surface navigation? This paper attempts to answer these and other related questions in the context of the June '97 geoacoustic inversion workshop data set.
The Inversion of Ocean Waveguide Parameters Using a Nonlinear Least Squares Approach
Authors: Knobles D. P. , Koch R. A. , Westwood E. K. , Udagawa T.
Published: August 2003

An optimization approach is used to estimate waveguide parameters for selected test cases of the Geoacoustic Benchmark Inversion Workshop held in Vancouver, June 1997. The approach uses multiple acoustic data samples to decouple the original N–dimensional problem into several smaller-dimensional problems. A nonlinear least squares approach is used to estimate parameters in each subset. The estimation of parameters in each subset proceeds until convergence is reached. Predicted values are in good agreement with the true values, which suggests that the decoupling of waveguide parameters allows a nonlinear least squares approach to be an effective tool in the inversion of ocean waveguide parameters.
Subspace Approach to Inversion by Genetic Algorithms Involving Multiple Frequencies
Authors: Ratilal Purnima , Gerstoft Peter , Goh Joo Thiam
Published: August 2003

Based on waveguide physics, a subspace inversion approach is proposed. It is observed that the ability to estimate a given parameter depends on its sensitivity to the acoustic wavefield, and this sensitivity depends on frequency. At low frequencies it is mainly the bottom parameters that are most sensitive and at high frequencies the geometric parameters are the most sensitive. Thus, the parameter vector to be determined is split into two subspaces, and only part of the data that is most influenced by the parameters in each subspace is used. The data sets from the Geoacoustic Inversion Workshop (June 1997) are inverted to demonstrate the approach. In each subspace Genetic Algorithms are used for the optimization — it provides flexibility to search over a wide range of parameters and also helps in selecting data sets to be used in the inversion. During optimization, the responses from many environmental parameter sets are computed in order to estimate the a posteriori probabilities of the model parameters. Thus the uniqueness and uncertainty of the model parameters are assessed. Using data from several frequencies to estimate a smaller subspace of parameters iteratively provides stability and greater accuracy in the estimated parameters.
Broadband Geoacoustic Inversion from Sparse Data Using Genetic Algorithms
Authors: Siderius Martin , Gerstoft Peter , Nielsen Peter
Published: August 2003

Matched-field acoustic inversion techniques were investigated using data from sparsely populated vertical receiving arrays and a single receiver element. The purpose of considering sparse data sets is to investigate, under simulation, the feasibility of reducing the number and complexity of acoustic measurements needed for geoacoustic inversion. The entire bandwidth of the 1997 Geoacoustic Inversion Workshop provided data (25–500 Hz) was used which compensates for the lack of spatial information when a limited number of receivers is considered. The forward model PROSIM and inversion code SAGA were applied to benchmark cases: sd, wa, and n. The inversion results generally showed good agreement with the ground truth for full arrays, sparse arrays and single receiver elements. With a simple two-layer model, an effective sound speed profile in the bottom was determined which produced a good fit between the model and observed pressure fields for the multi-layer case n.
Multi-Frequency Matched-Field Inversion of Benchmark Data Using a Genetic Algorithm
Authors: Simons D. G. , Snellen M.
Published: August 2003

For a selected number of shallow water test cases of the 1997 Geoacoustic Inversion Workshop we have applied Matched-Field Inversion to determine the geoacoustic and geometric (source location, water depth) parameters. A genetic algorithm has been applied for performing the optimization, whereas the replica fields have been calculated using a standard normal-mode model. The energy function to be optimized is based on the incoherent multi-frequency Bartlett processor. We have used the data sets provided at a few frequencies in the band 25–500 Hz for a vertical line array positioned at 5 km from the source. A comparison between the inverted and true parameter values is made.
Bottom Geoacoustic Inversion by "Broadband" Matched-Field Processing
Authors: Taroudakis Michael I. , Markaki Maria G.
Published: August 2003

Matched-Field Processing with a Genetic Algorithm is applied to the problem of bottom recognition with synthetic noise-free acoustic data. The data correspond to three classes of benchmark problems. Four alternative objective functions have been tested, all of them defined to be used with broadband data with either coherent or incoherent processing in the frequency domain. It has been concluded that the parameters corresponding to the sediment layer and especially the sound speed, are more accurately recovered by all means. Source localization and water depth estimation are made with good accuracy in all cases. It has also been shown that incoherent processing in the frequency domain has led to better results for the cases studied.
MFP Benchmark Inversions via the RIGS Method
Authors: Tolstoy A.
Published: August 2003

This paper discusses the geoacoustic inversion results obtained on the Workshop '97 benchmark data via the Refined Iterated Grid Search (RIGS) method. We find that the method can be highly accurate in estimating geoacoustic and source localization unknowns for the ten test scenarios attempted. The original method formulation using KRAKEN as the embedded propagation code produced the results presented at the workshop where we found that some parameters are extremely well determined, i.e. sediment attenuationα sed (within 1% in all 3 cases: ATa, ATb, ATc), sediment densityρ sed (within 5% in all ten subcases: SD, AT, SO, WAa), source ranger sou to within 40 m and source depthz sou to within 2 m (in all four subcases SO and WAa). Moreover, sediment sound-speed gradients γ were also well determined (within 8%) except for very thin sediments/subcase ATb where sediment thickness h sed ≈ 13 m). However, more recent, post-workshop results using ORCA embedded in the RIGS inversion software has resulted in even better results. Five of the original ten subcases have been re-done, and those results are also shown in this paper. In particular, we find that for the new results: r sou is now accurate to within 11 m, z sou to within 0.2 m, and all geoacoustic properties (except for half-space density ρ hsp ) are accurate to within 5%.
Multi-Frequency Inversion of Synthetic Transmission Loss Data Using a Genetic Algorithm
Authors: Westerlin Viggo
Published: August 2003

The organizers of the Benchmark Workshop for Geoacoustic Inversion Methods (Vancouver, June 1997) produced in advance several sound propagation scenarios, simulated using the wavenumber integration model SAFARI. The simulated pressure fields were made available to all interested, while several key geoacoustic properties of their environments were kept secret. For a number of these test cases we have applied Matched-Field Inversion to determine the unknown geometric and geoacoustic parameters. A Genetic Algorithm has been used together with the normal-mode model MODELOSS as a forward model. The parameters from the benchmark tests, which the forward model was most sensitive to, were well determined in this way (water depth, source depth and range, the attenuation in the sediment layer and the velocity in the upper part of the layer). The less influential parameters were not found with the same accuracy and were often not reliable. The density in the basement may have been just a random choice.
Estimation of Geoacoustic Parameters from Narrowband Data Using a Search-Optimization Technique
Authors: Zala Cedric A. , Ozard John M.
Published: August 2003

Geoacoustic parameters were estimated for vertical array data from the matched-field inversion benchmark data sets. Separate inversions were performed for narrowband data at 25 Hz, 50 Hz and 75 Hz, using a matching function consisting of the incoherent sum of the Bartlett outputs for the five vertical arrays at ranges of 1, 2, 3, 4 and 5 km. Parameter estimation was performed using a parabolic equation sound propagation algorithm to generate the replica fields, and a search-optimization technique to obtain estimates of the optimized parameter values. This technique involved an initial search stage in which the parameter space was sampled, and a second optimization stage in which each of a specified number of the best matches found in the search stage was used as the starting point for optimization. This approach provided multiple independent estimates of the geoacoustic parameters, and allowed assessment of the non-uniqueness of the problem and the sensitivity of the matching function to the individual parameters. A method was developed to combine the results for several frequencies to estimate the parameters. It used a weighted average with weights computed on the basis of the relative sensitivities at those frequencies; these sensitivities were estimated by the root-mean-square (RMS) gradient observed during the optimizations. Strong interdependencies among the parameters were found in the analysis, particularly between the sediment thickness and the sound speed at the bottom of the sediment. For the single-frequency matching function used here, it was observed that the inversion problems were ill-posed in that sets of parameter values from a wide region of the parameter space gave essentially perfect matches. The consistency of the parameter estimates was greatly improved by including a regularization term in the matching function. Regularized search-optimization provided an efficient method for estimating an effective geoacoustic model for acoustic field prediction.
Effects of Source Position and Frequency on Geoacoustic Inversion
Authors: Zhang Renhe , Li Fenghua , Luo Wenyu
Published: August 2003

In this paper, geoacoustic inversion based on simulated annealing and the BDRM propagation model is applied to the test cases from the 1997 Geoacoustic Inversion Workshop. The effects of the bottom parameters on the sound field are discussed theoretically and two characteristic angles dependent upon geoacoustic parameters are defined. Based on the theoretical analysis of the characteristic angles, a multi-frequency inversion scheme is given as follows: High frequency and farfield data are used to invert the upper bottom parameters first, and then low frequency and nearfield data are used to invert the lower bottom parameters. Simulated tests show that the results of multi-frequency inversion are more accurate and reliable than single frequency inversion.
Inversion of Pressure Data on a Vertical Array for Sea Floor Geoacoustic Properties
Authors: Ratilal Purnima , Gerstoft Peter , Goh Joo Thiam , Yeo Keng Pong
Published: August 2003

Estimation of the integral geoacoustic properties of the sea floor based on real data drawn from a shallow water site is presented. Two independent inversion schemes are used to deduce these properties. The first is matched-field processing of the pressure field on a vertical line array due to a projected source. The second approach is the inversion of ambient noise on a vertical array. Matched-field processing has shown to be successful in the inversion of high quality field data. Here, we show that it is also feasible with a more practical and less expensive data collection scheme. It will also be shown that low frequency inversion is more robust to variation and fluctuation in the propagating medium, whereas high frequencies are more sensitive to mismatches in a varying medium. A comparison is made of the estimates obtained from the two techniques and also with available historical data of the trial site.
Evaluation of a High-Accuracy MacCormack-Type Scheme Using Benchmark Problems
Authors: Hixon R.
Published: August 2003

Due to their inherent dissipation and stability, the MacCormack scheme and its variants have been widely used in the computation of unsteady flow and acoustic problems. However, these schemes require many points per wavelength in order to propagate waves with a reasonable amount of accuracy. Recently, much progress has been made in improving the wave propagation qualities of MacCormack-type schemes. In this work, the linear wave propagation characteristics of MacCormack-type schemes are compared using several of the CAA Benchmark Problems.
A Surface-Integral Formulation for Jet Noise Prediction Based on the Pressure Signal Alone
Authors: Mankbadi R. R. , Shih S. H. , Hixon D. R. , Stuart J. T. , Povinelli L. A.
Published: August 2003

While large-scale simulation of jet noise is the most thorough technique currently available for jet noise prediction, three-dimensional direct computation of both the near and far field requires prohibitive computational capability. In this work we propose to limit large-scale simulation to the near field to provide the pressure distribution over a cylindrical surface surrounding the jet. A surface-integral formulation is presented herein in which the calculated pressure on the cylindrical surface is used to obtain the far-field sound, without the need for the normal derivative of the pressure. The results are compared to that of direct large-scale simulation and to the zonal approach in which linearized Euler equations are used as an extension tool.
Direct Computations of Unsteady Flows About Thin Airfoils
Authors: Grace Sheryl M. , Hariharan S. I. , Atassi Hafiz M.
Published: August 2003

The intent of this paper is to investigate the effectiveness of direct numerical computation in capturing acoustic fields. It has been the trend to use high-order schemes whenever there is interest in resolving the acoustic field, even though there has never been a complete study of the accuracy of low-order schemes. We revisit a long-standing benchmark problem in aeroacoustics to show the validity of such low-order schemes. The problem we consider is that of a flat-plate airfoil in a non-uniform flow. We show that when the linearized Euler equations are used to model problems in aeroacoustics, a simple second-order numerical scheme is powerful enough to provide accurate aeroacoustic results. We validate this computational approach by comparing both the RMS and instantaneous pressure on the airfoil and in the far field to semianalytic and asymptotic results.
Estimation of Partial Discharge Parameters in GIS Using Acoustic Emission Techniques
Authors: Gupta Nandini , Ramu T. S.
Published: August 2003

Electrical discharge activity within an electrical power apparatus has detrimental effects on the insulating components of the system, and thus its prognosis and diagnosis are of utmost importance. Traditional electrical methods have been replaced by newer techniques such as acoustic detection. Among these, acoustic methods possess certain inherent advantages, especially where complex electrical systems like GIS are involved. The major concerns therein are the estimation of the magnitude of the discharge level as well as location of the source of discharge. The present work addresses, on a theoretical basis, problems connected with identification, measurement and location of electrical discharges, in particular in GIS. Models for the inception and propagation of p.d. within GIS have been proposed. This study, based essentially on a numerical simulation model, corroborates many of the experimental findings reported in the existing literature, and in addition attempts to suggest newer directions in magnitude estimation and location of p.d.
Acoustic Green's Function Approximations
Authors: Gilbert Robert P. , Lin Zhongyan , Hackl Klaus
Published: August 2003

Normal-mode expansions for Green's functions are derived for ocean–bottom systems. The bottom is modeled by Kirchhoff and Reissner–Mindlin plate theories for elastic and poroelastic materials. The resulting eigenvalue problems for the modal parameters are investigated. Normal modes are calculated by Hankel transformation of the underlying equations. Finally, the relation to the inverse problem is outlined.
REPRESENTING Ω(l∞) FOR REAL ABELIAN FIELDS
Authors: RITTER JÜRGEN , WEISS ALFRED
Published: August 2003

For real subfields K of a cyclotomic field ℚ(ς) we remove the tameness assumption at a given odd prime number l, which was needed in [11] in order to establish the equivalence of the Lifted Root Number Conjecture at l and an equivariant main conjecture of Iwasawa theory for abelian extensions of totally real number fields K/k.
On the moduli space of superminimal surfaces in spheres
Authors: Fernández Luis
Published: August 2003

Using a birational correspondence between the twistor space of S2n and projective space, we describe, up to birational equivalence, the moduli space of superminimal surfaces in S2n of degree d as curves of degree d in projective space satisfying a certain differential system. Using this approach, we show that the moduli space of linearly full maps is nonempty for sufficiently large degree and we show that the dimension of this moduli space for n = 3 and genus 0 is greater than or equal to 2d + 9. We also give a direct, simple proof of the connectedness of the moduli space of superminimal surfaces in S2n of degree d.
Archimedean unital groups with finite unit intervals
Authors: Foulis David J.
Published: August 2003

Let G be a unital group with a finite unit interval E, let n be the number of atoms in E, and let κ be the number of extreme points of the state space Ω(G). We introduce canonical order‐preserving group homomorphisms ξ : ℤn → G and ρ : G → ℤκ linking G with the simplicial groups ℤn and ℤκ.We show that ξ is a surjection and ρ is an injection if and only if G is torsion‐free. We give an explicit construction of the universal group (unigroup) for E using the canonical surjection ξ. If G is torsion‐free, then the canonical injection ρ is used to show that G is Archimedean if and only if its positive cone is determined by a finite number of
homogeneous linear inequalities with integer coefficients.
Forward‐backward resolvent splitting methods for general mixedvariational inequalities
Authors: Noor Muhammad Aslam , Akhter Muzaffar , Noor Khalida Inayat
Published: August 2003

We use the technique of updating the solution to suggest and analyze a class of new splitting methods for solving general mixed variational inequalities. It is shown that these modified methods converge for pseudomonotone operators, which is a weaker condition than monotonicity. Our methods differ from the known three‐step forward‐backward splitting of Glowinski, Le Tallec, and M. A. Noor for solving various classes of variational inequalities and complementarity problems. Since general mixed variational inequalities include variational inequalities and complementarity problems as special cases, our results continue to hold for these problems.
Method for solving a convex integer programming problem
Authors: Stefanov Stefan M.
Published: August 2003

We consider a convex integer program which is a nonlinear version of the assignment problem. This problem is reformulated as an equivalent problem. An algorithm for solving the original problem is suggested which is based on solving the simple assignment problem via some of known algorithms.
On a stochastic Burgers equation with Dirichlet boundary conditions
Authors: Kolkovska Ekaterina T.
Published: August 2003

We consider the one‐dimensional Burgers equation perturbed by a white noise term with Dirichlet boundary conditions and a non‐Lipschitz coefficient. We obtain existence of a weak solution proving tightness for a sequence of polygonal approximations for the equation and solving a martingale problem for the weak limit.
Moment inequalities connected with accompanying Poisson laws inAbelian groups
Authors: Borisov I. S.
Published: August 2003

We obtain exact inequalities which connect moments of some functions of sums of independent random variables taking values in a measurable Abelian group and those for the accompanying infinitely divisible laws. Some applications to empirical processes are studied.
Focal decompositions for linear differential equations of the second order
Authors: Birbrair L. , Sobolevsky M. , Sobolevskii P.
Published: August 2003

Focal decomposition associated to an ordinary differential equation of the second order is a partition of the set of all two‐points boundary value problems according to the number of their solutions. Two equations are called focally equivalent if there exists a homomorphism of the set of
two‐points problems to itself such that the image of the focal decomposition associated to the first equation is a focal decomposition associated to the second one. In this paper, we present a complete classification for linear second‐order equations with respect to this equivalence relation.
Periodic solutions of nonlinear vibrating beams
Authors: Berkovits J. , Leinfelder H. , Mustonen V.
Published: August 2003

The aim of this paper is to prove new existence and multiplicity results for periodic semilinear beam equation with a nonlinear time‐independent perturbation in case the period is not prescribed. Since the spectrum of the linear part varies with the period, the solvability of the equation depends crucially on the period which can be chosen as a free parameter. Since the period of the external forcing is generally unknown a priori, we consider the following natural problem. For a given time‐independent nonlinearity, find periods T for which the equation is solvable for any T‐periodic forcing. We will also deal with the existence of multiple solutions when the nonlinearity interacts with the spectrum of the linear part. We show that under certain conditions multiple solutions do exist for any small forcing term with suitable period T. The results are obtained via generalized Leray‐Schauder degree and reductions to invariant subspaces.
Local exact controllability of the diffusion equation in one dimension
Authors: Beceanu Marius
Published: August 2003

This paper establishes the local exact null controllability of the diffusion equation in one dimension using distributed controls in the case of the Dirichlet boundary value problem. Most of the techniques used in the course of the proof are borrowed from Barbu (2002).
On the existence of certainty equivalents of various relevant types
Authors: Alcantud J. C. R. , Bosi G.
Published: August 2003

We tackle the problem of associating certainty equivalents with preferences over stochastic situations, which arises in a number of different fields (e.g., the theory of risk attitudes or the analysis of stochastic cooperative games). We study the possibility of endowing such preferences with certainty equivalence functionals that satisfy relevant requirements (such as positive homogeneity, translation invariance, monotonicity with respect to first‐order stochastic dominance, and subadditivity). Uniqueness of the functional is also addressed in fairly general conditions.
Existence of weak solutions for a scale similarity model of the motion of large eddies in turbulent flow
Authors: Kaya Meryem
Published: August 2003

In turbulent flow, the normal procedure has been seeking means of the fluid velocity u rather than the velocity itself. In large eddy simulation, we use an averaging operator which allows for the separation of large‐ and small‐length scales in the flow field. The filtered field denotes the eddies of size O(δ) and larger. Applying local spatial averaging operator with averaging radius δ to the Navier‐Stokes equations gives a new system of equations governing the large scales. However, it has the well‐known problem of closure. One approach to the closure problem which arises from averaging the nonlinear term is the use of a scale similarity hypothesis. We consider one such scale similarity model. We prove the existence of weak solutions for the resulting system.
A Black Technician and Blue Babies
Authors: Timmermans Stefan
Published: August 2003

In this paper, I discuss the many contributions of a versatile black technician, Vivien Thomas, to surgical animal research between 1930 and 1979 at Vanderbilt University and Johns Hopkins University. Thomas' experimental work led to a surgical solution for a life-threatening heart defect, called tetralogy of Fallot. Children with this condition lack sufficient oxygenation and were referred to as `blue babies'. Following Thomas' research trajectory and his relationship with surgeon Dr Alfred Blalock, I review the conditions under which differing expectations towards race and occupation clashed, creating a status dilemma for Thomas. While the torsion originated in the laboratory where technical skills are valued, the research locale also facilitated a temporary, fragile solution for the status dilemma, because it separated Thomas from public view. Yet, Thomas' dexterity as a laboratory researcher enhanced his dilemma, because credit kept eluding him. In order to track the dynamics of race and occupational subordination as lived experience in the laboratory, I argue for an analysis of the process of crediting people for their scientific accomplishments.
Science Consultants, Fictional Films, and Scientific Practice
Authors: Kirby David A.
Published: August 2003

When scientists act as consultants during the production of a fictional film, it becomes an act of communication that plays a role in the process of science. Fictional film provides a space for scientists to visually model their conceptions of nature. Film impacts scientific practice as science consultants utilize film as a virtual witnessing technology to gather allies among specialists and non-specialists. Film not only has the ability to act as a virtual witnessing technology, but also forces consensus on the public version of scientific debates by presenting a single vision of nature in a perceptually realistic structure. This paper shows films to be successful communicative devices within the scientific community by showing that, and how, other scientists respond to the depictions in the films. It also demonstrates that science consultants use fictional films as promotional devices for their research fields.
Gender, Lifecourse and Publication Decisions in Toxic-Exposure Epidemiology:
Authors: Rier David A.
Published: August 2003

Existing studies of gender and lifecourse in science have not focused on publication decisions, and even less so for publication of studies liable to attract media and public attention. This paper is based on semi-structured interviews with 61 US toxic-exposure epidemiologists about their publication decisions. It examines gender differences in how scientists, as they move through the lifecourse, approach publication decisions for research bearing potential societal implications. Though preliminary, the data suggest that males are overall more comfortable than females with pursuing visible publication and handling media coverage. However, males and females may begin to crisscross over time. Specifically, males started out in publishing potentially controversial papers in visible journals likely to attract media and public attention, but grew more cautious with age, rank, and experience. Amongst females, the situation was less homogenous: while some (often, the most élite) reported patterns similar to males', more reported following the reverse pattern as they moved through the lifecourse. These differences may stem in part from gender differences in self-confidence, risk-taking, and competitiveness. The wider significance and limitations of the data are discussed, and lines of further research (including nine testable hypotheses) are suggested.
Distributed Cognition:
Authors: Giere Ronald N. , Moffatt Barton
Published: August 2003

Among the many contested boundaries in science studies is that between the cognitive and the social. Here, we are concerned to question this boundary from a perspective within the cognitive sciences based on the notion of distributed cognition. We first present two of many contemporary sources of the notion of distributed cognition, one from the study of artificial neural networks and one from cognitive anthropology. We then proceed to reinterpret two well-known essays by Bruno Latour, `Visualization and Cognition: Thinking with Eyes and Hands' and `Circulating Reference: Sampling the Soil in the Amazon Forest'. In both cases we find the cognitive and the social merged in a system of distributed cognition without any appeal to agonistic encounters. For us, results do not come to be regarded as veridical because they are widely accepted; they come to be widely accepted because, in the context of an appropriate distributed cognitive system, their apparent veracity can be made evident to anyone with the capacity to understand the workings of the system.
Fatal Large-Volume Mouthwash Ingestion in an Adult: A Review and the Possible Role of Phenolic Compound Toxicity
Authors: Hoo Guy W. Soo , Hinds Robert L. , Dinovo Eugene , Renner Stephen W.
Published: August 2003

Objective: To describe a case of fatal mouthwash ingestion and review possible sources of toxicity. Design: Case report. Setting: Veterans Administration Medical Center. Patient: Single patient with massive mouthwash ingestion. Main results: This patient was a 45-year-old man who developed cardiovascular collapse and multiorgan system failure following a massive ingestion of mouthwash (almost 3 liters). His presentation was remarkable for a profound anion-gap metabolic acidosis and a significant osmolar gap. No other co-ingestants were identified, and he expired despite full supportive care including dialysis and mechanical ventilation. An autopsy failed to identify any other cause of death. Nonalcoholic ingredients of this mouthwash are phenolic compounds (eucalyptol, menthol, and thymol), and large-volume mouthwash ingestion will produce exposure in the reported toxic range of these ingredients. Conclusions: When ingested in large quantities, the phenolic compounds in mouthwash may contribute to a severe anion-gap metabolic acidosis and osmolar gap, multiorgan system failure, and death. These compounds, in addition to alcohol, may account for the adverse effects associated with massive mouthwash ingestion.
National Survey of the Use of Sedating Drugs, Neuromuscular Blocking Agents, and Reversal Agents in the Intensive Care Unit
Authors: Rhoney Denise H. , Murry Kellie R.
Published: August 2003

The objectives of this study were to describe the sedative, neuromuscular blocking agents (NMBA) and reversal agents utilized in adult intensive care units across the United States and determine the adherence to American College of Critical Care Medicine and Society of Critical Care Medicine (SCCM) guidelines. In addition, the authors assessed the use of written protocols, criteria used for selecting these agents, and monitoring practices. Questionnaires were mailed to attending physician members of SCCM in the spring of 1998. A cover letter was enclosed that explained the purpose of the survey asking the respondent to forward the questionnaire to a colleague if unable to complete. Four-hundred fifty-seven questionnaires were returned representing 393 different institutions for a response rate of 50.4% (393/780). Respondents were physicians (91.2%) practicing in a community (49.7%) or university teaching hospital (38.3%). The sedative agents used most often were opioids and benzodiazepines for > 72 hours, and NMBA utilized were vecuronium and pancuronium for > 24 hours. The most often cited indications for sedatives were agitation, anxiety/fear, and facilitation of intubation and maintenance of mechanical ventilation for NMBA. Only 32.6% used written protocols for sedatives and 46.8% for NMBA. Decisions regarding agent selection were based on clinician preference and experience and agent duration of action. Seventy-eight percent monitored sedative use primarily with the Glasgow Coma Scale and the modified Ramsay score. Monitoring of NMBA was used more frequently (91.3%) with peripheral nerve stimulation. The most common reversal agents used were naloxone and flumazenil for adverse drug effects. While many of the respondents indicated they used morphine and lorazepam for long-term sedation, the majority utilized midazolam and propofol for > 24 hours despite the recommendation of SCCM. Vecuronium was prescribed more routinely than pancuronium. The number of institutions utilizing protocols for any of these agents was low; instead, decisions were based on clinician preference.
Update on Dialytic Management of Acute Renal Failure
Authors: Teehan Geoffrey S. , Liangos Orfeas , Jaber Bertrand L.
Published: August 2003

The potential impact of renal replacement therapy on clinical outcomes in acute renal failure (ARF) remains a subject of ongoing investigation and controversy. This article reviews in depth the clinical trials to date that have examined the effect of dialysis-related variables on outcomes of patients with hospital-acquired ARF. In particular, the role of the dialysis modality, dialyzer characteristics, and dosing strategies are discussed. Clinical trials comparing intermittent hemodialysis (HD) to continuous renal replacement therapies (CRRT) have failed to demonstrate a survival difference when adjusting for disease severity. Similarly, studies evaluating dialyzer membrane biocompatibility and flux properties had no impact on survival. Efforts aimed at measuring dialysis adequacy in patients with ARF receiving HD using urea kinetic modeling are hindered by a lack of understanding of solute kinetics in this setting. However, dosing strategies during CRRT are promising. Finally, the application of cell therapy to the successful substitution of renal function shows promise for the future.
Cardiovascular Manifestations of Acute Intracranial Lesions: Pathophysiology, Manifestations, and Treatment
Authors: Arab Dinesh , Yahia Abutaher M. , Qureshi Adnan I.
Published: August 2003

The objective of this article was to review the effects of acute intracranial lesions on myocardial function. The authors reviewed scientific and clinical literature retrieved from a computerized MEDLINE search from January 1965 through January 2002. Pertinent literature was referenced, including clinical and laboratory investigations, to demonstrate the effects of acute intracranial lesions on the cardiovascular system. The literature was reviewed to summarize the mechanisms of cardiac damage and clinical manifestations and treatment of cardiovascular dysfunction caused by acute intracranial lesions. Myocardial damage and rhythm disturbances were shown to occur with acute intracranial neurological disease. The subgroup of patients used in this study formed a substantial pool of cardiac donors for cardiac transplantation. The pathophysiology of myocardial dysfunction and the optimal management continues to be a source of debate. In this article, the authors will review the anatomy, the available evidence of the pathophysiology, and the management of this complex group of patients. They will also discuss areas that need to be further investigated. Cardiovascular effects of acute intracranial lesions are common and contribute to increased morbidity and mortality.
Intraoperative Administration of Nitric Oxide
Authors: Dietrich Cassie C. , Tobias Joseph D.
Published: August 2003

Despite its therapeutic efficacy in various clinical scenarios in the intensive care unit setting, there are limited reports regarding the intraoperative applications of nitric oxide (NO). The authors present 2 pediatric patients to whom inhaled NO was administered intraoperatively. In one patient, NO was used to treat hypoxemia that developed after the institution of one-lung ventilation during thoracoscopic resection of a bronchiectatic section of lung. In the second patient, NO was used to alleviate pulmonary hypertension and cardiovascular dysfunction with pulmonary artery cross-clamping for placement of a modified Blalock-Taussig shunt. The potential intraoperative applications and techniques for the intraoperative delivery of NO are presented.
Thrombotic Thrombocytopenic Purpura Associated with Abacavir in a Patient with HIV Infection
Authors: Olszewski Adam J. , Shapiro Janet M.
Published: August 2003

A 45-year-old woman with HIV infection presented with thrombotic microangiopathy 1 week after initiating therapy with the nucleoside analogue abacavir. She was successfully treated with plasmapheresis and corticosteroids.
Struggling for a New Self: In-Depth Interviews with 21 Patients with Hyperacusis after an Acute Head Trauma
Authors: Trulsson Ulrika , Johansson Mattias , Jansson Gunilla , Wiberg Agne , Hallberg Lillemor R.-M.
Published: August 2003

The aim of the study was to gain a better understanding of what suffering from hyperacusis means. Twenty-one out-patients referred to a hearing clinic due to persisting hypersensitivity to sounds after an acute head trauma were interviewed. Before the head trauma, they had lived an independent, active and externally oriented life. As a consequence of the trauma, the patients became psychosocially vulnerable and suffered from a variety of symptoms: hypersensitivity to sounds, difficulties with concentrating and remembering, increased anxiety and sensitivity to stress. Structuring everyday life and using a variety of coping strategies was necessary for reducing life stress and symptoms in the process of adjusting to the changed life situation.
Anger Experience and Anger Inhibition in Sub-Populations of African American and European American Older Adults and Relation to Circulatory Disease
Authors: Magai Carol , Kerns Michael-David , Gillespie Michael , Huang Bu
Published: August 2003

This study examined ethnic differences in the link between anger experience and anger inhibition and that of circulatory disease (CD). To ascertain the effects of anger inhibition in older persons, health data from groups of African American, African Caribbean, Eastern European and European American adults were collected. Experienced anger and anger inhibition were significant predictors of CD only for the African American group and the relation between experienced anger and CD was mediated by anger inhibition. The data suggest that cultural factors play a role in the development of an angerinhibitory style and that this trait may pose a serious risk factor for circulatory disease.
Stress, Burnout and Coping: Differences between Women with Coronary Heart Disease and Healthy Matched Women
Authors: Hallman Tina , Thomsson Helene , Burell Gunilla , Lisspers Jan , Setterlind Sven
Published: August 2003

Stress is becoming more significant for women, along with the increasing number of women in the workforce. The present study compared women with respect to burnout and coping abilities, and related to the impact of educational level on differences in coping strategies. Women with coronary heart disease reported a higher level of burnout and had the highest scores demonstrating lack of coping, which indicates lesser coping abilities. Differences concerning strain reduction, self-control and emotional distancing are discussed in terms of living conditions. We also discuss that in order to optimize the outcome of rehabilitation and prevention we need more research on women, of women and especially from women’s point of view.
Translating Exercise Intentions into Behavior: Personality and Social Cognitive Correlates
Authors: Rhodes Ryan E. , Courneya Kerry S. , Jones Lee W.
Published: August 2003

The purpose of this study was to detail the variability found in the exercise intention–behavior relationship and investigate social cognitive and personality correlates of successful intention translation. Participants were 300 undergraduate students who completed measures of exercise social cognition (theory of planned behavior), personality (five-factor model) and a twoweek follow-up of exercise behavior. Results suggested intention translation at a frequency of zero was significantly more successful than intending to exercise at all other weekly frequencies. Moreover, intending to exercise one or two times per week resulted in better intention translation than intending to exercise four or more bouts per week. Discriminant function analysis and follow-up F-tests found instrumental attitude, affective attitude and perceived behavioral control (PBC) discriminated between nonintenders, unsuccessful intenders and successful intenders. Further, extroversion predicted unsuccessful intenders versus successful intenders. Results underscore the importance of attitude, PBC and extroversion as action control constructs in the exercise domain.