bluuebunny/crossref_metadata_2025 huggingface dataset:
When fish shoals meet: outcomes for evolution and fisheries
Authors: Croft Darren P , Krause Jens , Couzin Iain D , Pitcher Tony J
Published: December 2004

The mechanisms underlying the social structure of free‐ranging fish shoals have received little attention in comparison to functional studies on shoaling. Recently, however, a number of investigations, both in the marine and in the freshwater environment, have begun to address the underlying mechanisms by concentrating on interactions between free‐ranging shoals. The rates of shoal encounters can influence the opportunities for individual assortment by phenotype and selection of shoal size; act as a constraint on the observed patterns of shoal structure by restricting individual choice behaviour and were found to be high in several small freshwater species (where intershoal distances were small), but lower in marine species where shoals were more dispersed. The duration of encounters may play a role in that it affects both the time available for assessment (of the encountered shoal) as well as that for exchange of individuals. Scarce published information on the outcome of shoal encounters suggests that the outcome of shoal encounters is influenced by shoal composition but not by shoal size. Individual behaviour may have evolved to maintain shoal size when shoals encounter, but when fish populations are depleted by fishing, this trait can exacerbate range and stock collapse. Furthermore, an understanding of the dynamics of shoal encounters has important consequences for the evolution of reciprocal altruism and the transmission of information through social learning within populations. Finally, information on encounter rates between shoals and the number of individuals that are exchanged on such occasions could be important for making predictions about the spread of disease through fish populations.
Learning about danger: chemical alarm cues and local risk assessment in prey fishes
Authors: Brown Grant E
Published: December 2004

An individual's behaviour patterns can be conceptualized as a series of threat‐sensitive trade‐offs between ambient predation pressure and a suite of fitness‐related activities, such as resource defence, foraging and mating. Individuals that can reliably assess local predation risk could increase their fitness potential by exhibiting predator avoidance behaviours only at appropriate times. However, such learned risk assessment requires reliable information regarding current predation risks.

A diverse range of prey fishes are known to possess chemical alarm cues, which when detected by conspecifics and some heterospecifics, elicit a variety of overt and covert responses. These chemical cues, either alone or as a part of a predator's dietary odour, provide reliable information regarding local predation risk. In this review, I describe recent works examining the role of chemosensory information in: (i) acquired predator recognition, (ii) predator inspection behaviour and (iii) the use of conspecific and heterospecific cues as social information sources.
Medical history for tomorrow—preserving the record of today
Authors: Pearson David
Published: December 2004

This paper addresses the need to recognize the importance, and the challenges, of preserving the hugely expanding record of medicine today for historians of the future. We are faced not only with an increase in traditional publishing formats, but also with the rapid growth in electronic communications. Two celebrated medical cases, one from the late seventeenth century and one from the late twentieth, are used to illustrate the differences and the difficulties. The need for active and effective professional collaboration is stressed; libraries should work together to address these issues.
Using SERVQUAL in health libraries across Somerset, Devon and Cornwall
Authors: Martin Susan
Published: December 2004

This study provides the results of a survey conducted in the autumn of 2001 by ten NHS library services across Somerset, Devon and Cornwall. The aim of the project was to measure the service quality of each individual library and to provide an overall picture of the quality of library services within the south‐west peninsula. The survey was based on SERVQUAL, a diagnostic tool developed in the 1980s, which measures service quality in terms of customer expectations and perceptions of service. The survey results have provided the librarians with a wealth of information about service quality. The service as a whole is perceived to be not only meeting but also exceeding expectations in terms of reliability, responsiveness, empathy and assurance. For the first time, the ten health library services can measure their own service quality as well as benchmark themselves against others.
‘Rescue’ Therapy with Rifabutin after Multiple Helicobacter pylori Treatment Failures
Authors: Gisbert Javier P. , Calvet Xavier , Bujanda Luis , Marcos Santiago , Gisbert José Luis , Pajares José María
Published: December 2004

abstract

Aim. Eradication therapy with proton pump inhibitor, clarithromycin and amoxicillin is extensively used, although it fails in a considerable number of cases. A ‘rescue’ therapy with a quadruple combination of omeprazole, bismuth, tetracycline and metronidazole (or ranitidine bismuth citrate with these same antibiotics) has been recommended, but it still fails in approximately 20% of cases. Our aim was to evaluate the efficacy and tolerability of a rifabutin‐based regimen in patients with two consecutive H. pylori eradication failures.

Patients and Methods. Design: Prospective multicenter study. Patients: Consecutive patients in whom a first eradication trial with omeprazole, clarithromycin and amoxicillin and a second trial with omeprazole, bismuth, tetracycline and metronidazole (three patients) or ranitidine bismuth citrate with these same antibiotics (11 patients) had failed were included. Intervention: A third eradication regimen with rifabutin (150 mg bid), amoxicillin (1 g bid) and omeprazole (20 mg bid) was prescribed for 14 days. All drugs were administered together after breakfast and dinner. Compliance with therapy was determined from the interrogatory and the recovery of empty envelopes of medications. Outcome: H. pylori eradication was defined as a negative 13C‐urea breath test 8 weeks after completing therapy.

Results. Fourteen patients have been included. Mean age ± SD was 42 ± 11 years, 41% males, peptic ulcer (57%), functional dyspepsia (43%). All patients took all the medications and completed the study protocol. Per‐protocol and intention‐to‐treat eradication was achieved in 11/14 patients (79%; 95% confidence interval = 49–95%). Adverse effects were reported in five patients (36%), and included: abdominal pain (three patients), nausea and vomiting (one patient), and oral candidiasis (one patient); no patient abandoned the treatment due to adverse effects.

Conclusion. Rifabutin‐based rescue therapy constitutes an encouraging strategy after multiple previous eradication failures with key antibiotics such as amoxicillin, clarithromycin, metronidazole and tetracycline.
Interleukin‐6 Genetic Polymorphisms are not Related to Helicobacter pylori‐Associated Gastroduodenal Diseases
Authors: Hwang Il‐Ran , Hsu Ping‐I. , Peterson Leif E. , Gutierrez Oscar , Kim Jong G. , Graham David Y. , Yamaoka Yoshio
Published: December 2004

abstract

Background. Polymorphisms in the promoter region of the proinflammatory cytokine, interleukin (IL)‐6 have been related to several chronic inflammatory diseases. Inter‐individual variation in the severity of gastric inflammation may be important in determining the clinical outcome of an Helicobacter pylori infection and relate to polymorphisms in this region.

Materials and Methods. We studied H. pylori‐infected patients with duodenal ulcer or gastric cancer. In addition six gastric cancer cell lines, AGS, SNU‐668, MKN‐1, MKN‐7, MKN28 and KATOIII, were cocultured with both cag pathogenicity island‐positive and ‐negative H. pylori. Single nucleotide polymorphisms at positions −174, −572, and −597 in the IL‐6 promoter region were identified by PCR‐RFLP. The IL‐6 production from the cancer cells was determined by ELISA.

Results. Sixty patients with gastric cancer and 60 with duodenal ulcer were studied. The alleles at positions −174 and −597 were closely linked (−174G/−597G or −174C/−597A) regardless of the ethnic group or disease presentation. There was no difference in the allele frequency at any of the sites among patient groups. H. pylori‐induced IL‐6 production from the gastric cancer cell lines was also independent of the IL‐6 polymorphisms or the presence of the cag pathogenicity island.

Conclusions. The genetic polymorphisms in IL‐6 can be attributable to ethnicity and appear to be independent of the clinical outcome of an H. pylori infection.
Prevalence and Clinical Characteristics of Headache in a Rural Community in Oman
Authors: Deleu Dirk , Khan Mushtaq A. , Al Shehab Tariq A. H.
Published: December 2004

Objectives.—To perform a prospective epidemiological study of headache in a rural community in Oman, assessing prevalence, symptom profile, and health care utilization pattern.

Methods.—Using a door‐to‐door survey prevalence estimates were based on a detailed structured headache assessment questionnaire performed in 1158 subjects. Migraine and tension‐type headache were diagnosed according to the International Headache Society criteria.

Results.—The crude lifetime and last‐year prevalence of headache were 83.6% and 78.8%, respectively, with a female preponderance. The last‐year prevalence of migraine and tension headache was 10.1% and 11.2%, respectively. There was no significant gender difference in migraine prevalence (4.5% in male and 5.6% in female), but tension‐type headache was 2.6 times more common in females (3.1% in male and 8.1% in female). Last‐year prevalence of frequent headaches was 5.4%. Forty eight percent of respondents sought medical assistance for their headaches and 79% were using medication, 40% of them used self‐medication.

Conclusions.—This prospective study shows that headache is also highly prevalent in this community. Migraine and tension‐type headache have the same prevalence, but the sex distribution for migraine is different from that observed in the Western world. Tension‐type headache prevalence was substantially lower than that observed in other parts of the world. Frequent headaches were as common as in other population‐based studies worldwide. Analgesic use/overuse probably also coexisted with headache, because self‐medication was quite common.
Costs and Outcomes of Early Versus Delayed Migraine Treatment with Sumatriptan
Authors: Halpern Michael T. , Lipton Richard B. , Cady Roger K. , Kwong W. Jacqueline , Marlo Karen O. , Batenhorst Alice S.
Published: December 2004

Objective.—To evaluate the impact on costs and outcomes of early migraine treatment with sumatriptan while pain is mild versus sumatriptan treatment of moderate to severe pain.

Background.—Migraines result in substantial pain, impairment, and costs. Recent clinical studies have shown that early treatment with sumatriptan when migraine pain is mild is more effective than sumatriptan treatment when pain is moderate to severe.

Design/Methods.—We developed a decision analytical model to assess the costs and outcomes per treated migraine attack, comparing early treatment while pain is mild versus delayed treatment when pain may become moderate/severe using 50 and 100 mg of sumatriptan. Parameters for the model were derived from published literature and analysis of migraine patient diary data. For each patient group the model determined the duration of mild and moderate/severe migraine pain, the proportion of patients pain free at 4 hours after initial therapy with no recurrence, medical care costs, and work loss costs (from migraine‐related absenteeism and decreased productivity) during a 24‐hour period. Total costs were calculated as the sum of medical care costs plus work loss costs.

Results.—Early treatment with sumatriptan when migraine pain is mild resulted in substantially decreased total costs per treated attack as compared with treatment when pain is moderate/severe. Early treatment also resulted in decreased time with headache pain, an increased proportion of patients pain free at 4 hours without recurrence, and decreased physician and emergency department visits. Treatment with 100 mg sumatriptan resulted in better outcomes than did treatment with 50 mg sumatriptan, but outcomes with either dose for early treatment of mild pain were superior to those for either dose in delayed treatment when pain may be moderate/severe.

Conclusions.—Model‐based results indicate that on a treated attack basis, early treatment of migraine with sumatriptan while pain is mild leads to decreased costs and improved outcomes compared to delayed sumatriptan treatment.
Prevalence and incidence of cluster headache in the Republic of San Marino.
Authors: Tonon C , Guttmann S , Volpini M , Naccarato S , Cortelli P , D'Alessandro R
Published: December 2004

Neurology. 2002 May 14;58(9):1407‐1409

Based on a preceding survey performed in 1985, the authors estimated the prevalence and incidence of cluster headache (CH) in the Republic of San Marino (26 628 inhabitants at 31 December 1999). All cases were diagnosed by direct interview according to International Headache Society criteria. The prevalence rate was 56/100 000 (95% CI 31.3 to 92.4), and the incidence rate was 2.5/100 000/year (95% CI 1.14 to 4.75). Most cases showed rare clusters. This is the first prospective study on the incidence of CH.

Comment: There continues to be debate on the prevalence of cluster in the general population. Since San Marino is small, the entire cluster population, with a smaller denominator for the general population, could be estimated, making this a very important study. SJT
Efficacy, tolerability and safety of oral eletriptan and ergotamine plus caffeine (Cafergot) in the acute treatment of migraine: a multicentre, randomised, double‐blind, placebo‐controlled comparison.
Authors: Diener HC , Jansen JP , Reches A , Pascual J , Pitei D , Steiner TJ
Published: December 2004

Eur Neurol. 2002;47(2):99‐107

The 5‐HT(1B/1D/1F) agonist eletriptan, at an oral dose of 80 mg, has been shown to be more efficacious than sumatriptan 100 mg and placebo in the treatment of migraine attacks with or without aura. Another commonly prescribed oral treatment for migraine attacks is Cafergot (1 mg ergotamine tartrate with 100 mg caffeine per tablet). The efficacy, tolerability and safety of 40‐ and 80‐mg doses of eletriptan and 2 tablets of Cafergot were compared in a double‐blind, randomised, placebo‐controlled, parallel‐group trial involving 733 migraine patients. Patients recorded symptoms at baseline (before treatment) and 1, 2, 4 and 24 h after dosing. Headache intensity was assessed on a 4‐point scale (3  =  severe pain, 2  =  moderate pain, 1  =  mild pain, 0  =  no pain). Significantly more eletriptan‐treated patients (80 mg, 68%; 40 mg, 54%) than Cafergot‐treated patients (33%; p  <  0.001) reported headache response (improvement from moderate‐to‐severe to mild or no pain) at 2 h. Substantially more eletriptan recipients reported no pain (80 mg, 38%; 40 mg, 28%; Cafergot, 10%; placebo, 5%; p  <  0.001). Eletriptan headache response rates at 1 h were significantly higher (80 mg, 39%; 40 mg, 29%; Cafergot, 13%; placebo, 13%; p  <  0.002 for each comparison). Both doses of eletriptan were significantly more effective than Cafergot in reducing nausea (p  <  0.0001), photophobia (80 mg, p  <  0.0001; 40 mg, p  <  0.002), phonophobia (80 mg, p  <  0.0001; 40 mg, p  <  0.003) and functional impairment (p  <  or  =  0.001) at 2 h. Adverse events were generally mild or moderate and transient. This randomised trial shows that oral eletriptan is more efficacious in the acute treatment of migraine than oral Cafergot and is well tolerated.

Comment: As with all comparative trials with eletriptan, this comparative trial raises the important issue of blinding. Was the Cafergot encapsulated (hence potentially hindering the early phase of absorbtion)? This approach has been a major issue with previous eletriptan studies and may potentially make the results from this trial difficult to interpret. DSM

One key issue in ensuring methodologically rigorous comparative trials is symmetry of comparative groups. I have come to believe that the controversy over encapsulation for blinding is neither about the pharmacokinetics of encapsulation, nor about the effectiveness of eletriptan, but rather about the methodology of comparison, which requires as much symmetry as possible. As Gawel and Wiebe wrote in a superb article explaining how to critically evaluate a comparison trial, “When faced with a potential confounder … readers need to estimate in which direction the results would be biased” in any comparative trial (Gawel M, Wiebe S. Evidence‐based analysis of a migraine treatment drug comparison trial. Cephalalgia. 2000;20[suppl 2]:33‐38). SJT
Increased motor drive and sleep loss in mice lacking Kv3‐type potassium channels
Authors: Espinosa F. , Marks G. , Heintz N. , Joho R. H.
Published: December 2004

The voltage‐gated potassium channels Kv3.1 and Kv3.3 are widely expressed in the brain, including areas implicated in the control of motor activity and in areas thought to regulate arousal states. Although Kv3.1 and Kv3.3‐single mutants show some physiological changes, previous studies revealed relatively subtle behavioral alterations suggesting that Kv3.1 and Kv3.3 channel subunits may be encoded by a pair of redundant genes. In agreement with this hypothesis, Kv3.1/Kv3.3‐deficient mice display a ‘strong’ mutant phenotype that includes motor dysfunction (ataxia, myoclonus, tremor) and hyperactivity when exposed to a novel environment. In this paper we report that Kv3.1/Kv3.3‐deficient mice are also constitutively hyperactive. Compared to wildtype mice, double mutants display ‘restlessness’ that is particularly prominent during the light period, when mice are normally at rest, characterized by more than a doubling of ambulatory and stereotypic activity, and accompanied by a 40% sleep reduction. When we reinvestigated both single mutants, we observed constitutive increases of ambulatory and stereotypic activity in conjunction with sleep loss in Kv3.1‐single mutants but not in Kv3.3‐single mutants. These findings indicate that the absence of Kv3.1‐channel subunits is primarily responsible for the increased motor drive and the reduction in sleep time.
Association analysis of the catechol‐o‐methyltransferase (COMT ), serotonin transporter (5‐HTT ) and serotonin 2A receptor (5HT2A) gene polymorphisms with obsessive‐compulsive disorder
Authors: Meira‐Lima I. , Shavitt R. G. , Miguita K. , Ikenaga E. , Miguel E. C. , Vallada H.
Published: December 2004

Family and twin studies have supported a strong genetic factor in the etiology of obsessive‐compulsive disorder (OCD), although the precise mechanism of inheritance is unclear. Clinical and pharmacological studies have implicated the serotonergic and dopaminergic systems in disease pathogenesis. In this cross‐sectional study, we have examined the allelic and genotypic frequencies of a Val‐158‐Met substitution in the COMT gene, a 44‐base pair (bp) length variation in the regulatory region of the serotonin transporter gene (5‐HTTLPR) and the T102C and C516T variants in the serotonin receptor type 2A (5HT2A) gene in 79 OCD patients and 202 control subjects. There were no observed differences in the frequencies of allele and genotype between patients and control groups for the COMT, the 5HTTLPR and the T102C 5HT2A gene polymorphisms. In contrast, a statistically significant difference between OCD patients and controls was observed on the genotypic distribution (χ2 = 16.7, 2df, P = 0.0002) and on the allelic frequencies (χ2 = 15.8, 1df, P = 0.00007) for the C516T 5HT2A gene polymorphism. The results suggest that the C516T variant of the 5HT2A gene may be one of the genetic risk factors for OCD in our sample. However, further studies using larger samples and family based methods are recommended to confirm these findings.
Equilibrium of Electron Clouds in Toroidal Magnetic Fields
Authors: Daugherty J. D. , Levy R. H.
Published: December 2004

The self-consistent equilibrium configurations available to low-density (q = ωp2/ωc2 ≪ 1) toroidal electron clouds under the influence of an external magnetic field and the electric fields due to space and image charges are discussed. The equilibria are dynamic rather than static, but steady. ▿B, centrifugal, and other drifts are shown to be unimportant, in contrast to the situation in toroidal neutral plasmas. Typical equilibria are shown in detail, to zero order in q. The construction of equilibria accurate to order q is shown to be possible but is not carried out in detail. Questions relating to the stability of these equilibria are not treated.
Oscillation of Two Cylinders in Liquid Helium
Authors: Hussey R. G. , Good B. J. , Reynolds J. M.
Published: December 2004

A torsion pendulum was used to oscillate two solid cylinders in liquid helium II at subcritical velocities. The cylinders were sections of Plexiglas rod, constrained to move with their axes parallel to and equidistant from the axis of rotation by means of two parallel disks (end plates). Theoretical expressions based on the two-fluid model are derived for the added moment of inertia Ia and the logarithmic decrement 2πδ. The experimental results between 2.17 and 1.25°K are in close agreement with theory except for a small (1 to 2%) end effect on Ia. Penetration depths ranged between 0.03 and 0.59 of the cylinder radius. No dependence of Ia and δ on amplitude was observed for amplitudes up to 0.5 radius.
Deflection of Charged Particles by a Current-Carrying Plasma
Authors: Joyce Glenn , Montgomery David , Roqúe Celso
Published: December 2004

Previously derived formal expressions for the mean-square deflection of a beam of energetic test particles from a spatially uniform plasma are evaluated numerically. The plasma electrons are assumed to be drifting relative to the ions with a velocity which ranges between zero and the critical drift velocity for the onset of the ion sound wave instability. Though the scattering angle diverges at the stability boundary, one must be able to make the drift velocity prohibitively close to the critical drift velocity (to within a small fraction of a percent of it) to see a marked enhancement. In no case was the scattering enhanced over the thermal value by as much as a factor of 10.
Theory of Simple Deformable Directed Fluids
Authors: Allen S. J. , DeSilva C. N. , Kline K. A.
Published: December 2004

The governing equations are given for a fluid with deforming microstructure by postulating an energy balance, an entropy production inequality, and a principle of material frame indifference. A canonical form of the energy equation is derived which serves as a guide to define a simple deformable directed fluid. A theory for such fluids is developed.
Nonlinear Theory of Unstable One-Dimensional Detonations
Authors: Erpenbeck Jerome J.
Published: December 2004

A method of calculating the behavior of one-dimensional detonations whose steady solutions are hydrodynamically unstable is presented. It is based on a perturbation technique which treats the nonlinear terms in the hydrodynamic equations as perturbations to the linear equations of hydrodynamic-stability theory. Special care is required to avoid the fallacious time dependence associated with the latter theory. Detailed calculations are presented for several ideal-gas unimolecular-reaction cases for which the predicted oscillations are found to agree reasonably well with those obtained by numerical integration of the hydrodynamic equations, as recently reported by Fickett and Wood.
Interparticle Interactions in Southern Bean Mosaic Virus Suspensions
Authors: Schmidt Paul W. , Taylor Ted R.
Published: December 2004

Small angle x-ray scattering data have been obtained for concentrated suspensions of southern bean mosaic virus containing approximately 20, 10, and 5 gm virus per 100 ml of suspension. In addition, the scattering from independent virus particles was determined from the scattering curves for dilute suspensions. The Zernike-Prins equation was used to compute the pair correlation functions for the concentrated suspensions. The pair correlation functions indicated relatively weak interparticle forces. The effective distance of closest approach of two particles was appreciably greater than the particle diameter, which was approximatley 285 Å. The interaction potential energy for a pair of molecules was estimated by three different approximate theories.
Coupling of Longitudinal and Transverse Modes in a Vlasov Plasma
Authors: Dolinsky A. , Goldman R.
Published: December 2004

Equations are obtained for the time and space development of a small number of transverse and longitudinal modes in a Vlasov plasma. The scale times and lengths are inversely proportional to the first power of the electric fields. For the special case of two transverse waves and a single resonantly driven longitudinal oscillation, frequency conversion and polarization rotation effects appear. Qualitative differences are found between the behavior in one and two independent coordinates. In most (but not all) cases treated, the mode interactions cause changes in the electric field amplitudes rather than shifts in resonant frequencies and wavenumbers.
Nonlinear Study of Vlasov's Equation for a Special Class of Distribution Functions
Authors: Berk H. L. , Roberts K. V.
Published: December 2004

Calculations on the ``water-bag model'' of a two-stream instability have been made by following the motion of the phase space boundaries. A large scale nonlinear wave is observed to evolve due to the condensation of holes in phase space.
Jump Conditions for a Two-Fluid Plasma
Authors: Sen Amiya K. , Spero Donald M.
Published: December 2004

The hydromagnetic jump conditions are derived for the two-fluid model of a plasma. Relevance to shocks in collisionless plasmas is discussed.
Resonant Diffusion of Plasma across a Magnetic Field
Authors: Stix Thomas H.
Published: December 2004

The particle transport associated with low-frequency waves is calculated for a nonuniform plasma immersed in a magnetic field. Electrons and ions in a model plasma obey E × B drift across B, and are accelerated by Ez along B. Their distribution function is given by the solution of the kinetic drift equation. The first-order density perturbation, n(1), is made consistent with the first-order electric field, E, and the flux cEyn(1)/B is averaged over large periods in t and z. The method of calculation is equivalent to quasi-linear theory and yields the following results: the process for transport may be described as a diffusion in (x, vz) phase space which, for each Fourier component, is restricted to resonant particles (i.e., particles moving along B = ẑB with zero-order velocity vz = ω/kz) and to lines in (x, vz) space with the slope (qB/mc)(Ẽz/Ẽy)—hence ``resonant diffusion''; the transport is ambipolar, the direction of transport can be parallel or anti-parallel not only to −dn/dx, but also to −∂f0(x, ω/kz)/∂x, leading to situations of ``pump-out,'' ``normal pump-in'' or ``anomalous pump-in''; using a zero-order velocity distribution in which the density, parallel flow velocity, and temperature may be functions of x, it is possible to balance destabilizing and damping forces against each other to create states of marginal stability—these states, for which small-amplitude theory is valid, still show pump-in or pump-out. As a final result, it is found that the wave-energy conservation equation can be restated in a manner which relates cross-B particle fluxes to the product of instability growth rate and wave energy density.
Kinetic Equation for a Weakly Unstable Plasma
Authors: Price John C.
Published: December 2004

A kinetic equation is derived for a spatially uniform unstable plasma. The collision term contains the effects of waves (plasmons) in the system as well as the terms of the Lenard-Balescu equation. The wave effects arise from initial fluctuations in the system and from waves emitted by particles; the latter are represented by a time integral over earlier times. The limitation of the work is the neglect of three particle effects (mode coupling).
Nonlocal Drift Modes in Cylindrical Geometry
Authors: Chen Francis F.
Published: December 2004

Numerical computations are given for resistive drift instabilities of a plasma in a conducting cylinder, for cases where the usual WKB analysis fails because the waves are not localized radially by shear in the drift velocity. The finite boundary conditions are found to have a stabilizing effect on flute modes (k∥ = 0) and a destabilizing effect on drift modes (k∥ ≠ 0). The growth rate for drift waves is more than three times larger than that given by ``local'' dispersion relations. These computations are particularly relevant to oscillations in cesium and potassium plasmas.
Electromagnetic Wave Scattering from a High-Temperature Plasma
Authors: Pechacek R. E. , Trivelpiece A. W.
Published: December 2004

Electromagnetic wave scattering from a tenuous high-temperature plasma is studied for cases where relativistic corrections must be included in the analysis to obtain a valid description for the spatial and spectral distribution of the scattered radiation. The peak of the spectrum of scattered radiation is shifted toward a shorter wavelength, e.g., the peak of the back-scattered radiation from a 50-keV plasma is at 4000 Å for 6943-Å incident radiation. The spectrum is no longer symmetrical about the scattering peak. It is also shown that the correct spectrum of scattering for a confined high-temperature plasma is not the same as the spectrum obtained using the model infinite plasma irradiated by a homogeneous plane wave. The difference in these two situations is a term of order v/c which is negligible only for the zero-order case (i.e., v/c ≪ 1). Thus, experiments to study the scattering of laser beams from high-temperature plasma should take account of these effects.
Model Equations for Strong Turbulence in a Vlasov Plasma
Authors: Orszag Steven A. , Kraichnan Robert H.
Published: December 2004

Approximate integrodifferential equations are proposed to determine the ensemble mean and covariance of the particle-distribution function for the one-species self-consistent Vlasov problem and for acceleration of particles in a prescribed stochastic electric field. The approximations correspond to the direct-interaction approximations for incompressible Navier—Stokes turbulence and turbulent convection. The final equations are exact statistical descriptions of model dynamical systems. This assures realizability of the covariance and conservation of energy, momentum, and probability. In addition, the model representation implies irreversible relaxation of the initial distribution. The relation of the proposed approximations to quasilinear theory and to the strong-turbulence theories of Mikhailovskii, Kadomtsev, and Dupree is analyzed. The diffusion limit and short-time limit of the stochastic-acceleration model are examined by an adaptation of Roberts' analysis for turbulent convection.
Quasi-One-Dimensional, Nonequilibrium Gas Dynamics of Partially Ionized Two-Temperature Argon
Authors: Hoffert Martin I. , Lien Hwachii
Published: December 2004

A set of equations governing the quasi-one-dimensional flow of a nonequilibrium argon plasma is formulated. The kinetic model includes ionization by atom-atom and electron-atom impacts, together with the three-body recombination counterparts of these processes. The electron gas temperature—a key variable in controlling ionization reaction rates in a noble gas—is not necessarily equal to that of the heavy particles and must in general be found by simultaneous solution of a differential electron energy equation together with the usual conservation equations. Numerical solutions are obtained for the special case of the relaxation zone behind strong normal shocks which give good agreement with shock tube measured ionization times. For these normal-shock calculations, a local steady-state approximation to the electron energy equation is found to be useful in view of an insensitivity, demonstrated by the numerical results, to arbitrarily selected initial values of post-translational shock electron temperature.
Shielding in Anisotropic Plasmas
Authors: Joyce Glenn , Montgomery David
Published: December 2004

The shielding of charges by spatially uniform electron plasmas with nonzero streaming is considered. Both shielding clouds surrounding ``test charges'' and density-density correlation functions are calculated. The result emerges that the shielding is not of the exponential Debye type, but is of much longer range, falling off in general as some inverse power of the distance.
Effect of Magnetic Shear on Plasma Instabilities
Authors: Drummond W. E. , Gentle K. W.
Published: December 2004

The magnetic shear is introduced directly in the basic plasma equation to provide a new formulation of the effects of shear on waves in a plasma. The linearized Vlasov equation is solved in the natural coordinate system that shears with the magnetic field. Instead of an algebraic dispersion relation for waves, a differential equation in k-space results. The solutions of this equation must be explored to determine effects of shear on plasma waves. An approximate solution is obtained for the drift-wave instability and the criterion for shear stabilization is calculated. The criterion is close to previous results, but more general stable modes may be considered.
Ion Emission from Laser-Produced Plasmas
Authors: Koopman David W.
Published: December 2004

Energy and time-of-flight measurements on ions from LiH and LiD plasmas, using an electrostatic analyzer, have shown fast ions traveling ahead of the high-density plasma boundary observable with probes and photography.
Review of Kraichnan's Theory of Turbulence
Authors: Betchov Robert
Published: December 2004

The principal assumptions used by Kraichnan in formulating a theory of turbulence are reviewed, and their meaning is examined in the light of a mathematical model. A regression function is defined and used to evaluate the triple correlations. The importance of the fourth-order cumulants is discussed. The merits of the theory are illustrated by comparison with experimental results—in the case of the mathematical model—of grid turbulence (skewness factor) and of turbulence at very large Reynolds number.
B1-Phytoprostanes Trigger Plant Defense and Detoxification Responses
Authors: Loeffler Christiane , Berger Susanne , Guy Alexandre , Durand Thierry , Bringmann Gerhard , Dreyer Michael , von Rad Uta , Durner Jörg , Mueller Martin J.
Published: December 2004

Phytoprostanes are prostaglandin/jasmonate-like products of nonenzymatic lipid peroxidation that not only occur ubiquitously in healthy plants but also increase in response to oxidative stress. In this work, we show that the two naturally occurring B1-phytoprostanes (PPB1) regioisomers I and II (each comprising two enantiomers) are short-lived stress metabolites that display a broad spectrum of biological activities. Gene expression analysis of Arabidopsis (Arabidopsis thaliana) cell cultures treated with PPB1-I or -II revealed that both regioisomers triggered a massive detoxification and defense response. Interestingly, expression of several glutathione S-transferases, glycosyl transferases, and putative ATP-binding cassette transporters was found to be increased by one or both PPB1 regioisomers, and hence, may enhance the plant's capacity to inactivate and sequester reactive products of lipid peroxidation. Moreover, pretreatment of tobacco (Nicotiana tabacum) suspension cells with PPB1 considerably prevented cell death caused by severe CuSO4 poisoning. Several Arabidopsis genes induced by PPB1, such as those coding for adenylylsulfate reductase, tryptophan synthase β-chain, and PAD3 pointed to an activation of the camalexin biosynthesis pathway that indeed led to the accumulation of camalexin in PPB1 treated leaves of Arabidopsis. Stimulation of secondary metabolism appears to be a common plant reaction in response to PPB1. In three different plant species, PPB1-II induced a concentration dependent accumulation of phytoalexins that was comparable to that induced by methyl jasmonate. PPB1-I was much weaker active or almost inactive. No differences were found between the enantiomers of each regioisomer. Thus, results suggest that PPB1 represent stress signals that improve plants capacity to cope better with a variety of stresses.
Analysis of Detergent-Resistant Membranes in Arabidopsis. Evidence for Plasma Membrane Lipid Rafts
Authors: Borner Georg H.H. , Sherrier D. Janine , Weimar Thilo , Michaelson Louise V. , Hawkins Nathan D. , MacAskill Andrew , Napier Johnathan A. , Beale Michael H. , Lilley Kathryn S. , Dupree Paul
Published: December 2004

The trafficking and function of cell surface proteins in eukaryotic cells may require association with detergent-resistant sphingolipid- and sterol-rich membrane domains. The aim of this work was to obtain evidence for lipid domain phenomena in plant membranes. A protocol to prepare Triton X-100 detergent-resistant membranes (DRMs) was developed using Arabidopsis (Arabidopsis thaliana) callus membranes. A comparative proteomics approach using two-dimensional difference gel electrophoresis and liquid chromatography-tandem mass spectrometry revealed that the DRMs were highly enriched in specific proteins. They included eight glycosylphosphatidylinositol-anchored proteins, several plasma membrane (PM) ATPases, multidrug resistance proteins, and proteins of the stomatin/prohibitin/hypersensitive response family, suggesting that the DRMs originated from PM domains. We also identified a plant homolog of flotillin, a major mammalian DRM protein, suggesting a conserved role for this protein in lipid domain phenomena in eukaryotic cells. Lipid analysis by gas chromatography-mass spectrometry showed that the DRMs had a 4-fold higher sterol-to-protein content than the average for Arabidopsis membranes. The DRMs were also 5-fold increased in sphingolipid-to-protein ratio. Our results indicate that the preparation of DRMs can yield a very specific set of membrane proteins and suggest that the PM contains phytosterol and sphingolipid-rich lipid domains with a specialized protein composition. Our results also suggest a conserved role of lipid modification in targeting proteins to both the intracellular and extracellular leaflet of these domains. The proteins associated with these domains provide important new experimental avenues into understanding plant cell polarity and cell surface processes.
Evidence in Favor of a Broad Framework for Pronunciation Instruction
Authors: Derwing Tracey M. , Munro Murray J. , Wiebe Grace
Published: December 2004

We had native English‐speaking (NS) listeners evaluate the effects of 3types of instruction (segmental accuracy; general speaking habits and prosodic factors; and nospecific pronunciation instruction) on the speech of 3 groups of English as a second language(ESL) learners. We recorded their sentences and extemporaneously produced narratives at thebeginning and end of a 12‐week course of instruction. In a blind rating task, 48 native Englishlisteners judged randomized sentences for accentedness and comprehensibility. Six experiencedESL teachers evaluated narratives for accent, comprehensibility, and fluency. Although bothgroups instructed in pronunciation showed significant improvement in comprehensibility andaccentedness on the sentences, only the global group showed improvement in comprehensibilityand fluency in the narratives. We argue that the focus of instruction and the attentional demandson speakers and listeners account for these findings.
Structural Monitoring System Based on Sensitivity Analysis and a Neural Network
Authors: Kim Sang‐Hyo , Yoon Chongyul , Kim Byoung‐Jin
Published: December 2004

A design procedure for a structure's monitoring system using sensitivity analysis and a neural network is developed. The monitoring system is to be used to monitor damage to members critically affecting the overall safety of structures. Recently, many techniques for evaluating the damage of isolated members and models of simple structures have been investigated. However, actual structures are large, and their complex behavior may not be based on damage of isolated members or their simple models. To monitor large structures realistically, structures' data on behavior at many points need to be monitored. Identifying the optimal locations and numbers of these monitoring points and assessing the safety of the entire structure from the limited data are the monitoring system design problem. The procedure presented for this design problem is a two‐step process. In the first step, using sensitivity analysis and damage‐assessment techniques, individual members are ranked according to their influence on the failure probability of the entire structure or according to their effect on the abnormal behavior of the structure. Based on the rank, critical members are identified. In the second step, sensitivity analysis and a neural network are used to determine the optimal locations. In addition, the optimal number of sensors for monitoring damage to the critical members selected in step 1 is also suggested. Truss and frame examples are used to show the validity and applicability of the monitoring system design procedure.
Monitoring Structural Health Using a Probabilistic Measure
Authors: Beck James L. , Au Siu‐Kui , Vanik Michael W.
Published: December 2004

A Bayesian probabilistic methodology for structural health monitoring is presented. The method uses a sequence of identified modal parameter data sets to continually compute the probability of damage. In this approach, a high likelihood of a reduction in model stiffness at a location is taken as a proxy for damage at the corresponding structural location. The concept extends the idea of using as indicators of damage the changes in model parameters identified using a linear finite‐element model and modal parameter data sets from the structure in undamaged and possibly damaged states. This extension is needed because of uncertainties in the updated model parameters that in practice obscure health assessment. These uncertainties arise due to effects such as variation in the identified modal parameters in the absence of damage, as well as unavoidable model error. The method is illustrated by simulating on‐line monitoring, wherein specified modal parameters are identified on a regular basis and the probability of damage for each substructure is continually updated. Examples are given for abrupt onset of damage and progressive deterioration.
Managing Transportation Infrastructure for Sustainable Development
Authors: Akinyemi Edward O. , Zuidgeest Mark H. P.
Published: December 2004

Major requirements for operationalization of the concept of sustainable development in urban transportation infrastructure operations management are presented. In addition, it is shown that the current approach to management is incompatible with the requirements for sustainable urban development. Consequently, the conceptual framework of a desirable approach is proposed. The philosophy of this approach is that the basic mission of infrastructure operations management is to obtain and maintain the maximum levels of people and goods mobility possible within the resources and environmental capacities in an area. A mathematical model is presented for obtaining the desirable levels and characteristics of traffic on each segment of an urban transportation network. In addition, three illustrative applications of the implemented model are presented.
Permanent Disadvantage or Gradual Integration: Explaining the Immigrant–Native Earnings Gap in Sweden
Authors: Grand Carl le , Szulkin Ryszard
Published: December 2004

Theoretical explanations suggest that wage differentials between immigrant and native workers are generated either by differences in the acquisition of human capital or by various forms of exclusion of immigrants from fair labour market rewards. We evaluate the labour quality and labour market discrimination hypotheses by using a large sample of Swedish employees in 1995. Our findings show that labour market integration is relatively unproblematic for immigrants from Western countries, whereas immigrants from other countries, especially from Africa, Asia and Latin America, face substantial obstacles to earnings progress when entering the Swedish labour market. For the latter group of countries, extensive controls for general and country‐specific human capital reduce the earnings differentials. However, the remaining gap is of a non‐trivial magnitude. Thus, the labour quality hypothesis accounts for a part of the observed native–immigrant wage gap, but the remaining differentials can be interpreted in terms of labour market discrimination.
Efficient Universal Portfolios for Past‐Dependent Target Classes
Authors: Cross Jason E. , Barron Andrew R.
Published: December 2004

We present a new universal portfolio algorithm that achieves almost the same level of wealth as could be achieved by knowing stock prices ahead of time. Specifically the algorithm tracks the best in hindsight wealth achievable within target classes of linearly parameterized portfolio sequences. The target classes considered are more general than the standard constant rebalanced portfolio class and permit portfolio sequences to exhibit a continuous form of dependence on past prices or other side information. A primary advantage of the algorithm is that it is easily computable in a polynomial number of steps by way of simple closed‐form expressions. This provides an edge over other universal algorithms that require both an exponential number of computations and numerical approximation.
Fairness in the Mail and Opportunism in the Internet: A Newspaper Experiment on Ultimatum Bargaining
Authors: Güth Werner , Sutter Matthias
Published: December 2004

On 11 May 2001, readers of the Berliner Zeitung were invited to participate in an ultimatum bargaining experiment played in the strategy vector mode: each participant chooses not only how much (s)he demands of the DM1,000 pie but also which of the nine possible offers of DM100, 200,y, 900 (s)he would accept or reject. In addition, participants were asked to predict the most frequent type of behavior. Three randomly selected proposer-responder pairs were rewarded according to the rules of ultimatum bargaining and three randomly chosen participants of those who predicted the most frequent type of behavior received a prize of DM500. Decisions could be submitted by mail, fax or via the internet. Behavior is described, statistically analyzed and compared to the usual laboratory ultimatum bargaining results.