bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth of inertia–gravity waves in sheared inertial currents
Authors: WINTERS K. B.
Published: April 2008

The linear stability of inviscid non-diffusive density-stratified shear flow in a rotating frame is considered. A temporally periodic base flow, characterized by vertical shear S, buoyancy frequency N and rotation frequency f, is perturbed by infinitesimal inertia–gravity waves. The temporal evolution and stability characteristics of the disturbances are analysed using Floquet theory and the growth rates of unstable solutions are computed numerically. The global structure of solutions is addressed in the dimensionless parameter space (N/f, S/f, φ) where φ is the wavenumber inclination angle from the horizontal for the wave-like perturbations. Both weakly stratified rapidly rotating flows (Nf) are examined. Distinct families of unstable modes are found, each of which can be associated with nearby stable solutions of periodicity T or 2T where T is the inertial frequency 2π/f. Rotation is found to be a destabilizing factor in the sense that stable non-rotating shear flows with N2/S2>1/4 can be unstable in a rotating frame. Morever, instabilities by parametric resonance are found associated with free oscillations at half and integer multiples of the inertial frequency.
Energy amplification in channel flows of viscoelastic fluids
Authors: HODA NAZISH , JOVANOVIĆ MIHAILO R. , KUMAR SATISH
Published: April 2008

Energy amplification in channel flows of Oldroyd-B fluids is studied from an input–output point of view by analysing the ensemble-average energy density associated with the velocity field of the linearized governing equations. The inputs consist of spatially distributed and temporally varying body forces that are harmonic in the streamwise and spanwise directions and stochastic in the wall-normal direction and in time. Such inputs enable the use of powerful tools from linear systems theory that have recently been applied to analyse Newtonian fluid flows. It is found that the energy density increases with a decrease in viscosity ratio (ratio of solvent viscosity to total viscosity) and an increase in Reynolds number and elasticity number. In most of the cases, streamwise-constant perturbations are most amplified and the location of maximum energy density shifts to higher spanwise wavenumbers with an increase in Reynolds number and elasticity number and a decrease in viscosity ratio. For similar parameter values, the maximum in the energy density occurs at a higher spanwise wavenumber for Poiseuille flow, whereas the maximum energy density achieves larger maxima for Couette flow. At low Reynolds numbers, the energy density decreases monotonically when the elasticity number is sufficiently small, but shows a maximum when the elasticity number becomes sufficiently large, suggesting that elasticity can amplify disturbances even when inertial effects are weak.
Receptivity of a hypersonic boundary layer over a flat plate with a porous coating
Authors: EGOROV I. V. , FEDOROV A. V. , SOUDAKOV V. G.
Published: April 2008

Two-dimensional direct numerical simulation (DNS) of receptivity to acoustic disturbances radiating onto a flat plate with a sharp leading edge in the Mach 6 free stream is carried out. Numerical data obtained for fast and slow acoustic waves of zero angle of incidence are consistent with the asymptotic theory. Numerical experiments with acoustic waves of non-zero angles of incidence reveal new features of the disturbance field near the plate leading edge. The shock wave, which is formed near the leading edge owing to viscous–inviscid interaction, produces a profound effect on the acoustic near field and excitation of boundary-layer modes. DNS of the porous coating effect on stability and receptivity of the hypersonic boundary layer is carried out. A porous coating of regular porosity (equally spaced cylindrical blind micro-holes) effectively diminishes the second-mode growth rate in accordance with the predictions of linear stability theory, while weakly affecting acoustic waves. The coating end effects, associated with junctures between solid and porous surfaces, are investigated.
Vapour bubble collapse in isothermal and non-isothermal liquids
Authors: YANG BINZE , PROSPERETTI ANDREA
Published: April 2008

The motion of a vapour bubble in a subcooled liquid is studied numerically assuming axial symmetry but allowing the surface to deform under the action of the fluid dynamic stress. The flattening of the bubble in the plane orthogonal to the translational velocity increases the added mass and slows it down, while, at the same time, the decreasing volume tends to increase the velocity. The deformation of the interface also increases the surface area exposed to the incoming cooler liquid. The competition among these opposing processes is subtle and the details of the condensation cannot be captured by simpler models, two of which are considered. In spite of these differences, the estimate of the total collapse time given by a spherical model is close to that of the deforming bubble model for the cases studied. In addition to an isothermal liquid, some examples in which the bubble encounters warmer and colder liquid regions are shown.
Supercritical transition to turbulence in an inertially driven von Kármán closed flow
Authors: RAVELET FLORENT , CHIFFAUDEL ARNAUD , DAVIAUD FRANÇOIS
Published: April 2008

We study the transition from laminar flow to fully developed turbulence for an inertially driven von Kármán flow between two counter-rotating large impellers fitted with curved blades over a wide range of Reynolds number (102–106). The transition is driven by the destabilization of the azimuthal shear layer, i.e. Kelvin–Helmholtz instability, which exhibits travelling/drifting waves, modulated travelling waves and chaos before the emergence of a turbulent spectrum. A local quantity – the energy of the velocity fluctuations at a given point – and a global quantity – the applied torque – are used to monitor the dynamics. The local quantity defines a critical Reynolds numberRecfor the onset of time-dependence in the flow, and an upper threshold/crossoverRetfor the saturation of the energy cascade. The dimensionless drag coefficient, i.e. the turbulent dissipation, reaches a plateau above this finiteRet, as expected for ‘Kolmogorov’-like turbulence forRe→∞. Our observations suggest that the transition to turbulence in this closed flow is globally supercritical: the energy of the velocity fluctuations can be considered as an order parameter characterizing the dynamics from the first laminar time-dependence to the fully developed turbulence. Spectral analysis in the temporal domain, moreover, reveals that almost all of the fluctuation energy is stored in time scales one or two orders of magnitude slower than the time scale based on impeller frequency.
Mode competition in modulated Taylor–Couette flow
Authors: AVILA M. , BELISLE M. J. , LOPEZ J. M. , MARQUES F. , SARIC W. S.
Published: April 2008

The effects of harmonically oscillating the inner cylinder about a zero mean rotation in a Taylor–Couette flow are investigated experimentally and numerically. The resulting time-modulated circular Couette flow possesses a Z2 spatio-temporal symmetry which gives rise to two distinct modulated Taylor vortex flows. These flows are initiated at synchronous bifurcations, have the same spatial symmetries, but are characterized by different spatio-temporal symmetries and axial wavenumber. Mode competition between these two states has been investigated in the region where they bifurcate simultaneously. In the idealized numerical model, the two flows have been found to coexist and be stable in a narrow region of parameter space. However, in the physical experiment, neither state has been observed in the coexistence region. Instead, we observe noise-sustained flows with irregular time-dependent axial wavenumber. Movies are available with the online version of the paper.
How We Trust One Another
Authors: Hanfling Oswald
Published: April 2008

How is the possibility of promising to be explained without circularity? Appeal is made to the role of natural inclinations in linguistic behaviour, which presupposes truth telling and promise keeping, and also to the social functions of human language which go beyond signalling and transmitting information and which are prior to any explicit conventions. Although promises are broken and lies told, we all have the right to feel resentment when these things happen.
Knowledge of Necessity: Logical Positivism and Kripkean Essentialism
Authors: McLeod Stephen K.
Published: April 2008

By the lights of a central logical positivist thesis in modal epistemology, for every necessary truth that we know, we know it a priori and for every contingent truth that we know, we know it a posteriori. Kripke attacks on both flanks, arguing that we know necessary a posteriori truths and that we probably know contingent a priori truths. In a reflection of Kripke's confidence in his own arguments, the first of these Kripkean claims is far more widely accepted than the second. Contrary to received opinion, the paper argues, the considerations Kripke adduces concerning truths purported to be necessary a posteriori do not disprove the logical positivist thesis that necessary truth and a priori truth are co-extensive.
False Emotions
Authors: Milligan Tony
Published: April 2008

This article sets out an account of false emotions and focuses upon the example of false grief. Widespread but short-lived mourning for well known public figures involves false grief on the part of at least some mourners. What is false about such grief is not any straightforward pretence but rather the inappropriate antecendents of the state in question and/or the desires that the relevant state involves. False grief, for example, often involves a desire for the experience itself, and this can be satisfied. By contrast, real grief is utterly without hope. (We cannot have the deceased back again.) However, because false emotions involve some desire, they can be motivating and may lead us to engage in actions and efforts of discernment that can result in the emergence of the real emotion that they mimic. For this reason, they are not always unwelcome.
The variable expression of future tense in Peninsular Spanish: The present (and future) of inflectional forms in the Spanish spoken in a bilingual region
Authors: Arroyo José Luis Blas
Published: April 2008

In line with trends observed in other Spanish and Romance-speaking regions, the morphological future tense MF (cantaré) is declining in the Castellón speech community (Spain) in favor of the periphrastic variant PF (voy a cantar) for the expression of future events. The multivariate analysis shows the relevance of some linguistic factors in this process, mainly the degree of proximity of the act of speech, the sentence and epistemic modality, the degree of adverbial specification, the class of verbs and, to a lesser extent, the semantic category of the subject (agency), and the types of clause and text. All in all, MF still enjoys a substantial vitality in this Spanish region unknown in other Hispanic areas and that can be related to a convergence process with Catalan, the other language of the region which shares a single variant for expressing the future, namely, the morphological form. Some additional data obtained from 191 interviews of theSociolinguistic Corpus of Castellón(CSCS) point out the relevance of social factors related with the density of the bilingual population in the speech community, both at the collective and individual levels. The vernacular profile of this MF, favored and retained for the most autochthones elements of society, also clashes with the sociolinguistic profile of this variant in other Spanish-speaking areas where the process of substitution has been described in many cases as a change for below. In sum, language contact can slow down and alter some linguistic change much more advanced in monolingual communities.
Counting and coding the past: Circumscribing the variable context in quantitative analyses of past inflection
Authors: Hackert Stephanie
Published: April 2008

Accurate circumscription of the variable context is crucial to any quantitative analysis of linguistic variation. Investigations of past inflection in African American Vernacular English and Caribbean English creoles thus generally include a more or less detailed section concerning the inclusion or exclusion of particular forms; the theoretical grounds on which these decisions are made, however, are not always spelled out. Consequently, there still does not seem to be agreement on what precisely constitutes the envelope of variation in such investigations—a fact that not only complicates data extraction and analysis but also hampers cross-variety comparisons. This article summarizes and evaluates previous definitions of the scope and relevant contexts of the variable (ed), providing internal (linguistic) argumentation supporting or contraindicating the inclusion or exclusion of particular tokens. My data stem from a larger study of past temporal reference in the urban variety of Bahamian Creole English (Hackert, Stephanie. [2004].Urban Bahamian Creole: System and variation. Amsterdam: Benjamins), an intermediate creole with close historical links with Gullah as well as relations with African American Vernacular English, Trinidadian Creole, and Barbadian.
Sociolinguistic patterns in grammaticalization:He, they, andthosein human indefinite reference
Authors: Laitinen Mikko
Published: April 2008

Sociolinguistic patterns in language change are largely based on generalizations from linguistic variables consisting of lexemes or morphemes. This article takes a diachronic, corpus-based approach to the diffusion of a change in a more extensive morphosemantic function consisting of several linguistic subsystems. It focuses on the pronoun variantshe, they, andthoseused for human indefiniteness in two contexts: (a) epicene anaphoric uses with indefinite pronouns and (b) cataphoric personal references. The quantitative corpus analyses show that the pronoun selection in Early and Late Modern English developed a greater tendency to use one pronoun type over the other in both contexts. The main data come from theCorpus of Early English Correspondenceand itsExtension. Statistical analyses compare the observed correlations of the pronouns with a set of social, external variables and language-internal factors. This article concludes that it is possible to establish sociolinguistic patterns in larger shifts if we account for the closely related internal developments in the language.
Regional differences in perceiving vowel tokens on Southerness, education, and pleasantness ratings
Authors: Fridland Valerie
Published: April 2008

This study investigates the role of regional dialect experience on the social awareness of synthesized vowel tokens to regional in-group and out-group members. For the study, speakers from Reno, NV, were given the same perception test used in a previous study in Memphis, TN. Comparing the Reno results to those found in Memphis, the study examines whether differences in regional vowel norms affect how Westerners rate Southern-shifted and non-Southern-shifted vowel variants on Southernness, education, and pleasantness scales. The study also looks at how Reno raters interpreted shifted back vowel variants, found productively in their local community, compared to front vowel shifts found exclusively in the South. Finally, the paper explores how the results suggest that regional dialect exposure attunes listeners to attend to different aspects of vowel quality than those outside the region. In examining how regional dialect experience affects listener recognition and evaluation of local and nonlocal vowel norms, the paper begins to explore how much the production/perception relationship is mediated by speakers' participation in locally constructed and defined speech communities.
The role of prosody in morphological change: The case of Hebrew bound numerals
Authors: Meir Irit
Published: April 2008

The morphological system of cardinal numerals in Modern Hebrew is currently undergoing rapid changes, enabling linguists to unravel the forces shaping the change as it takes place. In the free forms, gender marking on numerals is neutralized by collapsing both masculine and feminine forms into one paradigm, the feminine paradigm. In the bound (definite) forms, an opposite direction is attested, in that at least for some numerals, the masculine forms become more prevalent. The study reported here aims to determine whether the factor determining the change is prosodic or functional in nature, by eliciting production and grammaticality judgments of noun phrases containing bound numerals from five different age groups of native speakers. The results suggest that prosody plays a role in shaping the change, as forms with penultimate stress are favored over those with ultimate stress. In addition, processes of production and processes of grammaticality judgments seem to be subject to different kinds of constraints. This state of affairs indicates that the tension between the tendencies toward simplification on the one hand and maximal distinctness on the other occurs at the morphological level as well.
Effect of cytochalasins B and D on the developmental competence of somatic cell nuclear transfer embryos in miniature pigs
Authors: Sugimura Satoshi , Kawahara Manabu , Wakai Takuya , Yamanaka Ken-ichi , Sasada Hiroshi , Sato Eimei
Published: April 2008

In many animals, cytochalasins have generally been used as cytoskeletal inhibitors for the diploid complement retention of somatic cell nuclear transfer (SCNT) embryos. However, limited information is available on the effects of cytochalasins on the in vitro development of SCNT embryos. Hence, we compared the effects of cytochalasin B (CB) and cytochalasin D (CD) on pseudo-polar body (pPB) extrusion, cortical actin filament (F-actin) distribution in porcine parthenogenetic oocytes and in vitro development of SCNT embryos that were reconstructed using foetal fibroblasts in the G0/G1 phase derived from miniature pigs. CB (7.5 μg/ml) and CD (2.5 μg/ml) treatments effectively inhibited pPB extrusion in SCNT embryos. CB (2.5 μg/ml) treatment could not inhibit pPB extrusion and insufficiently destabilized F-actin immediately following artificial activation. In parthenogenetic oocytes treated with 2.5 μg/ml CD, normal reorganization and uniform distribution of cortical F-actin at the cytoplasmic membrane were observed at 8 h after artificial activation; this finding was similar to that of control oocytes. In contrast, parthenogenetic oocytes treated with 7.5 μg/ml CB showed non-uniform distribution of F-actin at 8 h after artificial activation. On day 5 after in vitro cultivation, the blastocyst formation rate of SCNT embryos treated with 2.5 μg/ml CD was significantly higher than that of SCNT embryos treated with 2.5 and 7.5 μg/ml CB (p < 0.05). Hence, the present findings suggest that CD is more effective than CB as the cytoskeletal inhibitor for the production of SCNT embryos in miniature pigs.
Ultrastructural changes in goat interspecies and intraspecies reconstructed early embryos
Authors: Tao Yong , Cheng Lizi , Zhang Meiling , Li Bin , Ding Jianping , Zhang Yunhai , Fang Fugui , Zhang Xiaorong , Maddox-Hyttel Poul
Published: April 2008

The low efficiency of somatic cell nuclear transfer may be related to the ultrastructural deviations of reconstructed embryos. The present study investigated ultrastructural differences between in vivo-produced and cloned goat embryos, including intra- and interspecies embryos. Goat ear fibroblast cells were used as donors, while the enucleated bovine and goat oocytes matured in vitro as recipients. Goat–goat (GG), goat–cattle (GC) and goat in vivo-produced embryos at the 2-cell, 4-cell, 8-cell and 16-cell stages were compared using transmission electron microscopy. These results showed that the three types of embryos had a similar tendency for mitochondrial change. Nevertheless, changes in GG embryos were more similar to changes in in vivo-produced embryos than were GC embryos, which had more extreme mitochondrial deviation. The results indicate the effects of the cytoplast on mitochondria development. The zona pellucida (ZP) in all three types of embryos became thinner and ZP pores in both GC and GG embryos showed an increased rate of development, especially for GC embryos, while in vivo-produced embryos had smooth ZP. The Golgi apparatus (Gi) and rough endoplasmic reticulum (RER) of the two reconstructed embryos became apparent at the 8-cell stage, as was found for in vivo embryos. The results showed that the excretion of reconstructed embryos was activated on time. Lipid droplets (LD) of GC and GG embryos became bigger, and congregated. In in vivo-produced embryos LD changed little in volume and dispersed gradually from the 4-cell period. The nucleolus of GC and GG embryos changed from electron dense to a fibrillo-granular meshwork at the 16-cell stage, showing that nucleus function in the reconstructed embryos was activated. The broken nuclear envelope and multiple nucleoli in one blastomere illuminated that the nucleus function of reconstructed embryos was partly changed. In addition, at a later stage in GC embryos the nuclear envelope displayed infoldings and the chromatin was concentrated, implying that the blastomeres had an obvious trend towards apoptosis. The gap junctions of the three types of embryos changed differently and GG and GC embryos had bigger perivitelline and intercellular spaces than did in vivo-produced embryos. These results are indicative of normal intercellular communication at an early stage, but this became weaker in later stages in reconstructed embryos. In conclusion, inter- and intraspecies reconstructed embryos have a similar pattern of developmental change to that of in vivo-produced embryos for ZP, rough ER, Gi and nucleolus, but differ for mitochondria, LD, vesicles, nucleus and gap junction development. In particular, the interspecies cloned embryos showed more severe destruction. These ultrastructural deviations might contribute to the compromised developmental potential of reconstructed embryos.
Bovine oocytes and early embryos express Staufen and ELAVL RNA-binding proteins
Authors: Calder M.D. , Madan P. , Watson A.J.
Published: April 2008

RNA-binding proteins (RBP) influence RNA editing, localization, stability and translation and may contribute to oocyte developmental competence by regulating the stability and turnover of oogenetic mRNAs. The expression of Staufen 1 and 2 and ELAVL1, ELAVL2 RNA-binding proteins during cow early development was characterized. Cumulus–oocyte complexes were collected from slaughterhouse ovaries, matured, inseminated and subjected to embryo culturein vitro. Oocyte or preimplantation embryo pools were processed for RT-PCR and whole-mount immunofluorescence analysis of mRNA expression and protein distribution. STAU1 and STAU2 and ELAVL1 mRNAs and proteins were detected throughout cow preimplantation development from the germinal vesicle (GV) oocyte to the blastocyst stage. ELAVL2 mRNAs were detectable from the GV to the morula stage, whereas ELAVL2 protein was in all stages examined and localized to both cytoplasm and nuclei. The findings provide a foundation for investigating the role of RBPs during mammalian oocyte maturation and early embryogenesis.
Sex determining of cat embryo and some feline species
Authors: Ciani Francesca , Cocchia Natascia , Rizzo Maria , Ponzio Patrizia , Tortora Gennaro , Avallone Luigi , Lorizio Roberto
Published: April 2008

Sex identification in mammalian preimplantation embryos is a technique that is used currently for development of the embryo transfer industry for zootechnical animals and is, therefore, a resource for biodiversity preservation. The aim of the present study was to establish a rapid and reliable method for the sexing of preimplantation embryos in domestic cats. Here we describe the use of nested PCR identify Y chromosome-linked markers when starting from small amounts of DNA and test the method for the purpose of sexing different species of wild felids. To evaluate the efficiency of the primers, PCR analysis were performed first in blood samples of sex-known domestic cats. Cat embryos were produced both in vitro and in vivo and the blastocysts were biopsied. A Magnetic Resin System was used to capture a consistent amount of DNA from embryo biopsy and wild felid hairs. The results from nested PCR applied on cat blood that corresponded to the phenotypical sex. Nested PCR was also applied to 37 embryo biopsies and the final result was: 21 males and 16 females. Furthermore, β-actin was amplified in each sample, as a positive control for DNA presence. Subsequently, nested PCR was performed on blood and hair samples from some wild felines and again the genotyping results and phenotype sex corresponded. The data show that this method is a rapid and repeatable option for sex determination in domestic cat embryos and some wild felids and that a small amount of cells is sufficient to obtain a reliable result. This technique, therefore, affords investigators a new approach that they can insert in the safeguard programmes of felida biodiversity.
Isolation of egg cells and zygotes of Torenia fournieri L. and determination of their surface charge
Authors: Chen S.H. , Yang Y.H. , Liao J.P. , Kuang A.X. , Tian H.Q.
Published: April 2008

Egg cells of Torenia fournieri were isolated from embryo sacs 1 day after anthesis using enzymatic digestion or mechanical dissection. About 5% of the egg cells and zygotes (2–3 from 50 ovules) could be mechanically dissected within 2 h. When 0.1% cellulase and 0.1% pectinase were added to the mannitol isolation solution, about 18% of the egg cells (8–10 from 50 ovules) could be isolated within 2 h. The egg cells isolated by mechanical dissection could be used for in vitro fertilization studies without any of the potentially deleterious effects of the enzymes on the plasma membrane of egg cell. The egg cells isolated using enzymatic digestion could be used in the study of the molecular biology of female gamete because more egg cells could be isolated with this technique. Using enzymatic digestion, over 10 zygotes from 50 ovules (over 20%) were isolated from the pollinated ovules. Coupled with our successful isolation of mature sperm cells, the isolation of egg cells of T. fournieri will make in vitro fertilization possible in a dicotyledon plant.
Assessment of diastolic ventricular function in fetuses of diabetic mothers using tissue Doppler
Authors: Hatém Maria Amélia Bulhões , Zielinsky Paulo , Hatém Domingos Mohamad , Nicoloso Luiz Henrique , Manica João Luiz , Piccoli Antonio L. , Zanettini Juliana , Oliveira Vinicius , Scarpa Fernanda , Petracco Rafaella
Published: April 2008

Objective

To identify the presence of ventricular diastolic dysfunction by tissue Doppler in fetuses of diabetic mothers, with or without septal hypertrophy, in comparison to fetuses of nondiabetic mothers.

Methods

A contemporary transverse study in fetuses with a gestational age between 25 weeks to term, studying diastolic function by assessment using tissue Doppler and pulsed wave Doppler of the atrioventricular diastolic flow. The mothers of the fetuses all had previous or gestational diabetes, and were referred to the Fetal Cardiology Unit of the Institute of Cardiology in Porto Alegre, Brazil. We analysed variance with the Student-Neumann-Keuls post hoc test. An alfa of 0.05 was considered significant for statistical analysis.

Results

The mean myocardial velocities of the E′and A′ waves at the mural mitral annulus, in fetuses of diabetic mothers with myocardial hypertrophy, were, respectively, 7.00 plus or minus 1.6 centimetres per second, and 10.24 plus or minus 3.3 centimetres per second. In the fetuses of diabetic mothers group without myocardial hypertrophy, the comparable values were 7.19 plus or minus 2.4 centimetres per second and 10.77 plus or minus 3.77 centimetres per second, respectively. In the control group, they were 4.81 plus or minus 0.85 centimetres per second and 8.01 plus or minus 2.2 centimetres per second. The difference between the velocities in fetuses of diabetic mothers and in fetal normal mothers was statistically significant (p less than 0.05). Statistically significant differences were also observed in E′ and A′ diastolic waves at the aortic mitral annulus, as well as for the tricuspid annulus when tissue Doppler assessment was carried out in the same sample. The mean ratio between the E and E′ of mitral and tricuspid waves in the control fetuses of normal mothers was significantly higher than in fetuses of diabetic mothers.

Conclusion

Pulsed tissue Doppler, when used in fetuses of diabetic mothers and compared with fetuses of nondiabetic mothers, shows evidence of impaired diastolic function, independently of the presence of myocardial hypertrophy.
Differences according to gender in reporting physical symptoms during echocardiographic screening in healthy teenage athletes
Authors: Movahed Mohammad Reza , Martinez Adolfo , Morrell Holly , Greaves Seaneen , Greaves Jeff , Sattur Sudhakar
Published: April 2008

Background

Many studies have suggested that more women then men present with physical symptoms. There is no data available, however, on the differences in reporting of physical symptoms between teenage male and female athletes. Our objective was to evaluate the differences according to gender in physical symptoms in healthy teenage athletes.

Methods

A total of 1,465 high school athletes, between the ages of 13 and 19 years participated in a mass echocardiographic screening programme for detection of cardiac abnormalities. Screening was conducted using a hand-carried cardiac ultrasound device (OptiGo, Philips). All participants were actively involved in a high school sport programme. Each athlete was required to fill out a questionnaire before the screening. The athletes were asked to report the occurrence of physical symptoms with activity or exercise. A physical examination was not performed during screening.

Results

There were 1,031 (70.4%) male and 434 (29.6%) female participants. Significantly more female teenage athletes reported physical symptoms (190/434, 43.8% versus 267/1,031, 25.9%, odds ratio: 2.28, confidence interval: 1.76–2.81, p less than 0.001). Symptoms did not correlate with any echocardiographically identified cardiac abnormalities in either gender. The differences in the reporting of symptoms were significant for all physical symptoms addressed by the questionnaire.

Conclusion

There is a high prevalence of reporting physical symptoms in young healthy athletes without any relation to cardiac abnormalities. Young female athletes report physical symptoms nearly twice as often as their male counterparts.
Paediatric cardiac assistance in developing and transitional countries: the impact of a fourteen year effort
Authors: Novick William M. , Stidham Gregory L. , Karl Tom R. , Arnold Robert , Anić Darko , Rao Sri O. , Baum Victor C. , Fenton Kathleen E. , Di Sessa Thomas G.
Published: April 2008

Background

Paediatric cardiac services are poorly developed or totally absent in underdeveloped countries. Institutions, foundations and interested individuals in those nations in which sophisticated paediatric cardiac surgery is practised have the ability to alleviate this problem by sponsoring paediatric cardio-surgical missions to provide care, and train local caregivers in developing, transitional, and third world countries. The ultimate benefit of such a programme is to improve the surgical abilities of the host institution. The purpose of this report is to present the impact of our programme over a period of 14 years.

Methods

We specifically reviewed our database of patients from our missions, our team lists, surgical results, and the number and type of personnel trained in the institutions that we have assisted. In order for the institution to be entered into the study, the foundation had to provide at least 2 months of training. In addition, the institution had to respond to a simple questionnaire concerning the number and types of surgery performed at their facility before and after intervention by the foundation.

Results

We made 140 trips to 27 institutions in 19 countries, with 12 of the visited institutions qualifying for inclusion. Of these, 9 institutions reported an increase in the number and complexity of cases currently being performed in their facility since the team intervened. This goal had not been accomplished in 3 institutions. The reasons for failure included the economic situation of the country, hospital and national politics, personality conflicts, and continued lack of hardware and disposables.

Conclusions

Paediatric cardiac service assistance can improve local services. A significant commitment is required by all parties involved.
Off-pump connection of the hepatic to the azygos vein through a lateral thoracotomy for relief of arterio-venous fistulas after a Kawashima procedure
Authors: Lopez Fatima E.F.G. , van den Heuvel Freek , Pieper Petronella G. , Waterbolk Tjalling W. , Ebels Tjark
Published: April 2008

Objective

To connect the hepatic veins to the azygos venous system through a lateral thoracotomy, and without the use of extracorporeal circulation, so as to relieve arteriovenous fistulas after a previous Kawashima operation.

Methods

Description of the operative technique by which the hepatic veins are anastomosed to the hepatic venous system.

Results

The surgical approach was successfully applied in 3 patients, all of whom showed an excellent rise of saturations of oxygen after redirection of the hepatic venous blood.

Conclusion

The operative method presented is an elegant means of redirecting the hepatic venous blood to the pulmonary circulation without the disadvantages of extracorporeal circulation and resternotomy.
The Zeroing Issue: a critical analysis of Softwood V
Authors: BOWN CHAD P. , SYKES ALAN O.
Published: April 2008

This paper addresses the issues that came before the Appellate Body in the Softwood V dispute, concerning an affirmative antidumping determination by the US Department of Commerce. The paper addresses both the original Appellate Body opinion in the dispute, and the later opinion reviewing the compliance panel findings. We focus primarily on the ‘zeroing’ issue in ‘transaction-to-transaction (T–T)’ calculations of dumping, and briefly on two other cost-allocation issues. In general, we are ambivalent about the Appellate Body's approach to the zeroing issue. On the one hand, zeroing inflates dumping margins without any sound economic rationale for doing so. On the other hand, zeroing has been a standard administrative practice for many years and the ADA does not clearly prohibit it. The Appellate Body's legal analysis of the matter in T–T cases, in particular, rests on shaky premises. We also consider the wisdom of addressing the zeroing issue in piecemeal fashion through what has proven to be a lengthy sequence of narrow decisions.
United States – Anti-Dumping Measures on Oil Country Tubular Goods (OCTG) from Mexico: a legal-economic assessment of sunset reviews
Authors: BOWN CHAD P. , WAUTERS JASPER
Published: April 2008

This paper reviews the WTO Appellate Body Report on United States – Anti-Dumping Measures on Oil Country Tubular Goods (OCTG) from Mexico (WT/DS282/AB/R 2 November 2005). This dispute concerns the disciplines imposed by the Anti-Dumping Agreement on WTO Members seeking to extend their anti-dumping measures beyond the original five-year period through a so-called sunset review. Our analysis focuses on the Appellate Body's finding in this case that no causation analysis is required in sunset reviews, and addresses the AB's approach towards the legal instrument that provides for the US policy in terms of sunset reviews, the Sunset Policy Bulletin. We conclude that the Anti-Dumping Agreement, as interpreted by the Appellate Body in this and other similar cases, imposes only minimal disciplines of a general nature on Members wishing to extend the anti-dumping measure beyond its original five-year period. We argue that the ‘textual’ argument relied on to support this deferential approach is weak and has resulted in undermining the practical effect of, what was considered to be, one of the major achievements of the Uruguay Round Anti-Dumping Agreement: limiting the life span of an anti-dumping measure to five years. From an economic perspective, Panels and the Appellate Body are simply debating the wrong type of questions. The prospective nature required by a sunset review analysis raises questions such as why exporters engaged in dumping in the first place, and what the conditions of the industry were so that the dumped imports caused injury. At the moment, sunset reviews seem adrift as panels and the Appellate Body fail to give guidance to Members on how to do a more economically sound and informed review.
Addiction: the clinical interface
Authors: Nutt D , Lingford‐Hughes A
Published: April 2008

This review gives an overview of what we see as the key issues in the human pharmacology of drugs of addiction. We review evidence of efficacy and mechanisms by which treatments act and point out areas where further work is needed. The role of agonist, partial agonist and antagonist treatments for opioid addiction is detailed and current issues relating to the mechanisms of actions at the receptor level and how to improve on compliance are discussed. The role of the brain dopamine and GABA‐A systems in drug dependence is considered in relation to the growing pharmacology of these receptor systems, and the current status of novel preclinical targets reviewed. In addition, the different roles of dynamic and kinetic factors in both addiction and its treatment are discussed in relation to the underlying neuropharmacology of the disorders as defined from human and preclinical studies. Finally, some pointers to future research and especially to drug development by pharma are elaborated.

British Journal of Pharmacology (2008) 154, 397–405; doi:fn1; published online 14 April 2008
Sildenafil reduces the alcohol‐induced gastric damage: just say ‘NO’
Authors: Duffin R , Shaw C A , Rossi A G
Published: April 2008

British Journal of Pharmacology (2008) 153, 1764; doi:10.1038/bjp.2008.103
Deciphering the β‐adrenergic response in human embryonic stem cell‐derived‐cardiac myocytes: closer to clinical use?
Authors: Catalucci D , Bang M L , Condorelli G
Published: April 2008

British Journal of Pharmacology (2008) 153, 1765; doi:10.1038/bjp.2008.104
Population pharmacokinetic modelling of the enterohepatic recirculation of diclofenac and rofecoxib in rats
Authors: Huntjens D R H , Strougo A , Chain A , Metcalf A , Summerfield S , Spalding D J M , Danhof M , Pasqua O Della
Published: April 2008

British Journal of Pharmacology (2008) 153, 1762; doi:10.1038/bjp.2008.105
Oxidative stress and COX cause hyper‐responsiveness in vascular smooth muscle of the femoral artery from diabetic rats
Authors: Shi Y , Vanhoutte P M
Published: April 2008

Background and purpose:

To investigate the dysfunction of vascular smooth muscle in streptozotocin‐induced diabetic rats.

Experimental approach:

Rings without endothelium of femoral arteries were suspended in organ chambers for isometric tension recording. The production of oxygen‐derived free radicals was measured with 2′,7′‐dichlorodihydrofluorescein diacetate using confocal microscopy. The protein expressions were measured by western blotting.

Key results:

The concentration–response curves to U46619 and phenylephrine, but not that to KCl, were shifted to the left, suggesting a hypersensitivity of cell membrane receptors in diabetes. Exogenous oxygen‐derived free radicals induced greater vasoconstrictions in the femoral artery from diabetic rats. Chronic treatment with apocynin (inhibitor of NADPH oxidase) and acute exposure to MnTMPyP (SOD/catalase mimetic) normalized the response. The catalase activity and the total glutathione level were reduced in arteries from streptozotocin‐treated rats, confirming a redox abnormality. The basal oxidative state was higher in arteries from streptozotocin‐treated rats and reduced in arteries from apocynin‐ and streptozotocin‐treated rats, suggesting that the functional changes in diabetes are due to a chronic increase in oxidative stress. In the arteries of streptozotocin‐treated rats, inhibitors of COX‐1 and/or COX‐2 prevented the hypersensitivity and reduced the increase in oxidative stress caused by phenylephrine and U46619, suggesting that both isoforms contribute to the smooth muscle dysfunction. The expression of proteins for COX‐1 and COX‐2 was increased in arteries of streptozotocin‐treated rats and reduced in preparations of apocynin‐ and streptozotocin‐treated rats.

Conclusions and implications:

Chronic diabetes and the resulting increased oxidative stress activate the production of COX‐derived vasoconstrictor prostanoids causing hypersensitivity of vascular smooth muscle.

British Journal of Pharmacology (2008) 154, 639–651; doi:10.1038/bjp.2008.110; published online 14 April 2008
Standard antiepileptic drugs fail to block epileptiform activity in rat organotypic hippocampal slice cultures
Authors: Albus K , Wahab A , Heinemann U
Published: April 2008

Background and purpose:

Earlier studies had demonstrated that tonic–clonic seizure‐like events (SLEs) resembling electrographic correlates of limbic seizures in animals and humans can be induced in organotypic hippocampal slice cultures (OHSCs). We have explored OHSCs for their suitability to serve as in vitro models of limbic seizures for studying seizure mechanisms and screening new antiepileptic compounds.

Experimental approach:

OHSCs were cultivated according to the interface method. Neuronal activity and extracellular potassium concentration were recorded under submerged conditions. SLEs were induced by lowering magnesium concentration or by applying the potassium channel blocker 4‐aminopyridine. The effects of standard antiepileptic drugs (AEDs), carbamazepine, phenytoin, valproic acid, clonazepam, diazepam and phenobarbital sodium on SLEs were analysed.

Key results:

In more than 93% of OHSCs, AEDs did not prevent the induction of SLEs or stop ongoing seizure activity even when toxic concentrations were applied. This pharmacoresistance was independent of the method of seizure provocation, postnatal age at explantation (P2–P10) and cultivation time in vitro (2 months). SLEs were reversibly blocked by glutamate antagonists or the GABAA‐agonist muscimol.

Conclusions and implications:

We present a simple to establish in vitro model of tonic–clonic SLEs that is a priori pharmacoresistant and thus has an advantage over animal models of pharmacoresistant seizures in which responders and non‐responders can be sorted out only after an experiment. OHSCs could be suitable for exploring mechanisms of pharmacoresistant seizures and be used for the identification of new anticonvulsive compounds eventually effective in drug refractory epilepsy.

British Journal of Pharmacology (2008) 154, 709–724; doi:10.1038/bjp.2008.112; published online 14 April 2008
Chronic heart rate reduction by ivabradine prevents endothelial dysfunction in dyslipidaemic mice
Authors: Drouin A , Gendron M‐È , Thorin E , Gillis M‐A , Mahlberg‐Gaudin F , Tardif J‐C
Published: April 2008

Background and purpose:

High resting heart rate is a predictor for total and cardiovascular mortality independent of other risk factors in patients with coronary artery disease. We tested the hypothesis that a reduction of resting heart rate with the cardiac pacemaker If current inhibitor ivabradine prevents the endothelial dysfunction associated with dyslipidaemia.

Experimental approach:

Three‐month‐old dyslipidaemic (DL) male mice expressing the human ApoB‐100 were assigned or not (DL, n=16), to treatment for 3 months with ivabradine (10 mg kg−1 d−1, n=17). Wild‐type C57Bl/6 mice (WT, n=15) were used as controls. Heart rate was measured at 3, 4.5 and 6 months. Dilatation to acetylcholine (ACh) of isolated cerebral and renal arteries was investigated at 6 months.

Key results:

Heart rate remained stable in anaesthetized WT mice, increased (25%, P<0.05) with age in DL mice but was limited (11%, P<0.05) by ivabradine. At 6 months, left ventricular maximal pressure was similar in all groups. The minimal and end‐diastolic left ventricular pressures were increased (P<0.05) in DL (10.2±1.0 and 18.7±1.4 mm Hg) compared to WT (−0.4±0.7 and 6.3±1.0 mm Hg) and reduced (P<0.05) by ivabradine (4.2±1.3 and 11.5±1.5 mm Hg). ACh‐induced maximal dilatation was impaired (P<0.05) in renal and cerebral arteries isolated from DL compared to WT (56±7 versus 83±3% in renal arteries; 22±2 versus 42±2% in cerebral arteries). Ivabradine completely prevented (P<0.05) this dysfunction in renal and cerebral arteries.

Conclusions and implications:

Selective heart rate reduction with ivabradine limits cardiac dysfunction and prevents the renovascular and cerebrovascular endothelial dysfunction associated with dyslipidaemia.

British Journal of Pharmacology (2008) 154, 749–757; doi:fn2; published online 14 April 2008
The endocannabinoid system in brain reward processes
Authors: Solinas M , Goldberg S R , Piomelli D
Published: April 2008

Food, drugs and brain stimulation can serve as strong rewarding stimuli and are all believed to activate common brain circuits that evolved in mammals to favour fitness and survival. For decades, endogenous dopaminergic and opioid systems have been considered the most important systems in mediating brain reward processes. Recent evidence suggests that the endogenous cannabinoid (endocannabinoid) system also has an important role in signalling of rewarding events. First, CB1 receptors are found in brain areas involved in reward processes, such as the dopaminergic mesolimbic system. Second, activation of CB1 receptors by plant‐derived, synthetic or endogenous CB1 receptor agonists stimulates dopaminergic neurotransmission, produces rewarding effects and increases rewarding effects of abused drugs and food. Third, pharmacological or genetic blockade of CB1 receptors prevents activation of dopaminergic neurotransmission by several addictive drugs and reduces rewarding effects of food and these drugs. Fourth, brain levels of the endocannabinoids anandamide and 2‐arachidonoylglycerol are altered by activation of reward processes. However, the intrinsic activity of the endocannabinoid system does not appear to play a facilitatory role in brain stimulation reward and some evidence suggests it may even oppose it. The influence of the endocannabinoid system on brain reward processes may depend on the degree of activation of the different brain areas involved and might represent a mechanism for fine‐tuning dopaminergic activity. Although involvement of the various components of the endocannabinoid system may differ depending on the type of rewarding event investigated, this system appears to play a major role in modulating reward processes.

British Journal of Pharmacology (2008) 154, 369–383; doi:10.1038/bjp.2008.130; published online 14 April 2008
Neuropharmacology of addiction—setting the scene
Authors: Lawrence A J , Beart P M , Kalivas P W
Published: April 2008

Addiction is a complex disorder, affecting not only the individual addict, but also their family and the community at large. While therapeutic strategies are available for the treatment of some forms of substance abuse/dependence, these are not without problems and are not universally efficacious. Moreover, in some instances (for example, cocaine addiction), there are still no medications specifically registered as treatment options. In this themed issue of the British Journal of Pharmacology, we highlight a number of addictions from a pharmacological perspective, with an emphasis on both mechanism and potential therapeutic approaches that are either under development or reflect preclinical work. As such, the authors endeavour to describe the latest thinking on the neural theory of addiction and corresponding novel pharmacotherapeutic targets, and in this way to set the stage for future advances in research and drug development. In addition, we have also attempted to draw attention to the clinicians' perspective in terms of the interface between basic science and care provision.

British Journal of Pharmacology (2008) 154, 259–260; doi: 10.1038/bjp.2008.131; published online 14 April 2008