bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors affecting 13C‐natural abundance measurement of breath carbon dioxide during surgery: absorption of carbon dioxide during endoscopic procedures
Authors: Eaton Simon , Pacilli Maurizio , Wood James , McHoney Merrill , Corizia Lucia , Kingsley Charlotte , Curry Joseph I. , Herod Jane , Cohen Ralph , Pierro Agostino
Published: April 2008

The aim of this paper is to review the factors which may affect breath 13CO2/12CO2 natural abundance in patients undergoing surgery or intensive care. Intravenous glucose administration is a major determinant of the 13CO2/12CO2 of breath as intravenous glucose preparations are almost all derived from cornstarch. In addition, the oxidation of endogenous substrates can affect the 13CO2/12CO2 ratio. During many endoscopic procedures, such as laparoscopic surgery, carbon dioxide insufflation is used to provide a working space. As medical CO2 is relatively depleted in 13CO2 compared with endogenous and exogenous metabolic CO2 sources, breath 13CO2/12CO2 measurements can be used to estimate CO2 absorption during these procedures. However, all these factors may also be affected by the bicarbonate pool, making a definitive attribution of changes in breath 13CO2/12CO2 to a single factor problematic. Copyright © 2008 John Wiley & Sons, Ltd.
The application of isotope ratio mass spectrometry for discrimination and comparison of adhesive tapes
Authors: Horacek Micha , Min Ji‐Sook , Heo Sangcheol , Park Jongseo , Papesch Wolfgang
Published: April 2008

Forensic scientists are frequently requested to differentiate between, or compare, adhesive tapes from a suspect or a crime scene. The most common polymers used to back packaging tape are polypropylene and polyvinyl chloride. Much of the oriented polypropylene (OPP) needed to produce packaging tapes, regardless of the tape brand, is supplied by just a few polymer manufacturers. Consequently, the composition of the backing material varies little. Therefore, the discriminating power of classical methods (physical fit, tape dimensions, colour, morphology, FTIR, PyGC/MS, etc.) is limited. Analysis of stable isotopes using isotope ratio mass spectrometry (IRMS) has been applied in the broad area of forensics and it has been reported that isotope analysis is a valuable tool for the identification of adhesive tapes. We have tested the usefulness of this method by distinguishing different South Korean adhesive tapes produced by just a few manufacturers in the small South Korean market. Korean adhesive tapes were collected and analysed for their isotope signatures. The glue of the tapes was separated from the backing material and these sub‐samples were analysed for their H‐ and C‐isotope composition. The result shows the possibility for discriminating most tape samples, even from the same brand. Variations within single rolls have also been investigated, where no variations in H‐ and C‐isotope composition significantly exceeding the standard deviation were found. Copyright © 2008 John Wiley & Sons, Ltd.
Optimized multi‐stage designs controlling the false discovery or the family‐wise error rate
Authors: Zehetmayer Sonja , Bauer Peter , Posch Martin
Published: April 2008

When a large number of hypotheses are investigated, we propose multi‐stage designs where in each interim analysis promising hypotheses are screened, which are investigated in further stages. Given a fixed overall number of observations, this allows one to spend more observations for promising hypotheses than with single‐stage designs, where the observations are equally distributed among all considered hypotheses. We propose multi‐stage procedures controlling either the family‐wise error rate (FWER) or the false discovery rate (FDR) and derive asymptotically optimal stopping boundaries and sample size allocations (across stages) to maximize the power of the procedure. Optimized two‐stage designs lead to a considerable increase in power compared with the classical single‐stage design. Going from two to three stages additionally leads to a distinctive increase in power. Adding a fourth stage leads to a further improvement, which is, however, less pronounced. Surprisingly, we found only small differences in power between optimized integrated designs, where the data of all stages are used in the final test statistics, and optimized pilot designs where only the data from the final stage are used for testing. However, the integrated design controlling the FDR appeared to be more robust against misspecifications in the planning phase. Additionally, we found that with increasing number of stages the drop in power when controlling the FWER instead of the FDR becomes negligible.

Our investigations show that the crucial point is not the choice of the error rate or the type of design, but the sequential nature of the trial where non‐promising hypotheses are dropped in the early phases of the experiment. Copyright © 2008 John Wiley & Sons, Ltd.
Phytotoxicity of chlorinated benzenes to Typha angustifolia and Phragmites communis
Authors: Ma Xingmao , Havelka Megan M.
Published: April 2008

Healthy growth of plants is a prerequisite for successful application of phytoremediation technologies. Typha angustifolia and Phragmites communis are common wetland plants and have shown potential for phytoremediation of hexachlorobenzene (HCB). However, the lack of phytotoxicity data impedes their application in field sites. This study investigated the phytotoxicity of HCB, and its two metabolites: 1,3,5‐trichlorobenzene (1,3,5‐TCB) and 1,4‐dichlorobenzene (1,4‐DCB) to Typha and the phytotoxicity of 1,3,5‐TCB to Phragmites. The phytotoxicity of 1,3,5‐TCB is species‐dependent, with Typha demonstrating significantly higher tolerance than Phragmites. The concentration of 1,3,5‐TCB causing zero growth of Phragmites was determined to be 1575 mg TCB/kg dry sediment. The concentration has to be doubled to completely inhibit the growth of Typha. Adverse effects of chlorinated benzenes in sediments on Typha increased with decreasing chlorine atoms. The concentrations causing zero growth of Typha are 5765 mg HCB/kg dry soil, 3157 mg 1,3,5‐TCB/kg dry soil, and 1325 mg 1,4‐DCB/kg dry soil. The higher toxicity of 1,4‐DCB than 1,3,5‐TCB and HCB in sediment was ascribed to its higher availability and easiness to be taken up by plants. The conclusion was supported by both growth rate calculations and plant height measurements. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Agronomic and nutritional characteristics of fourteen Ghanaian groundnut varieties
Authors: Frimpong A , Johnson P‐N T , Baidoo E
Published: April 2008

The growth and yield parameters of 14 groundnut varieties were evaluated at three locations in Ghana, and key physical and nutritional characteristics of the grains were measured and compared. Kernel yields ranged from 940 kg ha−1 to 1463 kg ha−1. Grain length and 100‐grain mass were not consistently and strongly correlated, and the inconsistency may be partly due to differences in oil content, which has implications for processing of the different varieties. The protein content of the varieties ranged from 25.6% to 29.6% and many of the varieties would be suitable for dietary protein supplementation. No variety scored consistently highly for all characteristics, but varieties CSTV404MB and CS‐49 grew very well, and had high protein contents and moderately high oil contents, so they can be recommended for oil extraction and protein supplementation of local diets low in protein. Copyright © 2008 John Wiley & Sons, Ltd
Second‐trimester fetal growth and the risk of poor obstetric and neonatal outcomes
Authors: Fox N. S. , Huang M. , Chasen S. T.
Published: April 2008

Objective

To compare outcomes of fetuses with an estimated fetal weight (EFW) < 25th percentile in the second trimester to those in fetuses with EFW ≥ 25th percentile in the second trimester.

Methods

We compared outcomes of 252 pregnancies with an EFW < 25th percentile at 18–24 weeks' gestation with those of 265 controls. All pregnancies had early dating by ultrasonography. We excluded fetuses with aneuploidy, major malformations, second‐trimester rupture of membranes, and multiple pregnancies.

Results

Second‐trimester EFW < 25th percentile was significantly associated with higher rates of fetal or neonatal death, third‐trimester small for gestational age (SGA), Doppler abnormalities, indicated preterm birth, gestational hypertension or pre‐eclampsia before labor, lower birth weight, birth weight < 10th percentile, birth weight < 5th percentile, and admission to the neonatal intensive care unit. Many of these associations remained even after excluding patients with oligohydramnios, fetal echogenic bowel, and growth asymmetry.

Conclusion

Second‐trimester SGA, as defined by an EFW < 25th percentile using current growth curves, is associated with poor obstetric and neonatal outcomes. Increased surveillance of such pregnancies may be necessary. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
A compositional Petri net translation of general
π
-calculus terms
Authors: Devillers Raymond , Klaudel Hanna , Koutny Maciej
Published: April 2008

We propose a finite structural translation of possibly recursive
π
-calculus terms into Petri nets. This is achieved by using high-level nets together with an equivalence on markings in order to model entering into recursive calls, which do not need to be guarded. We view a computing system as consisting of a main program (
π
-calculus term) together with procedure declarations (recursive definitions of
π
-calculus identifiers). The control structure of these components is represented using disjoint high-level Petri nets, one for the main program and one for each of the procedure declarations. The program is executed once, while each procedure can be invoked several times (even concurrently), each such invocation being uniquely identified by structured tokens which correspond to the sequence of recursive calls along the execution path leading to that invocation.
Entire spacelike radial graphs in the Minkowski space, asymptotic to the light-cone, with prescribed scalar curvature
Authors: Bayard Pierre , Delanoë Philippe
Published: April 2008

We prove the existence and uniqueness in

\mathbb{R}^{n,1}

of entire spacelike hypersurfaces contained in the future of the origin

O

and asymptotic to the light-cone, with scalar curvature prescribed at their generic point

M

as a negative function of the unit vector pointing in the direction of

\overrightarrow{OM}

, divided by the square of the norm of

\overrightarrow{OM}

(a dilation invariant problem). The solutions are seeked as graphs over the future unit-hyperboloid emanating from

O

(the hyperbolic space); radial upper and lower solutions are constructed which, relying on a previous result in the Cartesian setting, imply their existence.

On prouve l'existence et l'unicité dans

\mathbb{R}^{n,1}

d'hypersurfaces entières de genre espace contenues dans le futur de l'origine

O

et asymptotes au cône de lumière, dont la courbure scalaire est prescrite au point générique

M

comme fonction négative du vecteur unité pointant en direction de

\overrightarrow{OM}

, divisée par le carré de la norme du vecteur

\overrightarrow{OM}

(un problème invariant par homothétie). Les solutions sont cherchées comme graphes sur l'hyperboloïde-unité futur émanant de

O

(l'espace hyperbolique) ; des solutions supérieure et inférieure radiales sont construites qui, d'après un résultat antérieur en cartésien, impliquent l'existence de telles solutions.
Genetic polymorphism of the type A human natriuretic peptide receptor (NPR‐A) gene contributes to the interindividual variability in the BNP system
Authors: Weber Michael , Burian Maria , Dragutinovic Ivana , Moellmann Helge , Nef Holger , Elsaesser Albrecht , Mitrovic Veselin , Hamm Christian , Geisslinger Gerd
Published: April 2008

Aims:

To analyse the contribution of recently described genetic polymorphisms in the human natriuretic peptide receptor (NPR‐A) to the interindividual variability in the BNP system.

Methods and results:

We evaluated NT‐proBNP in 402 subjects, including healthy controls (n=93), patients with acute coronary syndrome (n=194) and heart failure (n=115). Three polymorphic sites encoding six common haplotypes of the NPR‐A receptor gene, including three haplotypes in the 5′ region (CT11, CT10 and CT6) and three haplotypes in the 3′ region (3‐plus, 4‐minus and 4‐plus), were studied.

The frequency of the identified “4‐minus” haplotype was higher in control subjects with high NT‐proBNP (>75th percentile) levels as compared to those with low NT‐proBNP levels (15.2% vs. 5.7%, p<0.05). In the control subjects, carriers of the “‐plus/4‐minus” genotype had about 2‐fold higher median NT‐proBNP levels than individuals with other genetic variants (142pg/ml (88–371pg/ml) vs. 71pg/ml (35–111pg/ml, p=0.011). In contrast, in patients with cardiovascular disorders no relation between NT‐proBNP and the described polymorphisms was observed.

Conclusion:

The “4‐minus” haplotype of the NPR‐A receptor gene is associated with high NT‐proBNP values and is a genetic determinant of the interindividual variability in the BNP system in healthy individuals but probably not in patients with cardiovascular disorders.
Haemodynamics and left ventricular function in heart failure patients: Comparison of awake versus intra‐operative conditions
Authors: ten Brinke Ellen A. , Klautz Robert J. , Tulner Sven A. , Engbers Frank H. , Verwey Harriette F. , Atsma Douwe E. , Schalij Martin J. , van der Wall Ernst E. , Bax Jeroen J. , Putter Hein , Dion Robert A. , Steendijk Paul
Published: April 2008

Background:

Heart failure patients are increasingly subjected to surgery. Left ventricular (LV) function is generally assessed in awake patients, but intra‐operative LV function is not well studied.

Aim:

To investigate the relation between LV function indices obtained in the catheterization laboratory and those obtained intra‐operatively.

Methods:

We enrolled 11 patients with heart failure (NYHA III–IV) scheduled for surgical interventions. LV function was assessed by pressure–volume loops (conductance catheter) during diagnostic catheterizations and intra‐operatively under anaesthetized conditions.

Results:

Compared to awake conditions, cardiac output was unchanged intra‐operatively but ejection fraction was significantly reduced (–16%) due to increased end‐diastolic volume (+13%). Systolic and diastolic LV pressure and afterload (EA) dropped significantly (–32%, −22%, −35%, respectively). LV systolic function assessed by dP/dtMAX and the end‐systolic pressure–volume relation (EES) was significantly reduced (–34%, −35%). LV diastolic stiffness was reduced (–44%). Ventricular–arterial coupling (EA/EES) was maintained.

Conclusion:

Intra‐operative cardiac output was unchanged compared to awake conditions due to a balance between reduced systolic and improved diastolic function. Ventricular–arterial coupling was maintained by a reduced afterload. Presumably, systolic function and afterload were reduced by anaesthesia, whereas diastolic function improved after pericardectomy. These findings provide insight into the combined effects of anaesthesia, thoracotomy and pericardectomy, and help to interpret LV function measurements in intra‐operative conditions.
Medicine, rhetoric and undermining: managing credibility in homeopathic practice
Authors: Campbell C.
Published: April 2008

This article examines homeopathic practitioners ‘real life’ accounts, and illustrates the ways in which they negotiate their homeopathic practices as contingently formulated ongoing social events in research interview settings. Interview transcripts were analysed in a qualitative framework using discourse analysis. The findings show that practitioners construct homeopathy and defend their own individual practices either by ‘alignment-with-medicine’ or by ‘boosting-the-credibility-of-homeopathy’. Homeopathy is also negotiated and sustained as an ‘alternative’ to notions of conventional medicine, which is the accepted yardstick for practice or as a practice that is portrayed as problematic. Overall, managing personal credibility is accomplished through specific ways of accounting that tend to marginalise homeopathy. Developing and establishing homeopathic practice further as a discipline in its own right is offered as a ‘nucleus’ to reduce continuing marginalisation.
Changes of RAPD profile of Trypanosoma cruzi II with Canova and Benznidazole
Authors: Aleixo Denise Lessa , Ferraz Fabiana Nabarro , de Melo Carolina Sundin , Gomes Mônica Lúcia , Toledo Max Jean , Kaneshima Edílson Noboyoshi , Bersani-Amado Ciomar Aparecida , Araújo Silvana Marques
Published: April 2008

Chagas disease, caused by the protozoan Trypanosoma cruzi, involves immunomediated processes. Canova (CA) is a homeopathic treatment indicated in the diseases in which the immune system is depressed. This study evaluated the Random Amplification of Polymorphic DNA (RAPD) profile of T. cruzi under the influence of CA and Benznidazole (BZ). Mice infected with the genetic lineage of T. cruzi II (Y strain) were divided into 4 groups:

Infected animals treated with saline solution (control group); treated with CA; treated with BZ; treated with CA and BZ combined.

Treatment was given at the 5th–25th days of infection (D5–25). The parasites were isolated by haemoculture in Liver Infusion Tryptose (LIT) medium: at D5 (before treatment), D13, 15 and 25 (during treatment) and D55 and 295 (after treatment). DNA was extracted from the mass of parasites. RAPD was done with the primers λgt11-F, M13F-40 and L15996, the amplified products were eletrophoresed through a 4% polyacrylamide gel. Data were analyzed by the coefficient of similarity using the DNA-POP program.

163 markers were identified, 5 of them monomorphic. CA did not act against the parasites when used alone. The RAPD profiles of parasites treated with BZ and CA + BZ were different from those in the control group and in the group treated with CA. The actions of the CA and BZ were different and the action of BZ was different from the action of CA + BZ. These data suggest that CA may interact with BZ. The differences in the RAPD profile of the Y strain of T. cruzi produced by BZ, CA + BZ and the natural course of the infection suggest selection/suppression of populations.
British media attacks on homeopathy: Are they justified?
Authors: Vithoulkas George
Published: April 2008

Homeopathy is being attacked by the British media. These attacks draw support from irresponsible and unjustified claims by certain teachers of homeopathy. Such claims include the use of ‘dream’ and ‘imaginative’ methods for provings. For prescribing some such teachers attempt to replace the laborious process of matching symptom picture and remedy with spurious theories based on ‘signatures’, sensations and other methods. Other irresponsible claims have also been made. These “new ideas” risk destroying the principles, theory, and practice of homeopathy.
Petroleum: a series of 25 cases
Authors: Gnaiger-Rathmanner J. , Schneider A. , Loader B. , Böhler M. , Frass M. , Singer S.R. , Oberbaum M.
Published: April 2008

This study is based on 25 well documented reports of cases which responded well to treatment with Petroleum. Materia medica data were compared with results in contemporary clinical practice. Many patients had characteristic skin problems; children often had recurrent or chronic upper respiratory tract problems. The most prominent mental feature is a quiet, withdrawn or stubborn disposition. The mental symptoms may be difficult to recognise.

Detailed documentation in daily practice can be helpful for preserving data of the effect of a medicine; confirmation of statements given in materia medica; improving understanding of homeopathic medicines and differentiating the indications for medicines.
Caregivers' assessments of preference‐based quality of life in Alzheimer's disease
Authors: Karlawish Jason H. , Zbrozek Art , Kinosian Bruce , Gregory Annemarie , Ferguson Allison , Low Dominique V. , Glick Henry A.
Published: April 2008

Background

This study was designed to evaluate the feasibility, reliability, and validity of use of caregivers' ratings of two health preference measures as outcomes for cost‐effectiveness analyses in persons with very mild to moderate Alzheimer's disease (AD).

Methods

Caregivers completed ratings of preference for AD patients' health by use of the EuroQol‐5D system (EQ‐5D) and the Health Utilities Index Mark 2 (HUI2). They also rated patients' cognition, mood, burden, AD‐specific and generic health‐related quality of life (QOL), and activities of daily living.

Results

Caregivers' HUI2 scores were reliable. Neither the caregiver ratings of the patients' health by use of the EQ‐5D nor the HUI2 had a relationship with severity of cognitive impairment. Both the EQ‐5D and the HUI2 had expected relationships with caregivers' assessments of patients' function, AD‐specific QOL, and physical and mental health and selected subscales of the measures of AD‐specific QOL and overall health. In addition, caregiver scores showed relationships with patient self‐rated function, mood, and physical health but not AD‐specific QOL. Caregiver burden was associated with caregivers' scores.

Conclusions

Caregiver‐completed ratings of preference for patients' health made by use of the EQ‐5D and the HUI2 have many of the characteristics of valid preference measures. However, the lack of association with patient Mini‐Mental Status Exam scores and patient self‐rated AD‐specific QOL and the associations with caregiver subjective burden might present limitations to their use as proxy measures for cost‐effectiveness analyses.
Revision of the apolipoprotein E compensatory mechanism recruitment hypothesis
Authors: Han S. Duke , Bondi Mark W.
Published: April 2008

The association between the apolipoprotein E ε4 allele and Alzheimer's disease (AD) is well‐established. Functional neuroimaging research has supported a compensatory mechanism recruitment hypothesis whereby nondemented ε4 participants use additional cognitive resources to buffer against episodic memory declines in older age, a mechanism that is presumably associated with encroaching disease. However, recent studies have implicated a beneficial effect associated with the ε4 allele early in the life span. These studies suggest a revised hypothesis whereby ε4 persons perform better on cognitive measures early in the life span and then show greater recruitment of brain regions during performance to compensate for declines in older age caused by preclinical AD.
Interference of β-eudesmol in nestmate recognition inAtta sexdens rubropilosa(Hymenoptera: Formicidae)
Authors: Marinho C.G.S. , Della Lucia T.M.C. , Ribeiro M.M.R. , Magalhães S.T.V. , Guedes R.N.C. , Jham G.N.
Published: April 2008

Leaf-cutter ant species (Attaspp.) are key pests of cultivated crops in the Neotropics, and recent studies have demonstrated that workers ofAttaspp., particularly ofAtta sexdens rubropilosa, exhibit aggressive behavior among nestmates when in contact with the sesquiterpene β-eudesmol, found in leaves ofEucalyptus maculata. However, the underlying mechanism sparking this behavior pattern has yet to be investigated. This work aimed to elucidate the mechanism by which this substance elicits aggression in workers ofA. sexdens rubropilosa. The results, thus obtained, showed that β-eudesmol is able to modify the chemical composition of the workers cuticle, impairing nestmate recognition, triggering alarm behavior and leading to nestmate aggression.
Cursorial spiders retard initial aphid population growth at low densities in winter wheat
Authors: Birkhofer K. , Gavish-Regev E. , Endlweber K. , Lubin Y.D. , von Berg K. , Wise D.H. , Scheu S.
Published: April 2008

Generalist predators contribute to pest suppression in agroecosystems. Spider communities, which form a substantial fraction of the generalist predator fauna in arable land, are characterized by two functional groups: web-building and cursorial (non-web-building) species. We investigated the relative impact of these two functional groups on a common pest (Sitobion avenae, Aphididae) in wheat by combining a molecular technique that revealed species-specific aphid consumption rates with a factorial field experiment that analyzed the impact, separately and together, of equal densities of these two spider functional groups on aphid population growth. Only cursorial spiders retarded aphid population growth in our cage experiment, but this effect was limited to the initial aphid-population growth period and low-to-intermediate aphid densities. The molecular analysis, which used aphid-specific primers to detect aphid DNA in predator species, detected the highest proportion of aphid-consuming individuals in two cursorial spiders: the foliage-dwelling Xysticus cristatus (Thomisidae) and the ground-active Pardosa palustris (Lycosidae). The results suggest that manipulating the community composition in favour of pest-consuming functional groups may be more important for improving biological control than fostering predator biodiversity per se. Agricultural management practices that specifically foster effective species or functional groups (e.g. mulching for cursorial spiders) should receive more attention in low-pesticide farming systems.
The dynamics and mixing of turbulent plumes in a turbulently convecting environment
Authors: WITHAM FRED , PHILLIPS JEREMY C.
Published: April 2008

The turbulent motion of buoyant plumes released into turbulently convecting environments is studied. By assuming that the turbulent environment removes fluid from the plume at a rate proportional to a characteristic environmental velocity scale, we derive a model describing the fluid behaviour. For the example of pure buoyancy plumes, entrainment dominates near the source and the plume radius increases with distance, while further from the source removal, or extrainment, of plume material dominates, and the plume radius decreases to zero. Theoretical predictions are consistent with laboratory experiments, a major feature of which is the natural variability of the convection. We extend the study to include the evolution of a finite confined environment, the end-member regimes of which are a well-mixed environment at all times (high convective velocities), and a ‘filling-box’ model similar to that of Baines & Turner (1969) (low convective velocities). These regimes, and the motion of the interface in a ‘filling-box’ experiment, match experimental observations. We find that the convecting filling box is not stable indefinitely, but that the density stratification will eventually be overcome by thermal convection. The model presented here has important applications in volcanology, ventilation studies and environmental science.
Experimental investigation and kinetic-theory-based model of a rapid granular shear flow
Authors: WILDMAN R. D. , MARTIN T. W. , HUNTLEY J. M. , JENKINS J. T. , VISWANATHAN H. , FEN X. , PARKER D. J.
Published: April 2008

An experimental investigation of an idealized rapidly sheared granular flow was performed to test the predictions of a model based on the kinetic theory of dry granular media. Glass ballotini beads were placed in an annular shear cell and the lower boundary rotated to induce a shearing motion in the bed. A single particle was tracked using the positron emission particle tracking (PEPT) technique, a method that determines the location of a particle through the triangulation of gamma photons emitted by a radioactive tracer particle. The packing fraction and velocity fields within the three-dimensional flow were measured and compared to the predictions of a model developed using the conservation and balance equations applicable to dissipative systems, and solved incorporating constitutive relations derived from kinetic theory. The comparison showed that kinetic theory is able to capture the general features of a rapid shear flow reasonably well over a wide range of shear rates and confining pressures.
Interleaving intrusions produced by internal waves: a laboratory experiment
Authors: GRIFFITHS ROSS W. , BIDOKHTI ALI A.
Published: April 2008

A statically stable stratified water column that also contains horizontal property contrasts (either of passive tracer alone or of two dynamically active solutes) is generated and continuously maintained for a long period by releasing two turbulent buoyant plumes of equal buoyancy fluxes into opposite ends of a long channel of water. The bottom outflows from the plumes also continuously excite internal gravity waves that produce a series of counter-flowing quasi-horizontal shear layers which are quasi-stationary relative to the box but whose phase propagates downward through the upward-moving water column. We report that the flow further involves an oscillation associated with the internal waves that gives rise to a sequence of interleaving intrusions across the horizontal gradient region. The wave-driven intrusions are advected upward with the ‘filling-box’ circulation and have the appearance of a spatially growing instability. The intrusions are examined in cases having no horizontal property differences other than a passive tracer. In further experiments where one plume is salt solution and the other is sugar solution, there is vigorous double-diffusive convection on the interleaving intrusions, including salt fingering and diffusive density interfaces, but this convection has only a weak influence on the intrusion thicknesses and velocities. We conclude that under all conditions attained in these experiments, the interleaving is driven by internal waves and not by the property gradients, and we infer that the wave-generated intrusions enhance double-diffusive buoyancy fluxes.
Reynolds stresses and mean fields generated by pure waves: applications to shear flows and convection in a rotating shell
Authors: PLAUT E. , LEBRANCHU Y. , SIMITEV R. , BUSSE F. H.
Published: April 2008

A general reformulation of the Reynolds stresses created by two-dimensional waves breaking a translational or a rotational invariance is described. This reformulation emphasizes the importance of a geometrical factor: the slope of the separatrices of the wave flow. Its physical relevance is illustrated by two model systems: waves destabilizing open shear flows; and thermal Rossby waves in spherical shell convection with rotation. In the case of shear-flow waves, a new expression of the Reynolds–Orr amplification mechanism is obtained, and a good understanding of the form of the mean pressure and velocity fields created by weakly nonlinear waves is gained. In the case of thermal Rossby waves, results of a three-dimensional code using no-slip boundary conditions are presented in the nonlinear regime, and compared with those of a two-dimensional quasi-geostrophic model. A semi-quantitative agreement is obtained on the flow amplitudes, but discrepancies are observed concerning the nonlinear frequency shifts. With the quasi-geostrophic model we also revisit a geometrical formula proposed by Zhang to interpret the form of the zonal flow created by the waves, and explore the very low Ekman-number regime. A change in the nature of the wave bifurcation, from supercritical to subcritical, is found.
Direct numerical simulations of forced and unforced separation bubbles on an airfoil at incidence
Authors: JONES L. E. , SANDBERG R. D. , SANDHAM N. D.
Published: April 2008

Direct numerical simulations (DNS) of laminar separation bubbles on a NACA-0012 airfoil at Rec=5×104 and incidence 5° are presented. Initially volume forcing is introduced in order to promote transition to turbulence. After obtaining sufficient data from this forced case, the explicitly added disturbances are removed and the simulation run further. With no forcing the turbulence is observed to self-sustain, with increased turbulence intensity in the reattachment region. A comparison of the forced and unforced cases shows that the forcing improves the aerodynamic performance whilst requiring little energy input. Classical linear stability analysis is performed upon the time-averaged flow field; however no absolute instability is observed that could explain the presence of self-sustaining turbulence. Finally, a series of simplified DNS are presented that illustrate a three-dimensional absolute instability of the two-dimensional vortex shedding that occurs naturally. Three-dimensional perturbations are amplified in the braid region of developing vortices, and subsequently convected upstream by local regions of reverse flow, within which the upstream velocity magnitude greatly exceeds that of the time-average. The perturbations are convected into the braid region of the next developing vortex, where they are amplified further, hence the cycle repeats with increasing amplitude. The fact that this transition process is independent of upstream disturbances has implications for modelling separation bubbles.
On the thickness of soap films: an alternative to Frankel's law
Authors: VAN NIEROP ERNST A. , SCHEID BENOIT , STONE HOWARD A.
Published: April 2008

The formation of soap films by vertical withdrawal from a bath is typically described by Frankel's law, which assumes rigid film ‘walls’ and shear-like dynamics. Since most soap films have interfaces that are not rigid, and as the flow in the withdrawal of thin free films is typically extensional, we reconsider the theory of soap film formation. By assuming extensional flow dominated by surface viscous stresses we find that the film thickness scales as the two-thirds power of the withdrawal speed U. This speed dependence is also predicted by Frankel's law; the difference lies in the origin of the viscous resistance which sets the pre-factor. When bulk viscous stresses are important the speed dependence can vary between U2/3 and U2.
On the deficiency of even-order structure functions as inertial-range diagnostics
Authors: DAVIDSON P. A. , KROGSTAD P.-Å.
Published: April 2008

In the limit of vanishing viscosity, ν→0, Kolmogorov's two-thirds, 〈(Δυ)2〉~ε2/3r2/3, and five-thirds, E~ε2/3k−5/3, laws are formally equivalent. (Here 〈(Δυ)2〉 is the second-order structure function, ε the dissipation rate, r the separation in physical space, E the three-dimensional energy spectrum, and k the wavenumber.) However, for the Reynolds numbers encountered in terrestrial experiments, or numerical simulations, it is invariably easier to observe the five-thirds law. We ask why this should be. To this end, we create artificial fields of isotropic turbulence composed of a random sea of Gaussian eddies whose size and energy distribution can be controlled. We choose the energy of eddies of scale, s, to vary as s2/3, in accordance with Kolmogorov's 1941 law, and vary the range of scales, γ=smax/smin, in any one realization from γ=25 to γ=800. This is equivalent to varying the Reynolds number in an experiment from Rλ=60 to Rλ=600. We find that, while there is some evidence of a five-thirds law for γ>50; (Rλ>100), the two-thirds law only starts to become apparent when γ approaches 200 (Rλ~240). The reason for this discrepancy is that the second-order structure function is a poor filter, mixing information about energy and enstrophy, and from scales larger and smaller than r. In particular, in the inertial range, 〈(Δυ)2〉 takes the form of a mixed power law, a1 + a2r2 + a3r2/3, where a2r2 tracks the variation in enstrophy and a3r2/3 the variation in energy. These findings are shown to be consistent with experimental data where the ‘pollution’ of the r2/3 law by the enstrophy contribution, a2r2, is clearly evident. We show that higher-order structure functions (of even order) suffer from a similar deficiency.
Stability and acoustic scattering in a cylindrical thin shell containing compressible mean flow
Authors: BRAMBLEY E. J. , PEAKE N.
Published: April 2008

We consider the stability of small perturbations to a uniform inviscid compressible flow within a cylindrical linear-elastic thin shell. The thin shell is modelled using Flügge's equations, and is forced from the inside by the fluid, and from the outside by damping and spring forces. In addition to acoustic waves within the fluid, the system supports surface waves, which are strongly coupled to the thin shell. Stability is analysed using the Briggs–Bers criterion, and the system is found to be either stable or absolutely unstable, with absolute instability occurring for sufficiently small shell thicknesses. This is significantly different from the stability of a thin shell containing incompressible fluid, even for parameters for which the fluid would otherwise be expected to behave incompressibly (for example, water within a steel thin shell). Asymptotic expressions are derived for the shell thickness separating stable and unstable behaviour.

We then consider the scattering of waves by a sudden change in the duct boundary from rigid to thin shell, using the Wiener–Hopf technique. For the scattering of an inbound acoustic wave in the rigid-wall section, the surface waves are found to play an important role close to the sudden boundary change. The solution is given analytically as a sum of duct modes.

The results in this paper add to the understanding of the stability of surface waves in models of acoustic linings in aeroengine ducts. The oft-used mass–spring–damper model is regularized by the shell bending terms, and even when these terms are very small, the stability and scattering results are quite different from what has been claimed for the mass–spring–damper model. The scattering results derived here are exact, unique and causal, without the need to apply a Kutta-like condition or to include an instability wave. A movie is available with the online version of the paper.
Gas flows through constricted shallow micro-channels
Authors: GAT A. , FRANKEL I. , WEIHS D.
Published: April 2008

We study the viscous compressible flow through micro-channels of non-uniform cross-section. A lubrication approximation is applied to analyse the flow through shallow configurations whose gap width is small in comparison with the other characteristic dimensions. Focusing on channels with a symmetric constriction (or cavity) we obtain the solution to the problem by means of a Schwarz–Christoffel transformation. This analytic solution is verified by examining the convergence of numerical simulations with diminishing Reynolds number and gap width. Explicit closed-form expressions for the pressure-head and mass-flow-rate losses in terms of the geometrical parameters characterizing the constriction are presented and discussed in the context of experimental data existing in the literature.
Laryngopyocoele: simple management of an acute airway crisis
Authors: Mace A T M , Ravichandran S , Dewar G , Picozzi G L
Published: April 2008

Objective:

We present the first reported case of ultrasound-guided aspiration of a laryngopyocoele in a patient with acute airway obstruction.

Case report:

A 71-year-old woman was diagnosed with a right-sided laryngocoele. Six weeks later, the patient was admitted as an emergency with a three-day history of increasing dyspnoea and stridor. Neck examination revealed a large, right-sided, soft neck mass, centred at level III, measuring approximately 10 × 5 cm. Fibre-optic laryngoscopy revealed a large, smooth, inflamed, right supraglottic mass obscuring the laryngeal inlet. The patient was taken directly to the radiology department, where ultrasound imaging confirmed a laryngopyocoele. Under ultrasound guidance, a 21-G needle was directed into the cyst and 30 ml of pus was aspirated. The dysphonia and stridor resolved immediately. Six weeks later, the patient underwent definitive surgical excision of the laryngocoele.

Conclusion:

Laryngopyocoele is a rare diagnosis. It can present as an acute airway emergency. We present the first reported case managed by ultrasound-guided aspiration, which averted the need for endotracheal intubation or tracheostomy.
Acaroconium punctiforme gen. sp. nov., a new lichenicolous coelomycete on Acarospora species and Sarcogyne regularis
Authors: KOCOURKOVÁ Jana , HAWKSWORTH David L.
Published: April 2008

The coelomycete Acaroconium punctiforme gen. sp. nov. is
described from four members of the lichen-forming family Acarosporaceae, three species of Acarospora and Sarcogyne regularis. The new fungus is characterized by pycnidial conidiomata with a distinct ostiolar collar, enteroblastic conidiogenesis, and the production of simple brown conidia. The separation of the fungus from other somewhat similar pycnidial fungi growing on lichens and plant material is discussed.
A new Scoliciosporum from Madagascar
Authors: APTROOT André
Published: April 2008

A new Scoliciosporum is described from rainforest in Madagascar. It superficially resembles S. pruinosum, but has an arachnoid hypothallus and prothallus and an olivaceous hypothecium and excipulum.
Effects of interspecific competition on asexual proliferation and clonal genetic diversity in larval trematode infections of snails
Authors: KEENEY D. B. , BOESSENKOOL S. , KING T. M. , LEUNG T. L. F. , POULIN R.
Published: April 2008

Interactions among different parasite species within hosts can be important factors shaping the evolution of parasite and host populations. Within snail hosts, antagonistic interactions among trematode species, such as competition and predation, can influence parasite abundance and diversity. In the present study we examined the strength of antagonistic interactions between 2 marine trematodes (Maritrema novaezealandensisandPhilophthalmussp.) in naturally infectedZeacumantus subcarinatussnails. We found approximately the same number of snails harbouring both species as would be expected by chance given the prevalence of each. However, snails infected with onlyM. novaezealandensisand snails withM. novaezealandensisandPhilophthalmussp. co-occurring were smaller than snails harbouring onlyPhilophthalmussp. In addition, the number ofPhilophthalmussp. rediae was not affected by the presence ofM. novaezealandensissporocysts and the within-host clonal diversity ofM. novaezealandensiswas not influenced by the presence ofPhilophthalmussp. Our results suggest that antagonistic interactions may not be a major force influencing the evolution of these trematodes and that characteristics such as host size and parasite infection longevity are shaping their abundance and population dynamics.
Health needs assessment tools: Progress and potential
Authors: Asadi-Lari Mohsen , Gray David
Published: April 2008

Objectives:Health needs has attracted the interest of policy-makers, health economists, and health professionals as modern health services try to satisfy individual and population health needs to optimize resource utilization. Health needs can be assessed by administering various types of survey or interview-based instruments. If health needs are to be satisfied in changing health agendas in developed and developing countries, it is essential to employ valid and reliable tools. Despite the importance of needs assessment, no comprehensive review of tools is currently available. We carried out a literature search to define and categorize existing health needs assessment tools.

Methods:We reviewed medical and social search engines for items containing specific health needs–related words to identify needs tools across a range of specialties. Papers were reviewed in terms of design, subject matter, psychometric features, and method of administration method.

Results:Thirty-one employed in 52 studies including cancer, mental health, palliative care, multiple sclerosis, and cardiovascular disease tools were identified.

Conclusions:This report summarizes available health needs instruments in a range of diseases to assist researchers in accessing health needs resources more easily and to encourage further research in this field.
Populating decision-analytic models: The feasibility and efficiency of database searching for individual parameters
Authors: Golder Su , Glanville Julie , Ginnelly Laura
Published: April 2008

Objectives: The aim of the study was to investigate the feasibility and effectiveness of searching selected databases to identify information required to populate a decision-analytic model.

Methods: Methods of searching for information to populate a decision-analytic model were piloted using a case study of prophylactic antibiotics to prevent recurrent urinary tract infections in children. This study explored how the information requirements for a decision-analytic model could be developed into searchable questions and how search strategies could be derived to answer these questions. The study also assessed the usefulness of three published search filters and explored which resources might produce relevant information for the various model parameters.

Results: Based on the data requirements for this case study, 42 questions were developed for searching. These questions related to baseline event rates, health-related quality of life and outcomes, relative treatment effects, resource use and unit costs, and antibiotic resistance. A total of 1,237 records were assessed by the modeler, and of these, 48 were found to be relevant to the model. Search precision ranged from 0 percent to 38 percent, and no single database proved the most useful for all the questions.

Conclusions: The process of conducting specific searches to address each of the model questions provided information that was useful in populating the case study model. The most appropriate resources to search were dependent on the question, and multiple database searching using focused search strategies may prove more effective in finding relevant data than thorough searches of a single database.
Cost-effectiveness of drug-eluting coronary stents in Quebec, Canada
Authors: Brophy James M. , Erickson Lonny J.
Published: April 2008

Objectives:The aim of this investigation was to assess the incremental cost-effectiveness of replacing bare metal coronary stents (BMS) with drug-eluting stents (DES) in the Province of Quebec, Canada.

Methods:The strategy used was a cost-effectiveness analysis from the perspective of the health-care provider, in the province of Quebec, Canada (population 7.5 million). The main outcome measure was the cost per avoided revascularization intervention.

Results:Based on the annual Quebec rate of 14,000 angioplasties with an average of 1.7 stents per procedure and a purchase cost of $2,600 Canadian dollar (CDN) for DES, 100 percent substitution of BMS with DES would require an additional $45.1 million CDN of funding. After the benefits of reduced repeat revascularization interventions are included, the incremental cost would be $35.2 million CDN. The cost per avoided revascularization intervention (18 percent coronary artery bypass graft, 82 percent percutaneous coronary intervention [PCI]) would be $23,067 CDN. If DES were offered selectively to higher risk populations, for example, a 20 percent subgroup with a relative restenosis risk of 2.5 times the current bare metal rate, the incremental cost of the program would be $4.9 million CDN at a cost of $7,800 per avoided revascularization procedure. Break-even costs for the program would occur at DES purchase cost of $1,161 for 100 percent DES use and $1,627 for selective 20 percent DES use for high-risk patients for restenosis (RR = 2.5). Univariate and Monte Carlo sensitivity analyses indicate that the parameters most affecting the analysis are the capacity to select patients at high risk of restenosis, the average number of stents used per PCI, baseline restenosis rates for BMS, the effectiveness ratio of restenosis prevention for DES versus BMS, the cost of DES, and the revascularization rate after initial PCI. Sensitivity analyses suggest little additional health benefits but escalating cost-effectiveness ratios once a DES penetration of 40 percent has been attained.

Conclusions:Under current conditions in Quebec, Canada, selective use of DES in high-risk patients is the most acceptable strategy in terms of cost-effectiveness. Results of such an analysis would be expected to be similar in other countries with key model parameters similar to those used in this model. This model provides an example of how to evaluate the cost-effectiveness of selective use of a new technology in high-risk patients.