bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Propagation Velocity of a Detonation‐Shock Combined Wave
Authors: Tsugé Shun‐I‐Chi , Fujiwara Toshitaka
Published: May 2007

Für die freie Detonation eines Gases in einer inaktiven Umgebung werden eine quasi‐eindimensionale Analysis und eine verallgemeinerte Chapman‐Jouget‐Bedingung entwickelt. Aus den Ergebnissen werden zwei charakteristische Merkmale abgeleitet: Für die Verbrennungswärme, den Ladungsdurchmesser und das Molekulargewicht des umgebenden Gases existiert je eine untere Grenze, und für eine Parameterkombination oberhalb eines kritischen Wertes werden zwei Ausbreitungsgeschwindigkeiten gefunden. Daher ist das Ausbleiben der Detonation einer freien Gassäule eher ein hydrodynamisches als eine chemisches Problem.
Optimale Schalengrundgleichungen und deren Leistungsfähigkeit
Authors: Krätzig Wilfried B.
Published: May 2007

Die vorliegende Arbeit gewinnt die Grundgleichungen der Theorie elastischer Schalen, unter Einschluß von Schubverformungen, als bestmögliche lineare Approximation eines dreidimensionalen Kontinuums. Ausgehend von einer Integraltransformation des Energiesatzes werden zunächst konsistente Grundgleichungen für ein Schalenkontinuum abgeleitet, die definitionsgemäß auf dünne Schalen spezialisiert werden. Sodann wird gezeigt, daß alle auf einem solchen Wege gewonnenen Elastizitätsgesetze einer ersten Approximation Unschärfen aufweisen müssen. Höhere Approximationen sind ableitbar, doch gleichzeitig mit zusätzlichen Unschärfequellen behaftet.
Synthesis and Antioxidancy of Some n‐Alkyl, t‐Alkyl, Homologous and Isomeric Lipidic Alkylthiobisphenols
Authors: Tyman John H. P. , Johnson Robert A.
Published: May 2007

To study the relationship between structure and properties of members of the lipidic thiobis phenol series, as extreme pressure additives in lubricants, a series of homologous compounds has been synthesised by the reaction of alkylphenols with sulphur dichloride. The isomeric n‐nonylphenols have been reacted to form the C9 isomeric 2,2′‐and 4,4′‐thiobisphenols. Longer alkyl side‐chains resulted mainly in the formation of 4,4′‐thiobisphenols and some of the 2,2′ isomer. With short alkyl, particularly t‐alkyl side‐chains, steric hindrance resulted in the 2,2′‐compound. Additive studies have indicated that the longer chain 4,4′ compounds possessed antioxidant properties comparable and superior to former commercial branched chain 2,2′ compounds produced from petrochemical intermediates.
Hereditäre Nierentumoren
Authors: Decker H.J.
Published: May 2007

Etwa 1–4% aller Nierentumoren sind mit spezifischen Keimbahndefekten assoziiert. Nierentumoren sind sehr heterogen. Eine neue histogenetische Klassifikation beruht auf pathomorphologischen wie auch auf genetischen Kriterien. Für jede der 4 häufigsten Tumortypen besteht ein Bezug zu einer hereditären Form bzw. den jeweils betroffenen Genen. Bis heute sind mindestens 10 hereditäre Konditionen bekannt, bei denen Nierentumoren auftreten. Dieser Review stellt die heute zur Verfügung stehenden Möglichkeiten einer individuellen Betreuung von Patienten mit diesen seltenen syndromalen und nichtsyndromalen hereditären Formen dar.
Ripply2 is essential for precise somite formation during mouse early development
Authors: Chan Techuan , Kondow Akiko , Hosoya Akihiro , Hitachi Keisuke , Yukita Akira , Okabayashi Koji , Nakamura Hiroaki , Ozawa Hidehiro , Kiyonari Hiroshi , Michiue Tatsuo , Ito Yuzuru , Asashima Makoto
Published: May 2007

The regions of expression of Ripply1 and Ripply2, presumptive transcriptional corepressors, overlap at the presomitic mesoderm during somitogenesis in mouse and zebrafish. Ripply1 is required for somite segmentation in zebrafish, but the developmental role of Ripply2 remains unclear in both species. Here, we generated Ripply2 knock‐out mice to investigate the role of Ripply2. Defects in segmentation of the axial skeleton were observed in the homozygous mutant mice. Moreover, somite segmentation and expression of Notch2 and Uncx4.1 were disrupted. These findings indicate that Ripply2 is involved in somite segmentation and establishment of rostrocaudal polarity.
Enhanced biological activity of polymeric osteopontin
Authors: Higashikawa Fumiko , Eboshida Akira , Yokosaki Yasuyuki
Published: May 2007

Osteopontin is a multifunctional glycoprotein with roles in immunomodulation, inflammatory response, tissue mineralization, and tissue remodeling, which are mediated primarily through integrins. Transglutaminase 2 selectively cross‐links proteins by isopeptide bonding. Osteopontin is one of the substrates of this enzyme and undergoes polymerization; however, the biological meaning of this polymerization remains unknown. Using recombinant osteopontin polymerized with purified transglutaminase 2, we examined cell adhesion, spreading, focal contact formation, and migration of SW480 or HUVE cells. All of these cellular behaviors were dramatically enhanced with polymeric osteopontin. These enhancements of cellular functions imply that polymerization might modulate physiological and pathological functions of osteopontin.
Interaction of the Coxsackie and adenovirus receptor (CAR) with the cytoskeleton: Binding to actin
Authors: Huang Kuo-Cheng , Yasruel Zivart , Guérin Claude , Holland Paul C. , Nalbantoglu Josephine
Published: May 2007

The Coxsackie and adenovirus receptor (CAR) is a cell adhesion molecule that is highly expressed in the developing brain. CAR is enriched in growth cone particles (GCP) after subcellular fractionation. In GCP, we identified actin as an interaction partner of the cytoplasmic domain of CAR. In vivo, actin and CAR co‐immunoprecipitate and co‐localize. In vitro, the binding is direct, with a K
d of ∼2.6 μM, and leads to actin bundling. We previously demonstrated that CAR interacts with microtubules. These data suggest a role for CAR in processes requiring dynamic reorganization of the cytoskeleton such as neurite outgrowth and cell migration.
The relation between solution association and surface activity of the hydrophobin HFBI from Trichoderma reesei
Authors: Szilvay Géza R. , Kisko Kaisa , Serimaa Ritva , Linder Markus B.
Published: May 2007

Hydrophobins are small fungal surface active proteins that self‐assemble at interfaces into films with nanoscale structures. The hydrophobin HFBI from Trichoderma reesei has been shown to associate in solution into tetramers but the role of this association on the function of HFBI has remained unclear. We produced two HFBI variants that showed a significant shift in solution association equilibrium towards the tetramer state. However, this enhanced solution association did not alter the surface properties of the variant HFBIs. The results show that there is not a strong relationship between HFBI solution association state and surface properties such as surface activity.
The IGF‐I splice variant MGF increases progenitor cells in ALS, dystrophic, and normal muscle
Authors: Ates Kenan , Yang Shi Yu , Orrell Richard W. , Sinanan Andrea C.M. , Simons Paul , Solomon Andrew , Beech Steven , Goldspink Geoffrey , Lewis Mark P.
Published: May 2007

The effects of muscle splice variants of insulin‐like growth factor I (IGF‐I) on proliferation and differentiation were studied in human primary muscle cell cultures from healthy subjects as well as from muscular dystrophy and ALS patients. Although the initial numbers of mononucleated progenitor cells expressing desmin were lower in diseased muscle, the E domain peptide of IGF‐IEc (MGF) significantly increased the numbers of progenitor cells in healthy and diseased muscle. IGF‐I significantly enhances myogenic differentiation whereas MGF E peptide blocks this pathway, resulting in an increased progenitor (stem) cell pool and thus potentially facilitating repair and maintenance of this postmitotic tissue.
Prevalence of cryptosporidian infection in cats in Turin and analysis of risk factors
Authors: Rambozzi Luisa , Menzano Arianna , Mannelli Alessandro , Romano Simona , Isaia Maria Cristina
Published: May 2007

An epidemiological study was carried out to identify factors associated with the risk of cryptosporidian infection in cats. Faecal samples from 200 domestic cats were collected in the small animal clinic at the Faculty of Veterinary Medicine in Turin (north-west Italy). The faecal samples were analysed for the presence of Cryptosporidium species oocysts using a centrifugation concentration floatation method. For each cat, age, sex, breed, indoor/outdoor status, diet, diarrhoea and presence of other enteric parasites were analysed for association with Cryptosporidium species infection. Cryptosporidia oocysts were identified in 49 cats (24.5%) aged from 2 months to 18 years. Statistical analysis revealed that four variables are significantly associated with an increased risk of infection: less than 1 year of age ( χ2=6.5, P=0.01), feeding home-cooked diet ( χ2=6.92, P<0.01), presence of diarrhoea ( χ2=4.34, P<0.037), and presence of other enteric parasites ( χ2=10.31, P<0.01). No statistical differences were found for sex ( χ2=1.56, P=0.21), breed ( χ2=0.78, P=0.38) and outdoor/indoor status ( χ2=1.49, P=0.22). Cryptosporidium species was the parasite most frequently detected in the cats surveyed.
Laparoscopic ovariectomy in cats: Comparison of laser and bipolar electrocoagulation
Authors: van Nimwegen Sebastiaan A , Kirpensteijn Jolle
Published: May 2007

Fourteen mixed-breed domestic cats underwent laparoscopic ovariectomy (lapOVE) using paediatric equipment, an Nd:YAG laser and a bipolar electrocoagulation forceps. Cats were placed in 10° Trendelenburg position (head down) and insufflation pressure was kept at 4 mmHg, while surgery was performed through three midline portals. Randomly-assigned unilateral laser resection of one ovary (laserOVE) and bipolar electrocoagulation (BECOVE) of the contralateral ovary were performed. Duration of predetermined surgery intervals was recorded, as well as occurrence of intra- and postoperative complications. Both methods were successful and without complications. Duration of laserOVE was significantly increased compared to BECOVE. The right ovary was more difficult to access; however, both ovaries were easy to manipulate because of the relatively long suspensory ligament. The ovarian ligaments contained minimal amounts of fat and obesity did not influence surgery duration. Convalescence period was short (0.9±0.4 days) and owner satisfaction high.
Marketing and Nursing: A Contemporary View
Authors: Schild S.M.
Published: May 2007

Marketing and Nursing: A Contemporary View By Mary Sayre Tilbury, Trevor A. Fisk 1989, 557 pp $30 clothbound
Communicating Like a Manager
Authors: Koch Frances A.
Published: May 2007

Communicating Like a Manager By Rebecca S. Weinfeld, Edith M. Donohue 1989, 127 pp $24.95 clothbound
Family‐Centered Nursing Care of Children
Authors: Snyder Rhonda P.
Published: May 2007

Family‐Centered Nursing Care of Children, second ed. By Roxie L. Romness Foster, Mabel Metzger Hunsberger, Jo Joyce Tackett Anderson 1989, 2150 pp $54.95 clothbound
General Ophthalmology
Authors: Edwards Mary Jane C.
Published: May 2007

General Ophthalmology, 12th ed. By Daniel Vaughan, Taylor Asbury, Khalid F. Tabbara 1989, 460 pp $27 paperback
Berry and Kohn's Operating Room Technique
Authors: Fortunato Nancy M.
Published: May 2007

Berry and Kohn's Operating Room Technique, seventh ed By Lucy Jo Atkinson 1992,733 pp $39.95 paperback
Case Studies in Neuroscience Critical Care Nursing
Authors: Volpicello Carolyn
Published: May 2007

Case Studies in Neuroscience Critical Care Nursing Edited by Susan M. Johnson 1991,211 pp $39.95 hardcover
Culture Care Diversity and Universality: A Theory of Nursing
Authors: Martin Susan N.
Published: May 2007

Culture Care Diversity and Universality: A Theory of Nursing Edited by Madeleine M. Leininger 1991, 432 pp $34.95 paperback
Electrocardiographic Interpretation: A Self‐Study Approach to Clinical Electrocardiography
Authors: Seifert Patricia C.
Published: May 2007

Electrocardiographic Interpretation: A Self‐Study Approach to Clinical Electrocardiography By Emanuel Stein 1991, 701 pp $39.50 paperback
Medication calculation ability of registered nurses
Authors: Bindler R. , Bayne T. , Johnson Jane H.
Published: May 2007

Medication calculation ability of registered nurses, R Bindler, T Bayne Image: Journal of Nursing Scholarship Vol23 (Winter 1991) 22 1–224
Supporting the staff nurse under stress
Authors: Albrecht TL , Halsey J , Diomede Barbara
Published: May 2007

Supporting the staff nurse under stress, T L Albrecht, J Halsey Nursing Management Vol 22 (July 1991) 60–64
Evaluation of a rapid readout biological indicator for flash sterilization with three biological indicators and three chemical indicators
Authors: SHOUP ANITA JO ,   Nursing Research Committee
Published: May 2007

Evaluation of a rapid readout biological indicator for flash sterilization with three biological indicators and three chemical indicators W. Rutala, M. Gergen, D. Weber Infection Control and Hospital Epidemiology Vol 14 (July 1993) 390–394
Validation of a food frequency questionnaire to assess folate intake of Dutch elderly people
Authors: van de Rest Ondine , Durga Jane , Verhoef Petra , Melse-Boonstra Alida , Brants Henny A. M.
Published: May 2007

Folate is required for 1-carbon metabolism and deficiency in folate leads to megaloblastic anemia. Low levels of folate have been associated with increased risk of vascular disease. To investigate whether RDA of folate are met, habitual folate intake needs to be assessed reliably. We developed a FFQ to specifically measure folate intake over the previous 3 months in elderly people in the Netherlands. Major sources of folate intake, i.e. foods contributing to at least 80 % of the average folate intake, were identified through an analysis of the second Dutch Food Consumption Survey for the sub-population of men and women aged 50–70. In 2000 and 2001, folate intake was estimated with this questionnaire in 1286 individuals aged 50–75 years. Concentrations of serum and erythrocyte folate served as biomarkers with which relative validity of the questionnaire was assessed. The same FFQ was repeated after 3 years in 803 subjects in order to assess long-term reproducibility. Mean folate intake was estimated to be 196 (sd 69) μg/d. Spearman correlation coefficients between folate intake and serum and erythrocyte concentrations were 0·14 (P < 0·01) and 0·05 (P = 0·06) respectively. Spearman correlations between folate intakes measured at baseline and after 3 years were 0·58 (P < 0·01). 47 % of the participants were classified in the same quartiles on the two occasions. Our FFQ showed a weak correlation between folate intake and blood folate concentrations and reproducibility was acceptable. This FFQ is able to rank subjects according to their folate intake.
Relationships between acceptance of sour taste and fruit intakes in 18-month-old infants
Authors: Blossfeld Ivonne , Collins Aoife , Boland Suzanne , Baixauli Raquel , Kiely Mairead , Delahunty Conor
Published: May 2007

The present study examined whether infants show an acceptance for extreme sour tastes and whether acceptance of sour taste is related to infants' fruit intake. Fruit intake of fifty-three infants at 6, 12 and 18 months was assessed using 3 d food records. Sour acceptance of these infants was studied at 18·1 (sd1·5) months. Acceptance for four solutions differing in citric acid concentrations (0·00m, 0·013m, 0·029mand 0·065m) was measured by allowing infantsad libitumingestion of each solution over brief time periods. The base solution to which citric acid was added was blackcurrant squash diluted in water. Infants' relative intake of each solution was used as a measure of sour acceptance. At 18 months, twelve infants readily accepted the two highest citric acid concentrations, whereas the remaining infants rejected these. Infants who accepted the most sour solutions had a significantly higher fruit intake (P = 0·025) and a higher fruit variety (P = 0·015) at 18 months than the infants who rejected the highly sour taste. Furthermore, infants who accepted the most sour solutions consumed fruits more frequently at 18 months (χ25·1;P = 0·024). Infants who accepted the sourest solutions also had a higher fruit intake at 6 months, and a significantly higher increase in their fruit intake from 12 to 18 months. This is the first scientific study that demonstrates the acceptance of sour tastes in some infants at the age of 18 months. Furthermore, the present results suggest a relationship between acceptance of sour tastes and infants' fruit intakes.
Multiple-trait QTL mapping for body and organ weights in a cross between NMRI8 and DBA/2 mice
Authors: NEUSCHL CHRISTINA , BROCKMANN GUDRUN A. , KNOTT SARA A.
Published: May 2007

Multiple-trait analyses have been shown to improve the detection of quantitative trait loci (QTLs) with multiple effects. Here we applied a multiple-trait approach on obesity- and growth-related traits that were surveyed in 275 F2 mice generated from an intercross between the high body weight selected line NMRI8 and DBA/2 as lean control. The parental lines differed 2·5-fold in body weight at the age of 6 weeks. Within the F2 population, the correlations between body weight and weights of abdominal fat weight, muscle, liver and kidney at the age of 6 weeks were about 0·8. A least squares multiple-trait QTL analysis was performed on these data to understand more precisely the cause of the genetic correlation between body weight, body composition traits and weights of inner organs. Regions on Chr 1, 2, 7 and 14 for body weights at different early ages and regions on Chr 1, 2, 4, 7, 14, 17 and 19 for organ weights at 6 weeks were found to have significant multiple effects at the genome-wide level.
Functional mapping of reaction norms to multiple environmental signals
Authors: WU JIASHENG , ZENG YANRU , HUANG JIANQING , HOU WEI , ZHU JUN , WU RONGLING
Published: May 2007

Whether there are different genes involved in response to different environmental signals and how these genes interact to determine the final expression of the trait are of fundamental importance in agricultural and biological research. We present a statistical framework for mapping environment-induced genes (or quantitative trait loci, QTLs) of major effects on the expression of a trait that respond to changing environments. This framework is constructed with a maximum-likelihood-based mixture model, in which the mean and covariance structure of environment-induced responses is modelled. The means for responses to continuous environmental states, referred to as reaction norms, are approximated for different QTL genotypes by mathematical equations that were derived from fundamental biological principles or based on statistical goodness-of-fit to observational data. The residual covariance between different environmental states was modelled by autoregressive processes. Such an approach to studying the genetic control of reaction norms can be expected to be advantageous over traditional mapping approaches in which no biological principles and statistical structures are considered. We demonstrate the analytical procedure and power of this approach by modelling the photosynthetic rate process as a function of temperature and light irradiance. Our approach allows for testing how a QTL affects the reaction norm of photosynthetic rate to a specific environment and whether there exist different QTLs to mediate photosynthetic responses to temperature and light irradiance, respectively.
Selection responses of means and inbreeding depression for female fecundity inDrosophila melanogastersuggest contributions from intermediate-frequency alleles to quantitative trait variation
Authors: CHARLESWORTH BRIAN , MIYO TAKAHIRO , BORTHWICK HELEN
Published: May 2007

The extent to which quantitative trait variability is caused by rare alleles maintained by mutation, versus intermediate-frequency alleles maintained by balancing selection, is an unsolved problem of evolutionary genetics. We describe the results of an experiment to examine the effects of selection on the mean and extent of inbreeding depression for early female fecundity inDrosophila melanogaster. Theory predicts that rare, partially recessive deleterious alleles should cause a much larger change in the effect of inbreeding than in the mean of the outbred population, with the change in inbreeding effect having an opposite sign to the change in mean. The present experiment fails to support this prediction, suggesting that intermediate-frequency alleles contribute substantially to genetic variation in early fecundity.
Flapping dynamics of a flag in a uniform stream
Authors: CONNELL BENJAMIN S. H. , YUE DICK K. P.
Published: May 2007

We consider the flapping stability and response of a thin two-dimensional flag of high extensional rigidity and low bending rigidity. The three relevant non-dimensional parameters governing the problem are the structure-to-fluid mass ratio, μ = ρsh/(ρfL); the Reynolds number,Rey=VL/ν; and the non-dimensional bending rigidity,KB=EI/(ρfV2L3). The soft cloth of a flag is represented by very low bending rigidity and the subsequent dominance of flow-induced tension as the main structural restoring force. We first perform linear analysis to help understand the relevant mechanisms of the problem and guide the computational investigation. To study the nonlinear stability and response, we develop a fluid–structure direct simulation (FSDS) capability, coupling a direct numerical simulation of the Navier–Stokes equations to a solver for thin-membrane dynamics of arbitrarily large motion. With the flow grid fitted to the structural boundary, external forcing to the structure is calculated from the boundary fluid dynamics. Using a systematic series of FSDS runs, we pursue a detailed analysis of the response as a function of mass ratio for the case of very low bending rigidity (KB= 10−4) and relatively high Reynolds number (Rey= 103). We discover three distinct regimes of response as a function of mass ratio μ: (I) a small μ regime of fixed-point stability; (II) an intermediate μ regime of period-one limit-cycle flapping with amplitude increasing with increasing μ; and (III) a large μ regime of chaotic flapping. Parametric stability dependencies predicted by the linear analysis are confirmed by the nonlinear FSDS, and hysteresis in stability is explained with a nonlinear softening spring model. The chaotic flapping response shows up as a breaking of the limit cycle by inclusion of the 3/2 superharmonic. This occurs as the increased flapping amplitude yields a flapping Strouhal number (St= 2Af/V) in the neighbourhood of the natural vortex wake Strouhal number,St≃ 0.2. The limit-cycle von Kármán vortex wake transitions in chaos to a wake with clusters of higher intensity vortices. For the largest mass ratios, strong vortex pairs are distributed away from the wake centreline during intermittent violent snapping events, characterized by rapid changes in tension and dynamic buckling.
Coupling modes between two flapping filaments
Authors: JIA LAI-BING , LI FANG , YIN XIE-ZHEN , YIN XIE-YUAN
Published: May 2007

The flapping coupling between two filaments is studied theoretically and experimentally in this paper. A temporal linear instability analysis is carried out based on a simplified hydrodynamic model. The dispersion relationship between the eigen-frequency ω and wavenumberkis expressed by a quartic equation. Two special cases of flapping coupling, i.e. two identical filaments having the same length and two filaments having different lengths, are studied in detail. In the case of two identical filaments, the theoretical analysis predicts four coupling modes, i.e. the stretched-straight mode, the antisymmetrical in-phase mode, the symmetrical out-of-phase mode and the indefinite mode. The theory also predicts the existence of an eigenfrequency jump during transition between the in-phase and out-of-phase modes, which has been observed in previous experiments and numerical simulations. In the case of two filaments having different lengths, four modes similar to those in the former case are identified theoretically. The distribution of coupling modes for both the cases is shown in two planes. One is a dimensionless plane ofSvs.U, whereSis the density ratio of solid filament to fluid andU2is the ratio of fluid kinetic energy to solid elastic potential energy. The other is a dimensional plane of the half-distance (h) between two filaments vs. the filament length (L). Relevant experiments are carried out in a soap-film tunnel and the stable and unstable modes are observed. Theory and experiment are compared in detail. It should be noted that the model used in our analysis is a very simplified one that can provide intuitional analytical results of the coupling modes as well as their qualitative distributions. The factors neglected in our model, such as vortex shedding, viscous and nonlinear effects, do not allow the model to predict results precisely consistent with the experiments. Moreover, the Strouhal numbers of the flapping filaments are found to be generally around a fixed value in the experiments for both cases, implying that the filaments try to maintain a lower potential energy state.
General dynamical sharp-interface conditions for phase transformations in viscous heat-conducting fluids
Authors: ANDERSON DANIEL M. , CERMELLI PAOLO , FRIED ELIOT , GURTIN MORTON E. , MCFADDEN GEOFFREY B.
Published: May 2007

We develop a complete set of equations governing the evolution of a sharp interface separating two fluid phases undergoing transformation. In addition to the conventional balances for mass, linear momentum and energy these equations include also a counterpart of the Gibbs–Thomson equation familiar from theories for crystal growth. This additional equation arises from a consideration of configurational forces within a thermodynamical framework. Although the notion of configurational forces is well-developed and understood for the description of materials, such as crystalline solids, that possess natural reference configurations, little has been done regarding their role in materials, such as viscous fluids, that do not possess preferred reference states. We therefore provide a comprehensive discussion of configurational forces, the balance of configurational momentum, and configurational thermodynamics that does not require a choice of reference configuration. The general evolution equations arising from our theory account for the thermodynamic structure of the bulk phases and the interface and for viscous and thermal dissipation in the bulk phases and for viscous dissipation on the interface. Because of the complexity of these equations, we provide a reduced system of equations based on simplified constitutive assumptions and approximations common in the literature on phase transformations. Using these reduced equations, we apply the theory to the radially symmetric problem for the condensation of a liquid drop into the vapour phase.
Torque scaling in turbulent Taylor–Couette flow between independently rotating cylinders
Authors: ECKHARDT BRUNO , GROSSMANN SIEGFRIED , LOHSE DETLEF
Published: May 2007

Turbulent Taylor–Couette flow with arbitrary rotation frequencies ω1, ω2 of the two coaxial cylinders with radii r1 < r2 is analysed theoretically. The current Jω of the angular velocity ω(x,t) = uϕ(r,ϕ,z,t)/r across the cylinder gap and and the excess energy dissipation rate ϵw due to the turbulent, convective fluctuations (the ‘wind’) are derived and their dependence on the control parameters analysed. The very close correspondence of Taylor–Couette flow with thermal Rayleigh–Bénard convection is elaborated, using these basic quantities and the exact relations among them to calculate the torque as a function of the rotation frequencies and the radius ratio η = r1/r2 or the gap width d = r2 − r1 between the cylinders. A quantity σ corresponding to the Prandtl number in Rayleigh–Bénard flow can be introduced, $\sigma = ((1 + \eta)/2)/\sqrt{\etaacute;)^4$. In Taylor–Couette flow it characterizes the geometry, instead of material properties of the liquid as in Rayleigh–Bénard flow. The analogue of the Rayleigh number is the Taylor number, defined as Ta ∝ (ω1 − ω2)2 times a specific geometrical factor. The experimental data show no pure power law, but the exponent α of the torque versus the rotation frequency ω1 depends on the driving frequency ω1. An explanation for the physical origin of the ω1-dependence of the measured local power-law exponents α(ω1) is put forward. Also, the dependence of the torque on the gap width η is discussed and, in particular its strong increase for η → 1.
A theoretical model for horizontal convection at high Rayleigh number
Authors: HUGHES G. O. , GRIFFITHS R. W. , MULLARNEY J. C. , PETERSON W. H.
Published: May 2007

We present a simple flow model and solution to describe ‘horizontal convection’ driven by a gradient of temperature or heat flux along one horizontal boundary of a rectangular box. Following laboratory observations of the steady-state convection, the model is based on a localized vertical turbulent plume from a line or point source that is located anywhere within the area of the box and that maintains a stably stratified interior. In contrast to the ‘filling box’ process, the convective circulation involves vertical diffusion in the interior and a stabilizing buoyancy flux distributed over the horizontal boundary. The stabilizing flux forces the density distribution to reach a steady state. The model predictions compare well with previous laboratory data and numerical solutions. In the case of a point source for the plume (the case which best mimics the localized sinking in the large-scale ocean overturning) the thermal boundary layer is much thicker than that given by the two-dimensional boundary layer scaling of H. T. Rossby (Tellus, vol. 50, 1965, p. 242).
Numerical study of a transitional synthetic jet in quiescent external flow
Authors: KOTAPATI RUPESH B. , MITTAL RAJAT , CATTAFESTA III LOUIS N.
Published: May 2007

The flow associated with a synthetic jet transitioning to turbulence in an otherwise quiescent external flow is examined using time-accurate three-dimensional numerical simulations. The incompressible Navier–Stokes solver uses a second-order accurate scheme for spatial discretization and a second-order semi-implicit fractional step method for time integration. The simulations are designed to model the experiments of C. S. Yaoet al. (Proc. NASA LaRC Workshop, 2004) which have examined, in detail, the external evolution of a transitional synthetic jet in quiescent flow. Although the jet Reynolds and Stokes numbers in the simulations match with the experiment, a number of simplifications have been made in the synthetic jet actuator model adopted in the current simulations. These include a simpler representation of the cavity and slot geometry and diaphragm placement. Despite this, a reasonably good match with the experiments is obtained in the core of the jet and this indicates that for these jets, matching of these key non-dimensional parameters is sufficient to capture the critical features of the external jet flow. The computed results are analysed further to gain insight into the dynamics of the external as well as internal flow. The results indicate that near the jet exit plane, the flow field is dominated by the formation of counter-rotating spanwise vortex pairs that break down owing to the rapid growth of spanwise instabilities and transition to turbulence a short distance from the slot. Detailed analyses of the unsteady characteristics of the flow inside the jet cavity and slot provide insights that to date have not been available from experiments.
Structural sensitivity of the first instability of the cylinder wake
Authors: GIANNETTI FLAVIO , LUCHINI PAOLO
Published: May 2007

The stability properties of the flow past an infinitely long circular cylinder are studied in the context of linear theory. An immersed-boundary technique is used to represent the cylinder surface on a Cartesian mesh. The characteristics of both direct and adjoint perturbation modes are studied and the regions of the flow more sensitive to momentum forcing and mass injection are identified. The analysis shows that the maximum of the perturbation envelope amplitude is reached far downstream of the separation bubble, where as the highest receptivity is attained in the near wake of the cylinder, close to the body surface. The large difference between the spatial structure of the two-dimensional direct and adjoint modes suggests that the instability mechanism cannot be identified from the study of either eigenfunctions separately. For this reason a structural stability analysis of the problem is used to analyse the process which gives rise to the self-sustained mode. In particular, the region of maximum coupling among the velocity components is localized by inspecting the spatial distribution of the product between the direct and adjoint modes. Results show that the instability mechanism is located in two lobes placed symmetrically across the separation bubble, confirming the qualitative results obtained through a locally plane-wave analysis. The relevance of this novel technique to the development of effective control strategies for vortex shedding behind bluff bodies is illustrated by comparing the theoretical predictions based on the structural perturbation analysis with the experimental data of Strykowski & Sreenivasan (J. Fluid Mech.vol. 218, 1990, p. 71).
Local stability analysis of an inviscid transverse jet
Authors: ALVES LEONARDO S. de B. , KELLY ROBERT E. , KARAGOZIAN ANN R.
Published: May 2007

A local linear stability analysis is performed for a round inviscid jet with constant density that is injected into a uniform crossflow of the same density. The baseflow is obtained from a modified version of the inviscid transverse jet near-field solution of Coelho & Hunt (J. Fluid Mech.vol. 200, 1989, p. 95) which is valid for small values of the crossflow-to-jet velocity ratio λ. A Fourier expansion in the azimuthal direction is used to couple the disturbances with the three-dimensional crossflow. The spatial growth rates of the modes corresponding to the axisymmetric and first helical modes of the free jet as λ → 0 increase as λ increases. The diagonal dominance of the dispersion relation matrix is used as a quantitative criterion to estimate the range of velocity ratios (0 < λ < λc) within which the transverse jet instability can be considered to have a structure similar to that of the free jet. Further, we show that for λ>0 positive and negative helical modes have different growth rates, suggesting an inherent weak asymmetry in the transverse jet.
Fluctuations above a burning heterogeneous propellant
Authors: MASSA L. , JACKSON T. L. , BUCKMASTER J. , NAJJAR F.
Published: May 2007

A numerical description of heterogeneous propellant combustion enables us to examine the spatial and temporal fluctuations in the flow field arising from the heterogeneity. Particular focus is placed on the fluctuations in a zone intermediate between the combustion field (where reaction is important) and the chamber flow domain, for these define boundary conditions for simulations of the turbulent chamber flow. The statistics of the temperature field and the normal velocity field are described, and characteristic length scales and time scales are identified. The length scales are small compared to any relevant length scale of the chamber flow, and so the boundary conditions for this flow at any mesh point are statistically independent of those at any other mesh point. But the temporal correlations at a fixed point are significant, and affect the nature of the chamber flow in a variety of ways. We describe the fluctuations in the head-end pressure that arise because of them, and contrast these results with those calculated using a white-noise assumption.
Behaviour of a conducting drop in a highly viscous fluid subject to an electric field
Authors: DUBASH N. , MESTEL A. J.
Published: May 2007

We consider the slow deformation of a relatively inviscid conducting drop surrounded by a viscous insulating fluid subject to a uniform electric field. The general behaviour is to deform and elongate in the direction of the field. Detailed numerical computations, based on a boundary integral formulation, are presented. For fields below a critical value, we obtain the evolution of the drop to an equilibrium shape; above the critical value, we calculate the drop evolution up to breakup. At breakup it appears that smaller droplets are emitted from the ends of the drop with a charge greater than the Rayleigh limit. As the electric field strength is increased the ejected droplet size decreases. A further increase in field strength results in the mode of breakup changing to a thin jet-like structure being ejected from the end. The shape of all drops is very close to spheroidal up to aspect ratios of about 5. Also, for fields just above the critical value there is a period of slow deformation which increases in duration as the critical field strength is approached from above. Slender-body theory is also used to model the drop behaviour. A similarity solution for the slender drop is obtained and a finite-time singularity is observed. In addition, the general solution for the slender-body equations is presented and the solution behaviour is examined. The slender-body results agree only qualitatively with the full numerical computations. Finally, a spheroidal model is briefly presented and compared with the other models.
Development of particle migration in pressure-driven flow of a Brownian suspension
Authors: SEMWOGERERE DENIS , MORRIS JEFFREY F. , WEEKS ERIC R.
Published: May 2007

An experimental investigation into the influence of Brownian motion on shear-induced particle migration of monodisperse suspensions of micrometre-sized colloidal particles is presented. The suspension is pumped through a 50 μm × 500 μm rectangular cross-section glass channel. The experiments are characterized chiefly by the sample volume fraction (φ = 0.1 − 0.4), and the flow rate expressed as the Péclet number (Pe = 10 − 400). For each experiment we measure the entrance length, which is the distance from the inlet of the channel required for the concentration profile to develop to its non-uniform steady state. The entrance length increases strongly with increasing Pe for Pe ≪ 100, in marked contrast to non-Brownian flows for which the entrance length is flow-rate independent. For larger Pe, the entrance length reaches a constant value which depends on the other experimental parameters. Additionally, the entrance length decreases with increasing φ; this effect is strongest for low φ. Modelling of the migration based on spatial variation of the normal stresses due to the particles captures the primary features observed in the axial evolution over a range of Pe and φ.
Auditory cortical activation and speech perception in cochlear implant users
Authors: Green K M J , Julyan P J , Hastings D L , Ramsden R T
Published: May 2007

Cochlear implantation is generally accepted as a successful means of restoring auditory sensation to profoundly deaf individuals. Although most patients can expect a satisfactory outcome following implantation, some have poor speech perception outcomes. This investigation used [18F]-fluorodeoxyglucose positron emission tomography to measure cortical activity resulting from auditory stimulation in seven ‘good’ and four ‘poor’ cochlear implant recipients. Activations were significantly greater in both the primary and association cortices in the good compared with the poor implant users. We suggest that the ability to access the more specialised speech processing abilities of the auditory association cortices helps determine outcome following cochlear implantation.
Buccinator myomucosal flap: clinical results and review of anatomy, surgical technique and applications
Authors: Van Lierop A C , Fagan J J
Published: May 2007

Background:

The buccinator musculomucosal flap is an axial-pattern flap based on either the buccal or the facial artery. We present our experience with this flap and describe its surgical anatomy, the surgical techniques utilised to raise the flap and its clinical applications.

Materials and methods:

We retrospectively reviewed all patients who had had buccinator myomucosal flaps created at the Groote Schuur Hospital between 1999 and 2004. Patients were also recalled to assess flap sensation and to record reduction of mouth opening as a consequence of donor site scarring.

Results:

Of the 14 patients who had had a buccinator myomucosal flap created, there was one flap failure. Sensation was present in 71 per cent of flaps, and there was no trismus due to donor site scarring.

Conclusions:

The buccinator myomycosal flap is a dependable flap with good functional outcome and low morbidity.
Challenges in management of chronic suppurative otitis media in a developing country
Authors: Akinpelu O V , Amusa Y B , Komolafe E O , Adeolu A A , Oladele A O , Ameye S A
Published: May 2007

Background:

In developing countries, the rate of complications from chronic suppurative otitis media is still high, due to factors associated with poverty. This study aimed to determine the prevalence of chronic suppurative otitis media and associated complications.

Patients and methods:

We prospectively studied all patients presenting with chronic suppurative otitis media to the ear, nose and throat unit of the Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria, over a two-year period.

Results:

One hundred and sixty new cases of chronic suppurative otitis media were seen. These constituted 11.1 per cent of all new cases and 21.5 per cent of all otological cases seen. About half (51.7 per cent) of these patients were younger than 15 years. Most patients were from rural areas and had been previously managed by unlicensed, untrained practitioners. Complications were mostly seen in children. Intracranial complications were seen in 10 (6.3 per cent) cases; this was associated with a high mortality rate.

Conclusion:

This study found that, in Nigeria, a developing country, ‘safe’ chronic suppurative otitis media was not without serious problems. Provision of adequate health facilities may reduce such problems.
Parallel electric fields: variations in space and time on auroral field lines
Authors: VEDIN J. , RÖNNMARK K.
Published: May 2007

We present results from a particle–fluid simulation of auroral electrons and discuss the distribution of parallel electric fields along auroral field lines and the processes occurring during the build up of these electric fields. Neglecting field-aligned ion dynamics, the main potential drop has a width of about 5000, km and is centered at an altitude of roughly 5000, km. We find that the gradient in the potential becomes steeper and the build up of the potential drop becomes faster if the temperature of the magnetospheric electrons is lower.
Comparison of cysteine peptidase activities inTrichobilharzia regentiandSchistosoma mansonicercariae
Authors: KAŠNÝ M. , MIKEŠ L. , DALTON J. P. , MOUNTFORD A. P. , HORÁK P.
Published: May 2007

Cercariae of the bird schistosomeTrichobilharzia regentiand of the human schistosomeSchistosoma mansoniemploy proteases to invade the skin of their definitive hosts. To investigate whether a similar proteolytic mechanism is used by both species, cercarial extracts ofT. regentiandS. mansoniwere biochemically characterized, with the primary focus on cysteine peptidases. A similar pattern of cysteine peptidase activities was detected by zymography of cercarial extracts and their chromatographic fractions fromT. regentiandS. mansoni.The greatest peptidase activity was recorded in both species against the fluorogenic peptide substrate Z-Phe-Arg-AMC, commonly used to detect cathepsins B and L, and was markedly inhibited (>96%) by Z-Phe-Ala-CHN2at pH 4·5. Cysteine peptidases of 33 kDa and 33–34 kDa were identified in extracts ofT. regentiandS. mansonicercariae employing a biotinylated Clan CA cysteine peptidase-specific inhibitor (DCG-04). Finally, cercarial extracts from bothT. regentiandS. mansoniwere able to degrade native substrates present in skin (collagen II and IV, keratin) at physiological pH suggesting that cysteine peptidases are important in the pentration of host skin.
Ω-estimates for a class of arithmetic error terms
Authors: KACZOROWSKI JERZY , WIERTELAK KAZIMIERZ
Published: May 2007

The main aim of this paper is to present a general method of proving Ω-estimates for a class of arithmetic error terms. We assume that error terms in question are boundary values of harmonic functions on the upper half-plane satisfying certain subsidiary conditions. We prove a general theorem for an axiomatically defined class of such functions and then we show how this result can be used to give statements in concrete situations. As examples we treat the classical case of the remainder term in the prime number formula obtaining a new proof of the well-known result of J. E. Littlewood, and the case of the remainder term in the asymptotic formula for the summatory function of the square-free divisor function. In the latter case our result is new.
On functional relations between the Mordell–Tornheim double zeta functions and the Riemann zeta function
Authors: TSUMURA HIROFUMI
Published: May 2007

In this paper, we give certain analytic functional relations between the Mordell–Tornheim double zeta functions and the Riemann zeta function. These can be regarded as continuous generalizations of the known discrete relations between the Mordell–Tornheim double zeta values and the Riemann zeta values at positive integers discovered in the 1950's.
Ecological processes in Antarctic inland waters: interactions between physical processes and the nitrogen cycle
Authors: Howard-Williams Clive , Hawes Ian
Published: May 2007

In this review we consider the physical processes that shape inland aquatic ecosystems and how these affect ecosystem processes, with particular focus on the nitrogen cycle. Inland Antarctica is dominated by microbial communities that are usually concentrated in, or adjacent to, habitats with free water. The presence of free vs frozen water is dependent on very small changes in temperature around 0°C, so significant variability in the distribution of free water can be expected in response to variations in climate over diel, decadal, to millennial time scales and a range of spatial scales. Antarctic inland waters take many forms: snow-surface melt pockets, cryoconites, basal regions of wet-based glaciers, ponds (varying in salinity and degree of desiccation), melt streams, perennially and seasonally ice covered lakes and even hypersaline, ice free lakes. The important processes and transformations that characterize the nitrogen cycle worldwide have all been identified in Antarctic inland waters and in some cases (e.g. N-uptake, N-fixation), rates are similar to those at lower latitudes. The unique features of Antarctic ecosystems stem from the extreme and variable physical conditions under which these processes operate rather than any unique ecosystem processes per se.
The mental health problems and needs of older people following lower-limb amputation
Authors: Briggs Wendy
Published: May 2007

In the past, most amputees have been veterans of war or other younger people who have sustained traumatic injury. There are now an increasing number of older people undergoing lower-limb amputation, most commonly because of vascular problems. Anecdotal evidence suggests that there is a lack of support for patients facing limb amputation, and a lack of recognition from staff that these patients may be at risk of ongoing psychological problems following the procedure.