bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zur Berechnung von Stäben mit 3‐Blech‐Querschnitt unter Normalkraft, doppelter Biegung und Wölbkrafttorsion
Authors: Rubin H. 
Published: April 2013

AbstractFür die Berechnung eines Stabes mit allgemeinem 3‐Blech‐Querschnitt (Steg vertikal, Gurte horizontal) unter Normalkraft, doppelter Biegung und Wölbkrafttorsion werden fertige Formeln angegeben. Als Bezugsachsen werden die vertikale Stegachse und die horizontale Achse in Stegmitte verwendet. Damit entfällt die Bestimmung von Schwerpunkt und Lage der Hauptachsen. Kenntnisse über die Theorie der Wölbkrafttorsion sind nicht erforderlich. Wölbwiderstand und Lage des Schubmittelpunktes werden im Verlauf der Rechnung erhalten. Die dargestellte Theorie wird sowohl für die Biegung als auch die Torsion mit Hilfe der (lagerungsunabhängigen) Übertragungsbeziehungen formuliert. Die Bestimmung der erforderlichen Anfangswerte wird für drei Stablagerungsfälle explizit angegeben. Es können alle interessierenden Schnittgrößen, Verschiebungsgrößen und Spannungen berechnet werden. Drei Zahlenbeispiele erläutern das Vorgehen.
Establishing Assessment Scales Using a Novel Disciplinary Rationale for Scientific Reasoning
Authors: Kind Per Morten 
Published: April 2013

AbstractThe article argues that science assessment should change from an item‐driven to a construct‐driven practice and pay more attention to disciplinary scientific reasoning. It investigates assessment scales developed from a novel theoretical rationale, describing scientific reasoning as three fundamental practices (hypothesizing, experimenting, and evidence evaluation) and building on three types of knowledge (science content knowledge, procedural knowledge, and epistemic knowledge). The scale development follows a construct‐driven approach by, first, detailing the knowledge involved and explaining progression; and second, operationalizing the theoretical construct into items and score criteria. The scales are trialled in a small‐scale study. The outcome is a coherent and supportive validity argument for two sub‐scales, but with a suggestion that merging these into one scale has higher validity. The main implication is rewriting rationales for many science assessments, including TIMSS, which emphasises domain‐general reasoning, and NAEP and PISA, which pay attention to domain‐specific reasoning but are unclear about the knowledge involved. © 2013 Wiley Periodicals, Inc. J Res Sci Teach 50: 530–560, 2013
Laminar‐turbulent flow simulation for wind turbine profiles using the γ– transition model
Authors: Khayatzadeh Peyman , Nadarajah Siva 
Published: April 2013

ABSTRACTThe accurate prediction of the laminar‐turbulence transition process is fundamental in predicting the aerodynamic performance of wind turbine profiles. Fully turbulent flow simulations have been shown to over‐predict the aerodynamic performance and thereby negatively impacting the design of airfoils in flow regimes where the possible presence of laminar flow could be exploited to improve the performance of wind turbine rotors. Correlation‐based transition modelling offers a fully computational fluid dynamics compatible approach, where the model integrates completely with the existing turbulence model, allows for the prediction of various transition mechanisms, is applicable to three‐dimensional flows and compatible to adjoint‐based design optimization frameworks. The present paper addresses several modifications necessary for a robust transition model and investigates the accuracy of the model for a wide range of angles of attack and Reynolds numbers, which are necessary for a thorough validation of the correlation‐based transition model for wind turbine profiles. The transition model was employed to predict the transition locations; and an assessment of the various transition mechanisms, Reynolds number effects, sectional characteristics and aerodynamic performance for the NLF(1)‐0416 and S809 airfoils is presented with comparisons to experimental data and numerical solutions. Copyright © 2013 John Wiley & Sons, Ltd.
Candidate Biomarker Discovery for Angiogenesis by Automatic Integration of Orbitrap MS1 Spectral- and X!Tandem MS2 Sequencing Information
Authors: Titulaer Mark K. 
Published: April 2013

Abstract
Candidate protein biomarker discovery by full automatic integration of Orbitrap full MS1 spectral peptide profiling and X!Tandem MS2 peptide sequencing is investigated by analyzing mass spectra from brain tumor samples using Peptrix. Potential protein candidate biomarkers found for angiogenesis are compared with those previously reported in the literature and obtained from previous Fourier transform ion cyclotron resonance (FT-ICR) peptide profiling. Lower mass accuracy of peptide masses measured by Orbitrap compared to those measured by FT-ICR is compensated by the larger number of detected masses separated by liquid chromatography (LC), which can be directly linked to protein identifications. The number of peptide sequences divided by the number of unique sequences is 9248/6911 ≈ 1.3. Peptide sequences appear 1.3 times redundant per up-regulated protein on average in the peptide profile matrix, and do not seem always up-regulated due to tailing in LC retention time (40%), modifications (40%) and mass determination errors (20%). Significantly up-regulated proteins found by integration of X!Tandem are described in the literature as tumor markers and some are linked to angiogenesis. New potential biomarkers are found, but need to be validated independently. Eventually more proteins could be found by actively involving MS2 sequence information in the creation of the MS1 peptide profile matrix.
Lubrication theory for electro-osmotic flow in a slit microchannel with the Phan-Thien and Tanner model
Authors: Bautista O. , Sánchez S. , Arcos J. C. , Méndez F. 
Published: April 2013

AbstractIn this work the purely electro-osmotic flow of a viscoelastic liquid, which obeys the simplified Phan-Thien–Tanner (sPTT) constitutive equation, is solved numerically and asymptotically by using the lubrication approximation. The analysis includes Joule heating effects caused by an imposed electric field, where the viscosity function, relaxation time and electrical conductivity of the liquid are assumed to be temperature-dependent. Owing to Joule heating effects, temperature gradients in the liquid make the fluid properties change within the microchannel, altering the electric potential and flow fields. A consequence of the above is the appearance of an induced pressure gradient along the microchannel, which in turn modifies the normal plug-like electro-osmotic velocity profiles. In addition, it is pointed out that, depending on the fluid rheology and the used values of the dimensionless parameters, the velocity, temperature and pressure profiles in the fluid are substantially modified. Also, the finite thermal conductivity of the microchannel wall was considered in the analysis. The dimensionless temperature profiles in the fluid and the microchannel wall are obtained as function of the dimensionless parameters involved in the analysis, and the interactions between the coupled momentum, thermal energy and potential electric equations are examined in detail. A comparison between the numerical predictions and the asymptotic solutions was made, and reasonable agreement was found.
Turbulent flow in the bulk of Rayleigh–Bénard convection: small-scale properties in a cubic cell
Authors: Kaczorowski Matthias , Xia Ke-Qing 
Published: April 2013

AbstractThe Rayleigh number ($\mathit{Ra}$) scaling of the global Bolgiano length scale ${L}_{B, global} $ and the local Bolgiano length scale ${L}_{B, centre} $ in the centre region of turbulent Rayleigh–Bénard convection are investigated for Prandtl numbers $\mathit{Pr}= 0. 7$ and $4. 38$ and $3\times 1{0}^{5} \leq \mathit{Ra}\leq 3\times 1{0}^{9} $. It is found that ${L}_{B, centre} $ does not necessarily exhibit the same scaling as ${L}_{B, global} $. While ${L}_{B, global} $ is monotonically deceasing as ${L}_{B, global} \sim {\mathit{Ra}}^{- 0. 10} $ for both $\mathit{Pr}$, ${L}_{B, centre} $ shows a steep increase beyond a certain $\mathit{Ra}$ value. The complex scaling of the local Bolgiano length scale in the centre is a result of the different behaviour of the temperature-variance dissipation rate, ${\epsilon }_{T} $, and the turbulent-kinetic-energy dissipation rate, ${\epsilon }_{u} $. This shows that for sufficiently high $\mathit{Ra}$ the flow is well-mixed and hence temperature is passively advected. It is also observed that the $\mathit{Ra}$-range in which ${L}_{B, centre} $ exhibits the same scaling as the global Bolgiano length scale is increasing with increasing $\mathit{Pr}$. It is further observed that for $\mathit{Pr}= 4. 38$ and $\mathit{Ra}\leq 3\times 1{0}^{7} $ the local vertical heat flux in the centre region is balanced by the turbulent-kinetic-energy dissipation rate. For higher $\mathit{Ra}$ we find that the local heat flux is decreasing. At $\mathit{Pr}= 0. 7$ we do not observe such a balance, as the measured heat flux is between the heat fluxes estimated through the turbulent-kinetic-energy dissipation rate and the temperature-variance dissipation rate. We therefore suggest that the balance of the local heat flux might be Prandtl-number dependent. The conditional average of the local vertical heat flux $\mathop{\langle \mathit{Nu}\vert {\epsilon }_{u} , {\epsilon }_{T} \rangle }\nolimits_{\mathit{centre}} $ in the core region of the flow reveals that the highest vertical heat flux occurs for rare events with very high dissipation rates, while the joint most probable dissipation rates are associated with very low values of vertical heat flux. It is also observed that high values of ${\epsilon }_{u} $ and ${\epsilon }_{T} $ tend to occur together. It is further observed that the longitudinal velocity structure functions approach Kolmogorov K41 scaling. The temperature structure functions appear to approach Bolgiano–Obukhov BO59 scaling for $r\gt {L}_{B, centre} $, while a scaling exponent smaller than the BO59 scaling is observed for separations $r\lt {L}_{B, centre} $. The mixed velocity and temperature structure function for $\mathit{Ra}= 1\times 1{0}^{9} $ and $\mathit{Pr}= 4. 38$ shows a short $4/ 5$-scaling for $r\gt {L}_{B, centre} $. Our results suggest that BO59 scaling might be more clearly observable at higher Prandtl and moderate Rayleigh numbers.
Turbulent drag reduction through rotating discs
Authors: Ricco Pierre , Hahn Stanislav 
Published: April 2013

AbstractAn active technique for friction drag reduction in a turbulent channel flow is studied by direct numerical simulations. The flow modification is induced by the steady rotation of rigid flush-mounted discs, located next to one another on the walls. The effect of the disc motion on the turbulent drag is investigated at a Reynolds number of ${R}_{\tau } = 180$, based on the friction velocity of the stationary-wall case and the half channel height. For a fixed maximum disc tip velocity, drag reduction can be achieved when the disc diameter is larger than a threshold, while below this threshold the drag increases. A maximum drag reduction of 23% is computed. The net power saved, obtained by taking into account the power spent to enforce the rotational motion against the fluid viscous resistance, is found to be positive and reach 10%. The disc-flow parameters required for commercial aircraft flight conditions and flows over high-speed trains and ship hulls are estimated and future implementations based on existing micro-electromagnetic motor and micro-air turbine technologies are discussed.
Dynamics and stability of the wake behind tandem cylinders sliding along a wall
Authors: Rao A. , Thompson M. C. , Leweke T. , Hourigan K. 
Published: April 2013

AbstractThe dynamics and stability of the flow past two cylinders sliding along a wall in a tandem configuration is studied numerically for Reynolds numbers ($\mathit{Re}$) between 20 and 200, and streamwise separation distances between 0.1 and 10 cylinder diameters. For cylinders at close separations, the onset of unsteady two-dimensional flow is delayed to higher $\mathit{Re}$ compared with the case of a single sliding cylinder, while at larger separations, this transition occurs earlier. For Reynolds numbers above the threshold, shedding from both cylinders is periodic and locked. At intermediate separation distances, the wake frequency shifts to the subharmonic of the leading-cylinder shedding frequency, which appears to be due to a feedback cycle, whereby shed leading-cylinder vortices interact strongly with the downstream cylinder to influence subsequent leading-cylinder shedding two cycles later. In addition to the shedding frequency, the drag coefficients for the two cylinders are determined for both the steady and unsteady regimes. The three-dimensional stability of the flow is also investigated. It is found that, when increasing the Reynolds number at intermediate separations, an initial three-dimensional instability develops, which disappears at higher $\mathit{Re}$. The new two-dimensional steady flow again becomes unstable, but with a different three-dimensional instability mode. At very close spacings, when the two cylinders are effectively seen by the flow as a single body, and at very large spacings, when the cylinders form independent wakes, the flow characteristics are similar to those of a single cylinder sliding along a wall.
Wavy liquid films in interaction with a confined laminar gas flow
Authors: Dietze Georg F. , Ruyer-Quil Christian 
Published: April 2013

AbstractA low-dimensional model capturing the fully coupled dynamics of a wavy liquid film in interaction with a strongly confined laminar gas flow is introduced. It is based on the weighted residual integral boundary layer approach of Ruyer-Quil & Manneville (Eur. Phys. J.B, vol. 15, 2000, pp. 357–369) and accounts for viscous diffusion up to second order in the film parameter. The model is applied to study two scenarios: a horizontal pressure-driven water film/air flow and a gravity-driven liquid film interacting with a co- or counter-current air flow. In the horizontal case, interfacial viscous drag is weak and interfacial waves are primarily driven by pressure variations induced by the velocity difference between the two layers. This produces an extremely thin interfacial shear layer which is pinched at the main and capillary wave humps, creating several elongated vortices in the wave-fixed reference frame. In the capillary wave region preceding a large wave hump, flow separation occurs in the liquid in the form of a vortex transcending the liquid–gas interface. For the gravity-driven film, a twin vortex (in the wave-fixed reference frame) linked to the occurrence of rolling waves has been identified. It consists of the known liquid-side vortex within the wave hump and a previously unknown counter-rotating gas-side vortex, which are connected by the same interfacial stagnation points. At large counter-current gas velocities, interfacial waves on the falling liquid film are amplified and cause flooding of the channel in a noise-driven scenario, while this can be delayed by forcing regular waves at the most amplified linear wave frequency. Our model is shown to exactly capture the long-wave linear stability threshold for the general case of two-phase channel flow. Further, for the two considered scenarios, it predicts growth rates and celerity of linear waves in convincing agreement with Orr–Sommerfeld calculations. Finally, model calculations of nonlinear interfacial waves are in good agreement with film thickness and velocity measurements as well as streamline patterns in both phases obtained from direct numerical simulations.
Kinetics of phosphate absorption in lactating dairy cows after enteral administration of sodium phosphate or calcium phosphate salts
Authors: Grünberg Walter , Dobbelaar Paul , Breves Gerhard 
Published: April 2013

Hypophosphataemia is frequently encountered in dairy cows during early lactation. Although supplementation of P is generally recommended, controversy exists over the suitability of oral P supplementation in animals with decreased or absent rumen motility. Since the effects of transruminal P absorption and the reticular groove reflex on the absorption kinetics of P are not well understood, it is unclear in how far treatment efficacy of oral P supplementation is affected by decreased rumen motility. Phosphate absorption was studied in six phosphate-depleted dairy cows fitted with rumen cannulas and treated with test solutions containing either NaH2PO4 or CaHPO4 with acetaminophen. Each animal was treated orally, intraruminally and intra-abomasally in randomised order. Absorption kinetics of P were studied and compared with the absorption kinetics of acetaminophen, a marker substance only absorbed from the small intestine. Intra-abomasal treatment with NaH2PO4 resulted in the most rapid and highest peaks in plasma inorganic P (Pi) concentration. Oral and intraruminal administration of NaH2PO4 resulted in similar increases in plasma Pi concentration from 4 to 7 h in both groups. Treatment with NaH2PO4 caused more pronounced peaks in plasma Pi concentration compared with CaHPO4. Neither transruminal P absorption nor the reticular groove reflex affected P absorption kinetics as determined by comparing plasma concentration–time curves of P and acetaminophen after administration of 1 m-phosphate salt solutions. It is concluded that oral treatment with NaH2PO4 but not CaHPO4 is effective in supplementing P in hypophosphataemic cows with adequate rumen motility. Decreased rumen motility is likely to hamper the efficacy of oral phosphate treatment.
A spatially explicit population model of the effect of spatial scale of heterogeneity in grass–clover grazing systems
Authors: SHARP J. M. , EDWARDS G. R. , JEGER M. J. 
Published: April 2013

SUMMARYThe benefits of using white clover (Trifolium repensL.) as a source of nitrogen (N) and nutritious feed in pasture grazed by ruminant livestock have been widely recognized. However, clover is considered inadequate and unreliable as the main source of N input, since its abundance in pasture is patchy, low (typically <0·20) and shows great year-to-year variation. This is thought to be due to the metabolic costs of N fixation, competition with grass, the preference for clover by grazing animals and patchy dung and urine deposition. One solution suggested by a number of authors is to increase the heterogeneity within the pasture by spatially separating clover from grass. This method of pasture management, in order to sustain higher clover content in both the sward and diet of grazing animals, would remove inter-specific competition and equalize grazing pressure, allowing clover to grow unimpeded in greater abundance than previously observed. An existing spatially explicit grass–clover simulation model, developed to investigate the intrinsic spatial and temporal variability within mixed grass–clover swards, was modified and then used to examine the impact of spatial separation on the content, variability and patchiness of clover in pasture. The results show that spatial separation increases both the content and spatial aggregation of clover and reduces year-to-year variation compared with a mixed pasture that fluctuates around a lower mean. The same model was also used to examine the impact of spatial separation across a range of spatial scales, from narrow strips to complete separation, as a means of managing the concerns over disruption to the N cycle within the pasture. The present study shows the importance of the initial sowing arrangement of plant species in sustaining a high content of clover within a pasture in the short term, to at least 20 years depending on the scale of separation, and demonstrates that the spatial separation of clover from grass within a grazed pasture may overcome some of the limitations associated with the use of clover in conventional grass–clover pastures. Results are discussed in terms of benefits to both herbage dry matter production and animal performance.
GLOBAL VARIANCE IN FEMALE POPULATION HEIGHT: THE INFLUENCE OF EDUCATION, INCOME, HUMAN DEVELOPMENT, LIFE EXPECTANCY, MORTALITY AND GENDER INEQUALITY IN 96 NATIONS
Authors: MARK QUENTIN J. 
Published: April 2013

SummaryHuman height is a heritable trait that is known to be influenced by environmental factors and general standard of living. Individual and population stature is correlated with health, education and economic achievement. Strong sexual selection pressures for stature have been observed in multiple diverse populations, however; there is significant global variance in gender equality and prohibitions on female mate selection. This paper explores the contribution of general standard of living and gender inequality to the variance in global female population heights. Female population heights of 96 nations were culled from previously published sources and public access databases. Factor analysis with United Nations international data on education rates, life expectancy, incomes, maternal and childhood mortality rates, ratios of gender participation in education and politics, the Human Development Index (HDI) and the Gender Inequality Index (GII) was run. Results indicate that population heights vary more closely with gender inequality than with population health, income or education.
The management of recurrent croup in children
Authors: Rankin I , Wang S M , Waters A , Clement W A , Kubba H 
Published: April 2013

AbstractObjective:To review the aetiology, investigation, diagnosis, treatment and clinical outcome of children with recurrent croup.Method:Retrospective case note review of all children with recurrent croup referred to the otolaryngology service at our hospital from November 2002 to March 2011.Results:Ninety children with recurrent croup were identified. Twenty-five children (28 per cent) had anatomical airway abnormalities, of which 16 (18 per cent) demonstrated degrees of subglottic stenosis. Twenty-three children (26 per cent) had positive microlaryngobronchoscopy findings suggestive of reflux. Eleven children were treated for gastroesophageal reflux disease, 10 (91 per cent) of whom responded well to anti-reflux medication (p = 0.006). No cause was identified for 41 (45 per cent) of the children; this was the group most likely to continue having episodes of croup at follow up. One death occurred in this group.Conclusion:Airway anomalies are common in children that present with recurrent croup. Laryngobronchoscopy allows identification of the cause of croup and enables a more accurate prognosis. In the current study, laryngobronchoscopy findings that indicated reflux were predictive of benefit from anti-reflux medications, whereas the clinical presentation of reflux was not. Routine measurement of immunoglobulin E and complement proteins did not appear to be helpful.