bluuebunny/crossref_metadata_2025 huggingface dataset:
Zur probabilistischen Deformationsmethode und ihrer Anwendung auf Stahltragwerke
Authors: Biehounek J. , Grolik H. , Herz S.
Published: April 2013

Im Beitrag wird ein neues Verfahren zur Berechnung der Versagenswahrscheinlichkeit ebener Stabtragwerke vorgestellt, das auf der Gesamt‐Steifigkeitsbeziehung der herkömmlichen Deformationsmethode beruht. Durch die Berücksichtigung zufälliger Bemessungsgrößen geht daraus die zufällige Steifigkeitsbeziehung als Grundlage des Verfahrens hervor. Ihre Lösung wird mit Hilfe eines deterministischen Ersatzsystems ermittelt. Dieses besitzt eine größere Dimension als das System der Deformationsmethode, steht aber mit ihm im direkten Zusammenhang. So läßt sich seine Koeffizientenmatrix in leicht erkennbarer Weise aus der Elastizitätsmatrix der Deformationsmethode zusammensetzen. Im Ergebnis gelingt es, die Verformungsgrößen und damit auch die Grenzzustandsgleichung analytisch durch die am Tragwerk wirkenden Zufallsgrößen auszudrücken und den Einfluß von Zufallsschwankungen der Stoff‐ und Geometriekenngrößen sowie der Belastung auf die Versagenswahrscheinlichkeit getrennt zu ermitteln. Da das Verfahren primär von den zufälligen Verformungsgrößen und nicht von deren Verteilungsfunktionen ausgeht, besteht eine enge inhaltliche und methodische Beziehung zur herkömmlichen Vorgehensweise. Die Anwendung wird an zwei Stahltragwerken vorgestellt.
Die Kotlarski‐Brücke in Kraków
Authors: Majcherczyk B. , Mendera Z. , Pilujski B.
Published: April 2013

Es wird das Projekt der Stahlbogenbrücke über die Weichsel in Kraków mit einer Spannweite von 166 m beschrieben und deren Konstruktion vorgestellt.

Dabei werden Berechnungsmodelle, Belastungen und die angenommenen Imperfektionen in der Globalanalyse und des Versteifungssystems vorgestellt. Es werden Untersuchungsergebnisse von Grenzzuständen der Tragfähigkeit und der Nutzung von ausgewählten Elementen der Brücke erläutert, welche von den polnischen Normen gefordert werden; sie knüpfen an die europäischen Normen an. Weiterhin wird die Methode der Brückenmontage charakterisiert und die Ergebnisse der Probebelastung beschrieben. Es werden auch technische und ökonomische Betrachtungen angestellt und eine Zusammenfassung gegeben.
Aspekte der Montage von Stahlkonstruktionen in der Gegend von Szczecin
Authors: Gàsior J. , Zóltowski K.
Published: April 2013

Szczecin ist sowohl das historische als auch gegenwärtige Industrie‐ und Kulturzentrum von Westpommern. Die Stadt wurde direkt am Oderdelta erbaut, da der Fluß die Hauptschlagader des geschäftlichen Zentrums der Hansestadt war. Aus diesem Grund befinden sich der Hafen und die Werft unmittelbar im Zentrum der Stadt. Die Verkehrszunahme in und um Szczecin erforderte den Bau neuer Brücken.

So wurden in den letzten 16 Jahren einige Großbrücke aus Stahl errichtet. Dieser Aufsatz befaßt sich mit der Technologie der Montage von Brückenfeldern. In allen beschriebenen Fällen wurde ein ähnliches Montageverfahren verwendet, das aus drei Grundschritten besteht:

‐ Vorfertigung der Elemente in für den Transport geeigneten Abmessungen

‐ Montage der Grundelemente zum Gesamtsegment an einem zentralen Ort

‐ Transport des Gesamtsegments und Montage am Zielort.

Besondere Aufmerksamkeit gilt den objektiven, bei den Montagen auftretenden Randbedingungen und den theoretisch‐technischen Problemen.
Untersuchungen wetterfester Baustähle in Polen
Authors: Borkowski M. , Wlodarczyk W.
Published: April 2013

Wetterfeste Stähle und die daraus hergestellten Hüttenerzeugnisse werden in Polen seit über 40 Jahren produziert. Es wurde die Produktion wetterfester Stähle in zehn verschiedenen Klassen und Sorten eingeführt und verwendet. Dabei handelt es sich um niedriglegierte Baustähle mit erhöhter Luftkorrosionsbeständigkeit gemäß der polnischen Norm PN‐83/ B‐84017 und den Hüttenfertigungsbedingungen. Diese Rohstoffe werden in Polen in begrenztem Umfang z. B. beim Bau von Brücken, Straßenüberquerungen, Gittermasten für Freileitungen, Schornsteine sowie im Bergbau und der Hüttenindustrie eingesetzt.

Untersuchungen zur Eigenschaft von Hüttenerzeugnissen aus wetterfesten Stählen werden in Polen seit über 30 Jahren durchgeführt. Nach einer Übersicht der in Polen durchgeführten Untersuchungen werden die Untersuchungen der Verfasser vorgestellt. Analysiert wurden die Stähle 10HA, 12HJA, 12H1JA, 12PJA, 10HNAP im Vergleich zum Kohlenstoffstahl St3SX. Neben Felduntersuchungen wurden auch Laboruntersuchungen, Strukturanalysen der Korrosionsprodukte, Stoffuntersuchungen und statistische Analysen der mechanischen Eigenschaften von wetterfesten Stählen durchgeführt. Die eigenen Untersuchungen bestätigten die Anwendbarkeit wetterfester Stähle für den Stahlbau, auch unter spezifischen Bedingungen einer petrochemischen Atmosphäre.
Zur Ähnlichkeit der Drill‐ und Biegeträger‐Formeln für dünnwandige Stäbe
Authors: Cywinski Z.
Published: April 2013

Formelsätze für dünnwandige Stäbe bei konzentrierter Torsionsbelastung ‐ den Kragträger, den einfachen Träger und den beiderseits eingespannten Träger ‐ wurden schon früher für den Fall der Proportionalitätskonstante k ungleich 0 vom Verfasser erörtert. Dieser Beitrag behandelt die Formelsätze um den Fall k = 0 sowie die gegenseitigen Beziehungen zu k ungleich 0 aufgrund entsprechender Grenzbereiche. Eine Dualität dieser Formeln für ruhende und bewegliche Lasten wird unterstrichen. Ein Beispiel des Verfassers stellt die negativen und positiven Seiten diesbezüglicher Stahlbauforschung dar.
Der Messeturm in Rostock ‐ ein Tensegrityrekord
Authors: Schlaich M.
Published: April 2013

Der Messeturm in Rostock ist wohl der bisher höchste Tensegrity‐Turm. Dieser Artikel streift kurz die Geschichte von "tensional integrity" und beschreibt dann ausführlich Entwurf, Konstruktion und Berechnung dieses hoch vorgespannten leichten Seiltragwerkes. Ein weiterer Aufsatz wird auf die Fertigung und Montage des Turmes eingehen.
Interaktion von Membran und biegesteifen Bogentragwerken
Authors: Alpermann H. , Gengnagel Ch.
Published: April 2013

Die Möglichkeiten, komplexe interaktive Tragsysteme in numerischen Gesamtmodellen zu untersuchen, haben in den letzten Jahren eine sprunghafte Entwicklung erfahren. Das erlaubt insbesondere für Leichtbaukonstruktionen wie Membrantragwerke eine differenziertere Betrachtungsweise. Bisher wurden meist für Membran‐ und Stützkonstruktion Schnittgrößen und Verformungen getrennt ermittelt. Eine Berücksichtigung der Interaktion und damit die Möglichkeit, die Membran zur Stabilisierung der Stützkonstruktion einzusetzen, wurden vernachlässigt. Dabei bietet insbesondere für bogengestützte Membrantragwerke die Betrachtung des Gesamtsystems die Möglichkeit, den druckbeanspruchten und damit knickgefährdeten Bogen durch die Membran zu stabilisieren und damit effizientere Tragwerke zu entwerfen. Das Ziel der Untersuchung war es, den Einfluß der Membran auf eine Stabilisierung des Bogens abzuschätzen. Dabei wurde insbesondere die Abhängigkeit von der Membranform sowie der Steifigkeit des Bogens betrachtet.
Ausgewählte Probleme bei statischen Berechnungen von Seilkonstruktionen
Authors: Palkowski S.
Published: April 2013

Im Aufsatz werden ausgewählte und für die Baupraxis wichtige Probleme der statischen Berechnung von Seilkonstruktionen vorgestellt. Als erstes werden einzelne Seile mit horizontalen und schrägen Sehnen unter Wirkung von verschiedenen Lastfällen betrachtet. Die angegebenen Seilgleichungen können auch die elastisch‐plastischen Eigenschaften von Seilen berücksichtigen. Entsprechende Zahlenbeispiele zeigen die praktische Anwendungen dieser Seilgleichungen. Ferner werden räumliche Seilsysteme, wie beispielsweise die Flächenseilnetze, betrachtet. Die theoretische und praktische Problematik der Berechnung derartiger Seilkonstruktionen wird diskutiert. Die in dem Aufsatz besprochenen iterativen Methoden der statischen Analyse von Seilnetzen berücksichtigen sowohl die Knoten‐ als auch die Interknotenlasten.
Nichtlinearer Längskraft‐ und Biegemomentenverlauf in der Schraube vorgespannter L‐Flansche ‐ Näherungslösungen mit und ohne Iteration ‐ Teil 2
Authors: Lehmann D.
Published: April 2013

Längskraft und Biegemoment in der Schraube vorgespannter L‐Flansche unter Zugbelastung zeigen im Versuch einen nichtlinearen Verlauf. Für den elastischen Bereich werden für diese Verläufe nichtlineare Berechnungsverfahren auf der Grundlage der Theorie des elastisch gebetteten Balkens angegeben. Das bisher ausschließlich für die iterative Berechnung der Schraubenkraft angewandte Verfahren wird auf die Berechnung des Biegemomentes in der Schraube erweitert. Den Schwerpunkt der Betrachtungen bildet das analytische Vorgehen bei dicken Flanschen mit Hilfe eines Systems nichtlinearer Verfahren ohne Iteration. Die nichtlinearen Verläufe der Schraubenkraft und des Biegemomentes werden mit Versuchsergebnissen verglichen.
Ein Rechenverfahren von Verbundträgern mit Stegöffnungen ‐ Teil 2
Authors: Zhou D.
Published: April 2013

Ein Ingenieurmodell zur Berechnung der Tragfähigkeit von Verbundträgern mit Stegöffnungen wurde mit Anwendung des Traglastverfahrens hergeleitet. Die Herleitung erfolgte unter Ausnutzung der Gleichgewichtsbedingungen und ist leicht nachvollziehbar. Einige Beispiele wurden mit dem Rechenmodell berechnet. Dabei lassen sich die Tragfähigkeit und Tragverhalten anschaulich darstellen.
Das große Millimeterwellen‐Teleskop auf dem Cerro la Negra in Mexiko
Authors: Kärcher H. J.
Published: April 2013

Astronomische Institute aus Mexiko und Massachusetts errichten zur Zeit ein 50 m großes Radioteleskop auf dem Cerro la Negra in Mexiko. Es ist mit Hilfe einer "aktiven" Reflektorfläche zum Empfang von Millimeterwellen geeignet und wurde von einem spezialisierten Ingenieurteam von MAN Technologie in Mainz entwickelt. Der Beitrag berichtet von den stahlbaulichen Aspekten des Teleskopentwurfes.
Ein Näherungsverfahren zur Bemessung von Verbundstützen
Authors: Eggemann H.
Published: April 2013

Der Beitrag stellt ein einfaches Verfahren zur Dimensionierung und Bemessung von Verbundstützen vor, das auf dem vereinfachten Verfahren des Eurocode 4 beruht. Die plastische Querschnittstragfähigkeit wird als Produkt der Gesamtfläche und einer ideellen Grenzspannung berechnet. Der Faktor k zur Knickberechnung wird nicht mit der bezogenen Schlankheit nach Eurocode 4, sondern mit einer ideellen "geometrischen" Schlankheit ermittelt. Für alle Typen von Verbundstützen werden Hilfsmittel entwickelt, die das Berechnen der ideellen Schlankheit der Verbundstütze mit dem Trägheitsradius des Stahlprofils ermöglichen. In vielen Fällen ist die so errechnete Stützentragfähigkeit identisch mit dem Ergebnis nach Eurocode 4.
Sprengtechnisches Trennen von Stahl ‐ Verbesserung der Arbeitssicherheit bei Rückbauarbeiten
Authors: Loose T. , Saal H.
Published: April 2013

Die Funktionsweise des sprengtechnischen Trennens von Stahl mittels Schneidladungen bietet insbesondere hinsichtlich der Arbeitssicherheit Vorteile gegenüber anderen Trennverfahren. Anhand von Beispielen wird dazu dargelegt, in welchen Fällen Schneidladungen eingesetzt werden. Beim Einsatz der Sprengtechnik ist generell eine Gefährdung der Umgebung vorhanden. Dazu werden mögliche Schutzmaßnahmen und deren Wirksamkeit aufgezeigt.
Zur Berechnung von Stäben mit 3‐Blech‐Querschnitt unter Normalkraft, doppelter Biegung und Wölbkrafttorsion
Authors: Rubin H.
Published: April 2013

Für 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

The 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

The 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.
Comparing multistate expected damages, option price and cumulative prospect measures for valuing flood protection
Authors: Farrow Scott , Scott Michael
Published: April 2013

Key Points

The key choice is between non‐expected and expected utility measures.

Continuous event modeling is useful

The basic non‐expected utility value is less than the expected utility value
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

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

In 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

The 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

An 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

The 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

A 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.
Digital Identity: The Construction of Virtual Selfhood in the Indigenous Peoples' Movement
Authors: Niezen Ronald
Published: April 2013

Inventions have their greatest impact when they go beyond their possible practical applications and act upon the imagination. When Martin Behaim invented the first globe in 1490, a functionally useless object consisting mostly of terra incognita, he was widely ridiculed; but somehow the ideas that his globe represented stuck, and within a few decades the basic validity of his construction was confirmed by the voyages of Columbus, Cabot, Vasco de Gama, Magellan, and others. Today, with efforts to situate the rapid growth of information and communication technologies (ICTs), especially the Internet, in the context of globalization, there is a similar division between those who dismiss it as being of no importance and those who see in it a looming (for good or ill) global revolution. But, as with Behaim's globe, the imaginary possibilities of these innovations are important in determining how and to what extent human existence is to be transformed by them.
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

The 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

Human 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

Objective:

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.
Chronic rhinosinusitis assessment using the Adelaide Disease Severity Score
Authors: Naidoo Y , Tan N , Singhal D , Wormald P J
Published: April 2013

Aim:

This study aimed to validate the use of the Adelaide Disease Severity Score for the assessment of chronic rhinosinusitis.

Study design:

A prospective cohort study supplying level 2b evidence.

Methods:

Forty-eight patients, scheduled for endoscopic sinus surgery for failed management of chronic rhinosinusitis, completed the Sino-Nasal Outcome Test 22 and the Adelaide Disease Severity Score tool (the latter assessing symptoms (i.e. nasal obstruction, rhinorrhoea, post-nasal drip, headache or facial pain, and olfaction) and quality of life). Lund–Mackay computed tomography scores and Lund–Kennedy endoscopic scores were also recorded. The Adelaide Disease Severity Score results were then compared with those of the other three tools to assess correlation.

Results:

Mean scores (95 per cent confidence intervals) were 22.31 (21.47–24.15) for the Adelaide Disease Severity Score and 30.6 (27.15–34.05) for the Sino-Nasal Outcome Test 22; there was a statistically significant correlation (Spearman coefficient = 0.45; p = 0.0015). A statistically significant correlation was also noted with the Lund–Mackay score (p = 0.04) and with the Lund–Kennedy score (p = 0.03).

Conclusion:

The Adelaide Disease Severity Score is a simple, valid tool for clinical assessment of chronic rhinosinusitis, which correlates well with the Sino-Nasal Outcome Test 22, Lund–Mackay and Lund–Kennedy tools.
Multiscale structures in a two-temperature relativistic electron-positron-ion plasma
Authors: IQBAL M. , SHUKLA P. K.
Published: April 2013

A relativistically hot electron, positron and ion (e–p–i) plasma relaxes to a triple curl Beltrami (TCB) field. The TCB field being the superposition of three Beltrami fields is characterized by three scale parameters and hence there exist multiscale structures in the system. It is shown that temperatures of the plasma constituents strongly affect the scale parameters. Generally, the scale parameters associated with the TCB field may be a combination of real and complex roots. The numerical results show that for given Beltrami parameters, an increase in the thermal energy of plasma particles could transform the real eigenvalues to complex ones. It is also observed that one component is more strongly affected relative to other components on increasing temperatures of plasma species. Two different vortices become the same at higher thermal energies. This suggests that it is possible to create high β (kinetic to magnetic pressure ratio) and fully diamagnetic plasma configurations. The study has a potential relevance to space, astrophysics and laboratory plasmas.
On the articulatory classification of (alveolo)palatal consonants
Authors: Recasens Daniel
Published: April 2013

Linguopalatal and sagittal vocal tract configuration data from a large number of languages reveal that the so-called palatal consonants (i.e. [ç ʎ c ɲ j]), as well as the vowel [i], are often realized simultaneously at the alveolar and palatal zones. Moreover, while some of these sound categories may also exhibit a palatal constriction ([ç c ɲj i]), others are exclusively alveolar or alveolopalatal in line with the manner of articulation characteristics involved ([ʎ], also [ɕ] and [tʃ]). Consonants may favor one or more places of articulation and differ in fronting degree depending on the language taken into consideration; moreover, there appears to be a symmetry requirement by which consonants differing in manner, such as [c] and [ɲ], may agree in place. The data reported in this paper argue in favor of a revision of the articulatory classification of palatal consonants by the International Phonetic Alphabet involving their subdivision into two classes, an alveolopalatal and a palatal one.
Differences in EPG contact dynamics between voiced and voiceless lingual fricatives
Authors: Liker Marko , Gibbon Fiona E.
Published: April 2013

Achieving voicing during fricatives is complex because voicing and frication require opposite production strategies that must be managed effectively at the supralaryngeal level. Previous research has suggested that there are differences in tongue-to-palate contact patterns that are conditioned by voicing. However, findings have been restricted to a single time point and have been generally inconclusive. This study used electropalatography (EPG) to investigate differences in the dynamics of contact in voiced and voiceless lingual fricatives. Participants were six typically speaking Croatian adults. The speech material consisted of symmetrical VCV sequences, where C was /s zʃ ʒ/. EPG measures were taken throughout the fricatives and indices were used to quantify place of articulation (CoG), groove width and target configuration onset. The EPG measures showed similar results for voiced and voiceless fricatives during their central portions. However, there were notable differences at the periphery of the fricative period, the most significant being that the voiceless fricatives reached a stable period in terms of tongue placement and groove configuration later than the voiced fricatives. The results support aerodynamic evidence that voiced and voiceless fricatives differ in the onset and the offset of turbulence.
Bodywork in dementia care: recognising the commonalities of selfhood to facilitate respectful care in institutional settings
Authors: KELLY FIONA
Published: April 2013

This paper draws on two data sources (Kelly's ethnographic study and a British Broadcasting Corporation television programme) to explore the practice of bodywork in the care of frail people with dementia in institutional settings. It explores the complexity of engaging in bodywork, particularly work that is distasteful to the care-worker, and shows how non-recognition of the selfhood of the person with dementia can result in practices that are demeaning and potentially abusive to those in receipt of such work. In contrast to a person-centred approach that urges practitioners to acknowledge people with dementia as unique individuals, with unique needs, wishes, abilities and desires, this paper argues for the use of Sabat's Selfs 1–3 construct to look for commonalities of selfhood, enabling care workers to recognise aspects of themselves in their patients as they carry out care, thereby facilitating care that empathically respects their patients' dignity and potential for vulnerability. Thus, it aims to advance theory and improve practice by arguing for the necessity of putting selfhood at the forefront of bodywork in order to facilitate respectful care that dignifies rather than objectifies the person.
Parameterization of clear sky effective emissivity under surface-based temperature inversion at Dome C and South Pole, Antarctica
Authors: Busetto Maurizio , Lanconelli Christian , Mazzola Mauro , Lupi Angelo , Petkov Boyan , Vitale Vito , Tomasi Claudio , Grigioni Paolo , Pellegrini Andrea
Published: April 2013

For most parts of the year the Antarctic Plateau has a surface temperature inversion with strength c. 20 K. Under such conditions the warmer air at the top of the inversion layer contributes more to the clear sky atmospheric longwave radiation at surface level than does the colder air near the ground. Hence, it is more appropriate to relate longwave irradiance (LWI) to the top of the inversion layer temperature (Tm) than to the ground level temperature (Tg). Analysis of radio soundings carried out at Dome C and South Pole during 2006–08 shows that the temperature at 400 m above the surface (T400) is a good proxy for Tm and is linearly related to Tg with correlation coefficients greater than 0.8. During summer, radiosonde measurements show almost isothermal conditions, hence T400 still remains a good proxy for the lower troposphere maximum temperature. A methodology is presented to parameterize the clear sky effective emissivity in terms of the troposphere maximum temperature, using ground temperature measurements. The predicted LWI values for both sites are comparable with those obtained using radiative transfer models, while for Dome C the bias of 0.8 W m-2 and the root mean square (RMS) of 6.2 W m-2 are lower than those calculated with previously published parametric equations.
Equity in mental health
Authors: Mangalore Roshni , Knapp Martin
Published: April 2013

Aim– The aim of this paper is to discuss the study of equity in mental health contexts.Methods– We review major principles and theories of distributive justice, covering various disciplines such as ethics, philosophy, economics, medicine and sociology. Recent literature on empirical analysis of inequalities in the mental health field is also reviewed.Results– The review of literature reveals a general lack of debate on equity principles in relation to mental health. Robust empirical evidence on inequalities in the field is also scarce.Conclusions– There is need for better exposition of the relevance of different equity principles for mental health policy and practice. There is also a need for developing standardised methods for the empirical analysis of equity, to examine the distribution of psychiatric morbidity and use of services by income, socioeconomic group, ethnicity, gender and place of residence, and, of course, to examine how equity can be promoted.

Declaration of Interest: This work was funded by the Department of Health programme grant to the PSSRU.
Cognitive Change in Newly-Diagnosed Patients with Parkinson's Disease: A 5-Year Follow-up Study
Authors: Broeders Mark , Velseboer Daan C. , de Bie Rob , Speelman Johannes D. , Muslimovic Dino , Post Bart , de Haan Rob , Schmand Ben
Published: April 2013

Cognitive change is frequently observed in patients with Parkinson's disease (PD). However, the exact profile and extent of cognitive impairments remain unclear due to the clinical heterogeneity of PD and methodological issues in many previous studies. In this study, we aimed to examine the severity, frequency, and profile of cognitive changes in newly diagnosed PD patients over 5 years. At baseline and after 3 and 5 years, a hospital-based sample of PD patients (n = 59) and healthy controls (n = 40) were given neuropsychological tests covering six cognitive domains. Patients showed greater decline over time than healthy controls on all cognitive domains, except for attention. The profile of decline showed that psychomotor speed and memory were most affected. At the individual level 53% of the patients showed more cognitive decline than controls. Age at onset and memory impairment at baseline predicted cognitive decline. Cognitive functions in PD patients show greater decline in most domains than in healthy elderly over the course of 5 years. Due to selection bias as a result of attrition, the actual degree of decline may be greater than reported here. (JINS, 2013, 19, 1–14)
The roles of civil society in the development of standards around new weapons and other technologies of warfare
Authors: Rappert Brian , Moyes Richard , Crowe Anna , Nash Thomas
Published: April 2013

This article considers the role of civil society in the development of new standards around weapons. The broad but informal roles that civil society has undertaken are contrasted with the relatively narrow review mechanisms adopted by states in fulfilment of their legal obligations. Such review mechanisms are also considered in the context of wider thinking about processes by which society considers new technologies that may be adopted into the public sphere. The article concludes that formalized review mechanisms, such as those undertaken in terms of Article 36 of Additional Protocol I (1977) of the Geneva Conventions of 1949, should be a focus of civil society attention in their own right as part of efforts to strengthen standard-setting in relation to emerging military technologies.
The long and winding helix
Authors: Jacobs Howy
Published: April 2013

Molecular biology celebrates its diamond jubilee this month, the 60th anniversary of the publication of Watson and Crick's seminal paper on the structure of DNA. It's an appropriate moment to ask how far the subject has come, and where we are headed.
Loneliness at the bench
Authors: Brown Paige
Published: April 2013

Many PhD students suffer from loneliness, but is the experience character building, or can it have long‐lasting psychological or physical health effects?