bluuebunny/crossref_metadata_2025 huggingface dataset:
A numerical study of the thermally induced stress distribution in a rotating hollow disc heated by a moving heat source acting on one of the side surfaces
Authors: Genç M S , Özşik G , Yapicr H
Published: April 2009

This study presents the effects of a moving heat source (MHS) on a rotating hollow steel disc heated from its one side surface under stagnant ambient conditions. As the disc rotates around the z-axis with a constant angular speed Ω, the heat source moves along from one radial segment to the next radial segment in the radial direction on the processed surface at the end of each revolution of the disc. Three-dimensional (3D) numerical calculations are performed individually for a wide range of thermal conductivity λ of steel and for different Ωs. In order to obtain the thermal stress per heat flux intensity q0, it is assumed that the thermo-physical properties of the disc do not change with temperature. The maximum effective thermal stress ratio varies in the range of 22–134 °C depending on λ and Ω. While the MHS passes from one radial segment to the next radial segment, it causes an additional steeping of the effective thermal stress. However, when the values of λ and Ω are increased, the maximum effective thermal stress ratio can be reduced by a considerable amount.
Assessment of residence time in a hydrodynamic vortex separator by applying distribution models
Authors: O'Doherty T , Egarr D A , Faram M G , Guymer I , Syred N
Published: April 2009

A number of models exist to simulate the residence time distribution (RTD) of a system or process. Four of these models known as the tanks in series model, axial dispersion model (ADM), aggregated dead zone model, and the advection dispersion equation, have been used to assess which is most suitable for representing the RTD of a hydrodynamic vortex separator (HDVS) when compared to RTD measurements taken under laboratory conditions on a full-scale 3.4 m diameter unit. Computational fluid dynamics (CFD) is also used to model the HDVS and compare with the RTD models and experimental measurements. It has been shown that the fit by each of the RTD models to observed RTDs vary quite considerably, with the ADM being the most appropriate for the HDVS studied, based on having the highest R t2 value. Given the number of model variables that influence CFD predictions, the outputs from the CFD models appear to be reasonable.
An investigation into the effects of track structural conditions on railway track geometry deviations
Authors: Sadeghi J , Askarinejad H
Published: April 2009

Track geometry, consisting of several parameters, is the main factor influencing the ride quality and track performance. Railway authorities are spending considerably to maintain track geometry conditions within acceptable tolerance. Optimization of this expenditure requires a thorough investigation into the track structural factors influencing the conditions of track geometry. The current methods of track inspection are based on automated inspection of track geometry conditions, using track-recording cars. These methods have their limitations in identifying track structural defects, and in turn, lack the recognition of the causes of track geometry problems. There is a need to develop a track structural inspection and to investigate the relationship between track structural defects and track geometry problems. This research is an attempt to response to this need. The most dominant observable track structural distresses were studied, a track structural inspection method was proposed, and track structural conditions were quantified. A technique was developed to correlate track structural defects to track geometry problems. This technique was applied to tracks with various conditions, carrying out a comprehensive field investigation. The results obtained were analysed to identify the role of each track component on track geometry deviations, and in turn, develop correlations between track structural quality and track geometry conditions.
Experimental and numerical aspects of simulating unsteady flows around the X-31 configuration
Authors: Schütte A , Rein M , Höhler G
Published: April 2009

The procedure of realizing aerodynamic aspects of experimental and numerical manoeuvre simulations of a fighter aircraft will be presented. The work is part of the DLR (Deutsches Zentrum für Luft- und Raumfahrt, German Aerospace Center) Project SikMa-‘Simulation of Complex Maneuvers’. In this project the X-31 configuration is used as a target configuration for numerical and experimental manoeuvre simulations. The numerical aerodynamic investigations using the DLR TAU-Code are part of an objective to develop and validate a numerical tool for simulating the unsteady aerodynamics of a free flying aeroelastic combat aircraft, by use of coupled aerodynamic, flight mechanics, and aeroelastic computations. In order to obtain a database for validation of the aerodynamic methods within the project, ground-based simulations of complex manoeuvres of a model of the X-31 aircraft have been performed in the low-speed wind tunnel NWB of the German-Dutch Wind Tunnels DNW. In the wind tunnel tests a newly installed, novel test rig with six degrees of freedom (DOF) was used for the first time. The focus of the article is on the validation process of steady and unsteady guided manoeuvre simulations of the X-31 configuration. Experimental and numerical requirements are discussed based on experimental and numerical results. Lessons learned and directions for future investigations are provided.
Example of integrated computational fluid dynamics and experimental studies: Design of flow control in the FOI-EIC-01 inlet
Authors: Jirásek A
Published: April 2009

This article describes a portion of the Propulsion Integration project that deals with the design and optimization of the flow control in the FOI-EIC-01 inlet. It uses both computational fluid dynamics (CFD) and wind tunnel testing in a way that both disciplines strongly interact with each other. Both the wind tunnel and CFD produce inputs for its counterpart and use outputs produced by their counterpart. The main chain of events during the design is the initial CFD analysis followed by the wind tunnel test and final CFD analysis.
Experimental and computational investigation of an ‘open’ transonic cavity flow
Authors: Atvars K , Knowles K , Ritchie S A , Lawson N J
Published: April 2009

This paper presents an investigation of a transonic flow ( M∞=0.85) over a rectangular cavity having a length-to-depth ratio of 5. Velocities were measured inside the cavity on the central plane and two off-centre planes using a two-component particle image velocimetry system. These measurements were supported by surface flow visualization, and mean and time-varying surface pressure measurements. The flow was also simulated using an unsteady Reynolds-averaged Navier—Stokes code, with a realizable k — ε turbulence model. It is shown that this CFD model does not capture all the characteristics of the flowfield correctly. However, by using this integrated experimental and computational approach we have been able to identify three-dimensional flowfield structures within the cavity. The influence of the thickness of the approaching boundary layer is discussed.
Assessment of common hyperelastic constitutive equations for describing normal and osteoarthritic articular cartilage
Authors: Brown C P , Nguyen T C , Moody H R , Crawford R W , Oloyede A
Published: April 2009

With the aim of providing information for modelling joint and limb systems, widely available constitutive hyperelastic laws are evaluated in this paper for their ability to predict the mechanical responses of normal and osteoarthritic articular cartilage. Load—displacement data from mechanical indentation were obtained for normal and osteoarthritic cartilage at 0.1 s−1 and 0.025 s−1 and converted to the stress—stretch ratio. The data were then fitted to the ArrudA—Boyce, Mooney—Rivlin, neo-Hookean, Ogden, polynomial, and Yeoh hyperelastic laws in the MATLAB environment. Although each of the hyperelastic laws performed satisfactorily at the higher rate of loading, their ability to fit experimental data at the lower loading rate varied considerably. For the preferred models, coefficients were provided for stiff, soft, and average tissues to represent normal and degraded tissue at high and low loading rates. The present authors recommend the use of the Mooney—Rivlin or the Yeoh models for describing both normal and degraded articular cartilage, with the Mooney—Rivlin model providing the best compromise between accuracy and required computational power.
Simultaneous estimation of two bending vibration frequencies for attitude control of a flexible launch vehicle
Authors: Khoshnood A M , Roshanian J , Jafari A A , Khaki-Sedigh A
Published: April 2009

Current developments in the aerospace flight devices have led to a control system being designed in the presence of elastic behaviour. However, there are several ways to reduce the destructive effects of vibration in flexible systems. In this paper, a practical approach called ‘rigid model reference’ is extended to two vibration modes based on the gradient method. Furthermore, the existence of two dominant bending vibration modes in the output of measurement devices leads to a redesign of the control system. Robust stability of the new algorithm is investigated by using Kharitonov theorem. Simulation results illustrate considerable reduction of vibration effects on the output of measurement system considering the first and the second bending vibration modes.
Non-linear dynamic behaviour of compound planetary gear trains: Model formulation and semi-analytical solution
Authors: Al-Shyyab A , Alwidyan K , Jawarneh A , Tlilan H
Published: April 2009

A discrete, non-linear, time-varying, torsional dynamic model of a multi-stage planetary train that is formed by any number of simple planetary stages is proposed in this study. Each planetary stage has a distinct fundamental mesh frequency and any number of planets spaced in any angular positions. The model allows the analysis of the gear train in all possible power flow configurations suitable for various gear drive ratios. It includes periodic variation of gear mesh stiffnesses as well as clearance (backlash) non-linearities that allow tooth separations. Equations of motion for the general case are formulated and solved semi-analytically using a hybrid harmonic balance method (HBM) in conjugate with inverse Fourier transform. Relative mesh displacements along lines of action of individual gear pairs were used as the continuation parameters to pass singular points and ill-conditioned equations in their proximity. At the end, a case study of a two-stage planetary train is used to demonstrate the effectiveness of the model and solution methods. The HBM solutions are compared to those obtained by a direct numerical integration method to assess their accuracy.
Large eddy simulation modelling of spray-induced turbulence effects
Authors: Bharadwaj N , Rutland C J , Chang S
Published: April 2009

This study is focused on the development of spray models for large eddy simulations (LESs) of high injection pressure diesel sprays. Basic governing equations are numerically solved using the Lagrangian—Eulerian approach for liquid and gas phases respectively, in the KIVA-3V code. Non-reacting simulations of evaporating spray are performed using a dynamic structure LES model in which the subgrid stress tensor is modelled with a non-viscosity tensor coefficient. This is a one equation based model, in which an extra transport equation for the subgrid kinetic energy ( k) is solved. Subgrid scale energy exchange between droplets and the gas phase is identified as an important mechanism to capture the correct scaling of k, which eventually feeds back to both the spray droplets and the gas phase turbulent mixing. Hence, to account for spray-induced gas turbulence, a LES spray source model for k is developed. This model requires subfilter scale velocities, which are obtained by defiltering the filtered velocity field available from LES. Results are compared with corresponding RANS results and available experimental data for various physical spray variables such as spray penetration, gas phase penetration, droplet distribution, etc. The LES spray model was found to be important in predicting the correct liquid spray evolution and responds correctly to varying parameters such as nozzle size and ambient density.
Residual gas homogeneity measurements
Authors: Ghandhi J B , Bright A G , Herold R E
Published: April 2009

Planar laser-induced fluorescence (PLIF) of a dopant added to the fuel, which was well mixed with the intake air upstream of the engine, was used to investigate inhomogeneities that arise from the incomplete mixing of the intake charge with the residual gas left in the cylinder from the previous cycle. The residual gas fraction was independently measured using a fast-acting solenoid valve and a cylinder dumping technique. The experiments were performed on a four-stroke homogeneous-charge spark-ignition engine operating at light load. The PLIF data were shot-noise-limited, permitting filtering to reduce some noise artefacts; and to further reduce system-induced biases associated with pulse-to-pulse laser variations the data were ray-mean-normalized, i.e. normalized by the mean of the data along the laser propagation direction. The filtered results had excellent noise characteristics, with a signal-to-noise ratio in excess of 50:1, and allowed the low levels of mixture unmixedness to be identified. The fresh charge was found to exhibit inhomogeneities up to 30° before top dead centre, the latest time investigated. The second moment of the ray-mean-normalized intensity distribution was found to be relatively insensitive to the total residual fraction up to a residual fraction of approximately 30 per cent, having a value of ∼0.04. At higher levels of residual there was a monotonic increase in the intensity distribution's second moment.
Virtual design of a novel two-stroke high-speed direct-injection diesel engine
Authors: Mattarelli E
Published: April 2009

The paper reviews the virtual design process of an automotive high-speed direct-injection (HSDI) two-stroke diesel engine, developed at the Department of Mechanical and Civil Engineering (DIMeC) of the University of Modena and Reggio Emilia. The new concept of the engine is the tumble-supported and spray-controlled combustion system, which enables the adoption of loop scavenging without valves, and the use of a very simple and compact combustion chamber, carved in the engine head.

The concept has been applied to a three-cylinder engine, with a capacity of 1050 cm3, supercharged by means of a Roots compressor and a variable geometry turbocharger. Some alternative configurations have been defined. Integrated one-dimensional and multidimensional computational fluid dynamics (CFD) simulations have been performed in order to optimize the main engine parameters, as well as to predict brake performance and emissions, in comparison with a reference four-stroke automobile diesel engine.

Simulation results demonstrate the potential of the concept, which may be applied to develop a new generation of ultra-compact and clean automotive diesel engines.
Specific and global regulation of mRNA stability during osmotic stress in Saccharomyces cerevisiae
Authors: Romero-Santacreu Lorena , Moreno Joaquín , Pérez-Ortín José E. , Alepuz Paula
Published: April 2009

Hyperosmotic stress yields reprogramming of gene expression in Saccharomyces cerevisiae cells. Most of this response is orchestrated by Hog1, a stress-activated, mitogen-activated protein kinase (MAPK) homologous to human p38. We investigated, on a genomic scale, the contribution of changes in transcription rates and mRNA stabilities to the modulation of mRNA amounts during the response to osmotic stress in wild-type and hog1 mutant cells. Mild osmotic shock induces a broad mRNA destabilization; however, osmo-mRNAs are up-regulated by increasing both transcription rates and mRNA half-lives. In contrast, mild or severe osmotic stress in hog1 mutants, or severe osmotic stress in wild-type cells, yields global mRNA stabilization and sequestration of mRNAs into P-bodies. After adaptation, the absence of Hog1 affects the kinetics of P-bodies disassembly and the return of mRNAs to translation. Our results indicate that regulation of mRNA turnover contributes to coordinate gene expression upon osmotic stress, and that there are both specific and global controls of mRNA stability depending on the strength of the osmotic stress.
Small RNA analysis in Petunia hybrida identifies unusual tissue-specific expression patterns of conserved miRNAs and of a 24mer RNA
Authors: Tedder Philip , Zubko Elena , Westhead David R. , Meyer Peter
Published: April 2009

Two pools of small RNAs were cloned from inflorescences of Petunia hybrida using a 5′-ligation dependent and a 5′-ligation independent approach. The two libraries were integrated into a public website that allows the screening of individual sequences against 359,769 unique clones. The library contains 15 clones with 100% identity and 53 clones with one mismatch to miRNAs described for other plant species. For two conserved miRNAs, miR159 and miR390, we find clear differences in tissue-specific distribution, compared with other species. This shows that evolutionary conservation of miRNA sequences does not necessarily include a conservation of the miRNA expression profile. Almost 60% of all clones in the database are 24-nucleotide clones. In accordance with the role of 24mers in marking repetitive regions, we find them distributed across retroviral and transposable element sequences but other 24mers map to promoter regions and to different transcript regions. For one target region we observe tissue-specific variation of matching 24mers, which demonstrates that, as for 21mers, 24mer concentrations are not necessarily identical in different tissues. Asymmetric distribution of a putative novel miRNA in the two libraries suggests that the cloning method can be selective for the representation of certain small RNAs in a collection.
DOCK 6: Combining techniques to model RNA–small molecule complexes
Authors: Lang P. Therese , Brozell Scott R. , Mukherjee Sudipto , Pettersen Eric F. , Meng Elaine C. , Thomas Veena , Rizzo Robert C. , Case David A. , James Thomas L. , Kuntz Irwin D.
Published: April 2009

With an increasing interest in RNA therapeutics and for targeting RNA to treat disease, there is a need for the tools used in protein-based drug design, particularly DOCKing algorithms, to be extended or adapted for nucleic acids. Here, we have compiled a test set of RNA–ligand complexes to validate the ability of the DOCK suite of programs to successfully recreate experimentally determined binding poses. With the optimized parameters and a minimal scoring function, 70% of the test set with less than seven rotatable ligand bonds and 26% of the test set with less than 13 rotatable bonds can be successfully recreated within 2 Å heavy-atom RMSD. When DOCKed conformations are rescored with the implicit solvent models AMBER generalized Born with solvent-accessible surface area (GB/SA) and Poisson–Boltzmann with solvent-accessible surface area (PB/SA) in combination with explicit water molecules and sodium counterions, the success rate increases to 80% with PB/SA for less than seven rotatable bonds and 58% with AMBER GB/SA and 47% with PB/SA for less than 13 rotatable bonds. These results indicate that DOCK can indeed be useful for structure-based drug design aimed at RNA. Our studies also suggest that RNA-directed ligands often differ from typical protein–ligand complexes in their electrostatic properties, but these differences can be accommodated through the choice of potential function. In addition, in the course of the study, we explore a variety of newly added DOCK functions, demonstrating the ease with which new functions can be added to address new scientific questions.
Mobility, Skills, and the Michigan Non-Compete Experiment
Authors: Marx Matt , Strumsky Deborah , Fleming Lee
Published: April 2009

Whereas a number of studies have considered the implications of employee mobility, comparatively little research has considered institutional factors governing the ability of employees to move from one firm to another. This paper explores a legal constraint on mobility—employee non-compete agreements—by exploiting Michigan's apparently inadvertent 1985 reversal of its non-compete enforcement policy as a natural experiment. Using a differences-in-differences approach, and controlling for changes in the auto industry central to Michigan's economy, we find that the enforcement of non-competes indeed attenuates mobility. Moreover, non-compete enforcement decreases mobility more sharply for inventors with firm-specific skills and for those who specialize in narrow technical fields. The results speak to the literature on employee mobility while offering a credibly exogenous source of variation that can extend previous research on the implications of such mobility.
Distinct Features of Angioimmunoblastic T-Cell Lymphoma With Bone Marrow Involvement
Authors: Cho Young-Uk , Chi Hyun-Sook , Park Chan-Jeoung , Jang Seongsoo , Seo Eul-Ju , Huh Jooryung
Published: April 2009

We retrospectively reviewed the clinical and laboratory data and bone marrow (BM) histomorphologic features in 33 angioimmunoblastic T-cell lymphoma (AITL) cases. Paraffin-embedded BM core biopsy specimens were reacted immunohistochemically with antibodies to pan–T-cell markers, CD20, CD10, CD21, and bcl-6. The frequency of BM involvement was 70% (23/33). The following features were more significant in patients with than without BM involvement: fever, hepatosplenomegaly, pleural effusion, elevated lactate dehydrogenase level, hypoalbuminemia, hyponatremia, hypocalcemia, anemia, circulating atypical cells, hypercellular marrow, and plasmacytosis in the BM. Morphologic features included nodular or interstitial infiltration in a paratrabecular distribution, periodic acid–Schiff–positive intercellular materials, mixed infiltrates of T and B cells, presence of clear cells, and blood vessel proliferation. Immunohistochemical assays revealed that CD5, bcl-6, and CD10 were useful markers of BM infiltration. Seven cases with BM involvement were interpreted as negative for lymphoma initially, mainly owing to insufficient information in nodal biopsy specimens. Several clinical and laboratory features indicate BM involvement of AITL at diagnosis. Laboratory physicians should be more familiar with BM histomorphologic and immunophenotypic characteristics suggesting AITL infiltration to make accurate diagnoses even without prior nodal biopsies.
Results of an External Proficiency Testing Exercise on Platelet Dense-Granule Deficiency Testing by Whole Mount Electron Microscopy
Authors: Hayward Catherine P.M. , Moffat Karen A. , Spitzer Ernie , Timleck Marnie , Plumhoff Elizabeth , Israels Sara J. , White James ,   on behalf of the NASCOLA Working Group on Platelet Dense Granule Deficiency
Published: April 2009

Performance on specialized diagnostic tests for platelet disorders, including dense-granule deficiency, is rarely evaluated by external quality assessment (EQA). Members of the North American Specialized Coagulation Laboratory Association that evaluate platelet dense-granule deficiency commonly use whole-mount electron microscopy (EM) methods. This observation led us to develop a pilot EQA survey with standardized EM images and clinical samples on grids from a healthy control subject and a subject with dense-granule deficiency. The survey participants were 8 centers, including 2 with no experience in platelet whole mount EM. All participants, including inexperienced sites, correctly interpreted findings for the normal and dense-granule-deficient platelets. Among experienced sites, agreement was excellent (>82%) on platelet structures to count or not count as dense granules. Participants indicated that future EQA challenges should include clinical samples on grids and standardized images. This is the first report that platelet EM can be assessed by EQA.
Constraints on Sustainable Energy Consumption: Market System and Public Policy Challenges and Opportunities
Authors: Press Melea , Arnould Eric J.
Published: April 2009

The purpose of this essay is to identify factors that constrain customers’ ability to engage in sustainable energy consumption, conceived of as a consumption practice that reduces the moral hazards associated with fossil fuel overconsumption. The authors outline some marketing policy and consumer research issues related to the market system and identify four constraints to sustainable energy consumption: policies and regulation, product accessibility and availability, pricing, and customer knowledge. This topic is important because of changes in the macro context of energy consumption—namely, the growing recognition of a fundamentally resource-constrained environment and the increased salience of various global commons effects to customers. The authors conclude with directions for further research.
Marketing to the Poor: An Integrative Justice Model for Engaging Impoverished Market Segments
Authors: Santos Nicholas J.C. , Laczniak Gene R.
Published: April 2009

The relatively recent entry of multinational corporations (MNCs) into low-income markets, particularly in developing countries, affords the opportunity for the more inclusive capitalism envisioned by globalists. Alternatively, an expansion of MNC marketing in less developed economies might foreshadow the greater exploitation of disadvantaged consumers predicted by many critics of expanded free trade. To diffuse the charge of “exploitative” marketing, it is imperative that corporate marketing efforts seeking to engage impoverished segments be grounded in a strong ethical framework. This article unveils one such framework—the “integrative justice model” (IJM). The IJM is an aspirational model that outlines how to market ethically to disadvantaged consumers in both developed and developing countries. The authors derive the elements of this model from frameworks of moral philosophy and management theory. Although the IJM is normative in nature, the authors connect it to real-world examples, which provides MNCs that market to the poor practical benchmarks for conducting their business operations with fairness and equity. The article concludes with a discussion of the implications of the IJM for public policy.
Designing Marketplace Literacy Education in Resource-Constrained Contexts: Implications for Public Policy and Marketing
Authors: Viswanathan Madhubalan , Sridharan Srinivas , Gau Roland , Ritchie Robin
Published: April 2009

This article describes the findings of an immersive program of field research on consumers living in poverty in South India and the lessons learned from the development and operation of educational interventions designed to enhance the marketplace literacy of these consumers. Whereas extant research and practice have traditionally addressed two key factors that facilitate market participation for the poor—market access and financial resources—the current research focuses on a third critical and complementary factor—namely, marketplace literacy. The authors contend that to sustainably benefit from enhanced market access and resources, (1) people living in subsistence conditions need to develop tactical or procedural knowledge, or concrete “know-how,” regarding how to be an informed consumer or seller, and (2) this know-how must be grounded in conceptual/strategic knowledge, or “know-why” understanding, of marketplace exchanges. To that end, the educational program outlined begins by familiarizing participants with the purpose and logic of marketplaces and then transitions to the tangible aspects of how these marketplaces function. The article concludes with reflection on the implications for consumer policy, marketing research, and business practice.
The Fast and Slow Afterhyperpolarizations Are Differentially Modulated in Hippocampal Neurons by Aging and Learning
Authors: Matthews Elizabeth A. , Linardakis John M. , Disterhoft John F.
Published: April 2009

Normal aging is usually accompanied by increased difficulty learning new information. One contributor to aging-related cognitive decline is decreased intrinsic excitability in aged neurons, leading to more difficulty processing inputs and remodeling synapses to store new memories. Two measures of excitability known to be altered by learning are the slow afterhyperpolarization (sAHP) after a burst of action potentials and the fast AHP (fAHP) after individual action potentials. Using rats trained in trace eyeblink conditioning, we examined how these two measures of excitability were modulated in CA1 hippocampal neurons from young (3–4 months) and aged (29–31 months) animals. Although both the sAHP and the fAHP were reduced by successful learning in both age groups, only the sAHP showed aging-related increases. The dichotomy of learning-related and aging-related effects on two very similar calcium-dependent potassium-driven hyperpolarizations suggests several interesting hypotheses for how cellular excitability is modulated by aging and learning.
Direct and Indirect Connections with Upper Limb Motoneurons from the Primate Reticulospinal Tract
Authors: Riddle C. Nicholas , Edgley Steve A. , Baker Stuart N.
Published: April 2009

Although the reticulospinal tract is a major descending motor pathway in mammals, its contribution to upper limb control in primates has received relatively little attention. Reticulospinal connections are widely assumed to be responsible for coordinated gross movements primarily of proximal muscles, whereas the corticospinal tract mediates fine movements, particularly of the hand. In this study, we used intracellular recording in anesthetized monkeys to examine the synaptic connections between the reticulospinal tract and antidromically identified cervical ventral horn motoneurons, focusing in particular on motoneurons projecting distally to wrist and digit muscles. We found that motoneurons receive monosynaptic and disynaptic reticulospinal inputs, including monosynaptic excitatory connections to motoneurons that innervate intrinsic hand muscles, a connection not previously known to exist. We show that excitatory reticulomotoneuronal connections are as common and as strong in hand motoneuron groups as in forearm or upper arm motoneurons. These data suggest that the primate reticulospinal system may form a parallel pathway to distal muscles, alongside the corticospinal tract. Reticulospinal neurons are therefore in a position to influence upper limb muscle activity after damage to the corticospinal system as may occur in stroke or spinal cord injury, and may be a target site for therapeutic interventions.
Kainate Receptors Act as Conditional Amplifiers of Spike Transmission at Hippocampal Mossy Fiber Synapses
Authors: Sachidhanandam Shankar , Blanchet Christophe , Jeantet Yannick , Cho Yoon H. , Mulle Christophe
Published: April 2009

Hippocampal mossy fiber (Mf) synapses are viewed as conditional detonators, assisting CA3 cells in complex network functions. By analyzing mice deficient for GluK2 (GluR6), GluK3 (GluR7) and GluK5 (KA2) genes we show that kainate receptors (KARs) play a crucial role in the control of synaptic integration and spike transmission efficacy at Mf synapses. We dissected out the role of the different KAR functions at Mf synapses and we show that presynaptic and postsynaptic KARs concur to amplify unitary Mf synaptic inputs to trigger spike discharge within a wide range of frequencies (from 1 to 50 Hz). Moreover, KARs strongly favor spike transmission in response to patterns of presynaptic activity mimickingin vivodentate granule cell activity. By amplifying spike transmission, KARs also facilitate the induction of associative long-term potentiation in CA3. Hence the actions of KARs as amplifiers of spike transmission contribute largely to the “conditional detonator” function of Mf synapses and are likely important for spatial information processing.
Touchscreen ohne Touch – Berührungslose 3D Gesten-Interaktion für den OperationssaalTouchscreen without Touch – Touchless 3D Gesture Interaction for the Operation Room
Authors: Penne Jochen , Soutschek Stefan , Stürmer Michael , Schaller Christian , Placht Simon , Kornhuber Johannes , Hornegger Joachim
Published: April 2009

Time-of-Flight-Kameras bieten die Möglichkeit, berührungslos in Echtzeit Distanzen zu messen. Diese technischen Möglichkeiten werden genutzt, um die dreidimensionale Zeigerichtung einer Hand relativ zu einem Monitor zu berechnen. Dadurch kann berechnet werden, wohin der Nutzer auf dem Monitor zeigt und der Mauszeiger an die entsprechende Position gesetzt werden. Durch das Heben und Senken des Daumens wird ein Klick ausgelöst. Somit werden die Basis-Funktionalitäten eines Touchscreens, ohne ihn dabei berühren zu müssen, zur Verfügung gestellt. Das berührunglose Messverfahren der Time-of-Flight-Kameras eignet sich hervorragend für den Einsatz im Operationssaal, da dort unter Sterilitätsbedingungen gearbeitet werden muss. Das vorgeschlagene Interaktionsparadigma ist wegen seiner intuitiven Nutzbarkeit auch gerade für die Nutzung durch Ärzte geeignet, was durch durchgeführte Studien bestätigt wird.
Bewertung sicherheitskritischer Systeme im OperationssaalEvaluation of Risk-Sensitive Systems in the OR
Authors: Janß Armin , Lauer Wolfgang , Radermacher Klaus
Published: April 2009

Im Rahmen des BMWi-geförderten Projektes INNORISK wird derzeit am Lehrstuhl für Medizintechnik der RWTH Aachen eine formal-analytische Methodik sowie ein flankierendes Softwaretool zur prospektiven Gebrauchstauglichkeitsprüfung komplexer Medizinprodukte entwickelt. Diese Module sollen die experimentelle Usability-Evaluierung sowie die Durchführung und Einhaltung des im Rahmen der europäischen Ergänzungsnorm IEC 60601-1-6 für medizinische elektrische Geräte geforderten Usability-Engineering Prozesses unterstützen. Der verfolgte modellbasierte Ansatz soll dabei die Analyse der Belastung bzw. Beanspruchung intraoperativ Tätiger sowie der hieraus resultierenden Risiken für Patient und OPTeam erleichtern. Basierend auf einem zweigeteilten Ansatz werden benutzerinteraktive Prozesssequenzen und deren möglicher Einfluss auf den Gesamtprozess bewertet. Zunächst wird eine Erweiterung der ConcurTaskTree (CTT) Methodik, eine High-Level Aufgabenanalyse, durchgeführt. Anschließend wird eine CPM-GOMS (Cognitive Perceptual Motor – Goals Operators Methods Selection Rules) Erweiterungsmethodik, eine Low-Level kognitive Aufgabenanalyse, angewendet und integriert. Ausgehend hiervon wird für kritische Prozesssequenzen eine kognitive Aufgabenanalyse unter Berücksichtigung unterschiedlicher leistungsbegrenzender Faktoren zur Bewertung der mentalen Belastung im spezifischen chirurgischen Nutzungskontext durchgeführt. Auf Basis verschiedener Fehlertaxonomien bezüglich menschlicher Fehler können dann gezielt potenzielle Risiken und Gefahren in den einzelnen Phasen der Informationsaufnahme, -verarbeitung und -ausgabe abgeleitet werden. Ziel dieses Ansatzes ist es, die Gebrauchstauglichkeit von Medizinprodukten in diesem speziellen Kontext zu verbessern und Interface-Designern sowie technischen Entwicklern methodische, softwaregestützte Analysewerkzeuge zur Erfassung inhärenter humaninduzierter Gefahrenpotentiale im Zusammenhang mit der Nutzung komplexer medizintechnischer Produkte zur Verfügung zu stellen. Kleine und mittlere Unternehmen, welche die Medizintechnikbranche prägen, sollen hierdurch im Rahmen des Zulassungsprozesses von Medizinprodukten unterstützt werden.
Überwachung von Kommunikationssatelliten – Fallstudie BenutzungsschnittstelleControlling Communication Satellits – Case Study: The User Interface
Authors: Linn Rolf
Published: April 2009

Für den Satellitenbetreiber SES ASTRA in Luxem burg wird vom Institut für Innovative Informatik-Anwendungen i3A der Fachhochschule Trier die Benutzungsschnittstelle eines Systems zur Leistungs messung von Kommunikations - satelliten entworfen. Wegen neuer Einsatzanforderungen, veralteter Hardware- und Softwaretechnologien und demzufolge anzupassender Nutzungsqualität soll das existierende System durch ein neues ersetzt werden. Diese Fallstudie stellt die Anwendung der DATech-Prüfverfahren für die Entwicklung und Qualitätssicherung der Benutzungsschnittstelle vor. Obwohl als ”Prüfverfahren“ bezeichnet, ist das Verfahren durchaus für Designprojekte anwendbar. In der hier beschriebenen ersten Phase wurden die Nutzungsanforderungen entwickelt, diese in Interaktionsentwurf sowie Systemoberfläche umgesetzt und ein Vorschlag für die grafische Gestaltung erarbeitet.
Blickbewegungsanalyse zur software-ergonomischen EvaluationEye Tracking Analysis for Software-Ergonomic Evaluation
Authors: Schmidt Ludger
Published: April 2009

Zur Bewertung der Gebrauchstauglichkeit von Mensch-Maschine-Schnittstellen bieten sich zahlreiche Methoden an, deren Ergebnisse als konstruktive Basis für die benutzungsbezogene Verbesserung herangezogen werden können. In diesem Beitrag wird die Methode der Blickbewegungsanalyse mit ihren zentralen Parametern als software-ergonomisches Evaluationsverfahren vorgestellt und beispielhaft für die Untersuchung und Bewertung einer webbasierten Buchungsoberfläche für Flugtickets verwendet. Zusätzlich zu Benutzerleistungsdaten (wie Ausführungszeiten und Fehler) stehen damit weitere verhaltensbeschreibende objektive Daten zur Verfügung, die durch in Benutzerbefragungen erhobene, subjektive software-ergonomische Bewertungen ergänzt werden. Durch diese Methodenkombination sollte auch der Frage nachgegangen werden, ob sich die subjektiven und objektiven Daten sinnvoll gegenseitig ergänzen, so dass im Ergebnis besser auf Benutzbarkeitsdefizite geschlossen werden kann. An der empirischen Untersuchung des Fallbeispiels nahmen 20 Probanden teil, die jeweils drei repräsentative Ticket-Buchungsaufgaben lösen mussten. Die Auswertung der Blickbewegungs- und Leistungsdaten sowie der verwendeten Fragebögen lieferte trotz des hohen Erprobungsgrades der Buchungsschnittstelle und ihrer Vorgängerversionen insgesamt zahlreiche Hinweise, die im Sinne einer formativen Evaluation für die Überarbeitung der Buchungsoberfläche genutzt werden konnten. Die Analyse identifizierte teilweise übereinstimmende Problembereiche, ein Teil der Defizite konnte jedoch nur anhand der Blickbewegungsdaten aufgedeckt werden.
Fiber intake predicts ghrelin levels in overweight and obese postmenopausal women
Authors: St-Pierre David H , Rabasa-Lhoret Rémi , Lavoie Marie-Ève , Karelis Antony D , Strychar Irene , Doucet Eric , Coderre Lise
Published: April 2009

Background

Ghrelin levels are decreased upon food intake, but the impact of specific diet-derived macronutrients on its regulation remains unclear. In addition, because of ghrelin's association with body weight regulation, it is important to understand the mechanisms regulating its levels in obese individuals.

Objective

To examine the effect of specific macronutrients on ghrelin levels in overweight and obese postmenopausal women.

Methods

Thirty-five subjects underwent a euglycemic/hyperinsulinemic clamp (EHC) to examine glucose disposal and total ghrelin (TotG) and acylated ghrelin (AG) levels. Macronutrient intake was evaluated with a 3-day food questionnaire.

Results

Under fasting conditions, positive associations were observed between fiber intake and TotG and AG levels. Fasting AG also correlated positively with the intake of total energy, as well as monounsaturated and polyunsaturated lipids. Importantly, fiber consumption explained up to 26 and 23% of the variation in TotG and AG respectively. During the EHC, TotG levels were significantly reduced at all times, while AG was decreased at 60 min only. TotG area under the curve (AUC) values were positively associated with fiber and polyunsaturated lipid intake, while AG AUC values correlated positively with fiber, total energy, carbohydrate, and lipid intake. Interestingly, fiber intake explained up to 21% of the variation in TotG AUC, while total energy intake predicted up to 21% of the variation in the AG AUC.

Conclusion

The present study suggests that fiber intake is an important regulator of ghrelin levels both in fasting and in hyperinsulinemic conditions. Overall, these results reinforce the importance of the intimate association between eating habits and gastrointestinal hormonal regulation.
Long‐acting reversible contraceptives
Authors: Fleming Charlotte F
Published: April 2009

The majority of women use the less reliable methods of contraception.

The majority of oral contraceptive users miss two or three pills per packet.

Thinking has changed from promoting user‐dependent to user‐independent contraceptive methods.

Intrauterine devices do not cause pelvic infection or ectopic pregnancy.

There is no lower age limit for users of any long‐acting reversible contraceptives, including intrauterine devices.

Learning objectives:

To understand the advantages of user‐independent methods of contraception.

To be able to combat myths and misunderstandings relating to them.

Ethical issues:

Fraser competence should be sought whenever a new method of contraception is chosen by someone under 16 who is not involving their parents in their decision.

Some people may find the intrauterine copper device unacceptable, as one of its contraceptive actions may be to prevent an embryo from implanting.

Please cite this article as: Fleming CF. Long‐acting reversible contraceptives. The Obstetrician & Gynaecologist 2009;11:83–88.
Prenatal diagnosis and management of fetal infections
Authors: To Meekai , Kidd Michael , Maxwell Darryl
Published: April 2009

The risks of transplacental transmission and fetal damage are pathogen‐ and gestation‐specific.

Amniocentesis is the mainstay of diagnosis of fetal infection.

Ultrasound surveillance is the primary tool for the detection of an affected fetus.

Therapeutic options are restricted to intrauterine blood transfusion in parvovirus infection and maternal antibiotic therapy in toxoplasmosis infection.

Learning objectives:

To gain an overview of prenatal diagnosis of the commonest congenital infections.

To appreciate that optimal care involves a multidisciplinary approach.

Ethical issues:

Detection of virus alone is not synonymous with fetal damage; a negative result does not completely exclude the possibility of fetal infection.

Presence or absence of sonographic markers of fetal infection may not accurately predict long‐term outcome.

Please cite this article as: To M, Kidd M, Maxwell D. Prenatal diagnosis and management of fetal infections. The Obstetrician & Gynaecologist 2009;11:108–116.
Making decisions together, or wake me up when it is over?
Authors: Leigh Bertie
Published: April 2009

Forty years ago, doctors were told that ‘doctor knows best’ was not a defence.

Twenty years ago they realised that, in seeking consent, they had to advise of the risks involved.

The General Medical Council recently revised their guidance on consent: doctors must work in partnership with patients and not press them to accept their advice.

Learning objectives:

To be aware of the guidance from the GMC on seeking consent.

To learn about some of the major legal cases involving consent.

To be able to consider the issues involved in consent.

Ethical issues:

Doctors carry the burden of acting as distributors of scarce resources.

The duty of doctors to make decisions about treatment jointly with patients can be hard to reconcile with the duty to give clear advice.

Please cite this article as: Leigh B. Making decisions together, or wake me up when it is over? The Obstetrician & Gynaecologist 2009;11:117–121.
Dealing with conflict and aggression in obstetrics and gynaecology
Authors: Strachan Bryony K , Fuller Jo Baden
Published: April 2009

Information points:

In a BMA survey, half of obstetricians and gynaecologists had experienced violence and aggression in the previous year.

Patients and staff have a right to be treated with respect; staff should not tolerate physical or verbal abuse.

Communication problems surrounding care and service provision are common causes of conflict.

Effective antenatal and pre‐admission planning can minimise conflict.

Learning objectives:

To understand the causes of conflict and aggression and to be aware of strategies for prevention.

To learn how to recognise potentially violent and aggressive situations and be able to manage them effectively.

Ethical issues:

Is it possible to protect oneself in an abusive situation without compromising care?

Healthcare staff have the right to work in a non‐abusive working environment.

Please cite this article as: Strachan BK, Baden Fuller J. Dealing with conflict and aggression in obstetrics and gynaecology. The Obstetrician & Gynaecologist 2009;11:122–128.
Prophylactic human papillomavirus vaccination update
Authors: Fiander Alison
Published: April 2009

Prophylactic human papillomavirus (HPV) vaccination was implemented in the UK in 2008 for girls aged 12–13 years.

There is a ‘catch‐up’ programme for girls up to the age of 18 years.

The bivalent vaccine (Cervarix®), covering HPV 16 and 18 was chosen for the first 3 years of the UK vaccination programme.

Surveillance is essential to evaluate long‐term effectiveness and answer the remaining questions.

Learning objectives:

To be aware of the implementation of HPV vaccination in the UK.

To be aware of remaining unanswered questions and the need for surveillance.

To understand the importance of key messages for girls being vaccinated against HPV.

Ethical issues:

Will HPV vaccination of girls in the UK be acceptable to everyone?

Have the key public health messages been clearly stated and understood?

Addressing the major burden of HPV‐related neoplasia in developing countries is an ethical imperative.

Please cite this article as: Fiander A. Prophylactic human papillomavirus vaccination update. The Obstetrician & Gynaecologist 2009;11:133–135.
Uso problemático de álcool e outras drogas em moradia estudantil: conhecer para enfrentar
Authors: Zalaf Marília Rita Ribeiro , Fonseca Rosa Maria Godoy Serpa da
Published: April 2009

Este artigo trata do uso problemático de álcool e outras drogas na moradia estudantil da Universidade de São Paulo. Seus objetivos foram compreender como se dá o processo saúde-doença dos moradores referente ao uso problemático de drogas, identificar as condições objetivas do uso de drogas e analisar as manifestações subjacentes às questões de gênero relacionadas ao uso de drogas pelos estudantes. A análise está apoiada na Teoria da Determinação Social. Os dados foram coletados em entrevistas semi-estruturadas que focalizaram a história do processo saúde-doença relacionado ao uso problemático de álcool e de outras drogas antes e depois do ingresso no Conjunto Residencial da USP (Crusp). Nos resultados obtidos, a moradia estudantil apareceu como mais um elemento favorecedor ao uso problemático de drogas, aliado à depressão, ao desemprego e às características próprias desse espaço acadêmico. Estereotipias de gênero relacionadas ao uso de drogas, como subalternidade feminina, preconceito e culpabilização, mostraram-se refletidas na moradia estudantil.