bluuebunny/crossref_metadata_2025_split huggingface dataset:
How much anatomy is enough?
Authors: Bergman Esther M. , Prince Katinka J.A.H. , Drukker Jan , van der Vleuten Cees P.M. , Scherpbier Albert J.J.A. 
Published: July 2008

AbstractInnovations in undergraduate medical education, such as integration of disciplines and problem based learning, have given rise to concerns about students' knowledge of anatomy. This article originated from several studies investigating the knowledge of anatomy of students at the eight Dutch medical schools. The studies showed that undergraduate students uniformly perceived deficiencies in their anatomical knowledge when they started clinical training regardless of their school's didactic approach. A study assessing students' actual knowledge of clinical anatomy revealed no relationship between students' knowledge and the school's didactic approach. Test failure rates based on absolute standards set by different groups of experts were indicative of unsatisfactory levels of anatomical knowledge, although standards differed markedly between the groups of experts. Good test performance by students seems to be related to total teaching time for anatomy, teaching in clinical context, and revisiting anatomy topics in the course of the curriculum. These factors appeared to outweigh the effects of disciplinary integration orwhether the curriculum was problem‐based or traditional. Anat Sci Ed 2008. © 2008 American Association of Anatomists.
Effect of the use of instructional anatomy videos on student performance
Authors: Saxena Varun , Natarajan Pradeep , O'Sullivan Patricia S. , Jain Sharad 
Published: July 2008

AbstractMedical schools have reduced the time allotted to anatomy instruction. Consequently, schools engage students in more independent settings using information and communication technologies (ICT). There has been limited research in the use of video aids, a type of ICT, to enhance anatomy examination performance. The objective of this study is to describe the design, usage, and effect on examination performance of eight locally developed instructional anatomy videos. First‐year UCSF medical students (n = 141) had access to the videos. They reported their video usage, reason for usage, and satisfaction. The prior year students (n = 141) served as a historical control group. Anatomy and radiology examination performance was compared between groups while controlling for prior performance. The students with and without access to the videos did not differ in examination performance. Sixty‐one (43%) students in the experimental group responded to the survey. Of these, 79% reported using at least one video, viewing an average of 4.75 of the eight videos. They watched 3.27 (SD = 1.57, range 1–5) of the five anatomy videos and 1.48 (SD = 1.35; range 0–3) of the three radiology videos. In a regression analysis controlling for age and MCAT scores, using the anatomy videos at least once improved anatomy examination performance by 3.4% (P‐value = 0.007). There was no relationship between radiology video usage and radiology exam score. Video resource availability did not enhance student performance in anatomy and radiology. However, when analyzing performance for those whom we knew level of video use, there was a statistically different and higher anatomy achievement. Anat Sci Ed, 2008. © 2008 American Association of Anatomists.
Das Angriffspotential sulfatsaurer Böden in Norddeutschland
Authors: Gröger Jens , Hamer Kay , Schulz Horst D. 
Published: July 2008

AbstractIn Norddeutschland treten verbreitet Moor‐ und Marschböden mit hohen Pyritgehalten auf, die bei der Oxidation große Mengen an Säure und Sulfat freisetzen können. Diese relativ jungen Bildungen (< 10.000 Jahre) werden als potentiell sulfatsaure Böden bezeichnet. Diese Böden stellen ein bedeutendes Gefährdungspotential für Betonbauteile dar, die im Kontakt zu diesen Böden stehen und finden in bisherigen Regelungen nur wenig Beachtung. Die Verbreitung ist häufig fleckenhaft und nicht an Gesteinsformationen gebunden, was die Identifizierung und Kartierung dieser Böden erschwert. Die oft niedrige Säureneutralisationskapazität der Böden bei gleichzeitig hohen Pyritgehalten führt bei der Oxidation zu einem kombinierten Säure‐ und Sulfatangriff auf in den Boden eingebrachte Betonteile.
Pilotprojekt der neuen Normengeneration im Kühlturmbau – Die Naturzugkühltürme von BoA 2 & 3 in Neurath
Authors: Wörmann Ralf , Haupt Ralf , Ohlmann Uwe 
Published: July 2008

AbstractSeit Anfang 2006 errichtet RWE Power am Standort Neurath zwei Braunkohlekraftwerksblöcke mit optimierter Anlagentechnik – kurz BoA. Nach der Inbetriebnahme von BoA1 in Niederaußem im Jahr 2003 werden sie die Blöcke 2 und 3 dieser modernsten Bauart sein. Zu den auffälligsten Bauwerken der neuen Kraftwerksblöcke gehören die beiden 173 m hohen Kühltürme. In diesem Beitrag wird ein Überblick über Planung und Ausführung der beiden Türme gegeben. Dabei erfolgt die Planung erstmals im Kühlturmbau auf Basis der neuen Normengeneration und der neuen Fassung der VGB‐Richtlinie “Bautechnik bei Kühltürmen” aus dem Jahr 2005.
Zum nachträglichen Kürzen und Verankern von glatten Spanngliedern im Verbund
Authors: Novák Balthasar , Sasmal Saptarshi , Röhm Constanze , Schnabel Thomas , Becker Reinhard 
Published: July 2008

AbstractDie Stuttgarter Straßenbahnen AG (SSB) plant derzeit zusammen mit der Stadt Stuttgart den Einbau eines Aufzugs in einer unterirdischen Straßenbahnhaltestelle. Zur Durchführung dieses Vorhabens wird es erforderlich, vorhandene Spannbetonträger unter einer dreispurigen Straße zu kürzen. Die Besonderheit ist, dass es sich hierbei um glatten Spannstahl mit nachträglichem Verbund handelt, bei dem eine Verankerung über Verbund nicht üblich ist. Hier galt es also, zunächst das Verbundverhalten zu studieren; alternativ wurde eine neue Spanngliedverankerung entwickelt. Neben Laborversuchen zum Verbundverhalten wurde ein Spannglied des bestehenden Tragwerks in Feldmitte durchtrennt, das vorher mit mehreren Dehnmessstreifen (DMS) im Verankerungsbereich versehen wurde. So konnte in einer Langzeitstudie die Entwicklung der Dehnungen sowohl unter laufendem Verkehr als auch unter definierter Belastung (48t‐Kran) verfolgt werden, und es konnte gezeigt werden, dass auch unter nicht vorwiegend ruhender Beanspruchung allein über den Verbund die Einleitung der Vorspannung sichergestellt werden kann. Mit den aus den durchgeführten push‐in Versuchen erzielten Ergebnissen der Verbundeigenschaften konnten die Ergebnisse des Feldversuchs sehr gut prognostiziert werden. Weiterhin wurden Laborversuche für das neue Verankerungselement unter statischer und nicht vorwiegend ruhender Belastung durchgeführt. Mit den Ergebnissen konnte die Tauglichkeit für den geplanten Einsatz nachgewiesen werden. Die Untersuchungen wurden durch numerische Untersuchungen zur Ermittlung der Beanspruchung im Verankerungsbereich abgerundet.
Besonderheiten bei der Beurteilung des Ankündigungsverhaltens von Spannbetonbrücken nach dem Riss‐vor‐Bruch‐Kriterium
Authors: Albertin‐Hummel Ursula , Brandt Bernd 
Published: July 2008

AbstractBrücken ohne ausreichendes Ankündigungsverhalten hinsichtlich eines Versagens nach dem Riss‐vor‐Bruch‐Kriterium bergen ein Versagensrisiko. Dieses Risiko ist besonders groß, wenn in den betreffenden Brücken ein gefährdeter Spannstahl eingebaut ist, der zur Spannungsrisskorrosion neigt. Auswirkungen aus der Tragkonstruktion und Unwägbarkeiten in der Bauausführung beeinflussen das Ankündigungsverhalten zusätzlich.Zur Beurteilung des Restrisikos für den Bauherrn werden verschiedene Einflüsse auf die Gesamtkonstruktion anhand numerischer Berechnungen untersucht. Dabei werden sowohl Einflüsse aus Temperaturbeanspruchungen als auch aus Querschnittsversagen mit Schnittgrößenumlagerung näher betrachtet.
Group Sequential and Adaptive Designs – A Review of Basic Concepts and Points of Discussion
Authors: Vandemeulebroecke Marc 
Published: July 2008

AbstractIn recent times, group sequential and adaptive designs for clinical trials have attracted great attention from industry, academia and regulatory authorities. These designs allow analyses onaccumulating data– as opposed to classical, “fixed‐sample” statistics. The rapid development of a great variety of statistical procedures is accompanied by a lively debate on their potential merits and shortcomings. The purpose of this review article is to ease orientation in both respects. First, we provide a concise overview of the essential technical concepts, with special emphasis on their interrelationships. Second, we give a structured review of the current controversial discussion on practical issues, opportunities and challenges of these new designs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Testing for Group Effect in a 2 × k Heteroscedastic ANOVA Model
Authors: Troendle James F. 
Published: July 2008

AbstractIt is natural to want to relax the assumption of homoscedasticity and Gaussian error in ANOVA models. For a two‐way ANOVA model with 2 × k cells, one can derive tests of main effect for the factor with two levels (referred to as group) without assuming homoscedasticity or Gaussian error. Empirical likelihood can be used to derive testing procedures. An approximate empirical likelihood ratio test (AELRT) is derived for the test of group main effect. To approximate the distributions of the test statistics under the null hypothesis, simulation from the approximate empirical maximum likelihood estimate (AEMLE) restricted by the null hypothesis is used. The homoscedastic ANOVA F ‐test and a Box‐type approximation to the distribution of the heteroscedastic ANOVA F ‐test are compared to the AELRT in level and power. The AELRT procedure is shown by simulation to have appropriate type I error control (although possibly conservative) when the distribution of the test statistics are approximated by simulation from the constrained AEMLE. The methodology is motivated and illustrated by an analysis of folate levels in the blood among two alcohol intake groups while accounting for gender. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unbiased Estimation of Selected Treatment Means in Two‐Stage Trials
Authors: Bowden Jack , Glimm Ekkehard 
Published: July 2008

AbstractStraightforward estimation of a treatment's effect in an adaptive clinical trial can be severely hindered when it has been chosen from a larger group of potential candidates. This is because selection mechanisms that condition on the rank order of treatment statistics introduce bias. Nevertheless, designs of this sort are seen as a practical and efficient way to fast track the most promising compounds in drug development. In this paper we extend the method of Cohen and Sackrowitz (1989) who proposed a two‐stage unbiased estimate for the best performing treatment at interim. This enables their estimate to work for unequal stage one and two sample sizes, and also when the quantity of interest is the best, second best, or j ‐th best treatment out of k. The implications of this new flexibility are explored via simulation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuous Multi‐Injection Reactor for Multipurpose Production – Part I
Authors: Barthe P. , Guermeur C. , Lobet O. , Moreno M. , Woehl P. , Roberge D. M. , Bieler N. , Zimmermann B. 
Published: July 2008

AbstractThe paper presents an analysis of chemical production requirements in an exclusive synthesis market environment and describes how this analysis guided the development of a modular multi‐injection reactor. Detailed engineering of a reactor in the light of the requirements of an organometallic reaction, as well as characterization of the reactor is reported. This reactor has provided the target chemistry result at Lonza Ltd. as detailed in a companion paper.
Liquid Extraction of Vanillin in Rectangular Microreactors
Authors: Fries D. Maria , Voitl T. , von Rohr P. Rudolf 
Published: July 2008

AbstractIn this paper, the extraction of vanillin dissolved in water with a suitable organic phase using microstructured devices made of PDMS is discussed. Two flow patterns, segmented and stratified flow, were compared. LIF and μ‐PIV measurements showed a laminar profile for stratified flow; whereas for segmented flow, vortices in the slug end were detected. Additionally, for the stratified flow regime, the influence of the channel width and therefore the surface‐to‐volume ratio was investigated. A decrease of the channel cross‐sectional area results in a significant enhancement of mass transfer for the stratified flow regime. A further increase in mass transfer was obtained using segmented flow instead of stratified flow. However, stratified flow may be favored due to the ease of implementation of phase separation on the chip.
Multiscale Modeling Approach for Production of Perfume Microcapsules
Authors: Vásquez R. V. Tona , Jiménez Esteller L. , Bojarski A. D. 
Published: July 2008

AbstractMicroreactors are currently showing great promise as novel tools upon which new chemical technology can be built and for support process intensification in many industrial sectors. In this work, a modeling strategy is presented that integrates process units at multiple scales with microstructured elements to support the synthesis and characterization of perfume‐containing microcapsules. The strategy concerns two interconnected modules: microreactor unit models, where microcapsules are produced (developed in MATLAB®), and normal scale unit operation models (performed in Aspen Plus®). Encapsulation of the microreactor model and integration of flows between micro and normal scale equipments are implemented within Aspen Plus. All former features are successfully presented together in an integrated fashion with other key issues like recovery and reuse of solvents used for the minimization of environmental impacts.
Propane Conversion at Ambient Temperatures C–C and C–H Bond Activation Using Cold Plasma in a Microreactor
Authors: Ağıral A. , Trionfetti C. , Lefferts L. , Seshan K. , (Han) Gardeniers J. G. E. 
Published: July 2008

AbstractIn this work, the oxidative conversion of propane was studied using a dielectric barrier discharge microreactor. This generates a cold microplasma at atmospheric pressure and ambient temperatures. Surprisingly, large amounts of products with molecular weight higher than propane, such as C4 and C4+, were mainly observed due to C–C bond formation, in contrast to what is usually observed for this reaction when it is carried out under thermal activation, which leads to cracking products. A chemical kinetic model was developed to better understand the radical reaction network. Interestingly, the results suggest that (i) at lower level of propane conversion the model can nicely predict the experimental results and (ii) depending on the radical density the product selectivity can be tailored. In particular, at higher radical density, enhanced C–C bond formation was observed.
Dispersion and Holdup in Multiphase Packed Bed Microreactors
Authors: Márquez N. , Castaño P. , Makkee M. , Moulijn J. A. , Kreutzer M. T. 
Published: July 2008

AbstractLiquid holdup and dispersion are reported for a column of 2 mm internal diameter, filled with 0.1 mm spherical particles, for multiphase flows with hydrocarbon liquid flow rates of 10–100 μL/min and nitrogen gas flow rates of 50–1000 μL/min using different tracers with varying diffusion coefficients and vapor pressures. It was found that the liquid holdup (liquid volume/external void volume) was between 0.65 and 0.85, with variations between different experiments and limited impact of flow rate on the holdup. The dispersion characteristics were very similar to single‐phase dispersion. The particle Peclet number for dispersion was close to 0.2. This value was of the same order of magnitude – just a factor of two to three lower – as the value that was obtained without gas flow. Tracer volatility did cause the tracer to elude earlier, but did not cause significant additional dispersion. The results suggest that the fluid mechanical interaction between the gas and the liquid was very limited.
“Sandwich Reactor” for Heterogeneous Catalytic Processes: N2O Decomposition as a Case Study
Authors: Bromley B. , Hessel V. , Renken A. , Kiwi‐Minsker L. 
Published: July 2008

AbstractA novel “sandwich” microreactor designed as a thin (∼ 300 μm) porous plate of sintered metal fibers (SMF), sandwiched between metallic plates is reported. The SMF surface was coated by Fe‐ZSM‐5 thin film (< 2 μm) rendering a catalyst highly active in the decomposition of N2O. The 3D open microstructure of SMF plates presents a low pressure drop during the passage of reacting gases. The high thermoconductivity of metallic SMF improves the heat transfer, avoiding hot‐spot formation during exothermic reactions. The temperature measured in the middle and at the outlet of the reactor confirmed the isothermal reactor operation. The sandwich microreactor showed high permeability and a narrow residence time distribution close to an ideal plug‐flow reactor. The kinetics of the N2O decomposition was studied and the reaction was shown not to be limited by mass transfer when conducted in the microreactor.
Microfluidic‐Assisted Synthesis of Polymer Particles
Authors: Serra C. A. , Chang Z. 
Published: July 2008

AbstractMicrofluidic devices have recently emerged as promising tools for the synthesis of polymer particles. Over conventional processes, microfluidic‐assisted processes allow the production of polymer particles with an improved control over their sizes, size distributions, morphologies, and compositions. In this paper, the most common microfluidic devices are reviewed. Both projection photolithography and emulsification processes are reported for the continuous flow synthesis of polymer particles from a stream of polymerizable liquids. For the latter process, two distinct categories of microfluidic devices have been identified: microchannel‐based and capillary‐based microsystems. For each category, the existing geometries are described and the different emulsification methods including the co‐flowing, cross‐flowing, or flow‐focusing of the continuous and dispersed phases are commented upon. Finally, for each microsystem the various polymer particles achieved in such devices including, but not restricted to, janus, core–shell, or porous particles and capsules are reported.
Characterization of a Redispersion Microreactor by Studying its Dispersion Performance
Authors: Rothstock S. , Hessel V. , Löb P. , Werner B. 
Published: July 2008

AbstractA redispersion microreactor concept developed for liquid‐liquid biphasic reactions was characterized by studying its dispersion performance for the n‐heptane/water system both with and without surfactant. The concept is based on repeated droplet breakage by so‐called redispersion units distributed over the length of the reactor, which either contain microstructured channels or consist of metal foam. The steel microchannel units lead to a higher pressure drop compared to the metal foam. In the presence of a surfactant, the droplet size is reduced stepwise by the redispersion units. At a given flow rate, the steel insets deliver smaller mean diameter droplets compared to the foam insets. Drop coalescence comes into play in the absence of the surfactant. In this instance, the redispersion units recreate and maintain the interfacial area along the length of the reactor albeit with coalescence.
Weighting hyperspectral image data for improved multivariate curve resolution results
Authors: Jones Howland D. T. , Haaland David M. , Sinclair Michael B. , Melgaard David K. , Van Benthem Mark H. , Pedroso M. Cristina 
Published: July 2008

AbstractThe combination of hyperspectral confocal fluorescence microscopy and multivariate curve resolution (MCR) provides an ideal system for improved quantitative imaging when multiple fluorophores are present. However, the presence of multiple noise sources limits the ability of MCR to accurately extract pure‐component spectra when there is high spectral and/or spatial overlap between multiple fluorophores. Previously, MCR results were improved by weighting the spectral images for Poisson‐distributed noise, but additional noise sources are often present. We have identified and quantified all the major noise sources in hyperspectral fluorescence images. Two primary noise sources were found: Poisson‐distributed noise and detector‐read noise. We present methods to quantify detector‐read noise variance and to empirically determine the electron multiplying CCD (EMCCD) gain factor required to compute the Poisson noise variance. We have found that properly weighting spectral image data to account for both noise sources improved MCR accuracy. In this paper, we demonstrate three weighting schemes applied to a real hyperspectral corn leaf image and to simulated data based upon this same image. MCR applied to both real and simulated hyperspectral images weighted to compensate for the two major noise sources greatly improved the extracted pure emission spectra and their concentrations relative to MCR with either unweighted or Poisson‐only weighted data. Thus, properly identifying and accounting for the major noise sources in hyperspectral images can serve to improve the MCR results. These methods are very general and can be applied to the multivariate analysis of spectral images whenever CCD or EMCCD detectors are used. Copyright © 2008 John Wiley & Sons, Ltd.
Mechanische Flüssigkeitsabtrennung in der Lebensmittelverfahrenstechnik
Authors: Anlauf H. , Nirschl H. 
Published: July 2008

AbstractIn der Lebensmitteltechnologie findet sich eine Vielzahl sehr unterschiedlicher Aufgabenstellungen für die mechanische Flüssigkeitsabtrennung. Dies ist durch die stark differierenden Produkteigenschaften, die zulässigen Prozessbedingungen und die Forderungen an das Verfahrensergebnis begründet. Zur Lösung dieser Trennaufgaben kann im Prinzip auf die ganze Breite der mechanischen Trenntechnik zurückgegriffen werden, welche auch in anderen Branchen Anwendung findet. Die speziellen Eigenschaften der hier zu behandelnden Produkte und die Anforderungen zur Gewährleistung der geforderten Produktqualitäten machen meist eine entsprechende Anpassung der trenntechnischen Apparate an diese Erfordernisse notwendig. Dies betrifft insbesondere den hygienischen Umgang mit den zu trennenden Stoffen oder auch die Sensorik, welche durch den Verarbeitungsprozess nicht negativ beeinflusst werden darf. Insbesondere im Bereich der Abtrennung von Kolloiden und gelöst vorliegenden Makromolekülen erobern sich mechanische Membrantrennverfahren immer weitere Anwendungsfelder, welche traditionell thermischen Verfahren vorbehalten waren.
Einfluss des Membranwiderstands auf die Filtrationsleistung bei der Proteinfraktionierung entlang von Mikrofiltrationsmodulen
Authors: Kühnl W. , Piry A. , Kulozik U. 
Published: July 2008

AbstractAdsorptionsprozesse und Deckschichtbildung limitieren Flux und Stoffpermeation bei der Proteinfraktionierung mittels Querstrommikrofiltration. Die abschnittsweise Erfassung des Stoffdurchgangs entlang einer Membran ermöglicht ein tiefer gehendes Verständnis der Stofftransportvorgänge und der Deckschichtbildung. Entscheidend ist, die anfängliche Schleppkraft zur Membran infolge des initialen Flux durch Optimierung des Membranwiderstands zu begrenzen.