bluuebunny/crossref_metadata_2025_split huggingface dataset:
Timing of first embryonic cleavage is a positive indicator of the in vitro developmental potential of porcine embryos derived from in vitro fertilization, somatic cell nuclear transfer and parthenogenesis
Authors: Isom S. Clay , Li Rong feng , Whitworth Kristin M. , Prather Randall S. 
Published: December 2011

AbstractEvidence in many species has suggested that those embryos that cleave earliest after fertilization are more developmentally competent than those that cleave relatively later after fertilization. Herein we document this phenomenon in porcine in vitro‐fertilized (IVF), somatic cell nuclear transfer (SCNT), and parthenogenetic (PA) embryos. In vitro‐matured pig oocytes were used to generate IVF, SCNT, and PA embryos. At 24 hr post‐activation (or insemination; hpa/hpi), embryos were visually assessed, and cleaved embryos were moved into a new culture well. This process was repeated at 30 and 48 hpa/hpi. All embryos were allowed to develop 7 days in culture. For IVF embryos, 39.9%, 24.6%, and 10.5% of fast‐, intermediate‐, or slow‐cleaving embryos, respectively, developed into blastocysts by day 7. For SCNT embryos, 31.8% of fast‐, 5.7% of intermediate‐, and 2.9% of late‐cleaving embryos achieved the blastocyst stage of development. For PA embryos, the percentages of those cleaved embryos that developed to blastocyst were 59.3%, 36.7%, and 7.5% for early‐, intermediate‐, and late‐cleaving embryos, respectively. Using RNA collected from early‐, intermediate‐, and late‐cleaving embryos, real‐time PCR was performed to assess the transcript levels of 14 different genes of widely varied function. The qPCR results suggest that maternal mRNA degradation may not proceed in an appropriate pattern in slow‐cleaving embryos. These findings (1) confirm that, as observed in other species, earlier‐cleaving porcine embryos are more successful at developing in culture than are slower‐cleaving embryos, and (2) implicate mechanisms of maternal transcript destruction as potential determinants of oocyte/embryo quality. Mol. Reprod. Dev. 79: 197–207, 2012. © 2011 Wiley Periodicals, Inc.
System and SAR characterization in parallel RF transmission
Authors: Zhu Yudong , Alon Leeor , Deniz Cem M. , Brown Ryan , Sodickson Daniel K. 
Published: December 2011

AbstractThe markedly increased degrees of freedom introduced by parallel radiofrequency transmission presents both opportunities and challenges for specific absorption rate (SAR) management. On one hand they enable E‐field tailoring and SAR reduction while facilitating excitation profile control. On other hand they increase the complexity of SAR behavior and the risk of inadvertently exacerbating SAR by improper design or playout of radiofrequency pulses. The substantial subject‐dependency of SAR in high field magnetic resonance can be a compounding factor. Building upon a linear system concept and a calibration scheme involving a finite number of in situ measurements, this work establishes a clinically applicable method for characterizing global SAR behavior as well as channel‐by‐channel power transmission. The method offers a unique capability of predicting, for any excitation, the SAR and power consequences that are specific to the subject to be scanned and the MRI hardware. The method was validated in simulation and experimental studies, showing promise as the foundation to a prospective paradigm where power and SAR are not only monitored but, through prediction‐guided optimization, proactively managed. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
High tip angle approximation based on a modified Bloch–Riccati equation
Authors: Boulant Nicolas , Hoult David I. 
Published: December 2011

AbstractWhen designing a radio‐frequency pulse to produce a desired dependence of magnetization on frequency or position, the small flip angle approximation is often used as a first step, and a Fourier relation between pulse and transverse magnetization is then invoked. However, common intuition often leads to linear scaling of the resulting pulse so as to produce a larger flip angle than the approximation warrants—with surprisingly good results. Starting from a modified version of the Bloch–Riccati equation, a differential equation in the flip angle itself, rather than in magnetization, is derived. As this equation has a substantial linear component that is an instance of Fourier's equation, the intuitive approach is seen to be justified. Examples of the accuracy of this higher tip angle approximation are given for both constant‐ and variable‐phase pulses. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Arterial spin labeling MRI study of age and gender effects on brain perfusion hemodynamics
Authors: Liu Yinan , Zhu Xiaoping , Feinberg David , Guenther Matthias , Gregori Johannes , Weiner Michael W. , Schuff Norbert 
Published: December 2011

AbstractNormal aging is associated with diminished brain perfusion measured as cerebral blood flow (CBF), but previously it is difficult to accurately measure various aspects of perfusion hemodynamics including: bolus arrival times and delays through small arterioles, expressed as arterial‐arteriole transit time. To study hemodynamics in greater detail, volumetric arterial spin labeling MRI with variable postlabeling delays was used together with a distributed, dual‐compartment tracer model. The main goal was to determine how CBF and other perfusion hemodynamics vary with aging. Twenty cognitive normal female and 15 male subjects (age: 23–84 years old) were studied at 4 T. Arterial spin labeling measurements were performed in the posterior cingulate cortex, precuneus, and whole brain gray matter. CBF declined with advancing age (P < 0.001). Separately from variations in bolus arrival times, arterial‐arteriole transit time increased with advancing age (P < 0.01). Finally, women had overall higher CBF values (P < 0.01) and shorter arterial‐arteriole transit time (P < 0.01) than men, regardless of age. The findings imply that CBF and blood transit times are compromised in aging, and these changes together with differences between genders should be taken into account when studying brain perfusion. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Irreducibility of joint inventory positions in an assemble‐to‐order system under (r, nQ) policies
Authors: Feng Jiejian , Liu Liming , Wan Yat‐wah 
Published: December 2011

AbstractIn a typical assemble‐to‐order system, a customer order may request multiple items, and the order may not be filled if any of the requested items are out of stock. A key customer service measure when unfilled orders are backordered is the order‐based backorder level. To evaluate this crucial performance measure, a fundamental question is whether the stationary joint inventory positions follow an independent and uniform distribution. In this context, this is equivalent to the irreducibility of the Markov chain formed by the joint inventory positions. This article presents a necessary and sufficient condition for the irreducibility of such a Markov chain through a set of simultaneous Diophantine equations. This result also leads to sufficient conditions that are more general than those in the published reports. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011
A variational framework for fiber‐reinforced viscoelastic soft tissues
Authors: Vassoler J. M. , Reips L. , Fancello E. A. 
Published: December 2011

SUMMARYThe mechanical properties of soft biological tissues vary depending on how the internal structure is organized. Classical examples of tissues are ligaments, tendons, skin, arteries, and annulus fibrous. The main element of such tissues is the fibers which are responsible for the tissue resistance and the main mechanical characteristic is their viscoelastic anisotropic behavior. The objective of this paper is to extend an existing model for isotropic viscoelastic materials in order to include anisotropy provided by fiber reinforcement. The incorporation of the fiber allows the mechanical behavior of these tissues to be simulated. The model is based on a variational framework in which its mechanical behavior is described by a free energy incremental potential whose local minimization provides the constraints for the internal variable updates for each load increment. The main advantage of this variational approach is the ability to represent different material models depending on the choice of suitable potential functions. Finally, the model is implemented in a finite‐element code in order to perform numerical tests to show the ability of the proposed model to represent fiber‐reinforced materials. The material parameters used in the tests were obtained through parameter identification using experimental data available in the literature. Copyright © 2011 John Wiley & Sons, Ltd.
A nodal variable method of structural topology optimization based on Shepard interpolant
Authors: Kang Zhan , Wang Yiqiang 
Published: December 2011

SUMMARYA method for topology optimization of continuum structures based on nodal density variables and density field mapping technique is investigated. The original discrete‐valued topology optimization problem is stated as an optimization problem with continuous design variables by introducing a material density field into the design domain. With the use of the Shepard family of interpolants, this density field is mapped onto the design space defined by a finite number of nodal density variables. The employed interpolation scheme has an explicit form and satisfies range‐restricted properties that makes it applicable for physically meaningful density interpolation. Its ability to resolve more complex spatial distribution of the material density within an individual element, as compared with the conventional elementwise design variable approach, actually provides certain regularization to the topology optimization problem. Numerical examples demonstrate the validity and applicability of the proposed formulation and numerical techniques. Copyright © 2011 John Wiley & Sons, Ltd.
A one‐dimensional lumped parameter model representing impedance functions in general structural systems with proportional damping
Authors: Saitoh Masato 
Published: December 2011

SUMMARYThis paper presents a one‐dimensional lumped parameter model (LPM) that accurately represents the impedance function between two nodes arbitrarily selected in general linear structural systems having proportional damping. Through a procedure based on the modal analysis, the impedance function can be transformed into an equivalent LPM consisting of units arranged in series, with each unit consisting of a spring, a dashpot, and a so‐called gyro mass element arranged in parallel. The gyro mass element generates a reaction force proportional to the relative acceleration of the nodes between where it is placed. Three application examples show that the LPMs accurately simulate the impedance functions in a mass–spring structure, a truss frame structure, and a cantilever plate. For a more efficient representation, a large number of units associated with high‐order modes in the high‐frequency region can be removed from the proposed gyro mass LPM (GLPM) as an approximation of the impedance functions in a target frequency region. The accuracy of the approximated GLPMs is improved by incorporating an additional unit associated with residual stiffness. This approximation greatly reduces the number of degrees of freedom of the GLPMs so that a marked decrease in the computational domain size and time can be expected for solving dynamic problems. Copyright © 2011 John Wiley & Sons, Ltd.
Simple Common Plane contact algorithm
Authors: Vorobiev Oleg 
Published: December 2011

SUMMARYThe common‐plane (CP) algorithm is widely used in the discrete element method to model contact forces between interacting particles or blocks of rock. A new simple contact algorithm, similar to the CP algorithm, is proposed to model discontinuities such as joints, faults and material interfaces in an explicit finite difference code. The CP is defined as a plane separating interacting faces of grid cells, instead of blocks or particles used in the original CP method. The new method does not require iterations even for very stiff contacts. It is very robust and easy to implement, both in 2D and 3D parallel codes. Copyright © 2011 John Wiley & Sons, Ltd.
control of LPV systems with saturating actuators: Pólya approach
Authors: Delibaşı Akın , Kucukdemiral Ibrahim B. , Cansever Galip 
Published: December 2011

SUMMARYThis paper addresses the design problem of , gain‐scheduling non‐linear state‐feedback controller for linear parameter varying (LPV) systems, subjected to actuator saturations and bounded energy disturbances, by using parameter‐dependent type Lyapunov functions. The paper provides a systematic procedure to generate a sequence of linear matrix inequality (LMI) type conditions of increasing precision for obtaining a suboptimal state‐feedback controller. The presented method utilizes the modified sector condition for formalization of actuator saturation and homogeneous polynomial parameter‐dependent representation of LPV systems. Both simulations and experimental studies on an inverted pendulum on a cart system illustrate the benefits of the approach. Copyright © 2011 John Wiley & Sons, Ltd.
Simultaneous fault detection and control design for switched linear systems based on dynamic observer
Authors: Davoodi M.R. , Golabi A. , Talebi H.A. , Momeni H.R. 
Published: December 2011

SUMMARYThe problem of simultaneous fault detection and control (SFDC) for linear continuous‐time switched systems is addressed in this paper. An H ∞  formulation of the SFDC problem using dynamic observer is presented. In essence, a single unit called detector/controller depending on the system modes is designed, where the detector is a dynamic observer, and the controller is a state feedback controller based on the dynamic observer. It is shown that the dynamic observer can be used effectively to tackle the drawbacks of the existing methods of SFDC design. Extended linear matrix inequalities (LMIs) characterization is used to reduce the conservativeness by introducing additional matrix variables, so as to eliminate the coupling of Lyapunov matrices with the system matrices. Indeed, the idea presented in this paper is based on average dwell time and conservatism reduction approaches and applying the advantages of dynamic observers, which leads to some sufficient conditions for solvability of the SFDC problem in terms of LMI feasibility conditions. Simulation results illustrate the effectiveness of the proposed design methodology. Copyright © 2011 John Wiley & Sons, Ltd.
A follow‐up study on men tested for BRCA1/BRCA2 mutations: impacts and coping processes
Authors: Shiloh Shoshana , Dagan Efrat , Friedman Irit , Blank Natalie , Friedman Eitan 
Published: December 2011

AbstractObjectiveThe objective of this study was to examine cognitive, emotional, and behavioral impacts of testing for germline mutations in breast/ovarian cancer‐associated genes (BRCA1/BRCA2) among men who undergo genetic testing.MethodsA cross‐sectional study compared 51 mutation carriers with 30 men who tested negative for the mutations in both genes. Telephone interviews were conducted with all participants at a median of 4 years after disclosure of test results in a genetic counseling context. Testing‐related distress, cancer risk perceptions, perceived behavioral changes following testing, and perceptions of breast cancer were measured using standard questionnaires.ResultsUp to 4 years postgenetic testing, 48% of those who tested positively report that the test increased their perceptions of risk, and 74% of them increased surveillance for cancer. Men who had been tested as non‐carriers did not report increased perceived risk (0%) and relatively few increased surveillance (31%). Carriers were significantly more distressed from testing, perceived breast cancer as having less consequences and emotional effects on the patient, and as being more treatable than non‐carriers.ConclusionsThese results have implications with regard to the Self Regulatory Theory. They show that (i) illness representations are affected by fear‐arousing health information; (ii) risk perceptions elicit health behaviors; and (iii) men tested for BRCA mutations have specific concerns that should be attended to. Copyright © 2011 John Wiley & Sons, Ltd.
Ventilation effects on humidity measurements in thermometer screens
Authors: Harrison R. G. , Wood C. R. 
Published: December 2011

AbstractRelative humidity (RH) measurements, as derived from wet‐bulb and dry‐bulb thermometers operated as a psychrometer within a thermometer screen, have limited accuracy because of natural ventilation variations. Standard RH calculations generally assume a fixed screen psychrometer coefficient, but this is too small during poor ventilation. By comparing a reference humidity probe—exposed within a screen containing a psychrometer—with wind‐speed measurements under controlled conditions, a wind‐speed correction for the screen psychrometer coefficient has been derived and is applicable when 2‐metre wind speeds fall below 3 m s−1. Applying this to hourly‐averaged data reduced the mean moist RH bias of the psychrometer (over the reference probe) from 1.2% to 0.4%, and reduced the interquartile range of the RH differences from 2.0% to 0.8%. This correction is particularly amenable to automatic measurement systems. Copyright © 2011 Royal Meteorological Society
New steel‐concrete connection for prefabricated composite bridges
Authors: Papastergiou Dimitrios , Lebet Jean‐Paul 
Published: December 2011

AbstractAn investigation of a new type of connection between precast concrete decks and steel girders, for composite steel‐concrete bridges, is being performed by the Steel Structures Laboratory, ICOM, of Ecole Polytechinque Fédéral de Lausanne, EPFL. The connection resists the loads by shear resistance between base materials. Hence, a fundamental part of the research focuses on the behaviour of the different confined interfaces of the connection, subjected to shear, static and fatigue loading. The confinement is a combined outcome of the kinematic law of the interfaces and the section geometry. Experimental investigation through a series of direct shear tests on confined interfaces has resulted in the development of failure criteria and constitutive and kinematic models describing the behaviour of the different interfaces. Those laws are used as an input for a model that simulates the connection behaviour. The model of the connection is validated by push‐out tests on large‐scale specimens. Finally, a composite beam has been tested under constant amplitude for five million cycles. A static test, following the fatigue sequence, has shown that the composite beam reaches its plastic moment capacity due to the sufficient ductility of the connection.Neue Stahl‐Beton‐Verbindung für vorgefertigte StahlverbundbrüKen. Im Labor für Stahlkonstruktionen (ICOM) der Eidgenössischen Polytechnischen Hochschule Lausanne werden Untersuchungen für eine neue Verbindungsart zwischen Betonfertigteil‐Fahrbahn und Stahlträgern bei Stahlverbundbrücken durchgeführt. Die Verbindung nimmt die Beanspruchungen über den Schubwiderstand zwischen den Grundmaterialien auf. Daher konzentriert sich ein wesentlicher Teil der Forschung auf das Verhalten der verschiedenen, eingeschlossenen Verbundfugen, die Schubkräften und statischen und ermüdungswirksamen Beanspruchungen ausgesetzt sind. Die Zwängungsbeanspruchung ist ein kombiniertes Ergebnis der Kinematik der Verbundfugen und der Profilgeometrie. Experimentelle Forschung anhand einer Reihe von direkten Abscherversuchen an eingeschlossenen Verbundfugen führte zur Entwicklung von Versagenskriterien, Materialgesetzen und kinematischen Modellen zur Beschreibung des Verhaltens der verschiedenen Verbundfugen. Diese Gesetze werden als Eingangsgrößen für ein Modell verwendet, welches das Verhalten der unterschiedlichen Verbundfugen simuliert. Das Modell der Verbindung wird durch Push‐ Out‐Versuche an großen Prüfkörpern validiert. Abschließend ist ein Verbundträger unter konstanter Amplitude mit 5 Millionen Lastwechseln geprüft worden. Eine statische Prüfung der Resttragfähigkeit hat gezeigt, dass der Verbundträger die vollplastische Momententragfähigkeit aufgrund einer ausreichenden Duktilität der Verbindung erreicht.
Hubschrauberlandeplattform Universitätsklinikum Aachen
Authors: Sauerborn Norbert , Stengel Jochen 
Published: December 2011

AbstractNeue europäische luftfahrtrechtliche Bestimmungen sowie der Wunsch nach einer bedeutenden Verkürzung des Transportweges von Notfallpatienten in die Notaufnahme erforderten am Universitätsklinikum Aachen einen neuen Hubschrauberlandeplatz in exponierter Lage. Eine aufregende architektonische Gestaltung, schwierige Montagerandbedingungen, der Einsatz unterschiedlicher Materialien und Bauarten, wie Stahlbau, Verbundbau, Fertigteilbau, eine Fassade teils aus textiler Bespannung und teils aus aufwändiger Blechkonstruktion, sowie besondere technische Ausstattungen machten das Projekt zu einer interessanten Planungs‐ und Bauaufgabe.Helicopter base of Universitätsklinikum Aachen, Germany. New European aviation regulations and the request for a significant shortening of the transport route of emergency patients in the emergency department required a new helicopter base in a prominent location at the Universitätsklinikum Aachen. The very interesting design and construction tasks are due to an exciting architectural design, difficult assembly conditions, the use of different materials and types of construction such as steel, composite and precast construction, a façade partly from textile fibre and partly out of complex metal sheets as well as special technical facilities.
Die Revitalisierung des Glockenstuhls der Dresdener Kreuzkirche
Authors: Stroetmann Richard , Kuhnen Lea , Schneider Sven 
Published: December 2011

AbstractDas Bronzegeläut der Dresdener Kreuzkirche aus dem Jahr 1899 gilt mit 28,5 t als eines der schwersten erhaltenen Großgeläute Deutschlands. Auf engstem Raum wird das fünfstimmige Geläut von einem stählernen Glockenstuhl getragen. Nach einer Begutachtung wurden dessen Schäden als so gravierend eingestuft, dass im März 2009 aus Sicherheitsgründen ein Läuteverbot erteilt wurde. Zudem vermutete man, dass durch den Glockenbetrieb erhebliche Rissschäden am Kirchturm entstanden waren. Im folgenden Beitrag werden nach einem geschichtlichen Rückblick und der Zustandsanalyse die Planungsschritte bis zur Revitalisierung des Glockenstuhls beschrieben.The revitalization of the bell frame of the Dresdener Kreuzkirche, Germany. The bronze church bells of the Dresdener Kreuzkirche, dated from 1900, are some of the heaviest preserved in Germany. The steel frame of the fife‐voice peal is located in a bell chamber with a minimum of space. After an inspection of the steel structure the damages have been classified such as serious, that starting from the 9th of March 2009 bell ringing was forbidden. In addition it was suspected, that significant cracks at the church tower were caused by ringing. After an historical review and the analysis of current state the following article describes the planning stages up to the revitalization of the bell frame.