bluuebunny/crossref_metadata_2025 huggingface dataset:
Significance of geomorphological and subsurface drainage controls on failures of peat‐covered hillslopes triggered by extreme rainfall
Authors: Dykes Alan P. , Warburton Jeff
Published: March 2007

On 19 September 2003, 40 landslides of 140–18 000 m3 volume occurred within 2·5 km2 on the slopes of Dooncarton Mountain (Republic of Ireland) during a storm that may have exceeded 90 mm within 90 minutes. The landslides were investigated to determine the reasons for such a high density of slope failures. All of the landslides were surveyed within four months, and nine of them were investigated in detail. The six largest landslides, all peat failures, accounted for 57% of the more than 100 000 m3 of material displaced during the event. A consistent sequence of superficial materials was found on the failed hillslopes, including an extensive iron pan at the base of a buried soil horizon 0·3 m below the base of the peat. Morphologically, almost all of the landslides occurred on steep planar slopes or around sharp convexities, with the latter failures developing retrogressively upslope. The only significant relationship found from analysis of 371 subsurface pipes and 142 seepage cracks (defined here as contiguous fissures conducting concentrated subsurface flow) across all the failures was that the thinner the peat cover, the deeper the pipes and seepage cracks occurred below the base of peat. It is concluded that most of the landslides were probably caused by a combination of excess water pressures in the buried soil horizon and the thinner overburden of peat or peaty soil associated with the steeper slope segments. Pipes and seepage cracks formed on the iron pan probably existed prior to the failure event and may have contributed to the high water pressures as rainwater inputs exceeded their discharge capacities. One large peat slide was probably triggered by excess water pressures developed within and between artificial tine cuts. The properties of the blanket peat were generally of little consequence in the occurrence of the landslides, but relict desiccation cracks and other structural weaknesses through the peat mass were probably highly significant. Although several aspects of the peat failures correspond to previously published examples, the context of these failures in terms of the topography and upland catena is distinctive. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of the constitutive parameters of a multiconductor transmission line model aimed at the representation of inductor windings at high frequencies
Authors: Brandão Faria J. A.
Published: March 2007

This paper is the first part of a work dedicated to the analysis and computation of the electric and magnetic behavior of inductor windings (e.g., power transformer windings) operating at high‐frequency regimes; a recognized key issue for very fast transient overvoltage studies. Here, the inductor winding, containing a total number of N turns, is modeled as a system of N‐coupled parallel conductors resembling a uniform inhomogeneous multiconductor transmission‐line structure (MTL) where proximity effects cannot be neglected. The characterization of the winding's equivalent MTL structure requires the specification and evaluation of its constitutive parameters, namely, the per‐unit‐length (PUL) capacitance and inductance matrices, and also the PUL resistance and conductance matrices, the latter two associated with losses. Close proximity between inductor turns together with the consideration of dielectric‐coated turns prevents the utilization of closed‐form expressions for the evaluation of most of the inductor constitutive parameters. Here we employ a harmonic expansion method (HEM) primarily aimed at the construction of the capacitance matrix from where the inductance and conductance matrices can be derived. A new theory based on Dubanton's approach but taking into account proximity effects related to eddy currents in the inductor core is also proposed and developed. This research paper provides, in a tutorial fashion, a comprehensive explanation of the details and approximations involved in the evaluation of the constitutive parameters of the MTL structure under analysis––an aspect that unfortunately is lightly tackled or even ill‐treated in the literature of winding models. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of volatile organic compounds in English vineyard grape juices by immersion stir bar sorptive extraction–gas chromatography/mass spectrometry
Authors: Caven‐Quantrill Darren J. , Buglass Alan J.
Published: March 2007

Immersion stir bar sorptive extraction–gas chromatography–mass spectrometry was used to analyse the volatile organic components of English vineyard grape juices. Four juices, Huxelrebe, Ortega, Schönburger and Siegerrebe, of the 2004 season, were from a commercial vineyard. The fifth, Madeleine Angevine 7672, of the 2000 vintage, was from a private vineyard. Madeleine Angevine juice exhibited the greatest number (113) of identified volatile components, followed by Siegerrebe, Huxelrebe, Schönburger and Ortega, with 78, 74, 70 and 69, respectively. Many compounds are common to all five varieties and very few of the more concentrated components are unique to a particular variety, except (E)‐anethole, estragole and methyl salicylate, which were unique to Madeleine Angevine, for these particular vintages. Of the compounds that are common to more than two varieties, Madeleine Angevine had the highest levels of (E)‐ethyl cinnamate, hexanol, (E)‐2‐hexenol, hotrienol, limonene and (E)‐methyl cinnamate. Siegerrebe had the highest concentrations of β‐citronellol, diendiol‐I, geraniol, dihydromethyl jasmonate, linalool (32 000 ng/l), (Z)‐ and (E)‐linalool oxide (both furanoid and pyranoid forms) and α‐terpineol. This variety also had high levels of 1‐hexanol, (E)‐2‐hexenal and (E)‐2‐hexenol. Huxelrebe had the highest concentrations of (E)‐2‐hexenal and (E)‐theaspirane; Schönburger had the highest levels of (Z)‐3‐hexenol, nerol and nerol oxide; and Ortega had the highest concentrations of β‐damascone and β‐damascenone. Copyright © 2007 John Wiley & Sons, Ltd.
A new approach to studying sponge cake aroma after storage in treated paper and plastic packaging by direct gas chromatography–olfactometry (D‐GC–O)
Authors: Dury‐Brun Cécile , Fournier Nicole , Pernin Karine , Guichard Elisabeth , Voilley Andrée
Published: March 2007

The objective of this study was to use D‐GC–O to compare the global odour of a sponge cake flavoured with either a ‘viennoiserie’ aromatic note or a simplified mixture of aroma compounds (used for physicochemical studies), then stored in a glass packaging (inert and impermeable) or in pouches made with treated papers or with plastic packaging, in accelerated ageing conditions (high temperature and relative humidity gradient). After 1 week of storage, the flavoured sponge cake headspace was SPME‐extracted directly into the packaging and analysed by D‐GC–O. The sponge cake global odour was better retained if plastic film rather than treated‐papers was used, for both flavourings. Changes in the relative proportions of aroma compounds in the sponge cake during storage modified the perceived global odour. This was due to their modified retention in the sponge cake and to their transfer through the packaging. SPME coupled to D‐GC–O was confirmed to be a rapid and sensitive method for comparing the aroma compound barrier properties of various packaging films with flavouring mixtures at concentrations close to reality. Copyright © 2007 John Wiley & Sons, Ltd.
Chemical composition and antimicrobial activity of essential oil of Ferula szovitsiana D.C.
Authors: Dehghan Gholamreza , Solaimanian Roya , Shahverdi Ahmad R. , Amin Gholamreza , Abdollahi Mohammad , Shafiee Abbas
Published: March 2007

The chemical composition of the essential oils obtained from stem/leaves and flowers/fruits of Ferula szovitsiana (Umbelliferae) were analysed by GC and GC–MS. The composition of the oils samples from stem/leaves and flower/fruits were compared: 51 and 47 compounds were identified in the essential oils of stem/leaves and flowers/fruits, representing 97.7% and 95.9% of the total oils, respectively. Both essential oils were rich in monoterpenes (66.7% and 62.1%, respectively) with neryl acetate as major component (33.0% and 41.5%, respectively). Other abundant compounds for stem/leaves oil were β‐caryophyllene (8.9%), α‐pinene (8.0%), β‐pinene (6.7%), bicyclogermacrene (4.5%), caryophyllene oxide (4.1%), limonene (4.6%) and α‐terpineol (3.2%). These values for flowers/fruits oil were bicyclogermacrene (9.0%), α‐pinene (5.5%), β‐pinene (3.9%), γ‐cadinene (3.5%), and calarene (3.2%). Furthermore, the oils were tested against Gram‐positive, Gram‐negative bacteria and two pathogenic fungi. It was found that oil from F. szovitsiana represents the most potent antimicrobial candidates with MIC of 1.25 mg/disk for Bacillus subtilis. Copyright © 2007 John Wiley & Sons, Ltd.
A modification of the artificial compressibility algorithm with improved convergence characteristics
Authors: Muldoon Frank , Acharya Sumanta
Published: March 2007

The artificial compressibility algorithm has a significant drawback in the difficulty of choosing the artificial compressibility parameter, improper choice of which leads either to slow convergence or divergence. A simple modification of the equation for pressure in the artificial compressibility algorithm which removes the difficulty of choosing the artificial compressibility parameter is proposed. It is shown that the choice of the relaxation parameters for the new algorithm is relatively straightforward, and that the same values can be used to provide robust convergence for a range of application problems. This new algorithm is easily parallelized making it suitable for computations such as direct numerical simulation (DNS) which require the use of distributed memory machines. Two key benchmark problems are studied in evaluating the new algorithm: DNS of a fully developed turbulent channel flow, and DNS of a driven‐cavity flow, using both explicit and implicit time integration schemes. The new algorithm is also validated for a more complex flow configuration of turbulent flow over a backward‐facing step, and the computed results are shown to be in good agreement with experimental data and previous DNS work. Copyright © 2007 John Wiley & Sons, Ltd.
Developing implicit pressure‐weighted upwinding scheme to calculate steady and unsteady flows on unstructured grids
Authors: Darbandi M. , Vakilipour S.
Published: March 2007

The finite‐volume methods normally utilize either simple or complicated mathematical expressions to interpolate the fluxes at the cell faces of their unstructured volumes. Alternatively, we benefit from the advantages of both finite‐volume and finite‐element methods and estimate the advection terms on the cell faces using an inclusive pressure‐weighted upwinding scheme extended on unstructured grids. The present pressure‐based method treats the steady and unsteady flows on a collocated grid arrangement. However, to avoid a non‐physical spurious pressure field pattern, two mass flux per volume expressions are derived at the cell interfaces. The dual advantages of using an unstructured‐based discretization and a pressure‐weighted upwinding scheme result in obtaining high accurate solutions with noticeable progress in the performance of the primitive method extended on the structured grids. The accuracy and performance of the extended formulations are demonstrated by solving different standard and benchmark problems. The results show that there are excellent agreements with both benchmark and analytical solutions as well as experimental data. Copyright © 2007 John Wiley & Sons, Ltd.
Adapting simulation codes to compute unstable solutions and bifurcation behaviour
Authors: Grande Beau B. , Tavener Simon J. , Thomas James W.
Published: March 2007

Simulation codes for solving large systems of ordinary differential equations suffer from the disadvantage that bifurcation‐theoretic results about the underlying dynamical system cannot be obtained from them easily, if at all. Bifurcation behaviour typically can be inferred only after significant computational effort, and even then the exact location and nature of the bifurcation cannot always be determined definitively. By incorporating relatively minor changes to an existing simulation code for the Taylor–Couette problem, specifically, by implementing the Newton–Picard method, we have developed a computational structure that enables us to overcome some of the inherent limitations of the simulation code and begin to perform bifurcation‐theoretic tasks. While a complete bifurcation picture was not developed, three distinct solution branches of the Taylor–Couette problem were analysed. These branches exhibit a wide variety of behaviours, including Hopf bifurcation points, symmetry‐breaking bifurcation points, turning points and bifurcation to motion on a torus. Unstable equilibrium and time‐periodic solutions were also computed. Copyright © 2007 John Wiley & Sons, Ltd.
Simulations of the turbulent channel flow at Reτ = 180 with projection‐based finite element variational multiscale methods
Authors: John Volker , Roland Michael
Published: March 2007

Projection‐based variational multiscale (VMS) methods, within the framework of an inf–sup stable second order finite element method for the Navier–Stokes equations, are studied in simulations of the turbulent channel flow problem at Reτ = 180. For comparison, the Smagorinsky large eddy simulation (LES) model with van Driest damping is included into the study. The simulations are performed on very coarse grids. The VMS methods give often considerably better results. For second order statistics, however, the differences to the reference values are sometimes rather large. The dependency of the results on parameters in the eddy viscosity model is much weaker for the VMS methods than for the Smagorinsky LES model with van Driest damping. It is shown that one uniform refinement of the coarse grids allows an underresolved direct numerical simulations (DNS). Copyright © 2007 John Wiley & Sons, Ltd.
Multi‐resolution implicit large eddy simulations using a high‐order overset‐grid approach
Authors: Sherer S. E. , Visbal M. R.
Published: March 2007

A parallel, high‐order, overset‐grid method is validated for use in large eddy simulation (LES) through its application to fundamental turbulent flow problems. The current method employs a high‐order, compact finite‐difference approach to evaluate spatial derivatives, with up to tenth‐order low‐pass filters used to remove high‐frequency spurious wave content. These filters have also been found to be effective in modelling the dissipation that occurs at the unresolved scales in the flow for LES simulations. Temporal integration is based on an implicit, approximately factored and diagonalized, second‐order algorithm, which reduces the time‐step constraints present in explicit time‐marching methods for wall‐bounded viscous flows. Parallelization, geometric complexity, and local grid refinement are all addressed through the use of an overset‐grid approach, with grid communication provided by high‐order Lagrangian interpolation. The problems investigated in this work include fully turbulent channel flow at Reτ = 590 and 1017, and the transitional wake generated by flow over a single circular cylinder at ReD = 3900. The results obtained with the current approach are validated against well‐resolved benchmark calculations or experiments and the impact of the order‐of‐accuracy of the interpolation method is investigated. The benefits obtained by using the general overset‐grid technique to reduce grid point requirements compared to single‐grid simulations are also examined. It is shown that for the problems considered in this work, substantial grid‐point savings may be obtained with an overset‐grid approach compared to a single‐grid approach, and that the use of high‐order interpolation at overset boundaries is important in maintaining overall solution accuracy. Published in 2007 by John Wiley & Sons, Ltd.
Computation of fluid–solid and fluid–fluid interfaces with the CIP method based on adaptive Soroban grids—An overview
Authors: Yabe Takashi , Takizawa Kenji , Tezduyar Tayfun E. , Im Hyo‐Nam
Published: March 2007

We provide an overview of how fluid–solid and fluid–fluid interfaces can be computed successfully with the constrained interpolation profile/cubic interpolated pseudo‐particle (CIP) method (J. Comput. Phys. 1985; 61:261–268; Comput. Phys. Commun. 1991; 66:219–232; Comput. Phys. Commun. 1991; 66:233–242; J. Comput. Phys. 2001; 169:556–593) based on adaptive Soroban grids (J. Comput. Phys. 2004; 194:57–77). In this approach, the CIP combined unified procedure (CCUP) technique (J. Phys. Soc. Jpn 1991; 60:2105–2108), which is based on the CIP method, is combined with the adaptive Soroban grid technique. One of the superior features of the approach is that even though the grid system is unstructured, it still has a simple data structure that renders remarkable computational efficiency. Another superior feature is that despite the unstructured and collocated nature of the grid, high‐order accuracy and computational robustness are maintained. In addition, because the Soroban grid technique does not have any elements or cells connecting the grid points, the approach does not involve mesh distortion limitations. While the details of the approach and several numerical examples were reported in (Comput. Mech. 2006; published online), our objective in this paper is to provide an easy‐to‐follow description of the key aspects of the approach. Copyright © 2007 John Wiley & Sons, Ltd.
Cerebral volume measurements and subcortical white matter lesions and short‐term treatment response in late life depression
Authors: Janssen Joost , Pol Hilleke E. Hulshoff , Schnack Hugo G. , Kok Rob M. , Lampe Indrag K. , de Leeuw Frank‐Erik , Kahn Rene S. , Heeren Thea J.
Published: March 2007

Background

Late life depression is associated with volumetric reductions of gray matter and increased prevalence of subcortical white matter lesions. Previous studies have shown a poorer treatment outcome in those with more severe structural brain abnormalities. In this study, quantitative and semi‐quantitative magnetic resonance imaging (MRI) measures were studied in relation to response to a 12‐week controlled antidepressant monotherapy trial.

Methods

MRI (1.5T) brain scans of 42 elderly inpatients with major depression, of which 23 were non‐responder to a controlled 12‐week antidepressant monotherapy trial, were acquired. In addition, clinical outcome was assessed after a one year period. Measures were volumes of global cerebral and subcortical structures.

Results

After controlling for confounding, no differences were found between non‐responders and responders after 12 weeks and after one year in volumes of cerebral gray and white matter, orbitofrontal cortex, hippocampus and white matter lesions.

Conclusions

Structural brain measures associated with late life depression may not be related to short‐term treatment response. Copyright © 2007 John Wiley & Sons, Ltd.
Simulated groundwater interaction with rivers and springs in the Heihe river basin
Authors: Hu Li‐Tang , Chen Chong‐Xi , Jiao Jiu Jimmy , Wang Zhong‐Jing
Published: March 2007

Surface water and groundwater in the Heihe river basin of China are interconnected and the pattern of water resources exploitation has a direct effect on the interaction of groundwater and surface water, especially on a downstream oasis. A three‐dimensional groundwater flow simulation model with eight model layers was established to simulate the regional groundwater flow in the multilayered aquifer system and the interaction among the rivers, springs, and groundwater. The model was calibrated not only with historical water levels but also with the investigated baseflow and spring flux. The simulation results of the numerical model match reasonably well with the observed groundwater levels, baseflow to rivers, and spring flux. The numerical simulation also demonstrates that the hydraulic connection between the river and the aquifers has transferred from the coupling to decoupling at some reaches. It is suggested that there is a vital need to reduce groundwater withdrawal and to rationalize the use of both groundwater and surface water in order to maintain sustainable development in the study area. Copyright © 2007 John Wiley & Sons, Ltd.
Modelling the impact of recent land‐cover changes on the stream flows in northeastern Puerto Rico
Authors: Wu Wei , Hall Charles A. S. , Scatena Frederick N.
Published: March 2007

We investigated the influence of recent and future land‐cover changes on stream flow of a watershed northeastern Puerto Rico using hydrological modeling and simulation analysis. Monthly and average annual stream flows were compared between an agricultural period (1973–1980) and an urbanized/reforested period (1988–1995) using the revised Generalized Watershed Loading Function model. Our validated results show that a smaller proportion of rainfall became stream flows in the urbanized/forested period compared with the agricultural period, apparently because of reforestation. Sensitivity analysis of the model showed that evapotranspiration, precipitation, and curve number were the most significant factors influencing stream flow. Simulations of projected land‐cover scenarios indicate that annual stream flows would increase by 9·6% in a total urbanization scenario, decrease by 3·6% in a total reforestation scenario, and decrease by 1·1% if both reforestation and urbanization continue at their current rates to 2020. An imposed hurricane event that was similar in scale to the largest recent event on the three land‐cover scenarios would increase the daily stream flow by 62·1%, 68·4% and 67·1% respectively. Owing to the environmental setting of eastern Puerto Rico, where sea breezes caused by temperature differences between land surface and the ocean dominate the local climate, we suggest that managing local land‐cover changes can have important consequences for water management. Copyright © 2007 John Wiley & Sons, Ltd.
Further testing of the integrated hydrology model (InHM): multiple‐species sediment transport
Authors: Ran Qihua , Heppner Christopher S. , VanderKwaak Joel E. , Loague Keith
Published: March 2007

The sediment‐transport version of the Integrated Hydrology Model (InHM) is further tested for the case of multiple‐species sediment transport with both rainsplash and hydraulic erosion using data from the Johansen et al. (2001) field experiments. The ability to simulate sub‐plot scale interactions between surface water hydrology and multiple‐species sediment transport with InHM is clearly demonstrated. Sensitivity analysis reveals that the erodibility coefficient has a substantial impact on the simulated total sediment mass. New spatio‐temporal, data‐rich field experiments are needed to continue the evaluation of the sediment‐transport version of InHM and, subsequently, fully exploit the concept‐development capabilities of the model. Copyright © 2007 John Wiley & Sons, Ltd.
Exploring the international linkages of the euro area: a global VAR analysis
Authors: Dees Stephane , Mauro Filippo di , Pesaran M. Hashem , Smith L. Vanessa
Published: March 2007

This paper presents a quarterly global model combining individual country vector error‐correcting models in which the domestic variables are related to the country‐specific foreign variables. The global VAR (GVAR) model is estimated for 26 countries, the euro area being treated as a single economy, over the period 1979–2003. It advances research in this area in a number of directions. In particular, it provides a theoretical framework where the GVAR is derived as an approximation to a global unobserved common factor model. Using average pair‐wise cross‐section error correlations, the GVAR approach is shown to be quite effective in dealing with the common factor interdependencies and international co‐movements of business cycles. It develops a sieve bootstrap procedure for simulation of the GVAR as a whole, which is then used in testing the structural stability of the parameters, and for establishing bootstrap confidence bounds for the impulse responses. Finally, in addition to generalized impulse responses, the current paper considers the use of the GVAR for ‘structural’ impulse response analysis with focus on external shocks for the euro area economy, particularly in response to shocks to the US. Copyright © 2007 John Wiley & Sons, Ltd.
Unravelling financial market linkages during crises
Authors: Dungey Mardi , Martin Vance L.
Published: March 2007

An empirical model of multiple asset classes across countries is formulated in a latent factor framework. A special feature of the model is that financial market linkages during periods of financial crises, including spillover and contagion effects, are formally specified. The model also captures a range of common factors including global shocks, country and market shocks, and idiosyncratic shocks. The framework is applied to modelling linkages between currency and equity markets during the East Asian financial crisis of 1997–98. The results provide strong evidence that cross‐market links are important. Spillovers have a relatively larger effect on volatility than contagion, but both are statistically significant. Copyright © 2007 John Wiley & Sons, Ltd.
Blending ameliorative and transformative approaches in human service organizations: A case study
Authors: Evans Scot D. , Hanlin Carrie E. , Prilleltensky Isaac
Published: March 2007

This paper describes the challenges and benefits of an action‐research project with a Nashville‐based nonprofit human service organization. In our view, outmoded human service organizations are in serious need of innovation to promote psychological and physical wellness, prevention of social problems, empowerment, and social justice. This project aims to develop and evaluate value‐based organizational processes and outcomes designed to transform human services. Although the goal of moving human services from ameliorative to transformative approaches is invigorating, our efforts have revealed expected and unexpected barriers to this process of change. Two main barriers are a strong cultural current working against change and irregular pacing of the change efforts. Positive outgrowths of the project include a new organizational philosophy that includes attention to issues of justice and equality, and changing individual and organizational beliefs and practices. Clear messages regarding the changes desired and a highly participatory process have facilitated these initial outcomes. © 2007 Wiley Periodicals, Inc.
Homogeneity in community‐based rape prevention programs: Empirical evidence of institutional isomorphism
Authors: Townsend Stephanie M. , Campbell Rebecca
Published: March 2007

This study examined the practices of 24 community‐based rape prevention programs. Although these programs were geographically dispersed throughout one state, they were remarkably similar in their approach to rape prevention programming. DiMaggio and Powell's (1991) theory of institutional isomorphism was used to explain the underlying causes of the homogeneity among the programs. Qualitative data indicate that the mimetic, normative, and coercive contextual factors pushed the programs into homogeneity. Implications for community psychology and organizational theory will be discussed. © 2007 Wiley Periodicals, Inc.
Applying organizational theories to action research in community settings: A case study in urban schools
Authors: Bryan Keli S. , Klein Dena A. , Elias Maurice J.
Published: March 2007

Action research is well grounded in the worlds of organizational and community psychology. The practice of action research within each of these fields has been shaped by their dominant settings, theories, and values; where these diverge, rich learning opportunities have been created. Each phase of the action research cycle has particular challenges that can be overcome by integrating theories from both fields. This article outlines organizational theories as they apply to action research in community settings in three particular areas: the ecological context, collaboration and consensus, and sustainability. Using Price and Smith's (1985) four‐cycle model of action research as a framework, we then present a case study example of how organizational theories have become part of our action research practices. Specifically, we will illustrate issues and challenges involved in coordinating social and emotional learning programs in two overlapping contexts: urban elementary schools and high schools. We found that building explicit knowledge of organizational theory brings important perspectives and tools to action research in community settings. © 2007 Wiley Periodicals, Inc.
Morphing the hyomandibular skeleton in development and evolution
Authors: Kimmel Charles B. , Walker Macie B. , Miller Craig T.
Published: March 2007

How might changes in developmental regulatory pathways underlie evolutionary changes in morphology? Here we focus on a particular pathway regulated by a secreted, signaling peptide, Endothelin1 (Edn1). Developmental genetic analyses show the Edn1‐pathway to be crucial for hyomandibular patterning, and we discuss our work with zebrafish suggesting how the signal may function in regulating numbers of skeletal elements, their sizes and their shapes. We then review a broader collection of comparative studies that examine morphological evolution of a subset of the same skeletal elements–the opercular‐branchiostegal series of bones of the hyoid arch. We find that phenotypic changes in zebrafish mutants copy evolutionary changes that recur along many actinopterygian lineages. Hence the developmental genetic studies are informative for providing candidate pathways for macroevolution of facial morphology, as well as for our understanding of how these pathways work.J. Exp. Zool. (Mol. Dev. Evol.) 308B:609–624, 2007. © 2007 Wiley‐Liss, Inc.
Development and evolution of chordate cartilage
Authors: Rychel Amanda L. , Swalla Billie J.
Published: March 2007

Deuterostomes are a monophyletic group of animals containing vertebrates, lancelets, tunicates, hemichordates, echinoderms, and xenoturbellids. Four out of these six extant groups—vertebrates, lancelets, tunicates, and hemichordates—have pharyngeal gill slits. All groups of deuterostome animals that have pharyngeal gill slits also have a pharyngeal skeleton supporting the pharyngeal openings, except tunicates. We previously found that pharyngeal cartilage in hemichordates and cephalochordates contains a fibrillar collagen protein similar to vertebrate type II collagen, but unlike vertebrate cartilage, the invertebrate deuterostome cartilages are acellular. We found SoxE and fibrillar collagen expression in the pharyngeal endodermal cells adjacent to where the cartilages form. These same endodermal epithelial cells also express Pax1/9, a marker of pharyngeal endoderm in vertebrates, lancelets, tunicates, and hemichordates. In situ experiments with a cephalochordate fibrillar collagen also showed expression in pharyngeal endoderm, as well as the ectoderm and the mesodermal coelomic pouches lining the gill bars. These results indicate that the pharyngeal endodermal cells are responsible for secretion of the cartilage in hemichordates, whereas in lancelets, all the pharyngeal cells surrounding the gill bars, ectodermal, endodermal, and mesodermal may be responsible for cartilage formation. We propose that endoderm secretion was primarily the ancestral mode of making pharyngeal cartilages in deuterostomes. Later the evolutionary origin of neural crest allowed co‐option of the gene network for the secretion of pharyngeal cartilage matrix in the new migratory neural crest cell populations found in vertebrates. J. Exp. Zool. (Mol. Dev. Evol.) 308B:325–335, 2007. © 2007 Wiley‐Liss, Inc.
Mining of putative cis‐acting elements for chromatin mediated regulation of Hox genes in mammals by in‐silico analysis
Authors: Bengani Hemant , Ganapathi Mythily , Singh Gajinder Pal , Brahmachari Vani
Published: March 2007

The remarkable conservation in developmental strategies across phyla is well reflected in the conservation of the homeotic gene complexes responsible for establishing the body plan in embryonic development. On the other hand, changes in the strategy of transcription regulation are believed to form one of the major factors in the evolution of developmental mechanisms and phenotypic evolution of species. Apart from transcription regulation by gene specific transcription factors, the role of regulators mediating modifications of chromatin proteins, especially of HOX gene clusters in Drosophila is well documented. By comparative genomics we have identified novel motifs conserved in mouse, chimpanzee and human in the noncoding upstream/intronic sequences of Hox genes by in silico analysis. These motifs lack the binding sites for known transcription factors and are significantly over represented in the target genes of one of the core components of Polycomb Repressive Complex namely Supressor of zeste 12 (SUZ12) in human embryonic cells reported by Lee et al. [2006a. Cell 125:301–313]. Therefore, we predict that they could be the sites of interaction of chromatin modifying complexes for epigenetic regulation. J. Exp. Zool. (Mol. Dev. Evol.) 308B:384–395, 2007. © 2007 Wiley‐Liss, Inc.
Polyandry and female control: the red flour beetle Tribolium castaneum as a case study
Authors: Pai Aditi , Bernasconi Giorgina
Published: March 2007

Females of many animal species are polyandrous, and there is evidence that they can control pre‐ and post‐mating events. There has been a growing interest in consequences of polyandry for male and female reproductive success and offspring fitness, and its evolutionary significance. In several taxa, females exhibit mate choice both before and after mating and can influence the paternity of their offspring, enhancing offspring number and quality, but potentially countering male interests. Studying female mating biology and in particular post‐copulatory female control mechanisms thus promises to yield insights into sexual selection and the potential of male–female coevolution. Here, we highlight the red flour beetle Tribolium castaneum (Herbst), a storage pest, as a model system to study polyandry, and review studies addressing the effects of polyandry on male sperm competitive ability and female control of post‐mating events. These studies show that the outcome of sperm competition in the red flour beetle is influenced by both male and female traits. Furthermore, recent advances suggest that sexual conflict may have shaped reproductive traits in this species. J. Exp. Zool. (Mol. Dev. Evol.) 310B:148–159, 2008. © 2007 Wiley‐Liss, Inc.
Using zebrafish to investigate cypriniform evolutionary novelties: functional development and evolutionary diversification of the kinethmoid
Authors: Patricia Hernandez L. , Bird Nathan Craig , Staab Katie Lynn
Published: March 2007

Although the zebrafish has become a popular model organism for biomedical studies, we propose that the wealth of morphological novelties that characterize this cypriniform fish makes it well suited for investigating the development of evolutionary innovations. Morphological novelties associated with feeding in cypriniform fishes include: a unique structure of the pharyngeal jaws in which the lower pharyngeal jaws are enlarged and opposed to a pad on the basioccipital process; a palatal organ found on the roof of the buccal chamber that is thought to help process detrital food within the buccal chamber; and, the kinethmoid, a novel ossification that effects a unique means of premaxillary protrusion. We present new morphological and developmental data and review functional data regarding the role of the kinethmoid in premaxillary protrusion in the zebrafish. Premaxillary protrusion plays an important role in effective prey acquisition in teleosts and the evolution of a unique means of premaxillary protrusion within Cypriniformes may have led to a number of trophic radiations within this clade. Ontogenetic data from zebrafish show that substantial premaxillary protrusion is not seen until these fish have undergone metamorphosis at which point the adductor mandibulae musculature becomes divided and all ligamentous attachments become established. A comparative study of families within Cypriniformes shows diverse morphologies of the kinethmoid. The morphological diversification that characterizes the kinethmoid suggests that this feeding structure has played a role in trophic radiations within Cypriniformes, since the morphology of this feature is correlated with feeding habits.J. Exp. Zool. (Mol. Dev. Evol.) 308B:625–641, 2007. © 2007 Wiley‐Liss, Inc.
Studies on synthesis and anion recognition properties of (3′‐nitrobenzo)[2,3‐d]‐(3″‐nitrobenzo)[9,10‐d]‐1,4,8,11‐tetraazacyclotetradecane‐5,7,12,14‐tetraone
Authors: Shang Xue‐Fang , Xu Xiu‐Fang , Lin Hai , Shao Jie , Lin Hua‐Kuan
Published: March 2007

A novel artificial receptor, (3′‐nitrobenzo)[2,3‐d]‐(3″‐nitrobenzo)[9,10‐d]‐1,4,8,11‐tetraazacyclotetradecane‐5,7,12,14‐tetraone, was designed and synthesized. The interactions of this receptor with different anions were determined by UV‐vis and 1H NMR titration experiments, and their affinity constants to different anions were compared with those of other similar/different systems. The results indicated that this receptor showed a high selective and recognitive ability for F− among F−, Cl−, Br−, I−, AcO−, OH−, and H2PO. Moreover, the low energy configuration of this receptor was further determined by means of theoretical investigations. Copyright © 2007 John Wiley & Sons, Ltd.
MRI efficacy and effectiveness research: Who needs it and who pays for it?
Authors: Harms Steven E. , Radensky Paul , Sunshine Jonathan , Davis David O. , Okunieff Paul , Farr Christopher , Spettell Claire
Published: March 2007

This article is a summary of the workgroup on Audience/Funding at the recent Society of Magnetic Resonance Workshop on Efficacy and Effectiveness of Imaging: An Evaluation of Methodologies.
Economics of MRI technology
Authors: Bell Robert A.
Published: March 2007

MRI development in the United States is reviewed from 1983 to the present with the intent of projecting future utilization and reimbursement. Since 1992, a decreasing rate of new installations and an aging installed base have markedly lowered the ratio between fixed and variable costs, thereby improving the ability to project cost per study. Variable costs are now estimated to average $175 to $200 per examination, up sharply from earlier reports. Actual costs per study usually exceed $400, even for high volume sites. Major cost contributors are reviewed and methods for identifying impediments to efficient operation are suggested.
Health economics in diagnostic imaging
Authors: Högström B , Sverre J‐M
Published: March 2007

New technologies, such as magnetic resonance imaging, are frequently cited as major contributors to the growth of national health care expenditure. The cost‐effectiveness of this modality is commonly challenged, and the lack of health economic documentation increases the level of criticism. Some common methods for evaluating imaging methods with regard to efficacy, cost, and benefits are, therefore, reviewed. Limitations in the assessment of diagnostic imaging are discussed, together with some suggestions as to which methodological approaches may be useful in this field of research.
Evaluation of the quality of clinical research studies of magnetic resonance angiography: 1991‐1994
Authors: Sostman H. Dirk , Beam Craig A.
Published: March 2007

To evaluate the quality of clinical research studies of magnetic resonance angiography (MRA), the authors reviewed studies of carotid, renal, and lower extremity MRA published in English during 1991‐1994. The purpose, design, and implementation of the study, and the type of statistical information presented, were evaluated. The results were compared with those of previous studies that assessed the quality of MRI research. Fifty‐nine studies of renal (n=10), carotid (n=29), and lower extremity (n=20) MRA were identified; 30 met the inclusion criteria for the analysis. In these papers, presentation of a reference standard was routine, observer blinding was usual, information often was given about patient selection and exclusion, sample sizes were always given, and parameter estimates and statistical analyses were common. However, evidence of research planning was not routine, measurement of interobserver variability was occasional, variability of parameter estimates was usually not estimated, and validation of statistical assumptions was uncommon. On balance the authors conclude that the scientific quality of recent investigations of MRA is better than that of older studies of MRI.
Malignant liver lesions: Comparison of spiral CT arterial portography and MR imaging for diagnostic accuracy, cost, and effect on patient management
Authors: Semelka Richard C. , Schlund James F. , Molina Paul L. , Willms Ann Bagley , Kahlenberg Morton , Mauro Matthew A. , Weeks Susan M. , Cance William G.
Published: March 2007

We compared two imaging techniques, spiral CT arterial portography (CTAP) and MR imaging, for diagnostic accuracy, procedural cost, and effect on management of 26 patients referred for hepatic surgery for suspected limited malignant liver disease. CTAP and MR imaging were done within a 1‐week period (19 within 24 hours); the results of the studies were interpreted prospectively by separate reviewers. Surgical data were evaluated in conjunction with imaging data in 10 patients. Lesion detection and segmental involvement were determined and sensitivity and specificity were calculated. Procedural cost was determined from hospital billing codes. Effect on patient management was determined by the referring oncologic surgeon. CTAP and MR imaging showed 185 and 176 true‐positive malignant lesions, 15 and zero false‐positive malignant lesions, zero and 18 true‐negative malignant lesions, and 13 and 22 falsenegative malignant lesions, respectively. CTAP and MR imaging showed 107 and 105 true‐positive segments, 11 and zero false‐positive segments, 80 and 91 true‐negative segments, and four and six false‐negative segments, respectively. There was a significant difference in specificity of segmental involvement between MR imaging (1.0 ± 0) compared with CTAP (0.88 ± 0.05), P=.03. Total procedural cost was $3,499 for CTAP and $1,224 for MR imaging. CTAP findings did not change patient management over MR imaging findings in any patient, whereas MR imaging findings resulted in a change in patient management over CTAP findings in seven patients (P=.015). The results of our study suggest that MR imaging has higher diagnostic accuracy and greater effect on patient management than CTAP does and is 64% less expensive.
Detection of deep venous thrombosis: Prospective comparison of MR imaging and sonography
Authors: Evans Avery J. , Sostman H. Dirk , Witty Lynn A. , Paulson Erik K. , Spritzer Charles E. , Hertzberg Barbara S. , Carroll Barbara A. , Tapson Victor F. , Saltzman Herbert A. , Delong David M.
Published: March 2007

Seventy‐five patients (41 women and 34 men, 20‐85 years old) with clinically suspected deep venous thrombosis (DVT) were examined with MR imaging and sonography. In 26 patients, the final diagnosis was acute femoropopliteal DVT. The sensitivity of MR imaging for detecting this disease was 100% with a 95% confidence interval (CI) of 87‐100%; the specificity was 100% with a CI of 92‐100%; and the accuracy was 96% with a CI of 89‐99%. The correspond‐ ing sensitivity of sonography was 77% with a CI of 53‐92%; the specificity was 98% with a CI of 89‐100%; and the accuracy was 83% with a CI of 72‐90%. In four of the 75 patients, MR images revealed thrombus of the pelvis (n=1) or calf (n=3) without femoropopliteal involvement. The estimated prevalence of isolated calf and/or pelvic DVT was 5% with a CI of 1‐13%. MR imaging is significantly more sensitive (P=.02) and accurate (P < .01) than sonography in the detection of lower extremity DVT, but there was no difference in the specificity of MR imaging and that of sonography (P=.31).
The impact of field strength on image quality in MRI
Authors: Rutt Brian K. , Lee Donald H.
Published: March 2007

As clinical MRI has evolved, there have been numerous arguments for the use of different field strengths. Those favoring high magnetic field (1.5 T and above) include higher signal‐to‐noise ratio, capability for MR spectroscopy, and other forms of functional MRI, high speed imaging, and high resolution imaging. However, cost remains a significant limitation to the wider dissemination of high field MRI. There are definite cost advantages (capital, operating, siting) to the use of lower field MRI. Much debate has occurred over the past decade regarding the relative diagnostic benefits of high field MRI versus lower field MRI, but few randomized, controlled clinical trials have compared diagnostic accuracy of MRI at various field strengths. In this article, we review the physical principles of the field strength dependence of MRI in relation to image quality. The assessment of the importance of field strength in MR is incomplete without some analysis of diagnostic accuracy versus field strength. Such analysis is difficult to accomplish in an unbiased manner. The use of receiver‐operator‐characteristic (ROC) analysis is probably the best available method to measure diagnostic accuracy of various imaging methods without bias. An ROC study of diagnostic accuracy of 0.5 T versus 1.5 T MRI, examining several common clinical categories, has recently been conducted at our institution. Results from this study demonstrate diagnostic equivalence between these two field strengths in at least two common clinical disease categories (MS and internal derangement of the knee). These results are discussed and related to results from previous field strength studies.
Future cost‐effective MRI will be at high field
Authors: Bradley William G.
Published: March 2007

The most cost effective MR imaging system is the one that provides the highest quality images (allowing the earliest possible diagnosis), the largest number of applications (allowing bundling of services and one‐stop shopping for consumers), and the highest throughput (should it become necessary to scan a large number of patients in a capitated world). When all other parameters are normalized (eg, the skill and training of the radiologist and technologist as well as the RF, computer, and gradient subsystems), high field provides faster, higher resolution, thinner slice, and higher contrast MR images than low field. For these reasons, high field MRI will remain more cost effective than its lower field counterparts in the future.
Cardiovascular applications of magnetic resonance flow and velocity measurements
Authors: Szolar Dieter H. , Sakuma Hajime , Higgins Charles B.
Published: March 2007

With recent developments of MR techniques for blood flow measurements, qualitative and quantitative information on both flow volume and flow velocity in the major vessels can be obtained. MR flow quantitation uses the phase, rather than the amplitude of the MR signal, to reconstruct the images. Previous validation studies have demonstrated the accuracy of the phase shift techniques for measuring flow velocities. This technique is now being applied successfully in the cardiovascular system to quantify global and regional ventricular function, valvular heart disease, pulmonary artery disease, thoracic aortic disease, congenital heart disease, and ischemic heart disease.