bluuebunny/crossref_metadata_2025 huggingface dataset:
An adaptive parallel genetic algorithm system for i‐Computing environment
Authors: Wong Yuk‐Yin , Lee Kin‐Hong , Leung Kwong‐Sak
Published: April 2003

Many real‐world optimization problems in the scientific and engineering fields can be solved by genetic algorithms (GAs) but it still requires a long execution time for complex problems. At the same time, there are many under‐utilized workstations on the Internet. In this paper, we present a self‐adaptive parallel GA system named APGAIN, which utilizes the spare power of the heterogeneous workstations on the Internet to solve complex optimization problems. In order to maintain a balance between exploitation and exploration, we have devised a novel probabilistic rule‐driven adaptive model (PRDAM) to adapt the GA parameters automatically. APGAIN is implemented on an Internet Computing system called DJM. In the implementation, we discover that DJM's original load balancing strategy is insufficient. Hence the strategy is extended with the job migration capability. The performance of the system is evaluated by solving the traveling salesman problem with data from a public database. Copyright © 2003 John Wiley & Sons, Ltd.
A scalable HPF implementation of a finite‐volume computational electromagnetics application on a CRAY T3E parallel system
Authors: Pan Yi , Shang Joseph J. S. , Guo Minyi
Published: April 2003

The time‐dependent Maxwell equations are one of the most important approaches to describing dynamic or wide‐band frequency electromagnetic phenomena. A sequential finite‐volume, characteristic‐based procedure for solving the time‐dependent, three‐dimensional Maxwell equations has been successfully implemented in Fortran before. Due to its need for a large memory space and high demand on CPU time, it is impossible to test the code for a large array. Hence, it is essential to implement the code on a parallel computing system. In this paper, we discuss an efficient and scalable parallelization of the sequential Fortran time‐dependent Maxwell equations solver using High Performance Fortran (HPF). The background to the project, the theory behind the efficiency being achieved, the parallelization methodologies employed and the experimental results obtained on the Cray T3E massively parallel computing system will be described in detail. Experimental runs show that the execution time is reduced drastically through parallel computing. The code is scalable up to 98 processors on the Cray T3E and has a performance similar to that of an MPI implementation. Based on the experimentation carried out in this research, we believe that a high‐level parallel programming language such as HPF is a fast, viable and economical approach to parallelizing many existing sequential codes which exhibit a lot of parallelism. Copyright © 2003 John Wiley & Sons, Ltd.
Design and implementation of a user‐level Sockets layer over Virtual Interface Architecture
Authors: Kim Jin‐Soo , Kim Kangho , Jung Sung‐In , Ha Soonhoi
Published: April 2003

The Virtual Interface Architecture (VIA) is an industry standard user‐level communication architecture for system area networks. The VIA provides a protected, directly‐accessible interface to a network hardware, removing the operating system from the critical communication path. In this paper, we design and implement a user‐level Sockets layer over VIA, named SOVIA (Sockets Over VIA). Our objective is to use the SOVIA layer to accelerate the existing Sockets‐based applications with a reasonable effort and to provide a portable and high‐performance communication library based on VIA to application developers.

SOVIA realizes comparable performance to native VIA, showing a minimum one‐way latency of 10.5 $\mu$s and a peak bandwidth of 814 Mbps on Giganet's cLAN. We have shown the functional compatibility with the existing Sockets API by porting File Transfer Protocol (FTP) and Remote Procedure Call (RPC) applications over the SOVIA layer. Compared to the Giganet's LAN Emulation (LANE) driver which emulates TCP/IP inside the kernel, SOVIA easily doubles the file transfer bandwidth in FTP and reduces the latency of calling an empty remote procedure by 77% in RPC applications. Copyright © 2003 John Wiley & Sons, Ltd.
NPACI Rocks: tools and techniques for easily deploying manageable Linux clusters
Authors: Papadopoulos Philip M. , Katz Mason J. , Bruno Greg
Published: April 2003

High‐performance computing clusters (commodity hardware with low‐latency, high‐bandwidth interconnects) based on Linux are rapidly becoming the dominant computing platform for a wide range of scientific disciplines. Yet, straightforward software installation, maintenance, and health monitoring for large‐scale clusters has been a consistent and nagging problem for non‐cluster experts. The NPACI Rocks distribution takes a fresh perspective on management and installation of clusters to dramatically simplify software version tracking and cluster integration.

NPACI Rocks incorporates the latest Red Hat distribution (including security patches) with additional cluster‐specific software. Using the identical software tools used to create the base distribution, users can customize and localize Rocks for their site. Strong adherence to widely‐used (de facto) tools allows Rocks to move with the rapid pace of Linux development. Version 2.2.1 of the toolkit is available for download and installation. Over 100 Rocks clusters have been built by non‐cluster experts at multiple institutions (residing in various countries) providing a peak aggregate of 2 TFLOPS of clustered computing. Copyright © 2003 John Wiley & Sons, Ltd.
p‐Jigsaw: a cluster‐based Web server with cooperative caching support
Authors: Chen Ge , Wang Cho‐Li , Lau Francis C. M.
Published: April 2003

Clustering provides a viable approach to building scalable Web systems with increased computing power and abundant storage space for data and contents. In this paper, we present a pure‐Java‐based parallel Web server system, p‐Jigsaw, which operates on a cluster and uses the technique of cooperative caching to achieve high performance. We introduce the design of an in‐memory cache layer, called Global Object Space (GOS), for dynamic caching of frequently requested Web objects. The GOS provides a unified view of cluster‐wide memory resources for achieving location‐transparent Web object accesses. The GOS relies on cooperative caching to minimize disk accesses. A requested Web object can be fetched from a server node's local cache or a peer node's local cache, with the disk serving only as the last resort. A prototype system based on the W3C Jigsaw server has been implemented on a 16‐node PC cluster. Three cluster‐aware cache replacement algorithms were tested and evaluated. The benchmark results show good speedups with a real‐life access log, proving that cooperative caching can have significant positive impacts on the performance of cluster‐based parallel Web servers. Copyright © 2003 John Wiley & Sons, Ltd.
Clusterfile: a flexible physical layout parallel file system
Authors: Isaila Florin , Tichy Walter F.
Published: April 2003

This paper presents Clusterfile, a parallel file system that provides parallel file access on a cluster of computers. We introduce a file partitioning model that has been used in the design of Clusterfile. The model uses a data representation that is optimized for multidimensional array partitioning while allowing arbitrary partitions. The paper shows how the file model can be employed for file partitioning into both physical subfiles and logical views. We also present how the conversion between two partitions of the same file is implemented using a general memory redistribution algorithm. We show how we use the algorithm to optimize non‐contiguous read and write operations. The experimental results include performance comparisons with the Parallel Virtual File System (PVFS) and an MPI‐IO implementation for PVFS. Copyright © 2003 John Wiley & Sons, Ltd.
Flow cytometric characterization of perfused human bone marrow cultures: Identification of the major cell lineages and correlation with the CFU‐GM assay
Authors: Brott D. A. , Maher R. J. , Parrish C. R. , Richardson R. J. , Smith A. K.
Published: April 2003

Background

Prolific cultures of human bone marrow mononuclear cells (BM MNCs) were recently developed that include a full spectrum of hematopoietic and accessory cells, with the presence of autofluorescent cells indicating adequate cell expansion. However, phenotypic and functional clonogenic characterizations of the autofluorescent cells and the various other subpopulations present in these cultures have not been carried out.

Methods

Cells from a continuously perfused bioreactor inoculated with BM MNCs and cultured for 12 days in serum‐containing medium with PIXY321, erythropoietin, and with or without FLT3‐L were evaluated by using flow cytometry.

Results

Two antibodies, CD71 and CD13, allowed the separation of the autofluorescent cells into two distinct populations. The CD71+CD13++ autofluorescent population contained the colony‐forming unit (CFU) fibroblast, and the CD71++CD13++ autofluorescent population contained macrophage/dendritic like cells. The CFU‐granulocyte/macrophage (CFU‐GM) could not be thoroughly evaluated with CD71 and CD13. However, the number of CD13+/++Lin− cells correlated with the number of CFU‐GM (r = 0.83), with approximately 1 CFU‐GM for every 30 CD13+/++Lin− cells.

Conclusions

The data showed that CD71 and CD13 antibodies separate the autofluorescent cells into two populations but do not separate hematopoietic cells into specific phenotypic populations. The data also showed that the number of CD13+/++Lin− cells correlated with the number of CFU‐GM. These data present the initial step toward detailed phenotypic analysis of ex vivo expanded human BM MNC cultures. Cytometry Part A 53A:22–27, 2003. © 2003 Wiley‐Liss, Inc.
High‐throughput flow cytometry: Validation in microvolume bioassays
Authors: Ramirez Sergio , Aiken Charity T. , Andrzejewski Brett , Sklar Larry A. , Edwards Bruce S.
Published: April 2003

Background

We recently reported an automated sample handling system, designated HyperCyt, by which samples are aspirated from microplate wells and delivered to the flow cytometer for analysis at rates approaching 100 samples per minute. In this approach, an autosampler and peristaltic pump introduce samples into a tubing line that directly connects to the flow cytometer. Air bubbles are inserted between samples to prevent sample dispersion. In the present work, we compare results of HyperCyt with those of conventional manual flow cytometric analysis in representative flow cytometric bioassays and describe a cell suspension method in which HyperCyt exploits the use of microvolume wells.

Methods

Human eosinophils and neutrophils were treated with trypsin to generate a wide (>25‐fold) range of membrane P‐selectin glycoprotein ligand‐1 (PSGL‐1) expression and then stained with fluorescent anti–PSGL‐1 antibodies. Human peripheral blood mononuclear cells were stained with fluorescein isothiocyanate‐ and phycoerythrin‐conjugated monoclonal antibodies for multiparameter immunophenotype analysis. U937 cells labeled with PKH62GL were used to assess cell settling in microplate wells.

Results

Differences in PSGL‐1 expression levels were detected by HyperCyt autosampling of leukocytes from 96‐well plates at an analysis rate of approximately 1.5 s/well. HyperCyt measurements linearly correlated with parallel manual measurements (r2 = 0.98). Lymphocyte subpopulations were accurately distinguished and reproducibly quantified in multiparameter immunophenotyping assays performed over a range of HyperCyt analysis rates (1.4–5.5 s/sample). When assay volumes were reduced to 10 μl/well in 60‐well Terasaki plates, cells could be maintained in uniform suspension for up to 30 min by periodically inverting plates on a rotating carousel before HyperCyt analysis. HyperCyt analysis of five fluorescence‐level Cyto‐Plex beads sampled from Terasaki plate microwells at 2.5 s/well produced highly reproducible results over a wide range of input bead concentrations (from 7 × 105 to 20 × 106 beads/ml) that linearly correlated with manual analysis results.

Conclusions

The HyperCyt autosampling system enabled a 10‐fold or greater increase in sample thoughput compared with conventional manual flow cytometric sample analysis, with comparable analysis results. Assays were performed efficiently in 10‐μl volumes to enable significant reagent cost savings, use of quantity‐limited reagents at otherwise prohibitive concentrations, and maintenance of uniform suspensions of cells for prolonged periods. Cytometry Part A 53A:55–65, 2003. © 2003 Wiley‐Liss, Inc.
On synchronization techniques: performance and impact on time metrics monitoring
Authors: Adami Davide , Garroppo Rosario G. , Giordano Stefano , Lucetti Stefano
Published: April 2003

The paper presents an experimental comparison of device synchronization strategies to monitor quality of service (QoS) time metrics, such as the one‐way delay and the delay variation. The compared strategies are based on global positioning system (GPS), public Internet network time protocol (NTP) servers and ad hoc GPS‐based NTP servers with different treatments of the NTP traffic. The presented experimental results allow to quantitatively evaluate the level of performance achievable using each synchronization technique. Finally, considering a satellite test bed, we focus our analysis on two relevant aspects of time metrics monitoring: the impact of the synchronization errors on the metrics observation and the different values that can be measured when a metric is monitored at the application or data link level. Copyright © 2003 John Wiley & Sons, Ltd.
Translation of specification units between IP and ATM quality of service declarations
Authors: Schmitt Jens
Published: April 2003

An integral part of any network quality of service (QoS) system are its QoS declarations. QoS declarations consist of service classes, parameters, and specification units. QoS declarations are a component of the QoS architecture, as such they are a source of heterogeneity stemming from the fact that different QoS systems may be based on different QoS architectures and thus use different QoS declarations. A particular problem in that domain is thetranslationof specification units for QoS systems that are based on different forwarding technologies with respect to variable vs fixed packet sizes, i.e. packet vs cell switching. This is a problem that can be dealt with generically such that its solution can be applied to several situations of technically heterogeneous QoS systems like an RSVP/IntServ—or DiffServ—over an ATM‐based system. While straightforward translations have been proposed, we investigate how more efficient translations can be achieved by using a slight but effective modification of existing AAL framing schemes as well as making use of statistical knowledge about packet size distributions. Copyright © 2003 John Wiley & Sons, Ltd.
Cardiac muscle cell formation after development of the linear heart tube
Authors: Kruithof Boudewijn P.T. , van den Hoff Maurice J.B. , Wessels Andy , Moorman Antoon F.M.
Published: April 2003

After the development of the linear heart tube, additional myocardium is formed leading to the muscular mantle around the caval and pulmonary veins and the muscular septa in the embryonic heart. Here, we report the results of our in vivo and in vitro studies of this late myocardium‐generating process in the mouse. By using an immunohistochemical approach, we determined that myocardium formation starts around embryonic day 12 in the dorsal mesocardium. In subsequent stages of development, the process extends downstream into the intracardiac mesenchymal tissues of the atrioventricular canal and outflow tract and upstream into the extracardiac mediastinal mesenchyme embedding the pulmonary and caval veins. Given the spatiotemporal pattern of myocardium formation, we applied a three‐dimensional in vitro explant culture assay to investigate the myocardium‐generating potential of the different cardiac compartments. We determined that this potential is stage‐ and mesenchyme‐dependent. This latter finding suggests an important role for mesenchyme in myocardium formation after the development of the linear heart tube. Developmental Dynamics 227:1–13, 2003 © 2003 Wiley‐Liss, Inc.
Recapitulation of fast skeletal muscle development in zebrafish by transgenic expression of GFP under the mylz2 promoter
Authors: Ju Bensheng , Chong Shang Wei , He Jiangyan , Wang Xukun , Xu Yanfei , Wan Haiyan , Tong Yan , Yan Tie , Korzh Vladimir , Gong Zhiyuan
Published: April 2003

A 1,934‐bp muscle‐specific promoter from the zebrafish mylz2 gene was isolated and characterized by transgenic analysis. By using a series of 5′ promoter deletions linked to the green fluorescent protein (gfp) reporter gene, transient transgenic analysis indicated that the strength of promoter activity appeared to correlate to the number of muscle cis‐elements in the promoter and that a minimal −77‐bp region was sufficient for a relatively strong promoter activity in muscle cells. Stable transgenic lines were obtained from several mylz2‐gfp constructs. GFP expression in the 1,934‐bp promoter transgenic lines mimicked well the expression pattern of endogenous mylz2 mRNA in both somitic muscle and nonsomitic muscles, including fin, eye, jaw, and gill muscles. An identical pattern of GFP expression, although at a much lower level, was observed from a transgenic line with a shorter 871‐bp promoter. Our observation indicates that there is no distinct cis‐element for activation of mylz2 in different skeletal muscles. Furthermore, RNA encoding a dominant negative form of cAMP‐dependent protein kinase A was injected into mylz2‐gfp transgenic embryos and GFP expression was significantly reduced due to an expanded slow muscle development at the expense of GFP‐expressing fast muscle. The mylz2‐gfp transgene was also transferred into two zebrafish mutants, spadetail and chordino, and several novel phenotypes in muscle development in these mutants were discovered. Developmental Dynamics 227:14–26, 2003. © 2003 Wiley‐Liss, Inc.
Analysis of hindbrain patterning defects caused by the kreislerenu mutation reveals multiple roles of Kreisler in hindbrain segmentation
Authors: Sadl Virginia S. , Sing Angela , Mar Lynn , Jin Fuzi , Cordes Sabine P.
Published: April 2003

The embryonic hindbrain is subdivided into eight subunits, termed rhombomeres (r1–r8). The Kreisler (Krml1/MafB/val) transcription factor is expressed in and essential for patterning rhombomeres 5 and 6. Here, we have shown that in the chemically induced kreislerenu (krenu) allele, a point mutation in the DNA binding domain abolishes or severely reduces Kreisler‐dependent transcription. Comparison of krenu/krenu embryos with those homozygous for the classic kreisler (kr) mutation has reconciled past discrepancies and revealed multiple roles of Kreisler in hindbrain segmentation. These analyses demonstrate that Kreisler is required for maintenance and expansion but not initiation of the Krox20 expressing r5 domain. The differences in the “r5‐like” phenotype of krenu/krenu and kr/kr mouse embryos, and zebrafish carrying mutations in the Kreisler orthologue valentino (val) suggest that Kreisler performs many of its r5‐specific functions by associating with other proteins. By contrast, kr/kr and krenu/krenu mouse and val‐/‐ zebrafish embryos all exhibit indistinguishable defects in r6 specification. Thus, transcriptionally active Kreisler is required for r6 specification. Unlike mouse krenu/krenu and zebrafish val‐/‐ embryos, kr/kr embryos exhibited anterior defects. We determined that the kr chromosomal inversion caused ectopic Kreisler expression in r3 of kr/kr and kr/+ embryos. Hence, Kreisler regulates maintenance and expansion of r5 and specification of r6 but is not required for r3 development. Developmental Dynamics 227:134–142, 2003. © 2003 Wiley‐Liss, Inc.
Soluble and bound forms of GFRα1 elicit different GDNF‐independent neurite growth responses in primary sensory neurons
Authors: Mikaels‐Edman Åsa , Baudet Christel , Ernfors Patrik
Published: April 2003

We have investigated the role of glial cell‐line derived neurotrophic factor (GDNF) and the effect of soluble or immobilized localization of its GDNF family receptor α1 (GFRα1) on neurite growth in cultured embryonic Bax−/− dorsal root ganglion neurons, which survive in the absence of trophic support. Whereas GDNF alone has a moderate effect on neurite growth, soluble and immobilized GFRα1 elicit opposing and GDNF‐independent effects on neurite growth by a phospholipase C (PLC) γ‐dependent mechanism. Thus, GFRα1 elicits nerve growth responses independent of GDNF. However, GDNF in the presence of soluble or immobilized GFRα1 reverse the GDNF‐independent GFRα1 modulation of neurite growth. The different outcome of soluble and bound GFRα1 combined with our previous immunohistochemical data showing GFRα1‐protein in Schwann cells but not axons suggest terminal Schwann cells as a source of locally administered target‐derived GFRα1 and place this receptor in the path of axonal growth and guidance. Thus, target‐derived GFRα1 play opposing roles when presented alone and with GDNF and, therefore, can function as a nerve growth cue that both can promote and prevent growth in the developing peripheral nervous system. Developmental Dynamics 227:27–34, 2003 © 2003 Wiley‐Liss, Inc.
Loss of maternal Smad5 in zebrafish embryos affects patterning and morphogenesis of optic primordia
Authors: Hammerschmidt Matthias , Kramer Carina , Nowak Matthias , Herzog Wiebke , Wittbrodt Joachim
Published: April 2003

The mechanisms of patterning and morphogenesis of vertebrate eye primordia are heavily debated. Taking advantage of the maternal effect of a zebrafish smad5 null mutation (Mm169), we investigate the effect of early signaling by members of the bone morphogenetic proteins (Bmps) on eye field patterning and optic vesicle morphogenesis. In contrast to previous Xenopus and chick studies demonstrating a late dorsalizing effect of Bmp4 expressed in the dorsal neural retina itself, we show that patterning of the eye primordia already starts during blastula and early gastrula stages. At these stages, bmps expressed on the ventrolateral side of the embryo promote dorso‐distal fates in the entire neuroectoderm, including the eye primordia. Despite a normal split of the eye field in the midline, the eye primordia of Mm169 embryos fail to evaginate laterally. They display a concentric pattern with retinal cells in the center and optic stalk cells in the periphery, representing a flattened version of the topologic relationships present in the mature wild‐type eye. Different interpretations of these latter findings are presented. They can be best explained with a model according to which zebrafish eye morphogenesis occurs as a telescopic extension of disc‐like, concentric primordia, similar to the development of appendages from imaginal discs in Drosophila. Developmental Dynamics 227:128–133, 2003. © 2003 Wiley‐Liss, Inc.
Localization of aggrecan and versican in the developing rat central nervous system
Authors: Popp Susanna , Andersen Julie S. , Maurel Patrice , Margolis Richard U.
Published: April 2003

The localization of aggrecan and mRNA splice variants of versican in the developing rat central nervous system has been examined by using specific polyclonal antibodies to the nonhomologous glycosaminoglycan attachment regions of these hyaluronan‐binding chondroitin sulfate proteoglycans. At embryonic day 16 (E16), aggrecan and versican splice variants containing either or both the α‐and β‐domains are present in the marginal zone and subplate of the cerebral cortex and in the amygdala, internal capsule, and the optic and lateral olfactory tracts. There is strong staining of versican but not of aggrecan in the hippocampus and dentate gyrus by E19, whereas both aggrecan and α‐versican are present in the fimbria. At E19, aggrecan is seen throughout the cerebral cortex, whereas the distribution of versican is considerably more limited, being confined essentially to the marginal zone and subplate. At 1 week postnatal, both aggrecan and versican are present in the prospective white matter and in the molecular and granule cell layers of the cerebellum, but neither proteoglycan is seen in the external granule cell layer. α‐ but not β‐versican staining is seen in Purkinje cells, and aggrecan staining of Purkinje cells is also rather minimal. In the spinal cord at E13, aggrecan is present in the dorsal root entry zone, ventral funiculus, mantle layer, and floor plate, as well as in the dorsal root ganglia and ventral roots. However, α‐versican is confined to the dorsal root entry zone and the ependyma surrounding the spinal canal, and β‐versican is not present in spinal cord parenchyma at this developmental stage, being limited to the surrounding connective tissue. By E19, there are significant amounts of all three proteoglycans in the spinal cord. Aggrecan staining is most intense in the lateral funiculus and the fasciculi gracilis and cuneatus, where α‐versican staining is also strong. In contrast, β‐versican is seen predominantly in the motor columns. Differences in the localization and temporal expression patterns of these chondroitin sulfate proteoglycans suggest that, like neurocan and phosphacan, they have partially complementary roles during central nervous system development. Development Dynamics 227:143–149, 2003. © 2003 Wiley‐Liss, Inc.
RhoA is highly up‐regulated in the process of early heart development of the chick and important for normal embryogenesis
Authors: Kaarbø Mari , Crane Denis I. , Murrell Wayne G.
Published: April 2003

We have used molecular techniques, combined with classic embryological methods, to identify up‐regulated genes associated with early heart development. One of the cDNAs identified and isolated by screening a chick lambda cDNA library was the small guanosine triphosphatase RhoA. RhoA has at least three different length mRNA species, each varying in the length of the 3′ untranslated region. In situ hybridisation and immunocytochemistry analysis of RhoA expression show marked up‐regulation in the heart‐forming region. In other systems, RhoA signalling has been shown to be important for both gene expression and morphology. To investigate the function of RhoA in early heart development, we used small interfering RNAs (siRNA) in early chick embryos. Disruption of RhoA expression by siRNA treatment resulted in lack of heart tube fusion and abnormal head development. These data indicate that RhoA is important for normal embryogenesis. Developmental Dynamics 227:35–47, 2003. © 2003 Wiley‐Liss, Inc.
Epicardial‐like cells on the distal arterial end of the cardiac outflow tract do not derive from the proepicardium but are derivatives of the cephalic pericardium
Authors: Pérez‐Pomares José M. , Phelps Aimée , Sedmerova Martina , Wessels Andy
Published: April 2003

A series of recent studies strongly suggests that the myocardium of the cardiac distal outflow tract (d‐OFT) does not derive from the original precardiac mesoderm but, instead, differentiates from a so‐called anterior heart field. Similar findings were also reported for the endocardium of the d‐OFT. However, very little information is available on the origin of the epicardium of the OFT. To address this issue, we have performed a study in which we have combined experimental in vivo and in vitro techniques (construction of proepicardial chimeras, proepicardial ablation, OFT insertion of eggshell membrane pieces, and culture on collagen gels) with molecular characterization techniques to determine this origin and define the properties of d‐OFT epicardium compared with proepicardially derived epicardium. Our results demonstrate that the coelomic/pericardial epithelium in the vicinity of the aortic sac (and not the proepicardium) is the origin of d‐OFT epicardium. This “pericardially” derived epicardium and the proepicardially derived epicardial tissues differ in their morphologic appearance, gene‐expression profile, and in their ability to undergo epithelial‐to‐mesenchymal transformation. We conclude that the heterogeneity in the epicardial cell population of the OFT could be a factor in the complex developmental remodeling events at the arterial pole of the heart. Developmental Dynamics 227:56–68, 2003. © 2003 Wiley‐Liss, Inc.
TALE class homeodomain gene Irx5 is an immediate downstream target for Hoxb4 transcriptional regulation
Authors: Theokli Christopher , Morsi El‐Kadi Ali S. , Morgan Richard
Published: April 2003

The Hox genes are a family of homeodomain‐containing transcription factors that determine anteroposterior identity early on in development. Although much is now known about their regulation and function, very little is known of their effector (downstream target) genes. Here, we show that the TALE class homeodomain transcription factor Irx5 is a direct, positively regulated target of Hoxb4. Developmental Dynamics 227:48–55, 2003. © 2003 Wiley‐Liss, Inc.
Loss of the Tg737 protein results in skeletal patterning defects
Authors: Zhang Qihong , Murcia Noel S. , Chittenden Laura R. , Richards William G. , Michaud Edward J. , Woychik Richard P. , Yoder Bradley K.
Published: April 2003

Tg737 mutant mice exhibit pathologic conditions in numerous tissues along with skeletal patterning defects. Herein, we characterize the skeletal pathologic conditions and confirm a role for Tg737 in skeletal patterning through transgenic rescue. Analyses were conducted in both the hypomorphic Tg737orpk allele that results in duplication of digit one and in the null Tg737Δ2‐3βGal allele that is an embryonic lethal mutation exhibiting eight digits per limb. In early limb buds, Tg737 expression is detected throughout the mesenchyme becoming concentrated in precartilage condensations at later stages. In situ analyses indicate that the Tg737orpk mutant limb defects are not associated with changes in expression of Shh, Ihh, HoxD11–13, Patched, BMPs, or Glis. Likewise, in Tg737Δ2‐3βGal mutant embryos, there was no change in Shh expression. However, in both alleles, Fgf4 was ectopically expressed on the anterior apical ectodermal ridge. Collectively, the data argue for a dosage effect of Tg737 on the limb phenotypes and that the polydactyly is independent of Shh misexpression. Developmental Dynamics 227:78–90, 2003. © 2003 Wiley‐Liss, Inc.
Retinoic acid signalling centres in the avian embryo identified by sites of expression of synthesising and catabolising enzymes
Authors: Blentic Aida , Gale Emily , Maden Malcolm
Published: April 2003

Retinoic acid is an important signalling molecule in the developing embryo, but its precise distribution throughout development is very difficult to determine by available techniques. Examining the distribution of the enzymes by which it is synthesised by using in situ hybridisation is an alternative strategy. Here, we describe the distribution of three retinoic acid synthesising enzymes and one retinoic acid catabolic enzyme during the early stages of chick embryogenesis with the intention of identifying localized retinoic acid signalling regions. The enzymes involved are Raldh1, Raldh2, Raldh3, and Cyp26A1. Although some of these distributions have been described before, here we assemble them all in one species and several novel sites of enzyme expression are identified, including Hensen's node, the cardiac endoderm, the presumptive pancreatic endoderm, and the dorsal lens. This study emphasizes the dynamic pattern of expression of the enzymes that control the availability of retinoic acid as well as the role that retinoic acid plays in the development of many regions of the embryo throughout embryogenesis. This strategy provides a basis for understanding the phenotypes of retinoic acid teratology and retinoic acid–deficiency syndromes. Developmental Dynamics 227:114–127, 2003. © 2003 Wiley‐Liss, Inc.
Local activation of protein kinase A inhibits morphogenetic movements during Xenopus gastrulation
Authors: Song Byung‐Ho , Choi Sun‐Cheol , Han Jin‐Kwan
Published: April 2003

cAMP‐dependent protein kinase (PKA) has various biological roles in many organisms. However, little is known about its role in the developmental processes of vertebrates. In this study, we describe the functional analysis of PKA during gastrulation movements in Xenopus laevis. Overexpression of constitutively active PKA (cPKA) in the dorsal equatorial region of the embryo affects morphogenetic movement during gastrulation. We also show that intrinsic differences of PKA activities along the dorsoventral axis are set up and the level of PKA activity on the dorsal region is lower than that on the ventral region from late blastula to gastrula stages. In addition, PKA activation in animal explants inhibits activin‐induced elongation. In cPKA‐injected embryos, there were no changes in the expressions of markers involved in mesoderm specification, although the correct expression domains of these genes were altered. The effects of PKA activation can be restored by coexpression of PKI, a pseudosubstrate of PKA. We further analyzed the effects of PKA activation on the behavior of migratory gastrulating cells in vitro. Expression of cPKA in head mesoderm cells causes less polarized and/or randomized migration as demonstrated by a directional cell migration assay. Finally, we show that RhoA GTPase lies downstream of PKA, affecting activin‐induced convergent extension movements. Taken together, these results suggest that overexpressed PKA can modulate a pathway responsible for morphogenetic movements during Xenopus gastrulation. Developmental Dynamics 227:91–103, 2003. © 2003 Wiley‐Liss, Inc.
What Guides Evaluation? A Study of How Evaluation Practice Maps onto Evaluation Theory
Authors: Christie Christina A.
Published: April 2003

An empirically derived comparative framework offers an understanding of the similarities and differences between eight theories of evaluation when they are applied.
Important Questions, Intriguing Method, Incomplete Answers
Authors: Datta Lois‐ellin
Published: April 2003

Only one in ten evaluators reports using any theory to guide practice. Despite some methodological limitations, triangulation with other studies suggests that Christie's results would generalize to many of the relatively inexperienced, untrained persons now “committing” evaluations.
Stakeholder Bias
Authors: House Ernest R.
Published: April 2003

The handling of potential stakeholder bias distinguishes evaluation theorists from one another and from practitioners.
The Challenge of Studying Evalutation Theory
Authors: King Jean A.
Published: April 2003

This chapter discusses why evaluation as a field has not systematically studied its own theory and then examines the Christie research in detail to highlight its procedures and assumptions and the challenge of translating such theory into practice.
Toward an Agenda for Research on Evaluation
Authors: Henry Gary T. , Mark Melvin M.
Published: April 2003

Using Christie's research as an example, the authors describe a variety of forms that a more evidence‐based approach to evaluation theory could take and offer some suggestions to help increase the amount and impact of evidence in evaluation theory.
Revisiting the empirical estimation of the effect of margin changes on futures trading volume
Authors: Dutt Hans R. , Wein Ira L.
Published: April 2003

This study revisits the empirical estimation of the effect of margin requirements on trading volume. Although
theory suggests that margin requirements impose a cost to traders and will therefore likely reduce volume traded,
empirical examinations have generally failed to find this association. The contention of this article is that the
theory is correct, but empirical estimation has generally neglected to adjust margins for underlying price risk.
After adjusting for risk, this analysis finds economically and statistically significant negative effects of
margin requirements on trading volume as predicted by theory. This study examined 6 contracts over a
17‐year time period and found that financial futures contracts (gold, Dow Jones, and 10‐Year
Treasury Notes) were considerably more sensitive to changes in margin requirements than agricultural futures
(wheat, corn, and oats). © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:561–576, 2003
The effectiveness of coordinating price limits across futures and spot markets
Authors: Chou Pin‐Huang , Lin Mei‐Chen , Yu Min‐Teh
Published: April 2003

We extend the work of Brennan (1986) to investigate whether the imposition
of spot price limits can further reduce the default risk and lower the effective margin requirement for a futures
contract that is already under price limits. Our results show that spot price limits do indeed further reduce the
default risk and margin requirement effectively. In addition, the more precise the information is that comes from
the spot market, the more the spot price limit rule constrains the information available to the losing party. The
default probability, contract costs, and margin requirements are then lowered to a greater degree. Furthermore,
for a given margin, both spot price limits and futures price limits can partially substitute for each other in
ensuring contract performance. The common practice of imposing equal price limits on both the spot and futures
markets, though not coinciding with the efficient contract design, has a lower contract cost and margin
requirement than that without imposing spot price limits. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark
23:577–602, 2003
The valuation of multiple stock warrants
Authors: Lim Kian‐Guan , Terry Eric
Published: April 2003

The issue of multiple series of stock purchase warrants by the same firm is an interesting financial structure
not just in America, but is common in countries such as Switzerland, Malaysia, and Singapore. This paper derives
valuation formulas for multiple series of outstanding warrants. The theoretical warrant prices from this model are
compared against existing models. We report a subtle slippage effect and also a cross dilution effect that cause
the existing models, such as Galai‐Schneller model, to be inappropriate for pricing such classes of multiple
warrants. We also provide an example to illustrate the practicality of our model. The Greeks of the model are also
derived in this paper. The complexity of multiple warrants could extend to other classes of contingent securities
issued by the same firm but with differing expiry terms. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark
23:517–534, 2003
Dissociable neural responses in the hippocampus to the retrieval of facial identity and emotion: An event‐related fMRI study
Authors: Iidaka Tetsuya , Terashima Shigeo , Yamashita Koichi , Okada Tomohisa , Sadato Norihiro , Yonekura Yoshiharu
Published: April 2003

In studies with brain‐damaged patients and experimental animals, the medial temporal lobe, including the hippocampus and parahippocampal gyrus, has been found to play a critical role in establishing declarative or episodic memory. We measured the neural response in these structures, using event‐related functional magnetic resonance imaging, while six healthy subjects performed the retrieval task for facial identity and emotion, respectively. Under the identity condition, the subjects participated in a yes/no recognition test for neutral faces learned before the scanning. Under the emotion condition, the subjects learned the faces with positive or negative expression and retrieved their expressions from neutral cue faces. The results showed that the left hippocampus is primarily involved in the identification of learned faces, and that the adjacent parahippocampal gyrus responds more to target than to distracter events. These results indicate a specific engagement of the left hippocampal regions in conscious recollection and identification of physiognomic facial features. The activity in the right hippocampus increased under both the identity and emotion conditions. The present results may relate with the functional model of face recognition in which the left hemisphere contributes to the processing of detailed features and the right hemisphere is efficient in the processing of global features. Hippocampus 2003;13:429–436. © 2003 Wiley‐Liss, Inc.
Reversible inactivation of the hippocampal formation in food‐storing black‐capped chickadees (Poecile atricapillus)
Authors: Shiflett Michael W. , Smulders Tom V. , Benedict Lauryn , DeVoogd Timothy J.
Published: April 2003

The role of the hippocampal formation (HF) in memory processing was assessed in food‐storing black‐capped chickadees (Poecile atricapilla) by reversibly inactivating the HF during different memory tests. The memory tests required birds to remember a location based on spatial cues only, or based on a combination of both spatial and distinct visual cues. Inactivation of the HF impaired short‐term spatial memory, but not visual‐spatial memory. Inactivation of the HF impaired the retrieval of short‐term (15 min) spatial memories, but not long‐term (3‐h) spatial memories. The pattern of deficits produced by inactivation of the HF in chickadees suggests a possible function of the hippocampal specialization of food‐storing birds, as well as extends the notion of functional homology between the avian and mammalian HF. Hippocampus 2003;13:437–444. © 2003 Wiley‐Liss, Inc.
Density of μ‐opioid receptors in the hippocampus of adult male and female rats is altered by prenatal morphine exposure and gonadal hormone treatment
Authors: Šlamberová Romana , Rimanóczy Ágnes , Bar Noffar , Schindler Cheryl J. , Vathy Ilona
Published: April 2003

The present in vitro autoradiography study demonstrates that prenatal exposure to morphine alters the density of μ‐opioid receptors in the hippocampus of adult female but not adult male rats. Prenatal morphine exposure increased the μ‐opioid receptor density in the CA1 of ovariectomized (OVX) females and in the CA3 of OVX, estradiol benzoate‐plus progesterone (EB+P)‐treated females, but decreased it in CA3 of OVX females. There were also hormonal effects on μ‐opioid receptor density in adult female rats. In the CA1, only morphine‐exposed but not saline‐exposed, hormone‐treated females (EB, P, or EB+P) had a decrease in μ‐opioid receptor density relative to OVX females. Both saline‐exposed and morphine‐exposed, OVX females after gonadal hormone replacement had a lower density of μ‐opioid receptors in the CA3 and in the dentate gyrus (DG) than OVX females. In male rats, there was a decrease in μ‐opioid receptor density in the CA1 and CA3 of gonadectomized (GNX), testosterone 17β‐proprionate (TP)‐treated males relative to GNX males regardless of prenatal morphine exposure. In the DG, the μ‐opioid receptor density was reduced only in morphine‐exposed but not in saline‐exposed, TP‐treated males compared with GNX males. Thus, our data demonstrate that μ‐opioid receptor density in the hippocampus is affected by prenatal morphine exposure and by male and female gonadal hormones. Hippocampus 2003;13:461–471. © 2003 Wiley‐Liss, Inc.
Opioid peptide release in the rat hippocampus after kainic acid‐induced status epilepticus
Authors: Rocha L. , Maidment N.T.
Published: April 2003

It has been suggested that kainic acid enhances opioid peptide release. However, no direct evidence exists to support this hypothesis. The main aim of the present study was to determine whether such release occurs in the hippocampus of the rat after status epilepticus induced by kainic acid. Microdialysis experiments revealed significant opioid peptide release in the hippocampus 90–150 min (100%) and 270–300 min (50%) after kainic acid‐induced status epilepticus. The peptides released were identified by high‐performance liquid chromatography linked to radioimmunoassay as Met‐enkephalin, Leu‐enkephalin, Dynorphin‐A (1–6), and Dynorphin‐A (1–8). Reduced extracellular opioid peptide immunoreactivity was detected 28 days after status epilepticus (38% compared with control situation). The present results indicate an important activation of opioid peptide systems by kainic acid‐induced status epilepticus. In addition, the reduced hippocampal extracellular opioid peptide levels long‐term after kainic acid administration could have important implications for the progressive nature of epileptogenesis. Hippocampus 2003;13:472–480. © 2003 Wiley‐Liss, Inc.
Temporal firing characteristics and the strategic role of subicular neurons in short‐term memory
Authors: Hampson Robert E. , Deadwyler Sam A.
Published: April 2003

The role of subicular neurons is explored with respect to their participation in short‐term memory during performance of a spatial Delayed‐Nonmatch‐to‐Sample (DNMS) task by well‐trained rats. Subicular and CA1 neuron firing was examined in the same animals in relation to the encoding of task‐relevant events during the DNMS trial. The results indicate that subicular neurons have completely different firing signatures than well‐characterized hippocampal neurons in this task. Firing patterns of subicular neurons consisted of five different categories spanning all three phases of the DNMS trial, but concentrated mostly within the Sample and early portion of the Delay period. Unlike hippocampal neurons, subicular cells did not exhibit conjunctive firing correlates with respect to particular combinations of task events; rather, subicular cell firing was differentiated primarily on the basis of temporal specificity within the trial. Only two of the five subicular cell types fired differentially on correct versus error trials; however, one cell type exhibited such differential firing as an inverse function of duration of delay interval. Experiments employing γ‐aminobutyric acid GABAB receptor agonists and antagonists showed that both behavioral performance as well as subicular cell firing were disrupted significantly by baclofen at short delays, while performance at long delays and hippocampal cell firing were relatively immune to this effect. The relevance of subicular cell firing in the task with respect to its temporal relation to delay‐dependent hippocampal neuronal activity suggests that the structures have complementary roles in the encoding and representation of items in short‐term memory. Hippocampus 2003;13:529–541. © 2003 Wiley‐Liss, Inc.
Mitochondrial distribution and glycogen dynamics suggest diffusion constraints in muscle fibers of the blue crab, Callinectes sapidus
Authors: Boyle Kim‐Laura , Dillaman Richard M. , Kinsey Stephen T.
Published: April 2003

The scaling of mitochondrial distribution, citrate synthase activity, and post‐contractile glycogen recovery was examined in muscle fibers of the blue crab, Callinectes sapidus. The fast‐twitch muscle fibers of C. sapidus can reach extremely large dimensions, which may impose constraints on aerobic metabolic processes. However, muscle cells from small crabs are not giant, meaning that during development muscle fibers cross and greatly exceed the surface area to volume (SAV) and diffusion threshold that is adhered to by the cells of most organisms. Cell diameters in the smallest size class were ≃100 µm, while the largest size class had cell diameters in excess of 500 µm. In the smallest cells, the fractional area of subsarcolemmal and intermyofibrillar mitochondria was similar. However, in the largest cells, mitochondria were almost exclusively subsarcolemmal. Total fractional area of mitochondria was highest in the largest cells due to a proliferation of subsarcolemmal mitochondria. In contrast, citrate synthase activity decreased as cell size increased. Following burst contractile activity, glycogen concentrations decreased significantly and remained depressed for several hours in muscle comprised of giant cells, consistent with previous findings that anaerobic glycogenolysis fuels certain components of post‐contractile recovery. However, in muscle composed of the smallest muscle cells, glycogen levels did not decrease significantly following burst activity. While normal scaling of aerobic metabolism would predict a slower aerobic recovery in larger animals, the present results suggest that cellular organization, SAV, and intracellular diffusion distances also impose constraints on aerobic processes in C. sapidus. J. Exp. Zool. 297A:1–16, 2003. © 2003 Wiley‐Liss, Inc.