bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic evolution of the unsaturated hydraulic conductivity of a developing crust
Authors: Issa O. Malam , Cousin I. , Bissonnais Y. Le , Quétin P.
Published: August 2004

Understanding the evolution of hydraulic parameters during the different stages of crust formation is necessary to predict inﬁltration in crusted soil. However, only a few studies have focused on the dynamics of parameters that control inﬁltration through a developing crust. This study reports the results of laboratory experiments carried out with a speciﬁc device, the drip inﬁltrometer, which enables a crust to form at the surface, and the evolution of the pressure head and the hydraulic conductivity of the soil horizon underneath the crust to be followed simultaneously. Two soils of different susceptibility to crusting were used in the experiments: a silt loam and a silty clay loam of the Bassin de Paris (France). The results show matric potential in the unsaturated range developing below the surface from the early stage of crust formation. The values of matric potential show an increasing trend from the early stage of crust formation and at the late stage respectively for the silt loam and the silty clay loam soils. The hydraulic conductivity of the sub‐crust shows signiﬁcant changes from the early stage for the silt loam soil, but only at the ﬁnal stages for the silty clay loam. The initial value of the hydraulic conductivity of the sub‐crust drops by more than 50 per cent for silt loam compared to about 35 per cent for silty clay loam. The decrease of hydraulic conductivity beneath the surface crust is related to the changes in the soil matrix, induced by the migration of particles detached from aggregate breakdown. The different stages of crust formation were characterized by the variation of the unsaturated conductance of the soil crusted layer, calculated from the relationship between the ﬂux density through the crust and the sub‐crust pressure head. The results revealed rapid sealing at the surface of the silty loam soil, whereas sealing occurs gradually at the surface of the silty clay loam. The difference in the susceptibility to crusting and the difference in moisture characteristics between the two soils are probably the causes of the contrast in temporal variation of the sub‐crust matric potential. Copyright © 2004 John Wiley & Sons, Ltd.
Effectiveness of vegetation barriers for marly sediment trapping
Authors: Rey F.
Published: August 2004

Vegetation barriers can be effective in trapping eroded sediment, but little knowledge exists on the characteristics of vegetation barriers efﬁcient in trapping all sediments from an eroded zone upslope. The objective of this study is to quantify the effectiveness of vegetation barriers for marly sediment trapping. Relationships between eroded zones and vegetation barriers – composed of low vegetation, that is to say herbaceous and under‐shrub layers – located downslope and sufﬁcient to stop all the sediments eroded above, have been studied in the Brusquet experimental marly catchment in the French southern Alps. Forty plots with surface areas less than 500 m2 were studied. The eroded zones and the vegetation barriers were characterized by their surface areas, between which an average linear relationship exists. Results also showed that, for a marly plot with a given surface area, a downslope vegetation barrier covering only 20 per cent of this plot can be sufﬁcient to trap all the sediments eroded above it. Copyright © 2004 John Wiley & Sons, Ltd.
Variations in soil dispersivity across a gully head displaying shallow sub‐surface pipes, and the role of shallow pipes in rill initiation
Authors: Faulkner Hazel , Alexander Roy , Teeuw Richard , Zukowskyj Paul
Published: August 2004

A small bifurcating gully head displaying shallow pipe development was surveyed to explore how far three‐dimensional patterns of geochemistry and sediment size can be related to hydraulic gradients in the local marl bedrock (Almería, SE Spain).

The crust, sub‐crust and parent materials were sampled every 20 cm across a 2 m by 3 m grid, and then analysed for dispersive and granulometric characteristics. Spatial patterns of sodium adsoption ratio (SAR) for each layer were plotted separately. In‐situ material at depths of 5–10 cm was only weakly dispersive, and the thin (0–2 cm depth) crust is also found to be mostly non‐dispersive, paralleling ﬁndings from other ﬁeld sites in Almería. However, the ‘signature’ relating SAR to electrical conductivity for each layer shows that in places the immediate sub‐crust layer (2–5 cm) is highly dispersive. The pattern is not random; rather the SAR of this sub‐crust layer follows inferred hydraulic gradients, the dispersive ‘hot spots’ being located in the most incised part of the small gully, exacerbating the erodibility of that position.

Patterns of sediment particle size and sorting do not correlate with inferred hydraulic gradients but surface material is slightly siltier than the sub‐crust. Clay fraction increased with depth, and SAR is shown to have a weak inverse relationship to particle size. This association between SAR and the increased clay fractions in the lower layers supports the inference that massive pipe enlargement in the Messinian‐Rich Unit is suppressed by sub‐surface swelling. Since a reduction in inﬁltration capacity (fc) with depth can be inferred from these results, inﬁltrating water must be deﬂected into the already vulnerable sub‐crust layer during rainfall events, explaining the development of shallow pipe forms at preferential depths.

It is concluded that calcium replaces sodium in the crust during leaching, leaving a calcic crust, and a sub‐crust that is sodic and prone to subsequent pipe enlargement. Rill morphology in these materials also suggests that rills develop from these pipes when pipe roofs collapse (i.e. rill discontinuity; bridges; steep headwalls; and rills with excessively high depth‐to‐width ratios). Copyright © 2004 John Wiley & Sons, Ltd.
Graphical models for coded data transmission over inter‐symbol interference channels
Authors: Tüchler Michael , Koetter Ralf , Singer Andrew C.
Published: August 2004

We derive graphical models for coded data transmission over channels introducing inter‐symbol interference. These models are factor graph descriptions of the transmitter section of the communication system, which serve at the same time as a framework to define the corresponding receiver. The graph structure governs the complexity and nature (e.g. non‐iterative, iterative) of the receiver algorithm. A particular graph yields several algorithms optimizing various cost functions depending on the choice of messages communicated along the edges of the graph. We study these different outcomes of message passing and how the corresponding receiver algorithms are related to existing ones. We also devise strategies to find suitable graphs for communication problems of interest. Copyright © 2004 AEI
On computing the syndrome polynomial in Reed–Solomon decoder
Authors: Costa Elena , Fedorenko Sergei Valentinovich , Trifonov Peter Vladimirovich
Published: August 2004

Application of the cyclotomic fast Fourier transform (FFT) algorithm to the syndrome evaluation problem in classical Reed–Solomon decoders is described. A number of complexity reduction tricks is suggested. Application of the algorithm leads to significant reductions in the complexity of syndrome evaluation. Moreover, automatic generation of the program code implementing the described algorithm is possible. Copyright © 2004 AEI
Radio resource management in cellular multihop networks
Authors: Zirwas Wolfgang , Li Hui , Lott Matthias , Weckerle Martin , Schulz Egon , Lampe Mattias
Published: August 2004

In future mobile broadband radio systems, multihop for coverage extension is seen as a basic building block. Here, we investigate radio resource management (RRM) for multihop networks and assume that the central access point (AP) can control the whole multihop network based on channel state information (CSI) of all links. Specifically we investigate interference effects between neighboring multihop networks as well as within a single multihop network. Interference within a multihop network occurs only when the central scheduler allows simultaneous transmission at the same time and frequency, here called SIMU, on several radio links. It is shown, that SIMU can increase overall capacity of a multihop network compared to a fully orthogonal transmission, here called time division multiple access (TDMA), where only one single link is active at a time. For neighboring multihop networks it is shown that inter cell interference (ICI) may be treated as additive white Gaussian noise (AWGN) with typically only small performance degradation. Copyright © 2004 AEI
Asynchronous TDMA ad hoc networks: scheduling and performance
Authors: Salonidis Theodoros , Tassiulas Leandros
Published: August 2004

A common assumption of time division multiple access (TDMA)‐based wireless ad hoc networks is the existence of network‐wide slot synchronization. Such a mechanism is difficult to support in practice. In asynchronous TDMA systems, each link uses a local time slot reference provided by the hardware clock tick of one of the node endpoints. Inevitably, slots are wasted when nodes switch time slot references. This restricts the rate allocations that can be supported when compared to a perfectly synchronized system. To address this practical performance issue, we first introduce a general framework for conflict‐free scheduling in asynchronous TDMA networks. We then propose scheduling algorithms that target overhead minimization while ensuring upper bounds on the generated overhead. Through extensive simulations the algorithm performances are evaluated in the context of Bluetooth, a wireless technology that operates according to the asynchronous TDMA communication paradigm. Copyright © 2003 AEI
Secure and efficient voice‐over‐IP in a cdma2000® Network
Authors: McCann Peter J. , Rance Robert , Patel Sarvar
Published: August 2004

This paper examines how to provide secure and efficient voice‐over‐IP service on a cdma2000 network. Various alternative solutions and their relationship to header compression techniques are discussed. We propose a new method of end‐to‐end encryption that could be used to provide privacy even when Header Removal, a cdma2000‐specific technique where IP/UDP/RTP headers are discarded before transmission over the air, is in use. The new method relies on a novel variable‐length block cipher that can be re‐used with fixed parameters across many voice frames, eliminating the requirement to carry precise cryptographic synchronization with each and every voice frame. Instead, the parameters to the block cipher are varied on an infrequent basis, and synchronization information is communicated from the encryptor to the decryptor by overwriting the occasional voice frame, with minimal impact on resulting voice quality. The method offers provable security guarantees given some assumptions about the amount of entropy contained in the encoded speech data. Copyright © 2004 AEI
Haplotype block structures show significant variation among populations
Authors: Liu Nianjun , Sawyer Sarah L. , Mukherjee Namita , Pakstis Andrew J. , Kidd Judith R. , Kidd Kenneth K. , Brookes Anthony J. , Zhao Hongyu
Published: August 2004

Recent studies suggest that haplotypes tend to have block‐like structures throughout the human genome. Several methods were proposed for haplotype block partitioning and for tagging single‐nucleotide polymorphism (SNP) identification. In population genetics studies, several research groups compared block structures across human populations. However, the measures used to quantify population similarity are either less than satisfactory or nonexistent. In this article, we propose several similarity measures to facilitate the comparisons of haplotype structures, namely block boundaries and tagging SNPs, across populations. With these measures, we can more objectively compare haplotype block structures and tagging SNP sets between different populations. In addition, these measures allow us to compare the results of different methods for block partition and tagging SNP identification. When we applied these measures to a real data set on chromosome 10 in 16 worldwide populations, we found that in this genome region: 1) haplotype block boundaries vary among populations, with European and some African populations showing similar boundaries but other populations showing other patterns; 2) tagging SNP sets are generally similar for populations with similar haplotype block structures but differ if the block structures differ; and 3) all but one of the block finding methods we tested yield consistent results, although variations exist regarding consistency. Our tentative results show that at least in the genome region studied, it is unlikely that a common haplotype pattern exists for all human populations: many populations, even in the same geographical region, may have different haplotype patterns. © 2004 Wiley‐Liss, Inc.
The end of shared governance: Looking ahead or looking back
Authors: Birnbaum Robert
Published: August 2004

Proposals to make governance “more efficient” by reducing or limiting the faculty role in shared governance are likely to diminish institutional effectiveness.
Do governance structures matter?
Authors: Kaplan Gabriel E.
Published: August 2004

Using national survey data, the author finds little relationship between decision‐making authority and the actual decisions that are made.
What is more important to effective governance: Relationships, trust, and leadership, or structures and formal processes?
Authors: Kezar Adrianna
Published: August 2004

Changing structures may be a less important factor in creating an effective approach to governance than leadership, relationships, and trust.
The state and higher education: An essential partnership
Authors: Lingenfelter Paul E.
Published: August 2004

Twenty‐first century conditions are adding new dimensions to the relationship between states and higher education.
Disjointed governance in university centers and institutes
Authors: Mallon William
Published: August 2004

Research centers and institutes are one example of how institutional governance has become increasingly disjointed; as the “suburbs” of the university expand, core governance structures lose influence.
A cultural perspective on communication and governance
Authors: Tierney William G. , Minor James T.
Published: August 2004

Cultural and symbolic processes‐that is, communication‐quite frequently play as important a role as structural issues in enabling effective governance.
Exploring current issues on shared governance
Authors: Lechuga Vicente M.
Published: August 2004

A number of significant studies of shared governance have been carried out in the last decade.
Stability of hippocampal place cell activity across the rat estrous cycle
Authors: Tropp Jennifer , Figueiredo Cristina M. , Markus Etan J.
Published: August 2004

Findings from both in vitro and in vivo studies have shown that estrogen exerts pronounced effects on hippocampal morphology and physiology. The degree to which these molecular findings influence hippocampal processing in freely behaving animals is unclear. The present study assessed the effect of the estrous cycle on hippocampal place cells in naturally cycling rats during two behavioral states. Female Sprague‐Dawley rats were trained to alternate on a U‐shaped runway for food reinforcement. Single‐unit recordings of hippocampal CA1 cells were conducted under two conditions: (1) at rest on a holder, and (2) running on the maze. Spatial firing characteristics of the cells were examined at different stages of the estrous cycle (i.e., diestrus, proestrus, and estrus). Specifically, information was collected on (1) mean firing rates; (2) basic place field parameters; and (3) changes in the firing dynamics of these cells (e.g., burst properties). The findings showed a decrease in mean firing rate on the maze during proestrus. However, other basic measures of spatial tuning and burst properties were unchanged. The current study suggests that there is relative stability of hippocampal place cells across the estrous cycle during a well‐trained task. © 2004 Wiley‐Liss, Inc.
Experimental research on the effects of distributor configuration on flow distribution in plate‐fin heat exchangers
Authors: Zhang Zhe , Li Yanzhong , Xu Qing
Published: August 2004

The effects of different distributor configurations on the flow distribution in plate‐fin heat exchangers were studied. It was found that an irrational distributor configuration would lead to the flow maldistribution and a different degree of non‐uniformity of the flow distribution in the transverse and longitudinal directions. The distributor configuration and Reynolds number are the main factors affecting the flow distribution. An improved distributor configuration with a fluid complementary cavity has been brought forward. The experimental results showed that the improved distributor configuration can effectively improve the performance of flow distribution in heat exchangers. The best performance of flow distribution was obtained at h/H = 0.2. The correlations between the flow maldistribution characteristic and the flow Reynolds number for different distributor configurations were deduced according to the experimental data. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(6): 402–410, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20023
Effect of micro mass transfer through phase interface on numerical simulation of solidification process
Authors: Feng Yanhui , Zhang Xinxin
Published: August 2004

Existing models for the solute redistribution during solidification have been reviewed. Some typical models are applied for the numerical simulation of heat and mass transfer with phase change under experimental condition of inverse casting. The results show that the effect of micro mass transfer models on the formation of the new phase cannot be omitted. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(6): 393–401, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20024
Enhanced heat transfer analysis of latent functionally thermal fluid
Authors: Bai Fengwu , Lu Wen‐Qiang
Published: August 2004

A physical model has been developed to analyze the enhanced heat transfer process of the latent functionally thermal fluid with microencapsulated phase‐change material. The problem is solved by the combination of the finite difference method and the moving heat source method. The calculated results reveal that putting the phase‐change microcapsules into the fluids can enhance the heat transfer capabilities of the mixture. The effects of capsule radius and concentration of particles are numerically predicted. The numerical results provide the theoretical basis for the application and design of the latent functionally thermal fluid. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(6): 383–392, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20025
Applicability of spatially periodic boundary conditions to a numerical computation of flow in a channel obstructed by an array of square rods
Authors: Murata Hiroyuki , Sawada Ken‐ichi , Suzuki Kenjiro
Published: August 2004

Two‐dimensional numerical computation is performed for an unsteady laminar flow. Spatially the periodic boundary conditions are adopted in the streamwise direction and the adequacy of this treatment is studied by varying the computational domain size. The following results were obtained. The Strouhal number and the lift coefficient fluctuation amplitude may change with the domain size for the same flow conditions. Therefore, numerical simulation for a unitary periodic flow field, a “cell,” is valid for limited flow conditions, which depend on the Reynolds number, the blockage ratio of the rod, and its pitch. Research was carried out on a condition in which the numerical solution is determined uniquely, i.e., the calculated results do not change with the domain size, by paying attention to the change in the phase difference of the flow patterns between neighboring cells. The Strouhal number, the drag coefficient, and the lift coefficient fluctuation amplitude increase considerably with the blockage ratio in the calculated results. The lift coefficient fluctuation amplitude decreases slightly with the increase of the rod pitch. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(6): 357–370, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20027
Sarbanes‐oxley: Compliance or sham?
Authors: Smith Gordon
Published: August 2004

The author, an IT auditing expert, warns that some companies may be looking for ways to appear to be in compliance—when they really are not. © 2004 Canaudit, Inc.
How does SOX change IT?
Authors: Damianides Marios
Published: August 2004

The Sarbanes‐Oxley Act (SOX) will affect all computer systems involved in financial reporting. But exactly what does this mean? What must companies change to be in compliance? The article also features a comprehensive IT SOX checklist. © 2004 Wiley Periodicals, Inc.
SEC urges big changes in accounting and reporting
Authors: Kimmel Paul , Warfield Terry
Published: August 2004

The Sarbanes‐Oxley Act (SOX) will probably make the discourse between top management, audit committees, and auditors more contentious in the coming years. But the very nature of that discourse may change—if regulators adopt a new approach called “principles‐based accounting.” SOX mandated that the SEC study the usefulness of this approach. And the SEC's report, issued late last year, recommended a move to principles‐based accounting. So what are the implications of this change for top management? © 2004 Wiley Periodicals, Inc.
How SOX affects investing through credit rating agencies
Authors: Burnie David A. , Langsam Sheldon A.
Published: August 2004

The Sarbanes‐Oxley Act (SOX) has a long reach. Is your firm issuing debt or other securities? Or are you concerned about the cost of capital? Are you responsible for structuring financial transactions or for making investments? Then you may be surprised to learn that SOX Section 702(b) can affect all these activities and more. It regulates the hugely important credit rating agencies. © 2004 Wiley Periodicals, Inc.
Interprofessional collaboration: Implications for Combined‐Integrated doctoral training in professional psychology
Authors: Johnson Carolyn E. , Stewart Anne L. , Brabeck Mary M. , Huber Vida S. , Rubin Hank
Published: August 2004

Interprofessional collaboration (IPC) is becoming “best practice” in the field of professional psychology and other health care professions. It was named as a core competency at Competencies 2002 and the Consensus Conference and has been endorsed by the American Psychological Association on several occasions. The authors provide a definition of IPC, present conceptual, scholarly, and pragmatic support for IPC, and offer guidance on how Combined‐Integrated (C‐I) doctoral programs in professional psychology can include IPC to ensure students are well equipped to respond to a client's complex needs. Furthermore, although C‐I programs might be particularly well prepared to incorporate IPC into their training, it is argued that programs in the single practice areas of clinical, counseling, and school psychology also may benefit from the inclusion of IPC. © 2004 Wiley Periodicals, Inc. J Clin Psychol.
Development of a global curriculum for professional psychology: Implications of the Combined‐Integrated model of doctoral training
Authors: Burgess Gerald H. , Sternberger Lee G. , Sanchez‐Sosa Juan Jose , Lunt Ingrid , Shealy Craig N. , Ritchie Pierre
Published: August 2004

This article considers the development of a global training curriculum and qualification in professional psychology, with particular emphasis on the Combined‐Integrated (C‐I) model. The C‐I model exposes professional psychology trainees to two or more of the practice areas (i.e., clinical, counseling, school/educational). The authors argue that the C‐I approach is one that is well suited to the development of a global training curriculum due to its emphasis on broadly training psychologists as well as its respect for diversity and integration of various theoretical and professional orientations. A survey of training programs in 16 countries/regions on six continents found significant variation in training, minimal qualifications, and roles of the professional psychologist. The authors recommend that an international group of psychologists develop a regionally flexible, but common, training curriculum and qualification that would include a five‐ to six‐year competency‐based qualification. Ways in which the C‐I training model may serve to integrate and globalize professional psychology are discussed. © 2004 Wiley Periodicals, Inc. J Clin Psychol.
A systemic view of higher education and professional psychology: Implications of the Combined‐Integrated model of doctoral training
Authors: Brown Douglas T. , Benson A. Jerry , Walker N. William , Sternberger Lee G. , Lung Deborah S. , Kassinove Howard
Published: August 2004

This article was developed in response to the proceedings of the Consensus Conference on Combined and Integrated Doctoral Training in Psychology held at James Madison University in Harrisonburg, VA, May 2 to 4, 2003. The authors approach the recommendations of the conference from the perspective of their experiences in higher education administration at the national, regional, and state levels. The authors conclude that the Consensus Conference represents an exemplar of best practice in program planning. They suggest that a major reconceptualization of higher education is under way that emphasizes broad collaboration among various professional groups as a means of providing appropriate mental health and health care services. Consequently, professional psychology will need to reconceptualize its role in the broader context of other professions within the university setting. Recommendations for the education of psychologists and the development of future training programs are provided. Suggestions for implementation of various recommendations flowing from the Consensus Conference are delineated. © 2004 Wiley Periodicals, Inc. J Clin Psychol.
The Consensus Conference and Combined‐Integrated model of doctoral training in professional psychology—Overview of Part 2: Broader implications and potential applications of the Combined‐Integrated model
Authors: Shealy Craig N.
Published: August 2004

This special series of articles on the Consensus Conference and Combined‐Integrated (C‐I) model of doctoral training in professional psychology consists of 13 articles in two successive issues of the Journal of Clinical Psychology. Six articles were presented in Part 1 (Vol. 60, Issue 9), which collectively described the “nature and scope” of the C‐I model (e.g., historic and definitional issues; the potential advantages of this model; implications for the profession). In Part 2 of this special series (Vol. 60, Issue 10), articles 7 through 12 address the broader implications and potential applications of the C‐I model within a range of professional and societal contexts (e.g., for interprofessional collaboration; the health care field; development of a global curriculum; the unified psychology movement; issues of assessment and professional identity; and higher education); article 13 provides a summary of the series as well as a discussion of future directions. As an overview, this paper reviews the articles in Part 1 and describes the various topics of the articles in Part 2. Taken together, the articles in this special series are designed to provide a coherent account of how and why the C‐I model is timely and relevant, and therefore warrants serious consideration by the larger education and training community in professional psychology. © 2004 Wiley Periodicals, Inc. J Clin Psychol.
Spreading of embryologically distinct urothelial cells is inhibited by SPARC
Authors: Hudson Amber E. , Feng Waldo C. , Delostrinos Catherine F. , Carmean Nicole , Bassuk James A.
Published: August 2004

The AON epitope of secreted protein acidic and rich in cysteine (SPARC) is a conserved motif expressed by human SPARC in a variety of human cell types. Through the use of a monoclonal antibody that recognizes this epitope, transitional epithelium was found to restrict expression of SPARC to the suprabasal and intermediate layer. Such intracellular expression was defined by immunoreactive signals that localized to the apical plasma membranes of suprabasal and intermediate cells. Polarization of SPARC to apical plasma membranes of suprabasal cells was retained in vitro by a subpopulation of cells that exhibited characteristics of suprabasal cells—cell‐cycle quiescence, large cell volumes, and multiple nuclei. In contrast, the basal layer of transitional epithelium in vivo and cycling cells in vitro did not exhibit this apical staining pattern, but instead sequestered the SPARC polypeptide within urothelial cytoplasm and/or nuclei, as revealed by immunohistochemical analysis. Elution of soluble proteins and DNA from urothelial cells revealed the presence of SPARC within the nuclear matrix—and that SPARC colocalized with the nuclear matrix Ki‐67 antigen. rSPARC activity was demonstrated and quantified with a rounding assay whereby the spreading of freshly plated cells was inhibited by recombinant SPARC in a concentration‐ and time‐dependent manner. Inhibition of spreading was observed in urothelial cells derived from endoderm (bladder) and mesoderm (ureter) germ layers. Statistically significant differences were seen between urothelial cells from these two layers. Mesodermal cells recovered more slowly from the inhibitory effects of rSPARC, such that at hour 6 endodermal cells underwent significantly more spreading, as shown by a rounding index (RI). These experiments provide new insights about the matricellular trafficking of SPARC and suggest that intra‐ and extra‐cellular localization patterns influence the development, homeostasis, and differentiation of transitional epithelium. © 2004 Wiley‐Liss, Inc.
Ectodomain shedding of membrane‐anchored heparin‐binding EGF like growth factor and subcellular localization of the C‐terminal fragment in the cell cycle
Authors: Toki Fujio , Nanba Daisuke , Matsuura Nariaki , Higashiyama Shigeki
Published: August 2004

Heparin‐binding EGF‐like growth factor (HB‐EGF) is initially synthesized as a type I transmembrane protein (proHB‐EGF). The proHB‐EGF is shed by specific metalloproteases, releasing the N‐terminal fragment into the extracellular space as a soluble growth factor (HB‐EGF) and the C‐terminal fragment (HB‐EGF‐C) into the intracellular space, where it prevents transcriptional repression by the promyelocytic leukemia zinc finger protein (PLZF). The goal of the present study was to characterize regulation of proHB‐EGF shedding and study its temporal variations in HB‐EGF‐C localization throughout the cell cycle. Quantitative combination analyses of cell surface proHB‐EGF and HB‐EGF in conditioned medium showed that proHB‐EGF shedding occurred during the G1 cell cycle phase. Laser scanning cytometry (LSC) revealed that HB‐EGF‐C was internalized into the cytoplasm during the late G1 phase and accumulated in the nucleus beginning in the S phase. Subsequent nuclear export of PLZF occurred during the late S phase. Further, HB‐EGF‐C was localized around the centrosome following breakdown of the nuclear envelope and was localized to the interzonal space with chromosome segregation in the late M phase. Temporal variations in HB‐EGF localization throughout the cell cycle were also characterized by time‐lapse imaging of cells expressing YFP‐tagged proHB‐EGF, and these results were consistent with those obtained in cytometry studies. These results indicate that proHB‐EGF shedding and subsequent HB‐EGF‐C signaling are related with progression of the cell cycle and may provide a clue to understand the unique biological significance of non‐receptor‐mediated signaling of proHB‐EGF in cell growth. © 2004 Wiley‐Liss, Inc.
The use of a specific function to estimate maximum methane production in a batch‐fed anaerobic reactor
Authors: Redzwan Ghufran , Banks Charles
Published: August 2004

A readily biodegradable substrate was used to assess the value of using a mathematical function of y = ymaxexpm/x as a simplified method of determining the maximum methane production (Gmax) in a batch anaerobic reactor. Experimental results to test the method used three different initial substrate loadings in pre‐acclimatised completely mixed anaerobic reactors. Gas production was found to follow a typical trend that has previously been described by first order reaction kinetics; for the purpose of fitting the linearisation, it requires a value for maximum cumulative methane production. Use of the modified specific function to yield the equation G = Gmaxexpm/t showed that the experimental gas production curve could be estimated with a high degree of similarity. This was confirmed by a statistical analysis using the method of residuals which gave a correlation coefficient (R2) greater than 0.97 between experimental and estimated values. Using a graphical linearisation of the specific function produced a simplified method of predicting Gmax. The value obtained was then used in a first order kinetic model to derive the specific coefficient rate (Ko), which was in agreement with other methods used for its determination. Copyright © 2004 Society of Chemical Industry
Parallel acquisition techniques in cardiac cine magnetic resonance imaging using TrueFISP sequences: Comparison of image quality and artifacts
Authors: Hunold Peter , Maderwald Stefan , Ladd Mark E. , Jellus Vladimir , Barkhausen Jörg
Published: August 2004

Purpose

To compare image quality, artifacts, and signal‐to‐noise ratio (SNR) in cardiac cine TrueFISP magnetic resonance imaging (MRI) with and without parallel acquisition techniques (PAT).

Materials and Methods

MRI was performed in 16 subjects with a TrueFISP sequence (1.5 T; Magnetom Sonata, Siemens): TR, 3.0 msec; TE, 1.5 msec; flip angle (FA), 60°. Three axes were scanned without PAT (no PAT) and using the generalized autocalibrating partially parallel acquisition (GRAPPA) and modified sensitivity encoding (mSENSE) reconstruction algorithms with an autocalibration mode to reduce scan time. A conventional spine array and a body flex array were used. Artifacts, image noise, and overall image quality were classified on a 4‐point scale by an observer blinded to the implemented technique; for quantitative comparison, SNR was measured.

Results

With a PAT factor of two, acquisition time could be reduced by 39%. No PAT did not show artifacts, and GRAPPA revealed fewer artifacts than mSENSE. PAT provided inferior‐quality scores concerning image noise and overall image quality. In quantitative measurements, GRAPPA and mSENSE (20.1 ± 6.2 and 15.6 ± 6.2, respectively) yielded lower SNR than no PAT (30.6 ± 20.1; P < 0.05) and P < 0.001).

Conclusion

Time savings in PAT are accompanied by artifacts and an increase in image noise. The GRAPPA algorithm was superior to mSENSE concerning image quality, noise, and SNR. J. Magn. Reson. Imaging 2004;20:506–511. © 2004 Wiley‐Liss, Inc.
Adaptive subtraction as an aid in MR‐guided placement of catheters and guidewires
Authors: Bakker Chris J.G. , Seppenwoolde Jan‐Henry , Bartels Lambertus W. , van der Weide Remko
Published: August 2004

Purpose

To demonstrate the utility of mask subtraction optimization in magnetic resonance (MR)‐guided placement of catheters and guidewires.

Materials and Methods

MR‐guided positioning of magnetically prepared catheters and guidewires was done by dynamically imaging a single thick slab at two frames per second. Selective visualization of the prepared parts of the devices was achieved by the use of a conventional baseline subtraction technique and by the use of an adaptive subtraction technique. In the latter, the best reference image is automatically selected from a fixed or a sliding subset of hitherto acquired dynamic images. The efficacy of both approaches was compared by tracking experiments in a flow phantom and in the aortoiliac arteries of a pig.

Results

Baseline subtraction produced adequate visualization of paramagnetic markers in the absence of subject motion and for fixed scan conditions. The sensitivity to subject motion and interactive modification of the scan parameters was greatly reduced by using adaptive subtraction. Adaptive subtraction images, other than conventional subtraction images, appeared to be insensitive to slow periodic motion, e.g., respiratory motion, and were only transiently affected by gross subject motion and interactive alterations of the scan parameters.

Conclusion

Adaptive subtraction is superior to baseline subtraction for guiding the manipulation of catheters and guidewires in the presence of gross and periodic subject motion and whenever scan parameters are modified in the course of a procedure. J. Magn. Reson. Imaging 2004;20:470–474. © 2004 Wiley‐Liss, Inc.
Use of a three‐station phased array coil to improve peripheral contrast‐enhanced magnetic resonance angiography
Authors: Leiner Tim , Nijenhuis Robbert J. , Maki Jeffrey H. , Lemaire Etienne , Hoogeveen Romhild , van Engelshoven Jos M.A.
Published: August 2004

Purpose

To explore the imaging capabilities of a new commercially available, three‐station, 129‐cm long, 12‐element phased array coil for contrast‐enhanced magnetic resonance angiography (CE‐MRA) in patients with symptomatic peripheral arterial occlusive disease.

Materials and Methods

Nineteen patients, referred for peripheral CE‐MRA, were evaluated using the new three‐station coil. For each station four coil elements (two anterior and two posterior to the patient) were used. The expected improvements in signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) were used to improve spatial resolution and increase anatomic coverage for the distal two stations compared to our previous protocol. Images obtained in the 19 patients imaged with the new coil were compared to those of the last 19 patients scanned without the use of the new coil. Differences in image quality before vs. after the availability of the new coil were compared in terms of SNR and CNR, subjective interpretability score (SIS), degree of venous enhancement, and anatomic coverage. Images were interpreted by two experienced observers, blinded for imaging technique and each other's results.

Results

Use of the coil enabled acquisition of high resolution peripheral vasculature images in all cases and allowed for substantially smaller voxel sizes (thighs: 5.3 vs. 8.4 mm3 [–37%]; legs: 1.8 vs. 8.0 mm3 [–78%]) and much shorter acquisition durations in the aortoiliac and thighstations (aortoiliac: 16 vs. 27 seconds [–41%]; thighs: 11 vs. 23 seconds [–52%]). Acquisition duration in the leg station was prolonged (68 vs. 29 seconds [+134%]). SNR and CNR were significantly higher only in the aortoiliac station using the three‐station coil (both: P < 0.001). There were no significant differences in SIS for the aortoiliac and thigh stations (aortoiliac station: observer 1: P = 0.16, observer 2: P = 0.19; thigh station: both observers: P = 0.27). Images acquired with the new coil had significantly higher SIS for the leg station (both observers: P = 0.004). There were no significant differences in venous enhancement between the two protocols for any of the stations (all P > 0.11). In 12/12 (100%) requested cases the entire pedal arch was depicted using the new coil, whereas this was not possible with the old protocol.

Conclusion

The new three‐station dedicated peripheral vascular coil allows for much higher resolution imaging in the thigh and leg stations with greater anatomic coverage and substantially improves peripheral MRA quality of the lower leg vasculature. J. Magn. Reson. Imaging 2004;20:417–425. © 2004 Wiley‐Liss, Inc.
Angiogenesis in hepatocellular nodules: Correlation of MR imaging and vascular endothelial growth factor
Authors: Kanematsu Masayuki , Semelka Richard C. , Leonardou Polytimi , Mastropasqua Maria , Armao Diane , Vaidean Georgeta , Firat Zeynep , Woosley John T.
Published: August 2004

Purpose

To assess the correlation between magnetic resonance (MR) imaging findings and angiogenetic activity in hepatocellular nodules evaluated by immunohistochemical staining with antibody of vascular endothelial growth factor (VEGF).

Materials and Methods

We searched the pathologic records of our institution from December 1999 to April 2002, and included 16 patients with hepatocellular carcinoma (N = 14), large regenerative nodule (N = 1), and dysplastic nodule (N = 1) who underwent orthotopic liver transplantation (10 patients) or partial hepatectomy (six patients) and MR imaging within an interval of two weeks. The MR images were retrospectively assessed qualitatively and quantitatively. Angiogenetic activity of the hepatic nodules was evaluated by means of immunohistochemical study for VEGF. Analysis of variance and the Scheffé criterion were used for statistical evaluation.

Results

Hepatic nodules with moderate to strong immunoreactivity for VEGF showed higher signal intensity on T1‐weighted images (P < 0.05) and those with intense immunoreactivity for VEGF showed higher signal intensity on T2‐weighted images (P < 0.05). No correlation was found between the immunoreactivity for VEGF and tumor vascularity on postcontrast early‐ and late‐phase images.

Conclusion

Our current results suggest that signal intensity on unenhanced T1‐ and T2‐weighted MR images may correlate with immunoreactivity for VEGF. Correlation was not found between immunoreactivity for VEGF and signal intensity on gadolinium‐enhanced MR images. J. Magn. Reson. Imaging 2004;20:426–434. © 2004 Wiley‐Liss, Inc.
New FOCI pulses with reduced radiofrequency power requirements
Authors: Shen Jun , Chen Zhengguang , Yang Jehoon
Published: August 2004

Purpose

To propose new frequency offset corrected inversion (FOCI) pulses with significantly reduced radiofrequency (RF) power deposition for spin echo imaging by incorporating the variable‐rate selective excitation (VERSE) schemes into the pulse design.

Materials and Methods

Two schemes are proposed to design the new FOCI pulses with dramatically reduced peak RF power requirements. In scheme A, the time‐dilation function is derived from a predefined adiabaticity factor modulation function. In scheme B, the time‐dilation function is predefined, while the adiabaticity factor is conserved.

Results

The new FOCI pulses are shown to be able to operate at reduced specific absorption rate (SAR), specifically at the same peak RF power as that of a five‐ or seven‐lobe sinc inversion pulse of the same duration. Using the new FOCI pulse, significant gain in sensitivity was observed in in vivo spin‐echo echo‐planar imaging, which was attributed to the improved refocusing slice profile.

Conclusion

The new FOCI pulses can replace the 180° five‐ or seven‐lobe sinc pulses in spin‐echo imaging with the same peak RF power requirement and significantly improved slice profile. J. Magn. Reson. Imaging 2004;20:531–537. © 2004 Wiley‐Liss, Inc.
Inflammatory pseudotumor of the liver: Ferumoxide‐enhanced MR imaging as a tiebreaker
Authors: Kato Hiroki , Kanematsu Masayuki , Kondo Hiroshi , Osada Shinji , Goshima Satoshi , Yamada Tetsuya , Yamada Yasuhiro , Yokoyama Ryujiro , Hoshi Hiroaki , Moriyama Noriyuki
Published: August 2004

We examined a 70‐year‐old male patient with an inflammatory pseudotumor of the liver mimicking a peripheral‐type cholangiocellular carcinoma. Ferumoxide‐enhanced magnetic resonance (MR) imaging revealed residual Kupffer cell function in liver parenchyma in and surrounding the inflammatory pseudotumor involvement, which suggested the diagnosis of inflammatory pseudotumor of the liver. We correlate the MR imaging and pathologic findings in this report. J. Magn. Reson. Imaging 2004;20:501–505. © 2004 Wiley‐Liss, Inc.
Quantitative 1H‐MRS of healthy human cortex, hippocampus, and thalamus: Metabolite concentrations, quantification precision, and reproducibility
Authors: Geurts Jeroen J.G. , Barkhof Frederik , Castelijns Jonas A. , Uitdehaag Bernard M.J. , Polman Chris H. , Pouwels Petra J.W.
Published: August 2004

Purpose

To evaluate metabolite concentrations in cortical gray matter, hippocampus, and thalamus of healthy adults, and to investigate precision and reproducibility of quantitative proton magnetic resonance spectroscopy (1H‐MRS) in these gray matter regions.

Materials and Methods

Quantitative single‐voxel short echo‐time spectra were obtained from healthy human cortex, hippocampus, and thalamus. Subjects were examined twice. Metabolite concentrations, quantification precision, and reproducibility were determined.

Results

There were no significant differences between test and retest measurements. Regional differences were observed with respect to metabolite concentrations, quantification precision, and reproducibility. Quantification precision and reproducibility of N‐acetylaspartate and N‐acetyl aspartylglutamate (tNAA), creatine and phosphocreatine (tCr), choline‐containing compounds (Cho), and myo‐inositol (myo‐Ins), were better than those of glutamate (Glu) and glutamine (Gln). Generally, precision and reproducibility were better in cortex than in hippocampus or thalamus. The quantification precision was shown to correlate both with reproducibility and spectral linewidth.

Conclusion

The reliability of quantitative MRS depends on the metabolite concerned, its concentration, and on the brain area studied. Moreover, the quantification precision of a metabolite in a single spectrum appears to be a reliable measure for its reproducibility in a longitudinal study. J. Magn. Reson. Imaging 2004;20:366–371. © 2004 Wiley‐Liss, Inc.
Uterine peristalsis: Comparison of transvaginal ultrasound and two different sequences of cine MR imaging
Authors: Nakai Asako , Togashi Kaori , Kosaka Kenzo , Kido Aki , Hiraga Akira , Fujiwara Toshitaka , Koyama Takashi , Fujii Shingo
Published: August 2004

Purpose

To compare uterine peristalsis as seen on two different magnetic resonance (MR) imaging sequences and transvaginal ultrasound (TVUS), so as to better determine the best method for evaluating uterine peristalsis.

Materials and Methods

Eleven women in the periovulatory phase of the menstrual cycle underwent TVUS and cine MR imaging within a time period of three hours. Findings on cine MR images obtained with a serial 60 half‐Fourier acquisition single‐shot turbo spin‐echo (HASTE) sequence and a 300 true fast imaging with steady‐state precession (FISP) sequence were compared with TVUS.

Results

The image quality of the HASTE technique was the best among the three methods, followed by TVUS, and then true FISP technique (P < 0.001). Uterine peristalsis was detected in 100% of subjects using HASTE, 82% with True FISP, and 100% with TVUS. With HASTE technique, true FISP, and TVUS, respectively, endometrial stripping movement was identified in 100%, 82%, and 100%; direction was identified in 100%, 45% (P = 0.014), and 73%; and wave conduction toward the outer myometrium was identified in 55%, 9% (P = 0.025), and 0% (P = 0.014).

Conclusion

Cine MR imaging by HASTE technique with a time resolution of two seconds best delineated uterine peristalsis compared to that by true FISP technique or with TVUS. J. Magn. Reson. Imaging 2004;20:463–469. © 2004 Wiley‐Liss, Inc.