bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Use of Cyprinid Scales in the Diet Analysis of Piscivorous Species: How Much Information Is Hidden in a Fish Scale?
Authors: Miranda Rafael , Escala M. Carmen 
Published: June 2007

AbstractScales of eight common European cyprinid species were studied. Six scales were extracted from each specimen from three predetermined body areas. The main differences among the species' scales were described. Maximum and minimum lateral radius and maximum length were measured, and the number of radii noted. The relationships between standard length and scale measurements were best described by power functions, and maximum length showed the best fit in most of the analyzed cases. Scales from different body areas showed significant differences in body length estimates. The number of radii increased with age in all species, except for goldfish Carassius auratus, roach Rutilus rutilus, and rudd Scardinius erythrophthalmus. This number might be related to the general activity of the fish or to environmental conditions. Much information can be obtained from scales, but it should be interpreted with care. Detailed and precise scale studies are needed for diet analyses and piscivorous impact evaluation.
Malignant Transformation of Multipotent Muscle-Derived Cells by Concurrent Differentiation Signals
Authors: Pollett Jonathan B. , Corsi Karin A. , Weiss Kurt R. , Cooper Gregory M. , Barry Denise A. , Gharaibeh Burhan , Huard Johnny 
Published: June 2007

Abstract
Recent studies have shown that germ-line determination occurs early in development and that extracellular signaling can alter this fate. This denial of a cell's fate by counteracting its intrinsic signaling pathways through extrinsic stimulation is believed to be associated with oncogenesis. Using specific populations of multipotent skeletal muscle-derived stem cells (MDSCs), we have been able to generate tumors by subjecting cells with specific lineage predilections to concomitant differentiation signals. More specifically, when a stem cell that had a predilection toward osteogenesis was implanted into a skeletal muscle, tumors formed in 25% of implanted mice. When cells predilected to undergo myogenesis were pretreated with bone morphogenetic protein 4 (BMP4) for 4 days prior to implantation, they formed tumors in 25% of mice. These same myogenic predilected cells, when transduced to express BMP4 and implanted into either a long-bone or cranial defect, formed bone, but they formed tumors in 100% of mice when implanted into the skeletal muscle. The tumors generated in this latter study were serially transplantable as long as they retained BMP4 expression. Furthermore, when we impeded the ability of the cells to undergo myogenic differentiation using small interfering RNA to the myogenic regulator MyoD1, we stopped transformation. Based on our findings, we postulate that specific MDSC populations can undergo concomitant signal-induced transformation and that the initial stages of transformation may be due to changes in the balance between the inherent nature of the cell and extrinsic signaling pathways. This theory represents a potential link between somatic stem cells and cancer and suggests an involvement of the niche/environment in transformation.
Disclosure of potential conflicts of interest is found at the end of this article.
Timing and Expression Level of Protein Kinase Cε Regulate the Megakaryocytic Differentiation of Human CD34 Cells
Authors: Gobbi Giuliana , Mirandola Prisco , Sponzilli Ivonne , Micheloni Cristina , Malinverno Chiara , Cocco Lucio , Vitale Marco 
Published: June 2007

Abstract
Protein kinase C (PKC)-mediated intracellular signaling participates in several key steps of hematopoietic cell differentiation. The ε isoform of PKC has been associated with erythroid differentiation as well as with the early phases of megakaryocytic (MK) lineage commitment. Here, we worked on the hypothesis that PKCε expression levels might be modulated during MK differentiation, with a specific role in the early as well as in the late phases of thrombopoiesis. We demonstrate that—at variance with the erythroid lineage development—PKCε is completely downmodulated in TPO-induced CD34 cells from day 6 onward. The forced expression of PKCε in the late phases of MK differentiation delays the phenotypic differentiation of progenitors likely via Bcl-xL upregulation. Moreover, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), known as a negative regulator of early erythroid expansion, is not apoptogenic for thrombopoietin-induced CD34 cells, but rather accelerates their maturation. However, PKCε levels negatively interfere also with the effects of TRAIL in MK differentiation. PKCε can therefore be considered a signaling intermediate whose expression levels are finely tuned, with a virtually opposite kinetic, in erythroid versus megakaryocytic lineages, to adequately respond to the signaling requirements of the specific hematopoietic lineage.
Disclosure of potential conflicts of interest is found at the end of this article.
Novel Extracellular Matrix Structures in the Neural Stem Cell Niche Capture the Neurogenic Factor Fibroblast Growth Factor 2 from the Extracellular Milieu
Authors: Kerever Aurelien , Schnack Jason , Vellinga Dirk , Ichikawa Naoki , Moon Chris , Arikawa-Hirasawa Eri , Efird Jimmy T. , Mercier Frederic 
Published: June 2007

AbstractThe novel extracellular matrix structures called fractones are found in the lateral ventricle walls, the principal adult brain stem cell niche. By electron microscopy, fractones were shown to contact neural stem and progenitor cells (NSPC), suggesting a role in neurogenesis. Here, we investigated spatial relationships between proliferating NSPC and fractones and identified basic components and the first function of fractones. Using bromodeoxyuridine (BrdU) for birth-dating cells in the adult mouse lateral ventricle wall, we found most mitotic cells next to fractones, although some cells emerged next to capillaries. Like capillary basement membranes, fractones were immunoreactive for laminin β1 and γ1, collagen IV, nidogen, and perlecan, but not laminin-α1, in the adult rat, mouse, and human. Intriguingly, N-sulfate heparan sulfate proteoglycan (HSPG) immunoreactivity was restricted to fractone subpopulations and infrequent subependymal capillaries. Double immunolabel for BrdU and N-sulfate HSPG revealed preferential mitosis next to N-sulfate HSPG immunoreactive fractones. To determine whether N sulfate HSPG immunoreactivity within fractones reflects a potential for binding neurogenic growth factors, we identified biotinylated fibroblast growth factor 2 (FGF-2) binding sites in situ on frozen sections, and in vivo after intracerebroventricular injection of biotinylated FGF-2 in the adult rat or mouse. Both binding assays revealed biotinylated FGF-2 on fractone subpopulations and on infrequent subependymal capillaries. The binding of biotinylated FGF-2 was specific and dependent upon HSPG, as demonstrated in vitro and in vivo by inhibition with heparatinase and by the concomitant disappearance of N-sulfate HSPG immunoreactivity. These results strongly suggest that fractones promote growth factor activity in the neural stem cell niche.Disclosure of potential conflicts of interest is found at the end of this article.
Expression of the p16INK4A Gene Is Associated Closely with Senescence of Human Mesenchymal Stem Cells and Is Potentially Silenced by DNA Methylation During In Vitro Expansion
Authors: Shibata Kotaro R. , Aoyama Tomoki , Shima Yasuko , Fukiage Kenichi , Otsuka Seiji , Furu Moritoshi , Kohno Yoshiki , Ito Kinya , Fujibayashi Shunsuke , Neo Masashi , Nakayama Tomitaka , Nakamura Takashi , Toguchida Junya 
Published: June 2007

Abstract
The precise biological characteristics of human mesenchymal stem cells (hMSCs), including growth regulatory mechanisms, have not yet been defined. Using 29 strains of hMSCs isolated from bone marrow, we have performed extensive analyses of the growth profiles of hMSCs in vitro. All 29 strains stopped proliferating with a mean population doubling (PD) of 28, although there was a considerable difference among strains. The mean telomere restriction fragment length of the cells passaged twice correlated well with the final number of PDs in each strain, suggesting the value of this measurement to be predictive of the growth potential of hMSCs. The expression level of the p16INK4A gene was associated closely with the PD number of each strain (p = .00000001). Most of the p16INK4A-positive cells were Ki67-negative and senescence associated β-galactosidase-positive, and the suppression of p16INK4A gene expression by small interfering RNA in senescent hMSCs reduced the number of senescent cells and endowed them with the ability to proliferate. Twenty-five of the 29 strains showed a steady gradual increase in the expression of p16INK4A. The remaining four strains (13.8%) showed different profiles, in which DNA methylation in the promoter region occurred in vitro. One of the four strains continued to proliferate for much longer than the others and showed chromosomal aberrations in the later stages. These results indicated p16INK4A to be a key factor in the regulation of hMSC growth, and, most importantly, careful monitoring of DNA methylation should be considered during the culture of hMSCs, particularly when a prolonged and extended propagation is required.
Disclosure of potential conflicts of interest is found at the end of this article.
Disruption of Apical-Basal Polarity of Human Embryonic Stem Cells Enhances Hematoendothelial Differentiation
Authors: Krtolica Ana , Genbacev Olga , Escobedo Carmen , Zdravkovic Tamara , Nordstrom Adam , Vabuena Diana , Nath Aneel , Simon Carlos , Mostov Keith , Fisher Susan J. 
Published: June 2007

Abstract
During murine development, the formation of tight junctions and acquisition of polarity are associated with allocation of the blastomeres on the outer surface of the embryo to the trophoblast lineage, whereas the absence of polarization directs cells to the inner cell mass. Here, we report the results of ultrastructural analyses that suggest a similar link between polarization and cell fate in human embryos. In contrast, the five human embryonic stem cell (hESC) lines displayed apical-basal, epithelial-type polarity with electron-dense tight junctions, apical microvilli, and asymmetric distribution of organelles. Consistent with these findings, molecules that are components of tight junctions or play regulatory roles in polarization localized to the apical regions of the hESCs at sites of cell-cell contact. The tight junctions were functional, as shown by the ability of hESC colonies to exclude the pericellular passage of a biotin compound. Depolarization of hESCs produced multilayered aggregates of rapidly proliferating cells that continued to express transcription factors that are required for pluripotency at the same level as control cells. However, during embryoid body formation, depolarized cells differentiated predominantly along mesenchymal lineage and spontaneously produced hematoendothelial precursors more efficiently than control ESC. Our findings have numerous implications with regard to strategies for deriving, propagating, and differentiating hESC.
Disclosure of potential conflicts of interest is found at the end of this article.
Adaptive Multiscale Finite-Volume Framework for Reservoir Simulation
Authors: Tchelepi H. A. , Jenny P. , Lee S. H. , Wolfsteiner C. 
Published: June 2007

Summary
A multiscale finite-volume (MSFV) framework for reservoir simulation is described. This adaptive MSFV formulation is locally conservative and yields accurate results of both flow and transport in large-scale highly heterogeneous reservoir models. IMPES and sequential implicit formulations are described. The algorithms are sensitive to the specific characteristics of flow (i.e., pressure and total velocity) and transport (i.e., saturation). To compute the fine-scale flow field, two sets of basis functions - dual and primal - are constructed. The dual basis functions, which are associated with the dual coarse grid, are used to calculate the coarse scale transmissi-bilities. The fine-scale pressure field is computed from the coarse grid pressure via superposition of the dual basis functions. Having a locally conservative fine scale velocity field is essential for accurate solution of the saturation equations (i.e., transport). The primal basis functions, which are associated with the primal coarse grid, are constructed for that purpose. The dual basis functions serve as boundary conditions to the primal basis functions. To resolve the fine scale flow field in and around wells, a special well basis function is devised. As with the other basis functions, we ensure that the support for the well basis is local.
Our MSFV framework is designed for adaptive computation of both flow and transport in the course of a simulation run. Adaptive computation of the flow field is based on the time change of the total mobility field, which triggers the selective updating of basis functions. The key to achieving scalable (efficient for large problems) adaptive computation of flow and transport is the use of high fidelity basis functions with local support. We demonstrate the robustness and computational efficiency of the MSFV simulator using a variety of large heterogeneous reservoir models, including the SPE 10 comparative solution problem.
Fast Estimation of Connectivity in Fractured Reservoirs Using Percolation Theory
Authors: Masihi M. , King P. R. , Nurafza P. 
Published: June 2007

Summary
Investigating the impact of geological uncertainty (i.e., spatial distribution of fractures) on reservoir performance may aid management decisions. The conventional approach to address this is to build a number of possible reservoir models, upscale them, and then run flow simulations. The problem with this approach is that it is computationally very expensive. In this study, we use another approach based on the permeability contrasts that control the flow, called percolation approach. This assumes that the permeability disorder of a rock can be simplified to either permeable or impermeable. The advantage is that by using some universal laws from percolation theory, the effect of the complex geometry which influences the global properties (e.g., connectivity or conductivity) can be easily estimated in a fraction of a second on a spreadsheet.
The aim of this contribution is to establish the percolation framework to examine the connectivity of fracture systems at a given finite observation scale in 2D and 3D. In particular, we use numerical simulation to show how the scaling laws of the connectivity derived originally for constant-length isotropic systems can be expanded to cover more realistic cases including fracture systems with anisotropy and fracture-length distribution. Finally, the outcrop data of mineralized fractures exposed on the southern margin of the Bristol Channel Basin was used to show that the predictions from the percolation approach are in agreement with the results calculated from field data but can be obtained very quickly. As a result, this may be used for practical engineering purposes for decision making.
Streamline Tracing on General Triangular or Quadrilateral Grids
Authors: Matringe Sébastien F. , Juanes Ruben , Tchelepi Hamdi A. 
Published: June 2007

Summary
Streamline methods have received renewed interest over the past decade as an attractive alternative to traditional finite-difference (FD) simulation. They have been applied successfully to a wide range of problems including production optimization, history matching, and upscaling. Streamline methods are also being extended to provide an efficient and accurate tool for compositional reservoir simulation. One of the key components in a streamline method is the streamline tracing algorithm. Traditionally, stream-lines have been traced on regular Cartesian grids using Pollock's method. Several extensions to distorted or unstructured rectangular, triangular, and polygonal grids have been proposed. All of these formulations are, however, low-order schemes.
Here, we propose a unified formulation for high-order stream-line tracing on unstructured quadrilateral and triangular grids, based on the use of the stream function. Starting from the theory of mixed finite-element methods (FEMs), we identify several classes of velocity spaces that induce a stream function and are therefore suitable for streamline tracing. In doing so, we provide a theoretical justification for the low-order methods currently in use, and we show how to extend them to achieve high-order accuracy. Consequently, our streamline tracing algorithm is semi-analytical: within each gridblock, the streamline is traced exactly. We give a detailed description of the implementation of the algorithm, and we provide a comparison of low- and high-order tracing methods by means of representative numerical simulations on 2D heterogeneous media.
Carbon Dioxide Foam Rheology in Porous Media: A CT Scan Study
Authors: Du Dongxing , Zitha Pacelli L. J. , Uijttenhout Matthijs G. H. 
Published: June 2007

Summary
Carbon dioxide (CO2) foam has been widely studied in connection with its application in enhanced oil recovery (EOR). This paper reports an experimental study concerning CO2 foam propagation in a surfactant-saturated Bentheim sandstone core and the subsequent liquid injection with the aid of X-ray computed tomography (CT). The experiments were carried out under various system backpressures. It is found that CO2 foam flows in a characteristic front-like manner in the transient stage and that the water saturation keeps at relatively high level at the outlet of the porous media because of CO2 solubility and capillary end effect. The subsequent surfactant solution injection shows a significant fingering behavior, accompanied by a low flow resistance over the core. It is also found that CO2 foam flow shows higher liquid saturation near the outlet and lower pressure drops under higher system backpressures. This can be attributed to the solubility of CO2 in the liquid phase. The results indicate the advantage of using foam in EOR processes such as water alternating foam (WAF), in which foam flow has higher sweep efficiency and stronger mobility control ability compared, for instance, to water alternating gas (WAG). Nevertheless, care should be taken during the water-injection stage in order not to favor the fingering.
Bestandesdynamik zentralalpiner Waldföhrenwälder aufgezeigt anhand dendroökologischer Fallstudien aus dem Wallis, Schweiz | Stand dynamics of central alpine Scots pine using dendroecological case studies from Valais, Switzerland
Authors: Rigling Andreas , Weber Pascale , Cherubini Paolo , Dobbertin Matthias 
Published: June 2007

The aim of this paper is to demonstrate the use of dendroecological methods to analyse the various processes involved in forest dynamics. Using dendroecological case studies of the Scots pine forests of Valais (Switzerland) as an example we discuss the most relevant processes of forest dynamics and their consequences on stand structures and mortality rates. We focus on the development history of these Scots pine forests under human impact and on the impact of biotic and abiotic factors on tree growth.Most of today's extended Scots pine forests (&lt; 1500 m a.s.l.)must be interpreted as part of an ongoing natural succession under heavy human influence. In time, without management or natural disturbances, most of these pine forests will develop into broadleaved forests (lower altitudes) or spruce-firforests(higher altitudes).
Extraction, Liquid‐Liquid
Authors: Stevens G. W. , Lo Teh C. , Baird Malcolm H. I. 
Published: June 2007

AbstractLiquid–liquid extraction, also known as solvent extracting, is a well‐established separation technique that depends on the unequal distribution of a solute between two immiscible liquids. The initial feed liquid containing the solute is brought into contact with a solvent that is selected to have a greater affinity for the solute. The partition of the solute can be enhanced by adding a chemical extractant to the solvent; this practice is widespread in the hydrometallurgical and nuclear industries. Most industrial extractors operate continuously with countercurrent flow of the two phases. In mixer–settlers, the phases are contacted as a well‐agitated dispersion of drops, which are then sent to settling tanks for phase disengagement. In extraction columns, the dispersed drops move countercurrently against the flow of the second (continuous) phase. The physics, chemistry, and practice of extraction, with brief descriptions of important industrial extraction processes and equipment, are presented. Research on hydrodynamic aspects of process design, eg, axial mixing, drop dispersion, and coalescence, is reviewed. New extraction techniques, eg, membrane extraction, supercritical exctraction, and two‐phase aqueous extraction, are discussed.
Web Browsers
Authors: Marimuthu Ramesh , Agrawal M. , Rao H. Raghav , Salam A. F. 
Published: June 2007

Abstract
A browser is an application that allows people to view Web pages on the World Wide Web (a term first coined by Tim Berners‐Lee of CERN, Geneva), or at a local area network. The first browser, called Mosaic, was developed in 1993 at the University of Illinois, by Marc Andreessen—now at Netscape Communications Corp.—and others. This development resulted in an explosion of the popularity of the Web, and as interest mounted, other software developers created more advanced browsers. In addition to reading text, people using the latest browsers can watch video, listen to audio, and run various other applications.
This article is organized as follows: The next section discusses the Web browser technology. We then focus on alternative browsers, mobile browsers, and browsers for disabled people. The following section takes a look at communication and information exchange. Then, various business models of electronic commerce are discussed. The next section touches on the issue of security. Finally, the last section summarizes issues that are at the frontiers of WWW research.

Introduction

Internet and the World Wide Web (
WWW
)

Alternative Browsers

Communication and Information Exchange

Electronic Commerce

Security

Research Issues

Conclusion
Network Design: Algorithms and Examples
Authors: Somani Arun K. 
Published: June 2007

AbstractThis article addresses the issues in data network design. We discuss graph models for network, issues in topology design and optimization, link and node capacity assignment, path search Algorithms, and network flow assignments. The network can support point‐to‐point packet‐switched, connection‐oriented circuit‐switched, virtual circuit‐switched connections. We also address performance issues such as blocking probability, throughput, and delay and how to account for them in the design of a network. The issue of fault tolerance in network design is also examined. The design is explained using a context of wavelength division multiplexed (WDM) fiber‐optic network.Although Estrin‐first proposed the idea of a reconfigurable system in the form of a fixed plus variable structure computer in 1960it has only been in recent years that reconfigurable fabrics have reached sufficient density to make them a compelling implementation platform for high Performance applications and embedded systems. In this article, intended for the non‐specialist, we describe some of the basic concepts, tools and architectures associated with reconfigurable computing.