bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic Models of Complex Biochemical Reactions and Biological Processes
Authors: Peleg M. , Corradini M. G. , Normand M. D. 
Published: March 2004

AbstractThe momentary rate of complex biochemical reactions and biological processes may depend not only on temperature (or an equivalent factor like pH or moisture contents) but also on the system's momentary state. Also, complex reactions and processes need not have a single ‘energy of activation’ and their ‘kinetic order’ is not always clearly defined. Thus, the progress of such a reaction or process is governed by time dependent kinetics whose description requires a departure from the traditional models, which are based on an analogy to simple chemical reactions. A general model that takes these considerations into account is demonstrated with simulated biochemical reactions under monotonic temperature increase and decrease and under regular and irregular temperature fluctuations. Its potential application to microbial growth and growth followed by decay is also demonstrated. The model is in the form of a cumbersome differential equation, which, nevertheless, can be solved by standard mathematical software. In certain cases, the same software can also be used to determine the process's basic kinetic parameters, and their temperature dependence, from experimental data obtained under non‐isothermal conditions. This could simplify the study of fast reactions and processes, where shortening the come up and cooling times to insignificance, as required by the traditional isothermal analyses, is not a viable option.
Methoden zur Beurteilung des Befeuchtungs‐ und Dispergierverhaltens von Pulvern
Authors: Hogekamp S. , Pohl M. 
Published: March 2004

AbstractPulverförmige Produkte müssen in den meisten Fällen vor ihrer endgültigen Verwendung wieder in einer Flüssigkeit dispergiert werden. Idealerweise erlaubt ein Pulver das schnelle Eindringen von Flüssigkeit, sinkt bei Aufgeben auf eine Flüssigkeitsoberfläche schnell ein und kann mit geringem Aufwand dispergiert werden. Reale Pulver zeigen derartig ideales Verhalten häufig nicht, so dass Messverfahren zur Kontrolle ihrer Eigenschaften erforderlich sind. In diesem Artikel werden Verfahren zur Beurteilung des Befeuchtungs‐ und Dispergierverhaltens vorgestellt. Einfache Methoden zur Bestimmung des Befeuchtungsver‐haltens eignen sich vorzugsweise für die Qualitätskontrolle von Produkten. Aufwändigere Verfahren erlauben einen besseren Einblick in das Verhalten eines Produkts und die Bestimmung von Stoffeigenschaften. Die Beschreibung des Dispergierverhaltens eines Produkts erfordert den höchsten experimentellen Aufwand.
Emulgieren: Mehr als nur Zerkleinern
Authors: Schuchmann H. P. , Danner T. 
Published: March 2004

AbstractEmulsionen begleiten uns als industrielle Zwischenprodukte oder formulierte Produkte für Endverbraucher durch das tägliche Leben. Mikrostrukturell sind Emulsionen disperse Mehrphasensysteme aus mindestens zwei nahezu ineinander unlöslichen Flüssigkeiten. Zur Produktgestaltung müssen Eigenschafts‐ und Prozessfunktionen bekannt sein. In diesem Übersichtsartikel werden die Grundlagen des Emulgierens mit den Teilschritten Tropfenzerkleinerung und Koaleszenz dargestellt, typische Emulgiermaschinen und ‐apparate beschrieben sowie Prozess‐ und Eigenschaftsfunktionen aufgezeigt. Neben praxisrelevanten typischen Anwendungen des Emulgierens wird auch alternativ der Einsatz eines Emulgierschrittes zur Herstellung von feinsten Feststoffen mit modifizierten Produkteigenschaften diskutiert.
Loss of Gli3 and Shh function disrupts olfactory axon trajectories
Authors: Balmer Curtis William , LaMantia Anthony‐Samuel 
Published: March 2004

AbstractThe transcriptional regulator Gli3 and the secreted signal Shh influence induction, patterning, and differentiation at several sites of mesenchymal/epithelial (M/E) interaction including the limbs, heart, face, and forebrain. We asked whether loss of function of these two genes has specific consequences for early differentiation of the primary olfactory pathway—which comprises both craniofacial and forebrain structures and depends on M/E induction during initial stages of development. Loss of Gli3 or Shh function does not compromise several aspects of olfactory receptor neuron (ORN) and olfactory ensheathing cell maturation; however, directed outgrowth of ORN axons and their initial targeting to the telencephalon is altered. In Gli3 mutant extra toes‐Jackson (XtJXtJ) embryos, ORN axons defasciculate and project aberrantly near the forebrain. They rarely enter the central nervous system, and their association with mesenchymal laminin is disrupted. In Shh−/−embryos, ORN axons exit a single olfactory epithelium (OE) that develops centrally within an altered mesenchymal environment in a dysmorphic proboscis. These axons project as a single nerve toward the mutant forebrain; however, their trajectory varies according to the position of the proboscis relative to the forebrain. These alterations in axon outgrowth probably reflect compromised inductive interactions in the olfactory primordia because neither Gli3 nor Shh are expressed in olfactory neurons. Thus, two genes that influence induction and subsequent differentiation of craniofacial structures and the forebrain have distinct consequences for ORN axon growth during the initial genesis of the olfactory pathway. J. Comp. Neurol. 472:292–307, 2004. © 2004 Wiley‐Liss, Inc.
Effects of prolonged exposure to an augmented acoustic environment on the auditory system of middle‐aged C57BL/6J mice: Cochlear and central histology and sex differences
Authors: Willott James F. , Bross Lori 
Published: March 2004

AbstractGenetic progressive sensorineural hearing loss in mice of the C57BL/6J (B6) inbred strain begins at high frequencies during young adulthood and is severe by 12 months (middle age). Nightly treatment with an augmented acoustic environment (AAE)—12‐hour periods of exposure to repetitive noise bursts of moderate intensity, begun at age 25 days—resulted in less severe hearing loss compared with control mice. Cochlear histopathological correlates of AAE treatment, assessed at 12–14 months of age, included lessened severity of progressive loss of outer hair cells in both sexes as well as small savings of spiral ganglion cells in females and inner hair cells in males. AAE effects on the number of surviving neurons (age 12–14 months) in the anterior ventral cochlear nucleus (AVCN) depended on sex. Compared with controls, the loss of AVCN neurons that typically accompanies the initial period of hearing loss (between 2 and 7 months of age) was not significantly affected by AAE treatment in females. In contrast, males treated with the AAE exhibited more severe loss of neurons in the dorsal and ventral extremes of the AVCN than male controls of the same age. AAE treatment begun at age 3–5 months resulted in significant but less severe loss of AVCN neurons in 1‐year‐old male mice. J. Comp. Neurol. 472:358–370, 2004. © 2004 Wiley‐Liss, Inc.
Development of oculomotor axon projections in the chick embryo
Authors: Chilton John Kevin , Guthrie Sarah 
Published: March 2004

AbstractThe pattern of innervation of the extraocular muscles is highly conserved across higher vertebrate species and mediates sophisticated visuomotor processes. Defects in oculomotor development often lead to strabismus, a misalignment of the eyes that can cause partial blindness. Although it has been intensively studied from a clinical perspective, relatively little is known about how the system develops embryonically. We have therefore mapped the development of the oculomotor nerve (OMN) in chick embryos by using confocal microscopy. We show that OMN development follows a series of stereotyped steps that are tightly regulated in space and time. The OMN initially grows past three of its targets to innervate its distal target, the ventral oblique muscle, only later forming branches to the more proximal muscles. We have also investigated spatiotemporal aspects of the unusual contralateral migration of a subpopulation of oculomotor neurons by using molecular markers and have found the semaphorin axon guidance molecules and their receptors, the neuropilins, to be expressed in discrete subnuclei during this migration. Finally, we have created an embryological model of Duane retraction syndrome (DRS), a form of strabismus in which the OMN is believed to innervate aberrantly the lateral rectus, the normal target of the abducens nerve. By ablating rhombomeres 5 and 6 and hence the abducens, we have mimicked a proposed oculomotor deficit occurring in DRS. We find that the absence of the abducens nerve is not sufficient to produce this inappropriate innervation, so other factors are required to explain DRS. J. Comp. Neurol. 472:308–317, 2004. © 2004 Wiley‐Liss, Inc.
Perirhinal and parahippocampal cortices of the macaque monkey: Intrinsic projections and interconnections
Authors: Lavenex Pierre , Suzuki Wendy A. , Amaral David G. 
Published: March 2004

AbstractWe investigated the topographic and laminar organization of the intrinsic projections and interconnections of the macaque monkey perirhinal and parahippocampal cortices. Discrete anterograde tracer injections placed at various rostrocaudal and mediolateral levels in these cortices revealed extensive associational connections both within and between the perirhinal and parahippocampal cortices. Areas 35, 36rm, 36rl, 36cm, and 36cl are highly interconnected, whereas area 36d (encompassing the dorsal portion of the medial temporal pole) shares only modest connections with the rest of the perirhinal cortex. Areas TH, TFm, and TFl of the parahippocampal cortex also share an extensive network of associational connections that tend to be heaviest within a given subdivision. Area 36c of the perirhinal cortex is the main interface between the perirhinal and parahippocampal cortices. Its heaviest connections are with area 36r and the anterior aspect of area TF. The laminar organization of all these connections is typical of associational projections. Anterograde tracer experiments revealed that these projections are distributed through both deep and superficial layers, although heavier projections are directed toward the superficial layers. Results of retrograde tracer experiments suggested that the projections from caudal areas (36c or TF) to area 36r are of the feedforward type, whereas the projections from areas 36r and 36c to area TF are of the feedback type. These findings suggest that the perirhinal cortex is at a higher level than the parahippocampal cortex in the hierarchy of associational cortices. We discuss the functional implications of the organization of these extensive networks of intrinsic, associational projections. J. Comp. Neurol. 472:371–394, 2004. © 2004 Wiley‐Liss, Inc.
Grids of agents for computer and telecommunication network management
Authors: Assunção M. D. , Koch F. L. , Westphall C. B. 
Published: March 2004

AbstractThe centralized system approach for computer and telecommunication network management has been presenting scalability problems along with the growth in the amount and diversity of managed equipment. Moreover, the increase in complexity of the services being offered through the networks also contributes to adding extra workload to the management station. The amount of data that must be handled and processed by only one administration point could lead to a situation where there is not enough processing and storage power to carry out an efficient job. In this work we present an alternative approach by creating a highly distributed computing environment through the use of Grids of autonomous agents to analyze large amounts of data, which reduce the processing costs by optimizing the load distribution and resource utilization. Copyright © 2004 John Wiley & Sons, Ltd.
Applying the reflective middleware approach in Grid computing
Authors: Coulson Geoff , Blair Gordon , Parlavantzas Nikos , Yeung Wai Kit , Cai Wei 
Published: March 2004

AbstractSignificant progress has been made in the design and development of object‐based distributed systems and, more recently, in component‐based reflective middleware platforms—i.e. middleware platforms that, through reflection, can be flexibly configured, and runtime adapted/reconfigured—especially in terms of non‐functional properties like quality of service (QoS). In this paper we consider how ideas and principles from such platforms can usefully be applied in a Grid context, specifically, an Open Grid Services Architecture (OGSA) context. To this end, we identify weaknesses in OGSA in the areas of generic service provision, scalability/performance engineering, and, especially, lack of support for QoS specification and realization, and suggest how these can be alleviated. We believe that such areas will become increasingly important as sophisticated e‐Science applications start to exploit the potential of OGSA's service‐based architecture. We also report on our current research on developing a binding‐type framework, a resource management framework, and a set of performance optimizations for an ongoing OGSA implementation we are working on. Copyright © 2004 John Wiley & Sons, Ltd.
A resource management framework for interactive Grids
Authors: Kumar Raj , Talwar Vanish , Basu Sujoy 
Published: March 2004

AbstractTraditional use of Grid computing systems has been for batch jobs in the scientific and academic computing. We envision the next generation Grid computing systems to support graphical interactive sessions. In this paper, we propose a resource management framework for supporting graphical interactive sessions in a Grid computing system. We describe the high‐level architectural resource management framework distributed among the submission node, central scheduler node, and the execution node. We then describe in detail the resource management framework on the execution node. The description of the resource management framework on the scheduler node is kept at a high level in this paper. The framework on execution nodes consists of Resource Management Agents, an Admission Control system and Application Predictor system. The agents on the execution node are Startup Agents, Sensor Agents, Monitoring Agents, Aggregator Agents, Enforcement Agents and Registration Agents. The Session Admission Control system is responsible for determining if a new application session can be admitted to the execution node. An Application Predictor system is responsible for predicting the resource utilization behavior of applications based on data obtained from the Resource Management Agents. The proposed framework allows for implementation of a scalable and extensible middleware for interactive Grid resource management. It supports fine‐grained performance guarantees specified in service level agreements and brings forth some important and novel contributions to enable graphical interactive sessions on Grids. Copyright © 2004 John Wiley & Sons, Ltd.
GridSphere: a portal framework for building collaborations
Authors: Novotny Jason , Russell Michael , Wehrens Oliver 
Published: March 2004

AbstractGrid‐enabled portals are becoming increasingly popular as a platform for providing access to Grid services and resources. Unfortunately, much of the work done in portal development has led to vertically layered solutions that work for a particular project but are difficult to extend or reuse for other projects. The GridSphere portal framework seeks to address these limitations by providing a framework that will offer external developers a model for easily adding new functionality and hence increasing community collaboration. The GridLab portal will serve as an initial prototype to showcase the GridSphere framework and provide access to services being developed within the GridLab project. Copyright © 2004 John Wiley & Sons, Ltd.
Activation of nestin‐positive duct stem (NPDS) cells in pancreas upon neogenic motivation and possible cytodifferentiation into insulin‐secreting cells from NPDS cells
Authors: Kim So‐Yoon , Lee Seung‐Hee , Kim Byeong‐Moo , Kim Eun‐Ho , Min Bon‐Hong , Bendayan M. , Park In‐Sun 
Published: March 2004

AbstractStem cells in adult pancreas and their specific marker are poorly characterized. We hypothesized that pancreatic stem cells could evolve from the duct system in response to neogenic stimulation and may transiently express nestin during tissue regeneration. After partial pancreatectomy (Px), we found extensive formation of ductules consisting of nestin‐positive epithelial cells with higher replicating ability in the neogenic foci, particularly at day 3 after Px. Nestin was highly expressed in the earlier stages of ductule morphogenesis and then regressed as the cells evolved toward differentiated pancreatic cell types. The neogenic ductules were isolated for the culture of nestin‐positive duct stem cells. These nestin‐positive duct cells were numerous and displayed extensive self‐replication in the duct cell explants after 2–3 days of culture, thus depicted as nestin‐positive duct stem (NPDS) cells. As seen in the tissue of neogenic foci, NPDS cells were negative for cytokeratin‐20 and vimentin, the marker for duct epithelial and mesenchymal cells, respectively. Endocrine cells, mostly insulin cells, were present in the explants at day 2 as single cells or as small clusters adjacent to the NPDS cells, and formed islet‐like masses at day 3 of culture, suggesting islet cell differentiation from NPDS cells. In addition, insulin secretion from these beta cells responded to glucose stimulation. We found transient up‐regulation of PDX‐1 expression by reverse transcriptase‐polymerase chain reaction at day 3 after Px in pancreatic tissue. Higher expression of PDX‐1 was seen in the culture of neogenic ductules than that of ducts isolated from the sham‐operated pancreas. In particular, a subpopulation of nestin‐positive cells in the duct cell explants formed from the neogenic ductules expressed PDX‐1 in their nuclei. Taken together, this information suggests that NPDS cells could be generated from adult pancreas by neogenic motivations and they may differentiate into insulin‐secreting cells. Developmental Dynamics 230:1–11, 2004. © 2004 Wiley‐Liss, Inc.
VEGF coordinates interaction of pericytes and endothelial cells during vasculogenesis and experimental angiogenesis
Authors: Hagedorn Martin , Balke Maurice , Schmidt Annette , Bloch Wilhelm , Kurz Haymo , Javerzat Sophie , Rousseau Benoît , Wilting Joerg , Bikfalvi Andreas 
Published: March 2004

AbstractBiological activities of vascular endothelial growth factor (VEGF) have been studied extensively in endothelial cells (ECs), but few data are available regarding its effects on pericytes. In murine embryoid body cultures, VEGF‐induced expression of desmin and α‐smooth muscle actin (α‐SMA) in CD‐31+ cells. The number of CD‐31+/desmin+ vascular chords increased with VEGF treatment time and peaked during a differentiation window between 6 and 9 days after plating. In vivo, VEGF‐induced elongation and migration of desmin‐positive pericytes and coverage of angiogenic capillaries, as revealed by analysis of Sambucus nigra lectin‐stained vascular beds of the chick chorioallantoic membrane. VEGF also caused significant decrease of intercapillary spaces, an indicator for intussusceptive vascular growth. These VEGF‐mediated effects point at a more intricate interaction between ECs and pericytes cells than previously demonstrated and suggest that pericytes may be derived from EC progenitors in vitro and not only stabilize capillaries but also participate in vascular remodeling in vivo. Developmental Dynamics 230:23–33, 2004. © 2004 Wiley‐Liss, Inc.
Formation and remodeling of the coronary vascular bed in the embryonic avian heart
Authors: Kattan Javier , Dettman Robert W. , Bristow James 
Published: March 2004

AbstractTo study the formation of the coronary vessels in the developing avian heart, we stained developmentally staged quail hearts with the endothelial specific antibody QH‐1. QH‐1 reacted with individual cells in the proepicardial organ in Hamburger and Hamilton stage (HH) 17 embryos only after it had contacted the heart. In HH18–26 hearts, individual QH‐1+ cells accumulated over the surface of the atria and ventricles. The first endothelial vessels appeared in the dorsal atrioventricular groove in HH23 hearts. CD45+ hematopoietic precursors accumulated on the heart surface, demonstrating the close temporal relationship of hematopoiesis with vasculogenesis during heart development. However, CD45 expression preceded association of these cells with the vasculature, suggesting hematopoietic commitment precedes formation of blood islands in the coronary vasculature. Endothelial tubules first appeared on the dorsal and then the ventral aspects of the heart, coalescing into large sinusoids. These sinusoids remodeled into compact muscularized vessels by HH35. Smooth muscle cell markers were first expressed at HH27 and only in association with developing vasculature. We did not observe markers of smooth muscle differentiation in the proepicardium, but it remains uncertain whether cells in the proepicardium are committed to this cell fate. Our data support a strictly vasculogenic mechanism for the formation of the coronary vessels and blood islands. Developmental Dynamics 230:34–43, 2004. © 2004 Wiley‐Liss, Inc.
Regulatory analysis of the mouseFgf3gene: Control of embryonic expression patterns and dependence upon sonic hedgehog (Shh) signalling
Authors: Powles Nicola , Marshall Heather , Economou Androulla , Chiang Chin , Murakami Akira , Dickson Clive , Krumlauf Robb , Maconochie Mark 
Published: March 2004

AbstractFgf3displays a dynamic and complex expression pattern during mouse embryogenesis. To address the molecular mechanisms underlyingFgf3expression, we used a transgenic approach to assay genomic regions from the mouseFgf3gene for regulatory activity. We identified an enhancer that mediates major components of embryonic expression, governing expression in the midbrain, hindbrain, surface ectoderm, dorsal roots and dorsal root ganglia (DRG), proximal sensory ganglia, and the developing central nervous system (CNS). Deletional analysis of the enhancer further delimited this regulatory activity to a 5.7‐kb fragment. We have also revealed sonic hedgehog (Shh) ‐dependent and Shh‐independent aspects ofFgf3expression through breeding theFgf3reporter transgene intoShhmutants. In the absence of Shh signalling,Fgf3reporter expression is lost in the ventral CNS, DRG, and superior cervical nerves, whereas activation of reporter expression in cranial ganglion cells is Shh independent. Moreover, detailed re‐examination of theShhphenotype revealed that Shh signalling is required for the correct development/maturation of the DRG. Developmental Dynamics 230:44–56, 2004. © 2004 Wiley‐Liss, Inc.
Use of fluorescent dextran conjugates as a long‐term marker of osteogenic neural crest in frogs
Authors: Gross Joshua B. , Hanken James 
Published: March 2004

AbstractThe neural crest is a population of multipotent stem cells unique to vertebrates. In the head, cranial neural crest (CNC) cells make an assortment of differentiated cell types and tissues, including neurons, melanocytes, cartilage, and bone. The earliest understanding of the developmental potentiality of CNC cells came from classic studies using amphibian embryos. Fate maps generated from these studies have been largely validated in recent years. However, a fate map for the most late‐developing structures in amphibians, and especially anurans (frogs), has never been produced. One such tissue type, skull bone, has been among the most difficult tissues to study due to the long time required for its development during anuran metamorphosis, which in some species may not occur until several months, or even years, after hatching. We report a relatively simple technique for studying this elusive population of neural crest‐derived osteogenic (bone‐forming) cells in Xenopus laevis by using fluorescently labeled dextran conjugates. Developmental Dynamics 230:100–106, 2004. © 2004 Wiley‐Liss, Inc.