18 results on '"Quast, B"'
Search Results
2. Zwischen Mythos und Philosophie. Orpheus’ Entscheidung
- Author
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Wagner-Egelhaaf M., Quast B., Basu H., Musio, Alessio, Alessio Musio (ORCID:0000-0001-7462-3903), Wagner-Egelhaaf M., Quast B., Basu H., Musio, Alessio, and Alessio Musio (ORCID:0000-0001-7462-3903)
- Abstract
Der Beitrag widmet sich dem Mythos von Orpheus und Eurydike, der aus einer ungewohnten Perspektive gelesen wird, nämlich aus derjenigen der Entschei- dung in ihrer Beziehung zu dem Thema ›Zeit‹. Zunächst wird geklärt, unter welchen Rahmenbedingungen die Philosophie überhaupt autorisiert ist, über Mythen zu sprechen. Der zweite Teil ist der negativen Bedeutung des Mythos als einer Art vager, die Realität verfremdender intellektueller Konstruktion ge- widmet: Es gibt in der Tat auch inakzeptable Mythen über die Entscheidung, inakzeptabel deshalb, weil sie mit der Erfahrung des Ichs nicht kompatibel sind. Vor diesem Hintergrund wird eine philosophische Prüfung des Mythos von Orpheus und Eurydike vorgenommen.
- Published
- 2019
3. In silico evo-devo: reconstructing stages in the evolution of animal segmentation
- Author
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Hogeweg, Paulien, ten Tusscher, Kirsten H. W. J., Davis, GK, Patel, NH, Peel, A, Akam, M, Couso, JP, Budd, GE, Seaver, EC, Minelli, A, Fusco, G, Tautz, D, Jacobs, DK, Hughes, NC, Fitz-Gibbon, ST, Winchell, CJ, Blair, SS, Wanninger, A, Kristof, A, Brinkmann, N, Chipman, AD, Richmond, DL, Oates, AC, Gold, DA, Runnegar, B, Gehling, JG, Rivera, A, Weisblat, D, Williams, T, Blachuta, B, Hegna, TA, Nagy, LM, Balavoine, G, Bénazéraf, B, Pourquié, O, Mayer, G, Kato, C, Quast, B, Chisholm, RH, Landman, KA, Quinn, LM, Nakamoto, A, Hester, SD, Constantinou, SJ, Blaine, WG, Tewksbury, AB, Matei, MT, Williams, TA, Graham, A, Butts, T, Lumsden, A, Kiecker, C, François, P, Hakim, V, Siggia, ED, Fujimoto, K, Ishihara, S, Kaneko, K, Tusscher, KH, Hogeweg, P, Crombach, A, Salazar-Ciudad, I, Newman, SA, Solé, RV, Pankratz, MJ, Jäckle, H, Crampin, EJ, Hackborn, WW, Maini, PK, Harper, JL, Rosen, BR, White, J, Tusscher, KHWJ, Petersen, CP, Reddien, PW, Martin, BL, Kimelman, D, Young, T, Rowland, JE, Ven, C, Bialecka, M, Novoa, A, Carapuco, M, Nes, J, Graaff, W, Duluc, I, Freund, J-N, Beck, F, Mallo, M, Deschamps, J, Meinhardt, H, Kappen, C, Schughart, K, Ruddle, FH, Sub Theoretical Biology, Dep Biologie, and Theoretical Biology and Bioinformatics
- Subjects
0301 basic medicine ,lcsh:Evolution ,Biology ,Bilaterian evolution ,03 medical and health sciences ,0302 clinical medicine ,Segmentation ,Plant Genetics & Genomics ,lcsh:QH359-425 ,Genetics ,Determinate growth ,Ecology, Evolution, Behavior and Systematics ,Selection (genetic algorithm) ,Evolutionary Biology ,In silico evolution ,Mechanism (biology) ,Posterior signalling ,Research ,Paleontology ,Indeterminate growth ,030104 developmental biology ,Order (biology) ,Evolutionary biology ,Evolutionary developmental biology ,Axis extension ,Developmental biology ,Zoology ,030217 neurology & neurosurgery ,Morphogen ,Developmental Biology - Abstract
Background The evolution of animal segmentation is a major research focus within the field of evolutionary–developmental biology. Most studied segmented animals generate their segments in a repetitive, anterior-to-posterior fashion coordinated with the extension of the body axis from a posterior growth zone. In the current study we ask which selection pressures and ordering of evolutionary events may have contributed to the evolution of this specific segmentation mode. Results To answer this question we extend a previous in silico simulation model of the evolution of segmentation by allowing the tissue growth pattern to freely evolve. We then determine the likelihood of evolving oscillatory sequential segmentation combined with posterior growth under various conditions, such as the presence or absence of a posterior morphogen gradient or selection for determinate growth. We find that posterior growth with sequential segmentation is the predominant outcome of our simulations only if a posterior morphogen gradient is assumed to have already evolved and selection for determinate growth occurs secondarily. Otherwise, an alternative segmentation mechanism dominates, in which divisions occur in large bursts through the entire tissue and all segments are created simultaneously. Conclusions Our study suggests that the ancestry of a posterior signalling centre has played an important role in the evolution of sequential segmentation. In addition, it suggests that determinate growth evolved secondarily, after the evolution of posterior growth. More generally, we demonstrate the potential of evo-devo simulation models that allow us to vary conditions as well as the onset of selection pressures to infer a likely order of evolutionary innovations. Electronic supplementary material The online version of this article (doi:10.1186/s13227-016-0052-8) contains supplementary material, which is available to authorized users.
- Published
- 2016
4. Registerwechsel. Wiedererzählen, bibelepisch (Der Saelden Hort, Die Erlösung, Lutwins Adam und Eva)
- Author
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Quast, Bruno, Spreckelmeier, Susanne, Quast, B ( Bruno ), Spreckelmeier, S ( Susanne ), Köbele, Susanne, Quast, Bruno, Spreckelmeier, Susanne, Quast, B ( Bruno ), Spreckelmeier, S ( Susanne ), and Köbele, Susanne
- Abstract
Die Beiträge gehen zum grossen Teil auf das Kolloquium "Inkulturation. Literarische Strategien bibelepischen Schreibens in Mittelalter und Früher Neuzeit" zurück, das vom 19. bis 21. März 2014 in Münster stattfand.
- Published
- 2017
5. In silico evo-devo: reconstructing stages in the evolution of animal segmentation
- Author
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Sub Theoretical Biology, Dep Biologie, Theoretical Biology and Bioinformatics, Hogeweg, Paulien, ten Tusscher, Kirsten H. W. J., Davis, GK, Patel, NH, Peel, A, Akam, M, Couso, JP, Budd, GE, Seaver, EC, Minelli, A, Fusco, G, Tautz, D, Jacobs, DK, Hughes, NC, Fitz-Gibbon, ST, Winchell, CJ, Blair, SS, Wanninger, A, Kristof, A, Brinkmann, N, Chipman, AD, Richmond, DL, Oates, AC, Gold, DA, Runnegar, B, Gehling, JG, Rivera, A, Weisblat, D, Williams, T, Blachuta, B, Hegna, TA, Nagy, LM, Balavoine, G, Bénazéraf, B, Pourquié, O, Mayer, G, Kato, C, Quast, B, Chisholm, RH, Landman, KA, Quinn, LM, Nakamoto, A, Hester, SD, Constantinou, SJ, Blaine, WG, Tewksbury, AB, Matei, MT, Williams, TA, Graham, A, Butts, T, Lumsden, A, Kiecker, C, François, P, Hakim, V, Siggia, ED, Fujimoto, K, Ishihara, S, Kaneko, K, Tusscher, KH, Hogeweg, P, Crombach, A, Salazar-Ciudad, I, Newman, SA, Solé, RV, Pankratz, MJ, Jäckle, H, Crampin, EJ, Hackborn, WW, Maini, PK, Harper, JL, Rosen, BR, White, J, Tusscher, KHWJ, Petersen, CP, Reddien, PW, Martin, BL, Kimelman, D, Young, T, Rowland, JE, Ven, C, Bialecka, M, Novoa, A, Carapuco, M, Nes, J, Graaff, W, Duluc, I, Freund, J-N, Beck, F, Mallo, M, Deschamps, J, Meinhardt, H, Kappen, C, Schughart, K, Ruddle, FH, Sub Theoretical Biology, Dep Biologie, Theoretical Biology and Bioinformatics, Hogeweg, Paulien, ten Tusscher, Kirsten H. W. J., Davis, GK, Patel, NH, Peel, A, Akam, M, Couso, JP, Budd, GE, Seaver, EC, Minelli, A, Fusco, G, Tautz, D, Jacobs, DK, Hughes, NC, Fitz-Gibbon, ST, Winchell, CJ, Blair, SS, Wanninger, A, Kristof, A, Brinkmann, N, Chipman, AD, Richmond, DL, Oates, AC, Gold, DA, Runnegar, B, Gehling, JG, Rivera, A, Weisblat, D, Williams, T, Blachuta, B, Hegna, TA, Nagy, LM, Balavoine, G, Bénazéraf, B, Pourquié, O, Mayer, G, Kato, C, Quast, B, Chisholm, RH, Landman, KA, Quinn, LM, Nakamoto, A, Hester, SD, Constantinou, SJ, Blaine, WG, Tewksbury, AB, Matei, MT, Williams, TA, Graham, A, Butts, T, Lumsden, A, Kiecker, C, François, P, Hakim, V, Siggia, ED, Fujimoto, K, Ishihara, S, Kaneko, K, Tusscher, KH, Hogeweg, P, Crombach, A, Salazar-Ciudad, I, Newman, SA, Solé, RV, Pankratz, MJ, Jäckle, H, Crampin, EJ, Hackborn, WW, Maini, PK, Harper, JL, Rosen, BR, White, J, Tusscher, KHWJ, Petersen, CP, Reddien, PW, Martin, BL, Kimelman, D, Young, T, Rowland, JE, Ven, C, Bialecka, M, Novoa, A, Carapuco, M, Nes, J, Graaff, W, Duluc, I, Freund, J-N, Beck, F, Mallo, M, Deschamps, J, Meinhardt, H, Kappen, C, Schughart, K, and Ruddle, FH
- Published
- 2016
6. Frauenlobs 'Minne und Welt'. Paradoxe Effekte literarischer Säkularisierung
- Author
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Köbele, Susanne, Quast, Bruno, Köbele, S ( Susanne ), Quast, B ( Bruno ), Köbele, Susanne, Quast, Bruno, Köbele, S ( Susanne ), and Quast, B ( Bruno )
- Published
- 2014
7. Perspektiven einer mediävistischen Säkularisierungsdebatte. Zur Einführung
- Author
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Köbele, Susanne, Quast, Bruno, Köbele, S ( Susanne ), Quast, B ( Bruno ), Köbele, Susanne, Quast, Bruno, Köbele, S ( Susanne ), and Quast, B ( Bruno )
- Published
- 2014
8. Haematite recovery from a tailings stream.
- Author
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Quast K., XXV International Mineral Processing Congress: IMPC 2010 Brisbane, Australia 06-Sep-1010-Sep-10, Quast B., Quast K., XXV International Mineral Processing Congress: IMPC 2010 Brisbane, Australia 06-Sep-1010-Sep-10, and Quast B.
- Abstract
Laboratory and pilot scale tests were carried out in 1999 on the recovery of iron from a sample of tailings from an iron ore treatment plant. The tailings, from the Mount Wilson concentrator in Quebec, Canada, contained 16% Fe, mainly in the -38 micron fraction. The use of tabling and magnetic separation produced poor results, while a concentrate containing over 40% Fe was produced by flotation. The best results were obtained using a Kelsey Centrifugal Jig, where a high grade concentrate containing over 67% Fe was produced. Although recoveries were low, the process is considered to be worth further investigation., Laboratory and pilot scale tests were carried out in 1999 on the recovery of iron from a sample of tailings from an iron ore treatment plant. The tailings, from the Mount Wilson concentrator in Quebec, Canada, contained 16% Fe, mainly in the -38 micron fraction. The use of tabling and magnetic separation produced poor results, while a concentrate containing over 40% Fe was produced by flotation. The best results were obtained using a Kelsey Centrifugal Jig, where a high grade concentrate containing over 67% Fe was produced. Although recoveries were low, the process is considered to be worth further investigation.
- Published
- 2010
9. Growth patterns in Onychophora (velvet worms): lack of a localised posterior proliferation zone
- Author
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Mayer, G, Kato, C, Quast, B, Chisholm, RH, Landman, KA, Quinn, LM, Mayer, G, Kato, C, Quast, B, Chisholm, RH, Landman, KA, and Quinn, LM
- Abstract
BACKGROUND: During embryonic development of segmented animals, body segments are thought to arise from the so-called "posterior growth zone" and the occurrence of this "zone" has been used to support the homology of segmentation between arthropods, annelids, and vertebrates. However, the term "posterior growth zone" is used ambiguously in the literature, mostly referring to a region of increased proliferation at the posterior end of the embryo. To determine whether such a localised posterior proliferation zone is an ancestral feature of Panarthropoda (Onychophora + Tardigrada + Arthropoda), we examined cell division patterns in embryos of Onychophora. RESULTS: Using in vivo incorporation of the DNA replication marker BrdU (5-bromo-2'-deoxyuridine) and anti-phospho-histone H3 immunolabelling, we found that a localised posterior region of proliferating cells does not occur at any developmental stage in onychophoran embryos. This contrasts with a localised pattern of cell divisions at the posterior end of annelid embryos, which we used as a positive control. Based on our data, we present a mathematical model, which challenges the paradigm that a localised posterior proliferation zone is necessary for segment patterning in short germ developing arthropods. CONCLUSIONS: Our findings suggest that a posterior proliferation zone was absent in the last common ancestor of Onychophora and Arthropoda. By comparing our data from Onychophora with those from annelids, arthropods, and chordates, we suggest that the occurrence of a "posterior growth zone" currently cannot be used to support the homology of segmentation between these three animal groups.
- Published
- 2010
10. Mythos und Metapher : Die Kunst der Anspielung in Gottfrieds Tristan
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Friedrich, Udo, Quast, Bruno, Friedrich, U ( Udo ), Quast, B ( Bruno ), Köbele, Susanne, Friedrich, Udo, Quast, Bruno, Friedrich, U ( Udo ), Quast, B ( Bruno ), and Köbele, Susanne
- Published
- 2004
11. Arbeit am Absolutismus des Mythos: Mittelalterliche Supplemente zur biblischen Heilsgeschichte
- Author
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Friedrich, Udo, Quast, Bruno, Friedrich, U ( Udo ), Quast, B ( Bruno ), Kiening, Christian, Friedrich, Udo, Quast, Bruno, Friedrich, U ( Udo ), Quast, B ( Bruno ), and Kiening, Christian
- Published
- 2004
12. Mythen und Narrative des Entscheidens (Volume 3, Edition 1)
- Author
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Wagner-Egelhaaf, Martina, Basu, Helene, Baehr-Olivia, Antonius, Zimmermann, Bernhard, Friedrich, Udo, Musio, Alessio, Quast, Bruno, Schnocks, Johannes, Riedl, Peter Philipp, Keupp, Jan, Haferland, Harald, Grünbart, Michael, Quast, Bruno, Basu, Helene, and Wagner-Egelhaaf, Martina
- Subjects
Philosophy ,Criticism ,bic Book Industry Communication::H Humanities::HP Philosophy::HPC History of Western philosophy - Abstract
Es gibt Mythen des Entscheidens, die immer wieder erzählt werden, wie beispielsweise die Entscheidung von Adam und Eva im Paradies, vom Baum der Erkenntnis zu essen, das Urteil des Paris, Herakles am Scheideweg oder Buridans Esel, der sich zwischen zwei Heuhaufen nicht entscheiden kann und deshalb zugrunde geht. Der aus dem Münsteraner Sonderforschungsbereich 1150 »Kulturen des Entscheidens« hervorgegangene interdisziplinäre Tagungsband untersucht das Verhältnis von Mythos, Narration und Entscheiden. Er setzt in Mythos und Literatur erzählte Entscheidensszenarien in Bezug zu modernen Theorien des Entscheidens und fragt nach ihrer Funktion sowie den Veränderungen in unterschiedlichen historischen und kulturellen Kontexten. Analysiert werden einerseits Entscheidenssituationen, die in Mythen dargestellt werden; andererseits wird auch deutlich, in welcher Weise Mythen selbst Entscheidensdispositive darstellen. Die Beiträge des Bandes zeigen, wie Entscheidensmythen und -narrative der Kontingenzbewältigung dienen und betonen den sozialen Handlungscharakter des Entscheidens.
- Published
- 2019
- Full Text
- View/download PDF
13. SOCCOMAS: a FAIR web content management system that uses knowledge graphs and that is based on semantic programming.
- Author
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Vogt L, Baum R, Bhatty P, Köhler C, Meid S, Quast B, and Grobe P
- Subjects
- Pattern Recognition, Automated, Programming Languages, Semantic Web, User-Computer Interface
- Abstract
We introduce Semantic Ontology-Controlled application for web Content Management Systems (SOCCOMAS), a development framework for FAIR ('findable', 'accessible', 'interoperable', 'reusable') Semantic Web Content Management Systems (S-WCMSs). Each S-WCMS run by SOCCOMAS has its contents managed through a corresponding knowledge base that stores all data and metadata in the form of semantic knowledge graphs in a Jena tuple store. Automated procedures track provenance, user contributions and detailed change history. Each S-WCMS is accessible via both a graphical user interface (GUI), utilizing the JavaScript framework AngularJS, and a SPARQL endpoint. As a consequence, all data and metadata are maximally findable, accessible, interoperable and reusable and comply with the FAIR Guiding Principles. The source code of SOCCOMAS is written using the Semantic Programming Ontology (SPrO). SPrO consists of commands, attributes and variables, with which one can describe an S-WCMS. We used SPrO to describe all the features and workflows typically required by any S-WCMS and documented these descriptions in a SOCCOMAS source code ontology (SC-Basic). SC-Basic specifies a set of default features, such as provenance tracking and publication life cycle with versioning, which will be available in all S-WCMS run by SOCCOMAS. All features and workflows specific to a particular S-WCMS, however, must be described within an instance source code ontology (INST-SCO), defining, e.g. the function and composition of the GUI, with all its user interactions, the underlying data schemes and representations and all its workflow processes. The combination of descriptions in SC-Basic and a given INST-SCO specify the behavior of an S-WCMS. SOCCOMAS controls this S-WCMS through the Java-based middleware that accompanies SPrO, which functions as an interpreter. Because of the ontology-controlled design, SOCCOMAS allows easy customization with a minimum of technical programming background required, thereby seamlessly integrating conventional web page technologies with semantic web technologies. SOCCOMAS and the Java Interpreter are available from (https://github.com/SemanticProgramming)., (© The Author(s) 2019. Published by Oxford University Press.)
- Published
- 2019
- Full Text
- View/download PDF
14. Fiat or bona fide boundary--a matter of granular perspective.
- Author
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Vogt L, Grobe P, Quast B, and Bartolomaeus T
- Subjects
- Biological Evolution, Humans, Contrast Sensitivity physiology, Visual Perception physiology
- Abstract
Background: Distinguishing bona fide (i.e. natural) and fiat (i.e. artificial) physical boundaries plays a key role for distinguishing natural from artificial material entities and is thus relevant to any scientific formal foundational top-level ontology, as for instance the Basic Formal Ontology (BFO). In BFO, the distinction is essential for demarcating two foundational categories of material entity: object and fiat object part. The commonly used basis for demarcating bona fide from fiat boundary refers to two criteria: (i) intrinsic qualities of the boundary bearers (i.e. spatial/physical discontinuity, qualitative heterogeneity) and (ii) mind-independent existence of the boundary. The resulting distinction of bona fide and fiat boundaries is considered to be categorial and exhaustive., Methodology/principal Findings: By Referring to various examples from biology, we demonstrate that the hitherto used distinction of boundaries is not categorial: (i) spatial/physical discontinuity is a matter of scale and the differentiation of bona fide and fiat boundaries is thus granularity-dependent, and (ii) this differentiation is not absolute, but comes in degrees. By reducing the demarcation criteria to mind-independence and by also considering dispositions and historical relations of the bearers of boundaries, instead of only considering their spatio-structural properties, we demonstrate with various examples that spatio-structurally fiat boundaries can nevertheless be mind-independent and in this sense bona fide., Conclusions/significance: We argue that the ontological status of a given boundary is perspective-dependent and that the strictly spatio-structural demarcation criteria follow a static perspective that is ignorant of causality and the dynamics of reality. Based on a distinction of several ontologically independent perspectives, we suggest different types of boundaries and corresponding material entities, including boundaries based on function (locomotion, physiology, ecology, development, reproduction) and common history (development, heredity, evolution). We argue that for each perspective one can differentiate respective bona fide from fiat boundaries.
- Published
- 2012
- Full Text
- View/download PDF
15. Accommodating ontologies to biological reality--top-level categories of cumulative-constitutively organized material entities.
- Author
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Vogt L, Grobe P, Quast B, and Bartolomaeus T
- Subjects
- Cell Aggregation, Classification, Cluster Analysis, Biomedical Research, Database Management Systems, Databases, Factual, Vocabulary, Controlled
- Abstract
Background: The Basic Formal Ontology (BFO) is a top-level formal foundational ontology for the biomedical domain. It has been developed with the purpose to serve as an ontologically consistent template for top-level categories of application oriented and domain reference ontologies within the Open Biological and Biomedical Ontologies Foundry (OBO). BFO is important for enabling OBO ontologies to facilitate in reliably communicating and managing data and metadata within and across biomedical databases. Following its intended single inheritance policy, BFO's three top-level categories of material entity (i.e. 'object', 'fiat object part', 'object aggregate') must be exhaustive and mutually disjoint. We have shown elsewhere that for accommodating all types of constitutively organized material entities, BFO must be extended by additional categories of material entity., Methodology/principal Findings: Unfortunately, most biomedical material entities are cumulative-constitutively organized. We show that even the extended BFO does not exhaustively cover cumulative-constitutively organized material entities. We provide examples from biology and everyday life that demonstrate the necessity for 'portion of matter' as another material building block. This implies the necessity for further extending BFO by 'portion of matter' as well as three additional categories that possess portions of matter as aggregate components. These extensions are necessary if the basic assumption that all parts that share the same granularity level exhaustively sum to the whole should also apply to cumulative-constitutively organized material entities. By suggesting a notion of granular representation we provide a way to maintain the single inheritance principle when dealing with cumulative-constitutively organized material entities., Conclusions/significance: We suggest to extend BFO to incorporate additional categories of material entity and to rearrange its top-level material entity taxonomy. With these additions and the notion of granular representation, BFO would exhaustively cover all top-level types of material entities that application oriented ontologies may use as templates, while still maintaining the single inheritance principle.
- Published
- 2012
- Full Text
- View/download PDF
16. Top-level categories of constitutively organized material entities--suggestions for a formal top-level ontology.
- Author
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Vogt L, Grobe P, Quast B, and Bartolomaeus T
- Subjects
- Computational Biology
- Abstract
Background: Application oriented ontologies are important for reliably communicating and managing data in databases. Unfortunately, they often differ in the definitions they use and thus do not live up to their potential. This problem can be reduced when using a standardized and ontologically consistent template for the top-level categories from a top-level formal foundational ontology. This would support ontological consistency within application oriented ontologies and compatibility between them. The Basic Formal Ontology (BFO) is such a foundational ontology for the biomedical domain that has been developed following the single inheritance policy. It provides the top-level template within the Open Biological and Biomedical Ontologies Foundry. If it wants to live up to its expected role, its three top-level categories of material entity (i.e., 'object', 'fiat object part', 'object aggregate') must be exhaustive, i.e. every concrete material entity must instantiate exactly one of them., Methodology/principal Findings: By systematically evaluating all possible basic configurations of material building blocks we show that BFO's top-level categories of material entity are not exhaustive. We provide examples from biology and everyday life that demonstrate the necessity for two additional categories: 'fiat object part aggregate' and 'object with fiat object part aggregate'. By distinguishing topological coherence, topological adherence, and metric proximity we furthermore provide a differentiation of clusters and groups as two distinct subcategories for each of the three categories of material entity aggregates, resulting in six additional subcategories of material entity., Conclusions/significance: We suggest extending BFO to incorporate two additional categories of material entity as well as two subcategories for each of the three categories of material entity aggregates. With these additions, BFO would exhaustively cover all top-level types of material entity that application oriented ontologies may use as templates. Our result, however, depends on the premise that all material entities are organized according to a constitutive granularity.
- Published
- 2011
- Full Text
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17. Growth patterns in Onychophora (velvet worms): lack of a localised posterior proliferation zone.
- Author
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Mayer G, Kato C, Quast B, Chisholm RH, Landman KA, and Quinn LM
- Subjects
- Animals, Cell Division, Invertebrates cytology, Models, Theoretical, Invertebrates embryology, Invertebrates growth & development
- Abstract
Background: During embryonic development of segmented animals, body segments are thought to arise from the so-called "posterior growth zone" and the occurrence of this "zone" has been used to support the homology of segmentation between arthropods, annelids, and vertebrates. However, the term "posterior growth zone" is used ambiguously in the literature, mostly referring to a region of increased proliferation at the posterior end of the embryo. To determine whether such a localised posterior proliferation zone is an ancestral feature of Panarthropoda (Onychophora + Tardigrada + Arthropoda), we examined cell division patterns in embryos of Onychophora., Results: Using in vivo incorporation of the DNA replication marker BrdU (5-bromo-2'-deoxyuridine) and anti-phospho-histone H3 immunolabelling, we found that a localised posterior region of proliferating cells does not occur at any developmental stage in onychophoran embryos. This contrasts with a localised pattern of cell divisions at the posterior end of annelid embryos, which we used as a positive control. Based on our data, we present a mathematical model, which challenges the paradigm that a localised posterior proliferation zone is necessary for segment patterning in short germ developing arthropods., Conclusions: Our findings suggest that a posterior proliferation zone was absent in the last common ancestor of Onychophora and Arthropoda. By comparing our data from Onychophora with those from annelids, arthropods, and chordates, we suggest that the occurrence of a "posterior growth zone" currently cannot be used to support the homology of segmentation between these three animal groups.
- Published
- 2010
- Full Text
- View/download PDF
18. Dipeptidylpeptidase IV activities are elevated in prostate cancers and adjacent benign hyperplastic glands.
- Author
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Wilson MJ, Ruhland AR, Quast BJ, Reddy PK, Ewing SL, and Sinha AA
- Subjects
- Aged, Blotting, Western, Humans, Male, Middle Aged, Dipeptidyl Peptidase 4 metabolism, Prostatic Hyperplasia enzymology, Prostatic Neoplasms enzymology
- Abstract
Dipeptidylpeptidase IV (DPP IV) is a serine exopeptidase that has been implicated in cell-extracellular matrix interactions and bioactive peptide/cytokine/growth factor metabolism. The objective of this study was to determine if DPP IV activities were changed with development of cancer in the prostate. DPP IV activity was measured in human prostate cancer and benign prostatic hyperplasia (BPH) tissues by biochemical assays with glycylprolyl-p-nitroanalide as substrate in tissue extracts (BPH, n = 8: cancer, n = 7; 2 with Gleason score 5 and 5 with Gleason score 7) and quantitative morphometry of histochemical activities with glycylproline-4-methoxy-beta-naphthylamide as substrate (BPH, n = 9: cancer, n = 13, 1 with Gleason score 4, 10 with Gleason score 6, 2 with Gleason score 8) in frozen-tissue sections. Data were analyzed by analysis of variance. The peptidase activity was detected in epithelial but not stromal cells of BPH and cancer tissues, and it was present as a single band of activity of approximately 160 kDa in electrophoretically separated activity blots of the extracts. DPP IV activity was increased approximately twofold in cancer versus BPH tissues as determined by biochemical and quantitative histochemical methods. In addition, DPP IV activity was increased to a similar extent in BPH glands associated with the cancers. These data indicate that DPP IV activity is increased not only in primary prostatic cancers but also in associated BPH glands, suggesting that there may be some local factors produced by cancer cells that influence adjacent BPH epithelial cells to positively affect the immediate growth environment of the cancer.
- Published
- 2000
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