556 research outputs found
Rates of RNA and protein synthesis in the cold-sensitive mutant, crib-l
Rates of RNA and protein synthesis in cold-sensitive mutan
Optimization of an ih-cavity based high energy heavy-ion LINAC at GSI
A new high energy heavy-ion injector (HE-Linac) for the FAIR project was proposedas replacement for the existing post-stripper linac at the GSI UNILAC. Six 108 MHz IH-type drift-tube linac cavities within a total length of about 24m accelerate the ions (up to U28+) from1.4 MeV/u up to 11.4 MeV/u. Fast pulsed quadrupole triplet lenses are used for transverse focusing in between the IH cavities. The optimization of the HE linac with respect to the emittance growth reductionis investigated
Tailored graph ensembles as proxies or null models for real networks II: results on directed graphs
We generate new mathematical tools with which to quantify the macroscopic
topological structure of large directed networks. This is achieved via a
statistical mechanical analysis of constrained maximum entropy ensembles of
directed random graphs with prescribed joint distributions for in- and
outdegrees and prescribed degree-degree correlation functions. We calculate
exact and explicit formulae for the leading orders in the system size of the
Shannon entropies and complexities of these ensembles, and for
information-theoretic distances. The results are applied to data on gene
regulation networks.Comment: 21 pages, 1 figure, submitted to J. Phys.
Hepatic progenitor cells from adult human livers for cell transplantation.
Objective: Liver regeneration is mainly based on cellular
self-renewal including progenitor cells. Efforts have been
made to harness this potential for cell transplantation, but
shortage of hepatocytes and premature differentiated
progenitor cells from extra-hepatic organs are limiting
factors. Histological studies implied that resident cells in
adult liver can proliferate, have bipotential character and
may be a suitable source for cell transplantation.
Methods: Particular cell populations were isolated after
adequate tissue dissociation. Single cell suspensions were
purified by Thy-1 positivity selection, characterised in vitro
and transplanted in immunodeficient Pfp/Rag2 mice.
Results: Thy-1+ cells that are mainly found in the portal
tract and the surrounding parenchyma, were isolated from
surgical liver tissue with high yields from specimens with
histological signs of regeneration. Thy-1+ cell populations
were positive for progenitor (CD34, c-kit, CK14, M2PK,
OV6), biliary (CK19) and hepatic (HepPar1) markers
revealing their progenitor as well as hepatic and biliary
nature. The potential of Thy-1+ cells for differentiation in
vitro was demonstrated by increased mRNA and protein
expression for hepatic (CK18, HepPar1) and biliary (CK7)
markers during culture while progenitor markers CK14,
chromogranin A and nestin were reduced. After
transplantation of Thy-1+ cells into livers of immunodeficient
mice, engraftment was predominantly seen in the
periportal portion of the liver lobule. Analysis of in situ
material revealed that transplanted cells express human
hepatic markers HepPar1 and albumin, indicating functional
engraftment.
Conclusion: Bipotential progenitor cells from human
adult livers can be isolated using Thy-1 and might be a
potential candidate for cell treatment in liver diseases
Entwurfsmuster für verteilte Anwendungssystem-Architekturen
Aus der Motivation:
"In den letzten Jahren werden verstärkt neue Organisationsformen für Unternehmen diskutiert (vgl. [Zimm97], [DaMa93], [BuIl+97]). Diese reichen von innerbetrieblicher Dezentralisierung der Entscheidungsbefugnis bis hin zur Bildung autonomer Geschäftseinheiten, die in virtuellen Unternehmen kooperieren. Neben der stärkeren Verteilung der Entscheidungsbefugnis stehen neue Formen der Arbeitsverteilung sowie die Tendenz zur Globalisierung im Vordergrund. Daraus ergeben sich weitreichende Anforderungen an betriebliche Informationssysteme. Diese betreffen insbesondere technische Merkmale wie Flexibilität und Verteilbarkeit von Anwendungssystemkomponenten sowie die Verfügbarkeit und Performanz des Gesamtsystems. Aus betriebswirtschaftlicher Sicht müssen die Zielverfolgung, die Konsistenz sowie Aspekte der Datensicherheit berücksichtigt werden (vgl. [FeSi+97]). Konventionelle Anwendungssysteme, die auf Datenintegration basieren, erfüllen insbesondere die Anforderungen nach Flexibilität und Verteilbarkeit nicht in ausreichendem Maße. Daher ist es notwendig, Anwendungssystem-Architekturen zu entwickeln, welche die Realisierung unterschiedlicher technischer und organisatorischer Verteilungsformen unterstützen. Dies erfordert einen integrierten Ansatz zur Modellierung verteilter Anwendungssysteme im Kontext organisatorischer und technischer Rahmenbedingungen. Eine geeignete Modellierungsmethode sollte somit Verteilungskonzepte für alle angesprochenen Aspekte eines betrieblichen Systems beinhalten.
Deroceras panormitanum and congeners from Malta and Sicily, with a redescription of the widespread pest slug as Deroceras invadens n. sp.
The name Deroceras panormitanum is generally applied to a terrestrial slug that has spread worldwide and can be a pest; earlier this tramp species had been called Deroceras caruanae. Neither name is appropriate. The taxonomic descriptions apply to a species from Sicily and Malta. This true D. panormitanum and the tramp species are distinct in morphology and mating behaviour. For instance, the penial caecum of D. panormitanum is more pointed, everting faster at copulation. The size of the penial lobe varies considerably in preserved specimens but is always prominent at copulation. D. panormitanum is distinct from the Maltese endemic Deroceras golcheri, but a phylogeny based on mtDNA COI sequences implies that they are more closely related than is the tramp species. D. golcheri has a still closer counterpart on Sicily, but we leave the taxonomy of this species X unresolved. In interspecific crosses, D. panormitanum may transfer sperm to the partner's sarcobelum whereas the partner fails to evert its penis (D. golcheri) or to transfer sperm (the tramp species). Names previously applied to the tramp species originally referred to D. panormitanum or are otherwise invalid, so it is here formally redescribed as D. invadens. Deroceras giustianum Wiktor, 1998 is synonymised with D. panormitanum
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