539 research outputs found
About the relationship between science and policy. Why a difference exists between the (educational) sience and the trade union of education and science
No full textDer Beitrag ist eine Antwort auf einen vorherigen Artikel von Dieter Wunder, dem ehemaligen Vorsitzenden der Gewerkschaft Erziehung und Wissenschaft (GEW). "In Heft 2/06 hatte Dieter Wunder die Deutung zurückgewiesen, die Achim Leschinsky in der Zeitschrift für Pädagogik für \u27das Scheitern des Deutschen Bildungsrates\u27 formuliert hatte. In seiner Replik erläutert Leschinsky seine Position, dass zwischen Wissenschaft und Politik eine Differenz besteht, die nicht ignoriert werden darf." (DIPF/Orig./So)In number 2/06 of this journal Dieter Wunder rejected the interpretation which Achim Leschinsky (in Zeitschrift für Pädagogik) had formulated concerning the "failure" of the German educational council. In his reply the author explains his position that between science and policy a difference exists which must not be ignored. (DIPF/Orig.
Stellar Structure and Evolution
No full textThis long-awaited second edition of the classical textbook on Stellar Structure and Evolution by Kippenhahn and Weigert is a thoroughly revised version of the original text. Taking into account modern observational constraints as well as additional physical effects such as mass loss and diffusion, Achim Weiss and Rudolf Kippenhahn have succeeded in bringing the book up to the state-of-the-art with respect to both the presentation of stellar physics and the presentation and interpretation of current sophisticated stellar models. The well-received and proven pedagogical approach of the first edition has been retained. The book provides a comprehensive treatment of the physics of the stellar interior and the underlying fundamental processes and parameters. The models developed to explain the stability, dynamics and evolution of the stars are presented and great care is taken to detail the various stages in a star’s life. Just as the first edition, which remained a standard work for more than 20 years after its first publication, the second edition will be of lasting value not only for students but also for active researchers in astronomy and astrophysics
Crystallographic fragment screen of the c-di-AMP-synthesizing enzyme CdaA from Bacillus subtilis
No full textCrystallographic fragment screening has become a pivotal technique in structure-based drug design, particularly for bacterial targets with a crucial role in infectious disease mechanisms. The enzyme CdaA, which synthesizes an essential second messenger cyclic di-AMP (c-di-AMP) in many pathogenic bacteria, has emerged as a promising candidate for the development of novel antibiotics. To identify crystals suitable for fragment screening, CdaA enzymes from Streptococcus pneumoniae , Bacillus subtilis and Enterococcus faecium were purified and crystallized. Crystals of B. subtilis CdaA, which diffracted to the highest resolution of 1.1 Å, were used to perform the screening of 96 fragments, yielding data sets with resolutions spanning from 1.08 to 1.87 Å. A total of 24 structural hits across eight different sites were identified. Four fragments bind to regions that are highly conserved among pathogenic bacteria, specifically the active site (three fragments) and the dimerization interface (one fragment). The coordinates of the three active-site fragments were used to perform an in silico drug-repurposing screen using the OpenEye suite and the DrugBank database. This screen identified tenofovir, an approved drug, that is predicted to interact with the ATP-binding region of CdaA. Its inhibitory potential against pathogenic E. faecium CdaA has been confirmed by ITC measurements. These findings not only demonstrate the feasibility of this approach for identifying lead compounds for the design of novel antibacterial agents, but also pave the way for further fragment-based lead-optimization efforts targeting CdaA.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/50110000165
Combining dehydration, construct optimization and improved data collection to solve the crystal structure of a CRM1 RanGTP SPN1 Nup214 quaternary nuclear export complex
No full textHigh conformational flexibility is an intrinsic and indispensable property of nuclear transport receptors, which makes crystallization and structure determination of macromolecular complexes containing exportins or importins particularly challenging. Here, the crystallization and structure determination of a quaternary nuclear export complex consisting of the exportin CRM1, the small GTPase Ran in its GTP-bound form, the export cargo SPN1 and an FG repeat-containing fragment of the nuclear pore complex component nucleoporin Nup214 fused to maltose-binding protein is reported. Optimization of constructs, seeding and the development of a sophisticated protocol including successive PEG-mediated crystal dehydration as well as additional post-mounting steps were essential to obtain well diffracting crystals
Semi-empirical white dwarf initial-final mass relationships: a thorough analysis of systematic uncertainties due to stellar evolution models
No full textUsing the most recent results about white dwarfs (WDs) in ten open clusters, we revisit semiempirical estimates of the initial–final mass relation (IFMR) in star clusters, with emphasis on the use of stellar evolution models. We discuss the influence of these models on each step of the derivation. One intention of our work is to use consistent sets of calculations both for the isochrones and the WD cooling tracks. The second one is to derive the range of systematic errors arising from stellar evolution theory. This is achieved by using different sources for the stellar models and by varying physical assumptions and input data. We find that systematic errors, including the determination of the cluster age, are dominating the initial mass values, while observational uncertainties influence the final mass primarily. After having determined the systematic errors, the initial–final mass relation allows us finally to draw conclusions about the physics of the stellar models, in particular about convective overshooting.Fil: Salaris, Maurizio. Max-Planck-Institut fur Astrophysik; AlemaniaFil: Serenelli, Aldo. Max-Planck-Institut fur Astrophysik; AlemaniaFil: Weiss, Achim. Max-Planck-Institut fur Astrophysik; AlemaniaFil: Miller Bertolami, Marcelo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin
Fair Use
No full textZum Ausgleich des Interessenkonfliktes zwischen Urheberrechtsinhaber und Werknutzer haben sich im internationalen Vergleich zwei grundlegend unterschiedliche Regelungstechniken entwickelt. Das eine Modell – dessen prominentester und wirtschaftlich bedeutendster Vertreter die Vereinigten Staaten von Amerika sind – versucht den Interessenausgleich dadurch zu erreichen, dass einem umfassend gewährten Urheberrecht eine ebenso offene Schrankengeneralklausel gegenübergestellt wird. Der zweite, traditionell in den kontinentaleuropäischen Rechtsordnungen vorzufindende und auch in das deutsche Urheberrechtsgesetz übernommene Typus sieht dagegen einen abschließenden Katalog von Einzelausnahmen vor. Achim Förster widmet sich den Rechtssetzungsmöglichkeiten bei der Ausgestaltung urheberrechtlicher Schranken und stellt hierzu die Fair Use-Doktrin des US-amerikanischen Copyright Act (17 U.S.C. § 107) dem Schrankenkatalog des deutschen Urheberrechtsgesetzes (§§ 44a ff. UrhG) gegenüber. Er vergleicht Herkunft, Funktion und Handhabung der Schrankensysteme und untersucht deren Verwurzelung im Verfassungsrecht und in der Urheberrechtstheorie. Aus inter- und supranationaler Sicht stellt er die Frage, welche konkreten Vorgaben sich aus dem Völker- und Europarecht für die Ausgestaltung der nationalen Urheberrechtsschranken ableiten lassen. Der Autor wendet die so gewonnenen Erkenntnisse auf die aktuelle Diskussion zur Flexibilisierung des Schrankenkataloges an und bewertet die rechtspolitischen Optionen des deutschen Gesetzgebers.Addressing the different legislative approaches to copyright limitations, Achim Förster compares the wide scope of the U.S. fair use doctrine (17 U.S.C. § 107) with the German set of explicitly enumerated statutory exceptions. He assesses the major criteria for deciding whether or not certain uses are permitted under U.S. or German copyright law and addresses the question of why these criteria have emerged as a characteristic feature of each system. In addition, the author deals with the influence of international and European law on national copyright legislation and in conclusion makes a contribution to the German discussion on copyright reform
On the relevance of bubbles and potential flows for stellar convection
No full textRecently Pasetto et al. have proposed a new method to derive a convection theory appropriate for the implementation in stellar evolution codes. Their approach is based on the simple physical picture of spherical bubbles moving within a potential flow in dynamically unstable regions, and a detailed computation of the bubble dynamics. Based on this approach, the authors derive a new theory of convection which is claimed to be parameter-free, non-local and time-dependent. This is a very strong claim, as such a theory is the holy grail of stellar physics. Unfortunately, we have identified several distinct problems in the derivation which ultimately render their theory inapplicable to any physical regime. In addition, we show that the framework of spherical bubbles in potential flows is unable to capture the essence of stellar convection, even when equations are derived correctlyFil: Miller Bertolami, Marcelo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; Argentina. Gobierno de la Republica Federal de Alemania. Max Planck Institut Fur Astrophysik; AlemaniaFil: Viallet, Maxime. Gobierno de la Republica Federal de Alemania. Max Planck Institut Fur Astrophysik; AlemaniaFil: Prat, Vincent. Gobierno de la Republica Federal de Alemania. Max Planck Institut Fur Astrophysik; AlemaniaFil: Barsukow, Wasilij. Universität Würzburg; AlemaniaFil: Weiss, Achim. Gobierno de la Republica Federal de Alemania. Max Planck Institut Fur Astrophysik; Alemani
Effekte der Gonadotropin-releasing Hormon-Antagonisten Cetrorelix und Ganirelix auf IGF-II, IGFBP-2 und PAPP-A in humanen Granulosaluteinzellen
No full textHydrodynamic simulations of the core helium flash – CORRIGENDUM
No full textIt is regretted that the originally published paper (Mocák, Müller, Weiss & Kifonidis, 2008) was not the authors' final amended version. We apologise for this oversight and reproduce the entire corrected paper here on-line only, with revised figure captions.</jats:p
A small step towards an important goal: fragment screen of the c-di-AMP-synthesizing enzyme CdaA
No full textCdaA is the most widespread diadenylate cyclase in many bacterial species, including several multidrug-resistant human pathogens. The enzymatic product of CdaA, cyclic di-AMP, is a secondary messenger that is essential for the viability of many bacteria. Its absence in humans makes CdaA a very promising and attractive target for the development of new antibiotics. Here, the structural results are presented of a crystallographic fragment screen against CdaA from
Listeria monocytogenes
, a saprophytic Gram-positive bacterium and an opportunistic food-borne pathogen that can cause listeriosis in humans and animals. Two of the eight fragment molecules reported here were localized in the highly conserved ATP-binding site. These fragments could serve as potential starting points for the development of antibiotics against several CdaA-dependent bacterial species.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/50110000165
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