University of Cologne

About: University of Cologne is a education organization based out in Cologne, Germany. It is known for research contribution in the topics: Population & Transplantation. The organization has 32050 authors who have published 66350 publications receiving 2210092 citations. The organization is also known as: Universität zu Köln & Universitatis Coloniensis.

Immunodeficiency in Protein Kinase Cβ-Deficient Mice

Abstract: Cross-linking of the antigen receptor on lymphocytes by antigens or antibodies to the receptor results in activation of enzymes of the protein kinase C (PKC) family. Mice homozygous for a targeted disruption of the gene encoding the PKC-βI and PKC-βII isoforms develop an immunodeficiency characterized by impaired humoral immune responses and reduced cellular responses of B cells, which is similar to X-linked immunodeficiency in mice. Thus PKC-βI and PKC-βII play an important role in B cell activation and may be functionally linked to Bruton's tyrosine kinase in antigen receptor-mediated signal transduction.

Keldysh field theory for driven open quantum systems.

Abstract: Recent experimental developments in diverse areas-ranging from cold atomic gases to light-driven semiconductors to microcavity arrays-move systems into the focus which are located on the interface of quantum optics, many-body physics and statistical mechanics. They share in common that coherent and driven-dissipative quantum dynamics occur on an equal footing, creating genuine non-equilibrium scenarios without immediate counterpart in equilibrium condensed matter physics. This concerns both their non-thermal stationary states and their many-body time evolution. It is a challenge to theory to identify novel instances of universal emergent macroscopic phenomena, which are tied unambiguously and in an observable way to the microscopic drive conditions. In this review, we discuss some recent results in this direction. Moreover, we provide a systematic introduction to the open system Keldysh functional integral approach, which is the proper technical tool to accomplish a merger of quantum optics and many-body physics, and leverages the power of modern quantum field theory to driven open quantum systems.

Late formation and prolonged differentiation of the Moon inferred from W isotopes in lunar metals.

Abstract: A new tungsten isotope study presents revised ages for the formation of the Moon. The Moon is thought to have formed from debris ejected by a giant impact with the early Earth. The high energies involved would have caused melting, and the formation of a lunar magma ocean. Previous work on tungsten isotopes had suggested that the Moon solidified within the first 60 million years of the Solar System. The new data from lunar metals based on the hafnium/tungsten clock are consistent with samarium/neodymium chronometry, and point to a later date for solidification, when the Solar System was 50 to 150 million years old. The Moon is thought to have formed from debris ejected by a giant impact with the early ‘proto’-Earth1 and, as a result of the high energies involved, the Moon would have melted to form a magma ocean. The timescales for formation and solidification of the Moon can be quantified by using 182Hf–182W and 146Sm–142Nd chronometry2,3,4, but these methods have yielded contradicting results. In earlier studies3,5,6,7, 182W anomalies in lunar rocks were attributed to decay of 182Hf within the lunar mantle and were used to infer that the Moon solidified within the first ∼60 million years of the Solar System. However, the dominant 182W component in most lunar rocks reflects cosmogenic production mainly by neutron capture of 181Ta during cosmic-ray exposure of the lunar surface3,7, compromising a reliable interpretation in terms of 182Hf–182W chronometry. Here we present tungsten isotope data for lunar metals that do not contain any measurable Ta-derived 182W. All metals have identical 182W/184W ratios, indicating that the lunar magma ocean did not crystallize within the first ∼60 Myr of the Solar System, which is no longer inconsistent with Sm–Nd chronometry8,9,10,11. Our new data reveal that the lunar and terrestrial mantles have identical 182W/184W. This, in conjunction with 147Sm–143Nd ages for the oldest lunar rocks8,9,10,11, constrains the age of the Moon and Earth to Myr after formation of the Solar System. The identical 182W/184W ratios of the lunar and terrestrial mantles require either that the Moon is derived mainly from terrestrial material or that tungsten isotopes in the Moon and Earth’s mantle equilibrated in the aftermath of the giant impact, as has been proposed to account for identical oxygen isotope compositions of the Earth and Moon12.

The half-lives of serum immunoglobulins in adult mice

Abstract: We determined the half-lives of several sets of murine monoclonal antibodies spanning all immunoglobulin isotypes in the serum. The antibodies in each set possess the same V region. With this approach, the differences in half-life observed between the different isotypes are independent of the V region carried by the monoclonal antibodies and therefore must relate to each other in the same way as the half-lives of each class of serum immunoglobulins. The half-life of a monoclonal antibody of the gamma 2a isotype is identical to the average half-life of serum IgG2a as previously determined (6-8 days; P. Vieira and K. Rajewsky, Eur. J. Immunol. 1986. 16:871). Therefore, the half-lives determined with monoclonal antibodies possessing the same V region represent the half-life of the serum immunoglobulins. In this way we calculated the half-life of IgM as 2 days, IgG3 and IgG1 as 6-8 days, IgG2b has a half-life of 4-6 days. IgE has a half-life of 12 h. A polymeric form of IgA was found to be eliminated from the serum with a half-life of 17-22 h.

Transient Water Vapor at Europa’s South Pole

Abstract: In November and December 2012 the Hubble Space Telescope (HST) imaged Europa’s ultraviolet emissions in the search for vapor plume activity. We report statistically significant coincident surpluses of hydrogen Lyman-α and oxygen OI130.4 nm emissions above the southern hemisphere in December 2012. These emissions are persistently found in the same area over ~7 hours, suggesting atmospheric inhomogeneity; they are consistent with two 200-km-high plumes of water vapor with line-of-sight column densities of about 1020 m−2. Nondetection in November and in previous HST images from 1999 suggests varying plume activity that might depend on changing surface stresses based on Europa’s orbital phases. The plume was present when Europa was near apocenter and not detected close to its pericenter, in agreement with tidal modeling predictions.